The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 14, 2009
Systemic injection of lipopolysaccharide (LPS) is a widely used model of immune/inflammatory chal... more Systemic injection of lipopolysaccharide (LPS) is a widely used model of immune/inflammatory challenge, which can invoke a host of CNS responses, including activation of the hypothalamic-pituitary-adrenal (HPA) axis. Inducible vascular prostaglandin E(2) (PGE(2)) synthesis by endothelial (ECs) and/or perivascular cells (PVCs) (a macrophage-derived vascular cell type) is implicated in the engagement of HPA and other CNS responses, by virtue of their capacity to express cyclooxygenase-2 (COX-2) and microsomal PGE(2) synthase-1. Evidence from genetic and pharmacologic studies also supports a role for the constitutively expressed COX-1 in inflammation-induced activation of the HPA axis, although histochemical evidence to support relevant localization(s) and regulation of COX-1 expression is lacking. The present experiments fill this void in showing that COX-1 immunoreactivity (IR) and mRNA are detectable in identified PVCs and parenchymal microglia under basal conditions and is robustly...
International Journal of Neuropsychopharmacology, 2004
The 5-HT1A/beta-adrenoceptor ligand (+/-)pindolol has been used in clinical trials to enhance the... more The 5-HT1A/beta-adrenoceptor ligand (+/-)pindolol has been used in clinical trials to enhance the antidepressant effect of selective serotonin (5-HT) reuptake inhibitors (SSRIs). The accelerating effect of (+/-)pindolol is thought to derive from its blockade of the SSRI-induced, 5-HT1A autoreceptor-mediated inhibition of serotonergic cell firing and 5-HT release. However, controversial results have been reported in regard to its ability to antagonize the effect of 5-HT at such receptors. In the present study, we have analysed the effect of (+/-)pindolol on receptor-mediated G-protein activation by measuring guanylyl 5'-[gamma-[35S]thio]-triphosphate ([35S]GTPgammaS) binding onto tissue sections from the hippocampus and dorsal raphe nucleus from rat, guinea pig and human brain. In these regions, enriched in 5-HT1A receptors, (+/-)pindolol antagonized the stimulation of [35S]GTPgammaS binding induced by 5-HT in a concentration-dependent manner. We found that in both rat and human brain the calculated pEC50 values were higher in the dorsal raphe nucleus than in hippocampus. This suggests a higher potency of (+/-)pindolol at somatodendritic 5-HT1A receptors compared to post-synaptic 5-HT1A sites. In the absence of 5-HT, (+/-)pindolol (up to 10(-3) M) did not modify [35S]GTPgammaS binding, which remained at basal levels, indicating that, in this assay, (+/-)pindolol acts as a neutral antagonist rather than a partial agonist as it has been observed in other experimental models. The present data are relevant for the understanding of the neurobiological basis of pindolol acceleration of the action of SSRI antidepressants.
International journal of molecular sciences, Jan 27, 2012
Multiple sclerosis (MS) is a devastating neurological disease that predominantly affects young ad... more Multiple sclerosis (MS) is a devastating neurological disease that predominantly affects young adults resulting in severe personal and economic impact. The majority of therapies for this disease were developed in, or are beneficial in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. While known to target adaptive anti-CNS immune responses, they also target, the innate immune arm. This mini-review focuses on the role of dendritic cells (DCs), the professional antigen presenting cells of the innate immune system. The evidence for a role for DCs in the appropriate regulation of anti-CNS autoimmune responses and their role in MS disease susceptibility and possible therapeutic utility are discussed. Additionally, the current controversy regarding the evidence for the presence of functional DCs in the normal CNS is reviewed. Furthermore, the role of CNS DCs and potential routes of their intercourse between the CNS and cervical lymph nodes are considered. Finally, t...
The molecular mechanisms involved in the reversion of levodopa-induced motor fluctuations by the ... more The molecular mechanisms involved in the reversion of levodopa-induced motor fluctuations by the adenosine A2A antagonist 8-(3-chlorostryryl) caffeine (CSC) were investigated in rats with a 6-hydroxydopamine (6-OHDA)-induced lesion and compared with the ones achieved by the kappa-opioid agonist, U50,488. Animals were treated with levodopa (50 mg/kg/day) for 22 days and for one additional week with levodopa + CSC (5 mg/kg/day), levodopa + U50,488 (1 mg/kg/day), or levodopa + vehicle. The reversion of the decrease in the duration of levodopa-induced rotations by CSC, but not by U50,488, was maintained until the end of the treatment and was associated with a further increase in levodopa-induced preprodynorphin mRNA in the lesioned striatum, being higher in the ventromedial striatum. The increase in striatal preprodynorphin expression, particularly in the ventromedial striatum, may be related to the reversion of levodopa-induced motor fluctuations in the CSC-treated animals, suggesting a role of the direct striatal output pathway activity in the ventromedial striatum in the pathophysiology of motor fluctuations.
We used double-label in situ hybridization to examine the cellular localization of 5-ht(5B) recep... more We used double-label in situ hybridization to examine the cellular localization of 5-ht(5B) receptor mRNA in relation to serotonin transporter mRNA in the rat dorsal raphe (DR) and central superior nucleus (CS, median raphe nucleus). 5-ht(5B) receptor mRNA hybridization signal was often found on serotonin transporter mRNA-positive neuron profiles. The degree of cellular colocalization of these mRNAs notably varied among the different regions of the raphe nuclei. In the DR, cell bodies showing 5-ht(5B) receptor mRNA expression were abundant in the medial portions of the nucleus, all of them being also labeled for serotonin transporter mRNA. In contrast, in the ventrolateral regions (lateral wings) of the DR, we observed serotonin transporter mRNA-positive cells, but they were devoid of 5-ht(5B) receptor mRNA signal. In the CS, the level of coexpression of 5-ht(5B) receptor mRNA with serotonin transporter mRNA was high in the intermediate portions of the nucleus; however, we were unable to detect specific 5-ht(5B) receptor mRNA hybridization signal in its caudal extent. Our results support the presence of 5-ht(5B) receptor in serotonergic neurons in the DR and CS, suggesting an autoreceptor role for this receptor subtype.
All phases of lipopolysaccharide (LPS)-induced fever are mediated by prostaglandin (PG) E2. It is... more All phases of lipopolysaccharide (LPS)-induced fever are mediated by prostaglandin (PG) E2. It is known that the second febrile phase (which starts at approximately 1.5 h post-LPS) and subsequent phases are mediated by PGE2 that originated in endotheliocytes and perivascular cells of the brain. However, the location and phenotypes of the cells that produce PGE2 triggering the first febrile phase (which starts at approximately 0.5 h) remain unknown. By studying PGE2 synthesis at the enzymatic level, we found that it was activated in the lung and liver, but not in the brain, at the onset of the first phase of LPS fever in rats. This activation involved phosphorylation of cytosolic phospholipase A2 (cPLA2) and transcriptional up-regulation of cyclooxygenase (COX)-2. The number of cells displaying COX-2 immunoreactivity surged in the lung and liver (but not in the brain) at the onset of fever, and the majority of these cells were identified as macrophages. When PGE2 synthesis in the periphery was activated, the concentration of PGE2 increased both in the venous blood (which collects PGE2 from tissues) and arterial blood (which delivers PGE2 to the brain). Most importantly, neutralization of circulating PGE2 with an anti-PGE2 antibody both delayed and attenuated LPS fever. It is concluded that fever is initiated by circulating PGE2 synthesized by macrophages of the LPS-processing organs (lung and liver) via phosphorylation of cPLA2 and transcriptional up-regulation of COX-2. Whether PGE2 produced at the level of the blood-brain barrier also contributes to the development of the first phase remains to be clarified.
Cytokines produced during infection/inflammation activate adaptive CNS responses, including acute... more Cytokines produced during infection/inflammation activate adaptive CNS responses, including acute stress responses mediated by the hypothalamo-pituitary-adrenal (HPA) axis. The mechanisms by which cytokines engage HPA control circuitry remain unclear, though stimulated release of prostanoids from neighboring vascular cells has been implicated in this regard. How specific vascular cell types, endothelial cells (ECs) vs. perivascular cells (PVCs; a subset of brainresident macrophages), participate in this response remains unsettled. We exploited the phagocytic activity of PVCs to deplete them in rats by central injection of a liposome-encapsulated proapoptotic drug. This manipulation abrogated CNS and hormonal indices of HPA activation under immune challenge conditions (interleukin-1; IL-1) that activated prostanoid synthesis only in PVCs, while enhancing these responses to stimuli (lipopolysaccaride; LPS) that engaged prostanoid production by ECs as well. Thus, PVCs provide both prostanoid-mediated drive to the HPA axis, and an anti-inflammatory action that constrains endothelial, and overall CNS, responses to inflammatory insults.
We have used double-label in situ hybridization techniques to examine the cellular localization o... more We have used double-label in situ hybridization techniques to examine the cellular localization of GABA B receptor mRNA in relation to serotonin transporter mRNA and glutamic acid decarboxylase mRNA in the rat dorsal raphe, median raphe and raphe magnus nuclei. The degree of cellular co-localization of these markers notably varied among the different nuclei. In the dorsal raphe, cell bodies showing GABA B receptor mRNA were very abundant, the 85% being also labelled for serotonin transporter mRNA, and a low proportion (5%) showing glutamic acid decarboxylase mRNA. In the median raphe, the level of co-expression of GABA B receptor mRNA with serotonin transporter mRNA was significantly lower. Some cells were also identified that contained GABA B receptor mRNA in the absence of either one of the other mRNA species studied. Our results support the presence of GABA B receptors in serotonergic as well as GABAergic neurones in the dorsal and median raphe, providing the anatomical basis for the reported dual inhibitory/disinhibitory effect of the GABA B agonist baclofen on serotonergic function.
Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that engages the immune system in ... more Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that engages the immune system in a T-lymphocyte-dependent manner and induces a cytokine profile distinct from that elicited by the better-studied bacterial pathogen analog, lipopolysaccharide (LPS). Because of reports of SEB recruiting central nervous system (CNS) host defense mechanisms via pathways in common with LPS, we sought to further characterize central systems impacted by this agent. Rats were treated with SEB at doses of 50 -5,000 g/kg, and killed 0.5-6 hours thereafter. SEB injection produced a discrete pattern of Fos induction in brain that peaked at 2-3 hours postinjection and whose strength was dose-related. Induced Fos expression was predominantly subcortical and focused in a set of interconnected central autonomic structures, including aspects of the bed n. of the stria terminalis, central amygdala and lateral parabrachial nuclei; functionally related (and LPS-responsive) cell groups in the n. solitary tract, ventrolateral medulla, and paraventricular hypothalamic n. (PVH) were, by contrast, weakly responsive. SEB also activated cell groups in the limbic forebrain (lateral septal n, medial prefrontal cortex) and hypothalamic GABAergic neurons, which could account for its failure to elicit reliable increases in Fos-ir or corticotropin-releasing factor (CRF) mRNA in the PVH. SEB nevertheless did provoke reliable pituitary-adrenal secretory responses. The identification of subsets of central autonomic and limbic forebrain structures that are sensitive to SEB provides a basis for a systems-level understanding of the physiological and behavioral effects attributed to the superantigen. Core SEBresponsive cell groups exclude a medullary-PVH circuit implicated in pituitary-adrenal responses to LPS.
We have used double in situ hybridization to examine the cellular localization of 5-HT 2C recepto... more We have used double in situ hybridization to examine the cellular localization of 5-HT 2C receptor mRNA in relation to serotonergic and GABAergic neurons in the anterior raphe nuclei of the rat. In the dorsal and median raphe nuclei 5-HT 2C receptor mRNA was not detected in serotonergic cells identified as those expressing serotonin (5-HT) transporter mRNA. In contrast, 5-HT 2C receptor mRNA was found in most GABAergic cells, recognized by the presence of glutamic acid decarboxylase mRNA. Such 5-HT 2C receptor-positive GABAergic neurons were mainly located in the intermediolateral and lateral portions of the dorsal raphe and lateral part of the median raphe. The present data give anatomical support to a previous hypothesis that proposed a negative-feedback loop involving reciprocal connections between GABAergic interneurons bearing 5-HT 2A/2C receptors and 5-HT neurons in the dorsal raphe and surrounding areas. According to this model, the excitation of GABAergic interneurons through these 5-HT 2C (and also 5-HT 2A ) receptors would result in the suppression of 5-HT cell firing. #
Inflammation is associated with increased sympathetic drive in cardiovascular diseases. Blood-bor... more Inflammation is associated with increased sympathetic drive in cardiovascular diseases. Blood-borne proinflammatory cytokines, markers of inflammation, induce cyclooxygenase 2 (COX-2) activity in perivascular macrophages of the blood-brain barrier. COX-2 generates prostaglandin E(2), which may enter the brain and increase sympathetic nerve activity. We examined the contribution of this mechanism to augmented sympathetic drive in rats after myocardial infarction (MI). Approximately 24 hours after acute MI, rats received an intracerebroventricular injection (1 microL/min over 40 minutes) of clodronate liposomes (MI+CLOD) to eliminate brain perivascular macrophages, liposomes alone, or artificial cerebrospinal fluid. A week later, COX-2 immunoreactivity in perivascular macrophages and COX-2 mRNA and protein had increased in hypothalamic paraventricular nucleus of MI rats treated with artificial cerebrospinal fluid or liposomes alone compared with sham-operated rats. In MI+CLOD rats, ne...
Several observations support the hypothesis that kappa opioid (n-opioid) receptor agonism may con... more Several observations support the hypothesis that kappa opioid (n-opioid) receptor agonism may contribute to neurotoxicity, but other reports have suggested that certain n-agonists can attenuate neurological dysfunction. Degeneration of dopaminergic neurons in the substantia nigra is the pathological hallmark of Parkinson's disease. Therefore, it is of particular interest to study whether n-opioid receptor agonism has an influence on the progressive degeneration of dopaminergic neurons. We have investigated the effect exerted by the selective n-agonist U50,488 on the neurotoxicity induced by intrastriatal 6-hydroxydopamine (6-OHDA) administration on dopaminergic neurons.
In Parkinson's disease (PD), the striatal dopamine depletion and the following overactivation of ... more In Parkinson's disease (PD), the striatal dopamine depletion and the following overactivation of the indirect pathway of the basal ganglia leads to very early disinhibition of the subthalamic nucleus (STN) that may contribute to the progression of PD by glutamatergic overstimulation of the dopaminergic neurons in the substantia nigra. Adenosine A 2A antagonism has been demonstrated to attenuate the overactivity of the striatopallidal pathway. To investigate whether neuroprotection exerted by the A 2A antagonist 8-(3-chlorostyryl)caffeine (CSC) correlates with a diminution of the striatopallidal pathway activity, we have examined the changes in the mRNA encoding for enkephalin, dynorphin, and adenosine A 2A receptors by in situ hybridization induced by subacute systemic pretreatment with CSC in rats with striatal 6-hydroxydopamine(6-OHDA) administration. Animals received CSC for 7 days until 30 min before 6-OHDA intrastriatal administration. Vehicle-treated group received a solution of dimethyl sulfoxide. CSC pretreatment partially attenuated the decrease in nigral tyrosine hydroxylase immunoreactivity induced by 6-OHDA, whereas no modification of the increase in preproenkephalin mRNA expression in the dorsolateral striatum was observed. The neuroprotective effect of the adenosine A 2A antagonist CSC in striatal 6-OHDA-lesioned rats does not result from a normalization of the increase in striatal PPE mRNA expression in the DL striatum, suggesting that other different mechanisms may be involved.
In the rat, postsynaptic 5-hydroxytryptamine 2A receptors medial prefrontal cortex control the ac... more In the rat, postsynaptic 5-hydroxytryptamine 2A receptors medial prefrontal cortex control the activity of the serotonergic system through changes in the activity of pyramidal neurons projecting to the dorsal raphe nucleus. Here we extend these observations to mouse brain. The prefrontal cortex expresses abundant 5-hydroxytryptamine 2A receptors, as assessed by immunohistochemistry, Western blots and in situ hybridization procedures. The application of the 5-hydroxytryptamine 2A/2C agonist DOI (100 mM) by reverse dialysis in the medial prefrontal cortex doubled the local release of 5-hydroxytryptamine. This effect was reversed by coperfusion of tetrodotoxin, and by the selective 5-hydroxytryptamine 2A receptor antagonist M100907, but not by the 5-hydroxytryptamine 2C antagonist SB-242084. The effect of DOI was also reversed by prazosin (a 1 -adrenoceptor antagonist), BAY Â 3702 (5-hydroxytryptamine 1A receptor agonist), NBQX (a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate/kainic acid antagonist) and 1S,3S-ACPD (mGluR II/III agonist), but not by dizocilpine (N-methyl-D-aspartate antagonist). a-Amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate mimicked the 5-hydroxytryptamine elevation produced by DOI, an effect also reversed by BAY Â 3702. Likewise, the coperfusion of classical (chlorpromazine, haloperidol) and atypical antipsychotic drugs (clozapine, olanzapine) fully reversed the 5-hydroxytryptamine elevation induced by DOI. These observations suggest that DOI increases 5-hydroxytryptamine release in the mouse medial prefrontal cortex through the activation of local 5-hydroxytryptamine 2A receptors by an impulse-dependent mechanism that involves/requires the activation of local a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate receptors. This effect is reversed by ligands of receptors present in the medial prefrontal cortex, possibly in pyramidal neurons, which are involved in the action of antipsychotic drugs. In particular, the reversal by classical antipsychotics may involve blockade of a 1 -adrenoceptors, whereas that of atypical antipsychotics may involve 5-hydroxytryptamine 2A receptors and a 1 -adrenoceptors. 2003) and involve a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate (AMPA)-mediated glutamatergic inputs (Martõ Ân-Ruiz et al.
Serotonergic 5-HT 1A and 5-HT 2A receptors are abundantly expressed in prefrontal cortex (PFC) an... more Serotonergic 5-HT 1A and 5-HT 2A receptors are abundantly expressed in prefrontal cortex (PFC) and are targets of atypical antipsychotic drugs. They mediate, respectively, inhibitory and excitatory actions of 5-HT. The transcripts for both receptors are largely (∼80%) colocalized in rat and mouse PFC, yet their quantitative distribution in pyramidal and GABAergic interneurons is unknown. We used double in situ hybridization histochemistry to estimate the proportion of pyramidal and GABAergic neurons expressing these receptor transcripts in rat PFC. The number of GABAergic interneurons (expressing GAD mRNA) was a 22% of glutamatergic neurons (expressing vGluT1 mRNA, considered as putative pyramidal neurons). 5-HT 2A receptor mRNA was present in a large percentage of pyramidal neurons (from 55% in prelimbic cortex to 88% in tenia tecta), except in layer VI, where it was localized only in 30% of those neurons. 5-HT 2A receptor mRNA was present in ∼25% of GADcontaining cells except in layer VI (10%). Likewise, ∼60% of glutamatergic cells contained the 5-HT 1A receptor transcript. We also found that ∼25% of GAD-expressing cells contained the 5-HT 1A receptor mRNA. These data help to clarify the role of 5-HT in prefrontal circuits and shed new light to the cellular elements involved in the action of atypical antipsychotics.
The prefrontal cortex plays a key role in the control of higher brain functions and is involved i... more The prefrontal cortex plays a key role in the control of higher brain functions and is involved in the pathophysiology and treatment of schizophrenia. Here we report that ∼60% of the neurons in rat and mouse prefrontal cortex express 5-HT 1A and/or 5-HT 2A receptor mRNAs, which are highly co-localized (∼80%). The electrical stimulation of the dorsal and median raphe nuclei elicited 5-HT 1A -mediated inhibitions and 5-HT 2A -mediated excitations in identified pyramidal neurons recorded extracellularly in rat medial prefrontal cortex (mPFC). Opposite responses in the same pyramidal neuron could be evoked by stimulating the raphe nuclei at different coordinates, suggesting a precise connectivity between 5-HT neuronal subgroups and 5-HT 1A and 5-HT 2A receptors in pyramidal neurons. Microdialysis experiments showed that the increase in local 5-HT release evoked by the activation of 5-HT 2A receptors in mPFC by DOI (5-HT 2A/2C receptor agonist) was reversed by co-perfusion of 5-HT 1A agonists. This inhibitory effect was antagonized by WAY-100635 and the prior inactivation of 5-HT 1A receptors in rats and was absent in mice lacking 5-HT 1A receptors. These observations help to clarify the interactions between the mPFC and the raphe nuclei, two key areas in psychiatric illnesses and improve our understanding of the action of atypical antipsychotics, acting through these 5-HT receptors. Drugs 5-HT oxalate, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), alpha-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate [(S)-AMPA], buspirone, cirazoline, DOI, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), mianserin, pargyline, pertussis toxin, ritanserin and N-[2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl]-N-(2-pyridyl) cyclohexane carboxamide·3HCl (WAY-100635) were from Sigma/RBI (Natick, MA). Alnespirone (S-20499) was from Institut de Recherches Internationales Servier. R-(-)-2-{4-[(chroman-2-ylmethyl)-amino]-butyl}-1,1-dioxo-benzo[d]isothiazolone·HCl (BAY × 3702)and ipsapirone were from Bayer AG. Citalopram·HBr was from Lundbeck A/S and R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[4-fluorophenylethyl]-4-piperidinemethanol (M100907; Lilly code LY 368675) and fluoxetine were from Eli Lilly & Co.
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 14, 2009
Systemic injection of lipopolysaccharide (LPS) is a widely used model of immune/inflammatory chal... more Systemic injection of lipopolysaccharide (LPS) is a widely used model of immune/inflammatory challenge, which can invoke a host of CNS responses, including activation of the hypothalamic-pituitary-adrenal (HPA) axis. Inducible vascular prostaglandin E(2) (PGE(2)) synthesis by endothelial (ECs) and/or perivascular cells (PVCs) (a macrophage-derived vascular cell type) is implicated in the engagement of HPA and other CNS responses, by virtue of their capacity to express cyclooxygenase-2 (COX-2) and microsomal PGE(2) synthase-1. Evidence from genetic and pharmacologic studies also supports a role for the constitutively expressed COX-1 in inflammation-induced activation of the HPA axis, although histochemical evidence to support relevant localization(s) and regulation of COX-1 expression is lacking. The present experiments fill this void in showing that COX-1 immunoreactivity (IR) and mRNA are detectable in identified PVCs and parenchymal microglia under basal conditions and is robustly...
International Journal of Neuropsychopharmacology, 2004
The 5-HT1A/beta-adrenoceptor ligand (+/-)pindolol has been used in clinical trials to enhance the... more The 5-HT1A/beta-adrenoceptor ligand (+/-)pindolol has been used in clinical trials to enhance the antidepressant effect of selective serotonin (5-HT) reuptake inhibitors (SSRIs). The accelerating effect of (+/-)pindolol is thought to derive from its blockade of the SSRI-induced, 5-HT1A autoreceptor-mediated inhibition of serotonergic cell firing and 5-HT release. However, controversial results have been reported in regard to its ability to antagonize the effect of 5-HT at such receptors. In the present study, we have analysed the effect of (+/-)pindolol on receptor-mediated G-protein activation by measuring guanylyl 5'-[gamma-[35S]thio]-triphosphate ([35S]GTPgammaS) binding onto tissue sections from the hippocampus and dorsal raphe nucleus from rat, guinea pig and human brain. In these regions, enriched in 5-HT1A receptors, (+/-)pindolol antagonized the stimulation of [35S]GTPgammaS binding induced by 5-HT in a concentration-dependent manner. We found that in both rat and human brain the calculated pEC50 values were higher in the dorsal raphe nucleus than in hippocampus. This suggests a higher potency of (+/-)pindolol at somatodendritic 5-HT1A receptors compared to post-synaptic 5-HT1A sites. In the absence of 5-HT, (+/-)pindolol (up to 10(-3) M) did not modify [35S]GTPgammaS binding, which remained at basal levels, indicating that, in this assay, (+/-)pindolol acts as a neutral antagonist rather than a partial agonist as it has been observed in other experimental models. The present data are relevant for the understanding of the neurobiological basis of pindolol acceleration of the action of SSRI antidepressants.
International journal of molecular sciences, Jan 27, 2012
Multiple sclerosis (MS) is a devastating neurological disease that predominantly affects young ad... more Multiple sclerosis (MS) is a devastating neurological disease that predominantly affects young adults resulting in severe personal and economic impact. The majority of therapies for this disease were developed in, or are beneficial in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. While known to target adaptive anti-CNS immune responses, they also target, the innate immune arm. This mini-review focuses on the role of dendritic cells (DCs), the professional antigen presenting cells of the innate immune system. The evidence for a role for DCs in the appropriate regulation of anti-CNS autoimmune responses and their role in MS disease susceptibility and possible therapeutic utility are discussed. Additionally, the current controversy regarding the evidence for the presence of functional DCs in the normal CNS is reviewed. Furthermore, the role of CNS DCs and potential routes of their intercourse between the CNS and cervical lymph nodes are considered. Finally, t...
The molecular mechanisms involved in the reversion of levodopa-induced motor fluctuations by the ... more The molecular mechanisms involved in the reversion of levodopa-induced motor fluctuations by the adenosine A2A antagonist 8-(3-chlorostryryl) caffeine (CSC) were investigated in rats with a 6-hydroxydopamine (6-OHDA)-induced lesion and compared with the ones achieved by the kappa-opioid agonist, U50,488. Animals were treated with levodopa (50 mg/kg/day) for 22 days and for one additional week with levodopa + CSC (5 mg/kg/day), levodopa + U50,488 (1 mg/kg/day), or levodopa + vehicle. The reversion of the decrease in the duration of levodopa-induced rotations by CSC, but not by U50,488, was maintained until the end of the treatment and was associated with a further increase in levodopa-induced preprodynorphin mRNA in the lesioned striatum, being higher in the ventromedial striatum. The increase in striatal preprodynorphin expression, particularly in the ventromedial striatum, may be related to the reversion of levodopa-induced motor fluctuations in the CSC-treated animals, suggesting a role of the direct striatal output pathway activity in the ventromedial striatum in the pathophysiology of motor fluctuations.
We used double-label in situ hybridization to examine the cellular localization of 5-ht(5B) recep... more We used double-label in situ hybridization to examine the cellular localization of 5-ht(5B) receptor mRNA in relation to serotonin transporter mRNA in the rat dorsal raphe (DR) and central superior nucleus (CS, median raphe nucleus). 5-ht(5B) receptor mRNA hybridization signal was often found on serotonin transporter mRNA-positive neuron profiles. The degree of cellular colocalization of these mRNAs notably varied among the different regions of the raphe nuclei. In the DR, cell bodies showing 5-ht(5B) receptor mRNA expression were abundant in the medial portions of the nucleus, all of them being also labeled for serotonin transporter mRNA. In contrast, in the ventrolateral regions (lateral wings) of the DR, we observed serotonin transporter mRNA-positive cells, but they were devoid of 5-ht(5B) receptor mRNA signal. In the CS, the level of coexpression of 5-ht(5B) receptor mRNA with serotonin transporter mRNA was high in the intermediate portions of the nucleus; however, we were unable to detect specific 5-ht(5B) receptor mRNA hybridization signal in its caudal extent. Our results support the presence of 5-ht(5B) receptor in serotonergic neurons in the DR and CS, suggesting an autoreceptor role for this receptor subtype.
All phases of lipopolysaccharide (LPS)-induced fever are mediated by prostaglandin (PG) E2. It is... more All phases of lipopolysaccharide (LPS)-induced fever are mediated by prostaglandin (PG) E2. It is known that the second febrile phase (which starts at approximately 1.5 h post-LPS) and subsequent phases are mediated by PGE2 that originated in endotheliocytes and perivascular cells of the brain. However, the location and phenotypes of the cells that produce PGE2 triggering the first febrile phase (which starts at approximately 0.5 h) remain unknown. By studying PGE2 synthesis at the enzymatic level, we found that it was activated in the lung and liver, but not in the brain, at the onset of the first phase of LPS fever in rats. This activation involved phosphorylation of cytosolic phospholipase A2 (cPLA2) and transcriptional up-regulation of cyclooxygenase (COX)-2. The number of cells displaying COX-2 immunoreactivity surged in the lung and liver (but not in the brain) at the onset of fever, and the majority of these cells were identified as macrophages. When PGE2 synthesis in the periphery was activated, the concentration of PGE2 increased both in the venous blood (which collects PGE2 from tissues) and arterial blood (which delivers PGE2 to the brain). Most importantly, neutralization of circulating PGE2 with an anti-PGE2 antibody both delayed and attenuated LPS fever. It is concluded that fever is initiated by circulating PGE2 synthesized by macrophages of the LPS-processing organs (lung and liver) via phosphorylation of cPLA2 and transcriptional up-regulation of COX-2. Whether PGE2 produced at the level of the blood-brain barrier also contributes to the development of the first phase remains to be clarified.
Cytokines produced during infection/inflammation activate adaptive CNS responses, including acute... more Cytokines produced during infection/inflammation activate adaptive CNS responses, including acute stress responses mediated by the hypothalamo-pituitary-adrenal (HPA) axis. The mechanisms by which cytokines engage HPA control circuitry remain unclear, though stimulated release of prostanoids from neighboring vascular cells has been implicated in this regard. How specific vascular cell types, endothelial cells (ECs) vs. perivascular cells (PVCs; a subset of brainresident macrophages), participate in this response remains unsettled. We exploited the phagocytic activity of PVCs to deplete them in rats by central injection of a liposome-encapsulated proapoptotic drug. This manipulation abrogated CNS and hormonal indices of HPA activation under immune challenge conditions (interleukin-1; IL-1) that activated prostanoid synthesis only in PVCs, while enhancing these responses to stimuli (lipopolysaccaride; LPS) that engaged prostanoid production by ECs as well. Thus, PVCs provide both prostanoid-mediated drive to the HPA axis, and an anti-inflammatory action that constrains endothelial, and overall CNS, responses to inflammatory insults.
We have used double-label in situ hybridization techniques to examine the cellular localization o... more We have used double-label in situ hybridization techniques to examine the cellular localization of GABA B receptor mRNA in relation to serotonin transporter mRNA and glutamic acid decarboxylase mRNA in the rat dorsal raphe, median raphe and raphe magnus nuclei. The degree of cellular co-localization of these markers notably varied among the different nuclei. In the dorsal raphe, cell bodies showing GABA B receptor mRNA were very abundant, the 85% being also labelled for serotonin transporter mRNA, and a low proportion (5%) showing glutamic acid decarboxylase mRNA. In the median raphe, the level of co-expression of GABA B receptor mRNA with serotonin transporter mRNA was significantly lower. Some cells were also identified that contained GABA B receptor mRNA in the absence of either one of the other mRNA species studied. Our results support the presence of GABA B receptors in serotonergic as well as GABAergic neurones in the dorsal and median raphe, providing the anatomical basis for the reported dual inhibitory/disinhibitory effect of the GABA B agonist baclofen on serotonergic function.
Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that engages the immune system in ... more Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that engages the immune system in a T-lymphocyte-dependent manner and induces a cytokine profile distinct from that elicited by the better-studied bacterial pathogen analog, lipopolysaccharide (LPS). Because of reports of SEB recruiting central nervous system (CNS) host defense mechanisms via pathways in common with LPS, we sought to further characterize central systems impacted by this agent. Rats were treated with SEB at doses of 50 -5,000 g/kg, and killed 0.5-6 hours thereafter. SEB injection produced a discrete pattern of Fos induction in brain that peaked at 2-3 hours postinjection and whose strength was dose-related. Induced Fos expression was predominantly subcortical and focused in a set of interconnected central autonomic structures, including aspects of the bed n. of the stria terminalis, central amygdala and lateral parabrachial nuclei; functionally related (and LPS-responsive) cell groups in the n. solitary tract, ventrolateral medulla, and paraventricular hypothalamic n. (PVH) were, by contrast, weakly responsive. SEB also activated cell groups in the limbic forebrain (lateral septal n, medial prefrontal cortex) and hypothalamic GABAergic neurons, which could account for its failure to elicit reliable increases in Fos-ir or corticotropin-releasing factor (CRF) mRNA in the PVH. SEB nevertheless did provoke reliable pituitary-adrenal secretory responses. The identification of subsets of central autonomic and limbic forebrain structures that are sensitive to SEB provides a basis for a systems-level understanding of the physiological and behavioral effects attributed to the superantigen. Core SEBresponsive cell groups exclude a medullary-PVH circuit implicated in pituitary-adrenal responses to LPS.
We have used double in situ hybridization to examine the cellular localization of 5-HT 2C recepto... more We have used double in situ hybridization to examine the cellular localization of 5-HT 2C receptor mRNA in relation to serotonergic and GABAergic neurons in the anterior raphe nuclei of the rat. In the dorsal and median raphe nuclei 5-HT 2C receptor mRNA was not detected in serotonergic cells identified as those expressing serotonin (5-HT) transporter mRNA. In contrast, 5-HT 2C receptor mRNA was found in most GABAergic cells, recognized by the presence of glutamic acid decarboxylase mRNA. Such 5-HT 2C receptor-positive GABAergic neurons were mainly located in the intermediolateral and lateral portions of the dorsal raphe and lateral part of the median raphe. The present data give anatomical support to a previous hypothesis that proposed a negative-feedback loop involving reciprocal connections between GABAergic interneurons bearing 5-HT 2A/2C receptors and 5-HT neurons in the dorsal raphe and surrounding areas. According to this model, the excitation of GABAergic interneurons through these 5-HT 2C (and also 5-HT 2A ) receptors would result in the suppression of 5-HT cell firing. #
Inflammation is associated with increased sympathetic drive in cardiovascular diseases. Blood-bor... more Inflammation is associated with increased sympathetic drive in cardiovascular diseases. Blood-borne proinflammatory cytokines, markers of inflammation, induce cyclooxygenase 2 (COX-2) activity in perivascular macrophages of the blood-brain barrier. COX-2 generates prostaglandin E(2), which may enter the brain and increase sympathetic nerve activity. We examined the contribution of this mechanism to augmented sympathetic drive in rats after myocardial infarction (MI). Approximately 24 hours after acute MI, rats received an intracerebroventricular injection (1 microL/min over 40 minutes) of clodronate liposomes (MI+CLOD) to eliminate brain perivascular macrophages, liposomes alone, or artificial cerebrospinal fluid. A week later, COX-2 immunoreactivity in perivascular macrophages and COX-2 mRNA and protein had increased in hypothalamic paraventricular nucleus of MI rats treated with artificial cerebrospinal fluid or liposomes alone compared with sham-operated rats. In MI+CLOD rats, ne...
Several observations support the hypothesis that kappa opioid (n-opioid) receptor agonism may con... more Several observations support the hypothesis that kappa opioid (n-opioid) receptor agonism may contribute to neurotoxicity, but other reports have suggested that certain n-agonists can attenuate neurological dysfunction. Degeneration of dopaminergic neurons in the substantia nigra is the pathological hallmark of Parkinson's disease. Therefore, it is of particular interest to study whether n-opioid receptor agonism has an influence on the progressive degeneration of dopaminergic neurons. We have investigated the effect exerted by the selective n-agonist U50,488 on the neurotoxicity induced by intrastriatal 6-hydroxydopamine (6-OHDA) administration on dopaminergic neurons.
In Parkinson's disease (PD), the striatal dopamine depletion and the following overactivation of ... more In Parkinson's disease (PD), the striatal dopamine depletion and the following overactivation of the indirect pathway of the basal ganglia leads to very early disinhibition of the subthalamic nucleus (STN) that may contribute to the progression of PD by glutamatergic overstimulation of the dopaminergic neurons in the substantia nigra. Adenosine A 2A antagonism has been demonstrated to attenuate the overactivity of the striatopallidal pathway. To investigate whether neuroprotection exerted by the A 2A antagonist 8-(3-chlorostyryl)caffeine (CSC) correlates with a diminution of the striatopallidal pathway activity, we have examined the changes in the mRNA encoding for enkephalin, dynorphin, and adenosine A 2A receptors by in situ hybridization induced by subacute systemic pretreatment with CSC in rats with striatal 6-hydroxydopamine(6-OHDA) administration. Animals received CSC for 7 days until 30 min before 6-OHDA intrastriatal administration. Vehicle-treated group received a solution of dimethyl sulfoxide. CSC pretreatment partially attenuated the decrease in nigral tyrosine hydroxylase immunoreactivity induced by 6-OHDA, whereas no modification of the increase in preproenkephalin mRNA expression in the dorsolateral striatum was observed. The neuroprotective effect of the adenosine A 2A antagonist CSC in striatal 6-OHDA-lesioned rats does not result from a normalization of the increase in striatal PPE mRNA expression in the DL striatum, suggesting that other different mechanisms may be involved.
In the rat, postsynaptic 5-hydroxytryptamine 2A receptors medial prefrontal cortex control the ac... more In the rat, postsynaptic 5-hydroxytryptamine 2A receptors medial prefrontal cortex control the activity of the serotonergic system through changes in the activity of pyramidal neurons projecting to the dorsal raphe nucleus. Here we extend these observations to mouse brain. The prefrontal cortex expresses abundant 5-hydroxytryptamine 2A receptors, as assessed by immunohistochemistry, Western blots and in situ hybridization procedures. The application of the 5-hydroxytryptamine 2A/2C agonist DOI (100 mM) by reverse dialysis in the medial prefrontal cortex doubled the local release of 5-hydroxytryptamine. This effect was reversed by coperfusion of tetrodotoxin, and by the selective 5-hydroxytryptamine 2A receptor antagonist M100907, but not by the 5-hydroxytryptamine 2C antagonist SB-242084. The effect of DOI was also reversed by prazosin (a 1 -adrenoceptor antagonist), BAY Â 3702 (5-hydroxytryptamine 1A receptor agonist), NBQX (a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate/kainic acid antagonist) and 1S,3S-ACPD (mGluR II/III agonist), but not by dizocilpine (N-methyl-D-aspartate antagonist). a-Amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate mimicked the 5-hydroxytryptamine elevation produced by DOI, an effect also reversed by BAY Â 3702. Likewise, the coperfusion of classical (chlorpromazine, haloperidol) and atypical antipsychotic drugs (clozapine, olanzapine) fully reversed the 5-hydroxytryptamine elevation induced by DOI. These observations suggest that DOI increases 5-hydroxytryptamine release in the mouse medial prefrontal cortex through the activation of local 5-hydroxytryptamine 2A receptors by an impulse-dependent mechanism that involves/requires the activation of local a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate receptors. This effect is reversed by ligands of receptors present in the medial prefrontal cortex, possibly in pyramidal neurons, which are involved in the action of antipsychotic drugs. In particular, the reversal by classical antipsychotics may involve blockade of a 1 -adrenoceptors, whereas that of atypical antipsychotics may involve 5-hydroxytryptamine 2A receptors and a 1 -adrenoceptors. 2003) and involve a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate (AMPA)-mediated glutamatergic inputs (Martõ Ân-Ruiz et al.
Serotonergic 5-HT 1A and 5-HT 2A receptors are abundantly expressed in prefrontal cortex (PFC) an... more Serotonergic 5-HT 1A and 5-HT 2A receptors are abundantly expressed in prefrontal cortex (PFC) and are targets of atypical antipsychotic drugs. They mediate, respectively, inhibitory and excitatory actions of 5-HT. The transcripts for both receptors are largely (∼80%) colocalized in rat and mouse PFC, yet their quantitative distribution in pyramidal and GABAergic interneurons is unknown. We used double in situ hybridization histochemistry to estimate the proportion of pyramidal and GABAergic neurons expressing these receptor transcripts in rat PFC. The number of GABAergic interneurons (expressing GAD mRNA) was a 22% of glutamatergic neurons (expressing vGluT1 mRNA, considered as putative pyramidal neurons). 5-HT 2A receptor mRNA was present in a large percentage of pyramidal neurons (from 55% in prelimbic cortex to 88% in tenia tecta), except in layer VI, where it was localized only in 30% of those neurons. 5-HT 2A receptor mRNA was present in ∼25% of GADcontaining cells except in layer VI (10%). Likewise, ∼60% of glutamatergic cells contained the 5-HT 1A receptor transcript. We also found that ∼25% of GAD-expressing cells contained the 5-HT 1A receptor mRNA. These data help to clarify the role of 5-HT in prefrontal circuits and shed new light to the cellular elements involved in the action of atypical antipsychotics.
The prefrontal cortex plays a key role in the control of higher brain functions and is involved i... more The prefrontal cortex plays a key role in the control of higher brain functions and is involved in the pathophysiology and treatment of schizophrenia. Here we report that ∼60% of the neurons in rat and mouse prefrontal cortex express 5-HT 1A and/or 5-HT 2A receptor mRNAs, which are highly co-localized (∼80%). The electrical stimulation of the dorsal and median raphe nuclei elicited 5-HT 1A -mediated inhibitions and 5-HT 2A -mediated excitations in identified pyramidal neurons recorded extracellularly in rat medial prefrontal cortex (mPFC). Opposite responses in the same pyramidal neuron could be evoked by stimulating the raphe nuclei at different coordinates, suggesting a precise connectivity between 5-HT neuronal subgroups and 5-HT 1A and 5-HT 2A receptors in pyramidal neurons. Microdialysis experiments showed that the increase in local 5-HT release evoked by the activation of 5-HT 2A receptors in mPFC by DOI (5-HT 2A/2C receptor agonist) was reversed by co-perfusion of 5-HT 1A agonists. This inhibitory effect was antagonized by WAY-100635 and the prior inactivation of 5-HT 1A receptors in rats and was absent in mice lacking 5-HT 1A receptors. These observations help to clarify the interactions between the mPFC and the raphe nuclei, two key areas in psychiatric illnesses and improve our understanding of the action of atypical antipsychotics, acting through these 5-HT receptors. Drugs 5-HT oxalate, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), alpha-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionate [(S)-AMPA], buspirone, cirazoline, DOI, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), mianserin, pargyline, pertussis toxin, ritanserin and N-[2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl]-N-(2-pyridyl) cyclohexane carboxamide·3HCl (WAY-100635) were from Sigma/RBI (Natick, MA). Alnespirone (S-20499) was from Institut de Recherches Internationales Servier. R-(-)-2-{4-[(chroman-2-ylmethyl)-amino]-butyl}-1,1-dioxo-benzo[d]isothiazolone·HCl (BAY × 3702)and ipsapirone were from Bayer AG. Citalopram·HBr was from Lundbeck A/S and R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[4-fluorophenylethyl]-4-piperidinemethanol (M100907; Lilly code LY 368675) and fluoxetine were from Eli Lilly & Co.
Uploads
Papers by Jordi Serrats