Papers by Robert Aronstam
PloS one, 2016
Cell-penetrating peptides (CPPs) have been shown to deliver cargos, including protein, DNA, RNA, ... more Cell-penetrating peptides (CPPs) have been shown to deliver cargos, including protein, DNA, RNA, and nanomaterials, in fully active forms into live cells. Most of the CPP sequences in use today are based on non-native proteins that may be immunogenic. Here we demonstrate that the L5a CPP (RRWQW) from bovine lactoferricin (LFcin), stably and noncovalently complexed with plasmid DNA and prepared at an optimal nitrogen/phosphate ratio of 12, is able to efficiently enter into human lung cancer A549 cells. The L5a CPP delivered a plasmid containing the enhanced green fluorescent protein (EGFP) coding sequence that was subsequently expressed in cells, as revealed by real-time PCR and fluorescent microscopy at the mRNA and protein levels, respectively. Treatment with calcium chloride increased the level of gene expression, without affecting CPP-mediated transfection efficiency. Zeta-potential analysis revealed that positively electrostatic interactions of CPP/DNA complexes correlated with ...
Pharmacology Biochemistry and Behavior, Nov 30, 1986
Selective anta.eolzi.sm by clonidine ~/'the stereotyped and mm-stereotyp~'d motor a ('tivitv eli(... more Selective anta.eolzi.sm by clonidine ~/'the stereotyped and mm-stereotyp~'d motor a ('tivitv eli('ited by atropine. PHARMACOL BIOCHEM BEHAV 25(5) 985-988, 1986.--The effects of clonidine, an indirectly-acting cholinergic antagonist, on 5 behaviors elicited by atropine (locomotion, rearing, sniffing, grooming and gnawing) were studied in rats. Clonidine did not alter the prevalence or magnitude of atropineelicited locomotion and rearing. In contrast, clonidine suppressed the occurrence and degree of 3 stereotyped behaviors, namely, sniffing, grooming and gnawing. This selectivity of clonidine suggests differences in the neural pathways subserving the various stereotyped motor activities.
The Journal of Pharmacology and Experimental Therapeutics, Oct 1, 1986
Mice pretreated with the centrally active alpha-2 adrenergic agonist, clonidine, were protected f... more Mice pretreated with the centrally active alpha-2 adrenergic agonist, clonidine, were protected from several of the toxic manifestations of soman, an organophosphate acetylcholinesterase inhibitor. The protection resulted in increased survival rates and a reduction in centrally mediated symptoms of soman, including tremor and straub tail, as well as one peripheral muscarinic symptom, excessive salivation. Doses of clonidine between 0.1 and 1 mg/kg, administered between 5 and 40 min before LD80 to LD90 doses of soman, produced significant protection. Pretreatment with atropine (25 mg/kg) also protected against soman toxicity. When atropine was combined with clonidine, the degree of protection afforded by the combination was greater than that predicted for a simple additive effect. Mice protected by atropine from the initial toxicity of soman frequently died within 24 h; no such delayed lethality was observed with protective doses of clonidine. Clonidine noncompetitively inhibited acetylcholinesterase activity in vitro and after in vivo administration at protective doses. At brain concentrations obtained after in vivo administration in protective doses, clonidine also inhibited ligand binding to cortical muscarinic receptors in vitro. The protective effects of clonidine are likely to involve multiple effects, including blockade of acetylcholine release and postsynaptic muscarinic receptors and transient inhibition of acetylcholinesterase.
Molecular Pharmacology, Mar 1, 1979
Molecular Pharmacology
Several microtubule-active drugs block cholinergically mediated catecholamine secretion from adre... more Several microtubule-active drugs block cholinergically mediated catecholamine secretion from adrenal chromaffin cells without affecting secretion induced by other secretagogues. Interactions of these agents with nicotinic acetylcholine receptor-ion channel complexes from Torpedo californica electric organs were studied using radiolabeled probes for receptor and associated ion channel-binding sites. Colchicine, taxol, and the Vinca alkaloids had minimal affinity for cholinergic receptor-binding sites (nicotinic or muscarinic). The Vinca alkaloids (vinblastine, vincristine, vindesine) and colchicine inhibited [3H]perhydrohistrionicotoxin ([3H]H12-HTX) binding to the receptor-gated ion channel with IC50 values of 2-32 microM and 6 mM, respectively. The ability of the microtubule-active drugs to inhibit [3H]H12-HTX binding was increased by up to 5-fold in the presence of 1 microM carbamylcholine. The IC50 values for inhibition of [3H]H12-HTX binding by colchicine and three Vinca alkaloids were closely correlated with their abilities to inhibit acetylcholine-induced catecholamine secretion from cultured bovine adrenal chromaffin cells. As a consequence of its interaction (direct or indirect) with the ion channel, at least one Vinca alkaloid (vinblastine) stabilized a high agonist affinity conformation of the nicotinic receptor complex. beta-Lumicolchicine, an analog of colchicine devoid of microtubule activity, also blocked ion channel binding. On the other hand, taxol, a microtubule-stabilizing agent which also selectively blocks cholinergically mediated secretion, did not affect receptor or ion channel binding. The present results indicate that interactions with the nicotinic receptor-ion channel complex may underlie the actions of certain microtubule-active agents on catecholamine secretion by adrenal chromaffin cells.
Molecular Pharmacology
ABSTRACT
Molecular Pharmacology
ABSTRACT
Molecular Pharmacology
Isoarecolone methiodide (1-methyl-4-acetyl-1,2,3,6-tetrahydropyridine methiodide) was previously ... more Isoarecolone methiodide (1-methyl-4-acetyl-1,2,3,6-tetrahydropyridine methiodide) was previously shown to be among the most potent agonists tested at the frog neuromuscular junction. Because nicotinic receptors from different sources vary in their selectivities, isoarecolone methiodide as well as 19 additional congeners, most of which were also previously tested at the frog neuromuscular junction, were studied in binding assays. Torpedo nobiliana was the tissue source for nicotinic receptors. Two types of experiments were conducted. The first evaluated the affinities of the agonists (including acetylcholine and carbamylcholine) for the recognition site by allowing the agonists to compete for that site with 125I-alpha-bungarotoxin. The inhibition potencies obtained correlated strongly (Spearman's correlation coefficient,-0.91) with the potency obtained at the frog neuromuscular junction. The second type of experiment evaluated the agonists for their ability to activate the receptor. The binding of [3H]perhydrohistrionicotoxin, which was employed as an indicator of the activation of the receptor, was measured in the presence of each of the agonists. Isoarecolone methiodide was the most potent of all. A few of the agonists (partial agonists) were incapable of fully enhancing this binding. For the full agonists, the concentration that produced half of the maximum binding of [3H]perhydrohistrionicotoxin was defined as the EC50. The correlation coefficient (Spearman's) for EC50 versus potency at the frog neuromuscular junction was -0.73, indicating innate differences between Torpedo and frog receptors. In addition, these compounds were tested for their affinity at muscarinic receptors from rat brain. Competition experiments were carried out using [3H]N-methylscopolamine. The affinity of isoarecolone methiodide was only about 7-fold lower than that of acetylcholine and less than 2-fold lower than that of carbamylcholine. In contrast, 1-methyl-4-acetylpiperazine methiodide was much more selective for nicotinic receptors. Its activity was similar to isoarecolone methiodide at the nicotinic receptor, but it was among the weakest compounds in its affinity for the muscarinic receptor.
Developmental Brain Research
Muscarinic receptor density increased by approximately 36% after differentiation induced by retin... more Muscarinic receptor density increased by approximately 36% after differentiation induced by retinoic acid (Bmax, control = 126 +/- 13 fmol/mg protein; Bmax, retinoic acid-treated = 170 +/- 17 fmol/mg protein; P < 0.05), corresponding to a 170% increase in receptor content per cell. The affinity of [3H]NMS for the receptors was somewhat lower in the retinoic acid-treated cells (Kd, control = 0.14 +/- 0.04 nM; Kd, retinoic acid-treated = 0.25 +/- 0.04 nM; P < 0.05). Reverse transcriptase/polymerase chain reaction analysis using subtype-specific primers revealed that undifferentiated Sk-N-SH cells transcribed mRNA for all 5 receptor subtypes; this pattern was not affected by retinoic acid treatment. [3H]NMS displacement curves with subtype selective receptor ligands (pirenzepine, m1; AFDX-116, m2; 4-DAMP, m3) indicated the predominant expression of m3 and m1 receptor subtypes, and differentiation did not affect the pharmacological profile of the expressed receptor populations. Th...
Brain Research
The repeated administration of a high dose of substance P (SP) onto the spinal cord has been show... more The repeated administration of a high dose of substance P (SP) onto the spinal cord has been shown to attenuate behavioral responses to an intense heat (tail-flick) or noxious mechanical stimulus (paw pressure). Studies performed to investigate the action of spinal SP have suggested that changes in behavioral responses involve endogenous opiate or neurokinin systems. This study was performed to investigate whether the binding characteristics of SP receptors in the dorsal horn are altered following successive administration of SP. Two populations of [3H]-SP binding sites were distinguished on the basis of their binding affinity. Gpp(NH)p, a stable analogue of GTP, decreased the size and affinity of the high affinity binding component selectively labelled with [125I]-Bolton Hunter-SP. Repeated intrathecal administration of SP (15 micrograms) which reduced behaviors also reduced the number and affinity of high affinity binding sites. Thus, attenuated behaviors in response to repeated a...
Journal of Pharmacology and Experimental Therapeutics
Tachyphylaxis develops to the hypertensive response to central (i.c.v.) injection of carbachol in... more Tachyphylaxis develops to the hypertensive response to central (i.c.v.) injection of carbachol in conscious rats. This pressor response exhibits tachyphylaxis if the injection is repeated within 8 hr of the first injection. Blockade of brain prostaglandin synthesis with indomethacin does not inhibit the pressor response to carbachol in naive rats, but eliminates the pressor response to carbachol when the muscarinic agonist is repeated within a few hours of the first injection. If the time interval is extended to permit return of the full response (i.e., 24 hr later), indomethacin no longer inhibits the pressor response. The related cyclooygenase inhibitor meclofenamate produced effects which were identical to those of indomethacin, but at approximately 10-fold higher doses. When shorter acting drugs (duration of action < 30 min), physostigmine or arecoline, were used according to the same paradigm, indomethacin was less effective at inhibiting the pressor response to the second i...
BioMed Research International, 2015
Many viral and nonviral systems have been developed to aid delivery of biologically active molecu... more Many viral and nonviral systems have been developed to aid delivery of biologically active molecules into cells. Among these, cell-penetrating peptides (CPPs) have received increasing attention in the past two decades for biomedical applications. In this review, we focus on opportunities and challenges associated with CPP delivery of nucleic acids and nanomaterials. We first describe the nature of versatile CPPs and their interactions with various types of cargoes. We then discuss in vivo and in vitro delivery of nucleic acids and nanomaterials by CPPs. Studies on the mechanisms of cellular entry and limitations in the methods used are detailed.
The Journal of pharmacology and experimental therapeutics, 1993
Tachyphylaxis develops to the hypertensive response to central (i.c.v.) injection of carbachol in... more Tachyphylaxis develops to the hypertensive response to central (i.c.v.) injection of carbachol in conscious rats. This pressor response exhibits tachyphylaxis if the injection is repeated within 8 hr of the first injection. Blockade of brain prostaglandin synthesis with indomethacin does not inhibit the pressor response to carbachol in naive rats, but eliminates the pressor response to carbachol when the muscarinic agonist is repeated within a few hours of the first injection. If the time interval is extended to permit return of the full response (i.e., 24 hr later), indomethacin no longer inhibits the pressor response. The related cyclooygenase inhibitor meclofenamate produced effects which were identical to those of indomethacin, but at approximately 10-fold higher doses. When shorter acting drugs (duration of action < 30 min), physostigmine or arecoline, were used according to the same paradigm, indomethacin was less effective at inhibiting the pressor response to the second i...
Molecular pharmacology, 1979
Research communications in chemical pathology and pharmacology, 1984
Potassium-stimulated calcium uptake by rat brain synaptosomes was measured by placing synaptosome... more Potassium-stimulated calcium uptake by rat brain synaptosomes was measured by placing synaptosomes in a high (70 mM) potassium medium containing 45Ca. K+-stimulated uptake was essentially complete within 20 s. K+-stimulated calcium uptake was inhibited by pretreating the synaptosomes with N-ethylmaleimide, a sulfhydryl alkylating reagent. Methylmercury chloride and mercuric chloride inhibited K+-stimulated calcium uptake in the same concentration ranges at which they formed complexes with surface sulfhydryl groups. Ethylmercury chloride was considerably less effective at inhibiting calcium uptake and reacting with sulfhydryl groups. The presence of essential sulfhydryl moieties in the structures subserving K+-stimulated calcium uptake by nerve terminals is suggested.
The Journal of pharmacology and experimental therapeutics, 1986
Mice pretreated with the centrally active alpha-2 adrenergic agonist, clonidine, were protected f... more Mice pretreated with the centrally active alpha-2 adrenergic agonist, clonidine, were protected from several of the toxic manifestations of soman, an organophosphate acetylcholinesterase inhibitor. The protection resulted in increased survival rates and a reduction in centrally mediated symptoms of soman, including tremor and straub tail, as well as one peripheral muscarinic symptom, excessive salivation. Doses of clonidine between 0.1 and 1 mg/kg, administered between 5 and 40 min before LD80 to LD90 doses of soman, produced significant protection. Pretreatment with atropine (25 mg/kg) also protected against soman toxicity. When atropine was combined with clonidine, the degree of protection afforded by the combination was greater than that predicted for a simple additive effect. Mice protected by atropine from the initial toxicity of soman frequently died within 24 h; no such delayed lethality was observed with protective doses of clonidine. Clonidine noncompetitively inhibited ace...
Toxicology and applied pharmacology, Jan 30, 1988
The organophosphate cholinesterase inhibitor soman produced a dramatic increase in arterial blood... more The organophosphate cholinesterase inhibitor soman produced a dramatic increase in arterial blood pressure of up to 60 mm Hg in the unanesthetized rat with variable changes in heart rate. Pretreatment with clonidine resulted in a dose-related inhibition of soman-induced cardiovascular changes and enhanced the time of survival as well as the number of animals surviving 24 hr after soman injection. High doses of clonidine itself produced a transient pressor response; however, the peripheral actions of clonidine were not important for its protective actions. The paradigm of repeated injections of a sublethal dose of soman at regular intervals produced the most reliable cardiovascular changes and degree of lethality. The development of the pressor response under these conditions paralleled the increase in regional brain acetylcholine levels. Pretreatment with a protective dose of clonidine did not alter steady-state levels of acetylcholine, but did inhibit the soman-induced increase in ...
The Journal of pharmacology and experimental therapeutics, 1987
The cardiac cholinergic system was studied in streptozotocin (STZ)-diabetic and age-matched contr... more The cardiac cholinergic system was studied in streptozotocin (STZ)-diabetic and age-matched control rats. STZ-diabetic rats (8-10 weeks) were supersensitive to the negative chronotropic effects of acetylcholine, carbamylcholine and bethanechol; inotropic responses to these muscarinic agonists were unaltered. This phenomenon was associated with a decrease in acetylcholinesterase activity but no change in the rate and extent of neuronal choline uptake. [3H]N-methylscopolamine bound to muscarinic receptors in atria from both groups of rats with the same high affinity. The density of [3H]N-methylscopolamine binding sites, however, was 34% lower in atria from STZ-diabetic rats. Agonist binding affinity was lower in diabetes; carbamylcholine had a lower affinity for both the high- and low-affinity receptors. These results indicate that cardiac cholinergic supersensitivity in right atria in diabetes occurs before the development of autonomic neuropathy insofar as neuronal [3H]choline uptak...
Molecular pharmacology, 1989
Isoarecolone methiodide (1-methyl-4-acetyl-1,2,3,6-tetrahydropyridine methiodide) was previously ... more Isoarecolone methiodide (1-methyl-4-acetyl-1,2,3,6-tetrahydropyridine methiodide) was previously shown to be among the most potent agonists tested at the frog neuromuscular junction. Because nicotinic receptors from different sources vary in their selectivities, isoarecolone methiodide as well as 19 additional congeners, most of which were also previously tested at the frog neuromuscular junction, were studied in binding assays. Torpedo nobiliana was the tissue source for nicotinic receptors. Two types of experiments were conducted. The first evaluated the affinities of the agonists (including acetylcholine and carbamylcholine) for the recognition site by allowing the agonists to compete for that site with 125I-alpha-bungarotoxin. The inhibition potencies obtained correlated strongly (Spearman's correlation coefficient,-0.91) with the potency obtained at the frog neuromuscular junction. The second type of experiment evaluated the agonists for their ability to activate the recept...
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Papers by Robert Aronstam