Psychopharmacology
August 1, 1996
G D Ellison, A S Keys
Phencyclidine (PCP) can induce a model psychosis which has a number of similarities to dementias and schizophrenia. In some cases the psychosis persists for prolonged periods after drug discontinuation. N-Methyl-D-aspartate (NMDA) antagonists such as PCP induce increases in glucose metabolism in a variety of brain structures but most notably in limbic regions such as retrosplenial, piriform,...
Psychopharmacology
July 1996
A H Lichtman, B R Martin
The purpose of the present study was to investigate whether the cannabinoid and cholinergic systems impair working memory through a common mechanism. This hypothesis was tested by examining whether the cannabinoid antagonist SR141716A would ameliorate radial-arm performance deficits caused by either the naturally occurring cannabinoid, delta 9-THC, or scopolamine, a muscarinic antagonist. In...
Psychopharmacology
April 1996
R S Mansbach, C C Rovetti, E N Winston et al.
SR141716A (Sanofi Recherche), a pyrazole derivative with high affinity for rat and human CB1 cannabinoid receptors, has recently been reported to reverse biochemical, physiological and behavioral effects induced by cannabinoid agonists. The present experiments characterized the activity of SR141716A (SR) in behavioral procedures designed to assess its antagonistic and intrinsic effects on...
Psychopharmacology
March 1996
R A Padich, T C McCloskey, J H Kehne
Increasing evidence suggests an important role of 5-HT, and 5-HT2A receptors in particular, in the etiology and treatment of schizophrenia. The prepulse inhibition paradigm is used as a model for sensorimotor gating processes that are disrupted in schizophrenia. The present study used the selective serotonin2A (5-HT2A) antagonist and putative antipsychotic agent MDL 100,907 to evaluate the...
Psychopharmacology
March 1996
J H Kehne, R A Padich, T C McCloskey et al.
Increasing evidence suggests an important role for serotonin (5-HT) neurons in the etiology and treatment of schizophrenia. The prepulse inhibition paradigm is used as a model for sensorimotor gating processes that are disrupted in schizophrenia. The present study assessed the general role of 5-HT in modulating auditory and visual prepulse inhibition in Wistar rats. A general overactivation of...
Psychopharmacology
December 1995
David Fiorella, Scott Helsley, R A Rabin et al.
The present study was designed to investigate the hypothesis that agonist interactions at 5-HT2C receptors mediate the discriminative stimulus properties of m-chlorophenylpiperazine (mCPP). Three structural classes of compounds have been described to stimulate increases in phosphoinositide (PI) hydrolysis at the 5-HT2C receptor site: phenylpiperazines, phenylalkylamines, and indolamines. Four...
Psychopharmacology
October 1, 1995
S M Pearl, D W Johnson, Stanley D Glick
31 citations
Ibogaine is currently being investigated for its potential use as an anti-addictive agent. In the present study we sought to determine whether prior morphine exposure influences the ability of ibogaine to inhibit morphine-induced locomotor stimulation. Female Sprague-Dawley rats were pretreated once a day for 1-4 days with morphine (5, 10, 20 or 30 mg/kg, i.p.) or saline and then received...
Psychopharmacology
October 1995
David Fiorella, R A Rabin, Jerrold C Winter
Investigations conducted over the past 3 decades have demonstrated that serotonergic receptors, specifically the 5-HT2A and 5-HT2C subtypes, play an important role in the behavioral effects of hallucinogenic compounds. The present study was designed to determine the respective significance of these two receptors in the stimulus effects of LSD and (-)DOM in the rat. Specifically, the...
Psychopharmacology
October 1995
David Fiorella, R A Rabin, Jerrold C Winter
In the context of animal studies of hallucinogens, an LSD-false positive is defined as a drug known to be devoid of hallucinogenic activity in humans but which nonetheless fully mimics LSD in animals. Quipazine, MK-212, lisuride, and yohimbine have all been reported to be LSD false positives. The present study was designed to determine whether these compounds also substitute for the stimulus...
Psychopharmacology
October 1995
David Fiorella, Scott Helsley, D S Lorrain et al.
The present study was designed to determine the effects of p-chlorophenylalanine (PCPA) and p-chloroamphetamine (PCA) administration on (1) the levels of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in rat brain, (2) the sensitivity of LSD-trained rats to the stimulus effects of LSD, and (3) the maximal levels of 5-HT2A and 5-HT2C receptor mediated...
Psychopharmacology
August 1995
D Marona-Lewicka, D E Nichols
The influence of several alpha 2-adrenergic agents on the discriminative stimulus (DS) properties of lysergic acid diethylamide (LSD) was studied in rats trained to discriminate 0.08 mg/kg (186 nmol/kg) of LSD from saline in a two-lever operant paradigm. Only yohimbine fully mimicked LSD with an ED50 of 2.05 mg/kg (5.24 mumol/kg). Yohimbine's 5-HT1A agonist properties may be responsible for...
Psychopharmacology
July 1995
P Popoli, R Reggio, A Pezzola et al.
The influence of cholecystokinin (CCK), bilaterally injected into the rostral nucleus accumbens, on the EEG and behavioural effects induced by phencyclidine (PCP) has been studied in rats. CCK (10 ng) significantly inhibited PCP-induced EEG effects (increase of spectral power with respect to pre-drug tracing; increase of relative power distribution in the slowest frequency bands), and...
Psychopharmacology
June 1995
A R Green, A J Cross, G M Goodwin
3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") was first synthesised 80 years ago, but has recently received prominence as an illegally synthesised recreational drug of abuse. There is a widely held belief among misusers that it is safe. In the last 2-3 years there have been a number of reports of the drug producing severe acute toxicity and death and there are concerns that it may cause...
Psychopharmacology
June 1995
A H Lichtman, K R Dimen, B R Martin
The purpose of the present study was to investigate the disruptive effects of cannabinoids on working memory as assessed in the eight-arm radial-maze. Systemic administration of delta 9-THC, WIN-55,212-2, and CP-55,940 increased the number of errors committed in the radial-maze. CP-55,940 was the most potent cannabinoid in impairing memory (ED50 = 0.13 mg/kg). delta 9-THC and WIN-55,212-2...
Psychopharmacology
May 1995
David Fiorella, P A Palumbo, R A Rabin et al.
The pharmacodynamic characteristics of the stimulus effects of the hallucinogens d-LSD and (-)DOM were investigated in the rat. The stimulus control induced by (-)DOM (0.56 mg/kg) was significantly less stable at the 15-min pretreatment time than at the 75-min pretreatment time. In addition, (-)DOM (0.8 mg/kg) produced a time-dependent substitution for the LSD stimulus in LSD trained subjects...
Psychopharmacology
April 1, 1995
P M Sweetnam, J Lancaster, A Snowman et al.
109 citations
The indole alkaloid ibogaine (NIH 10567, Endabuse) is currently being examined for its potential utility in the treatment of cocaine and opioid addiction. However, a clearly defined molecular mechanism of action for ibogaine's putative anti-addictive properties has not been delineated. Radioligand binding assays targeting over 50 distinct neurotransmitter receptors, ion channels, and select...
Psychopharmacology
April 1995
K M Hegadoren, M T Martin-Iverson, G B Baker
Spontaneous behaviours were assessed in freely moving rats after treatment with equimolar doses of drugs that share a basic amphetamine structure. The drugs used included a psychomotor stimulant [(+)-amphetamine (AMPH)], an hallucinogen [para-methoxyamphetamine (PMA)] and the entactogens 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and...
Psychopharmacology
April 1995
V J Watts, C P Lawler, D R Fox et al.
The hallucinogenic effects of lysergic acid diethylamide (LSD) have been attributed primarily to actions at serotonin receptors. A number of studies conducted in the 1970s indicated that LSD also has activity at dopamine (DA) receptors. These latter studies are difficult to interpret, however, because they were completed before the recognition of two pharmacologically distinct DA receptor...
Psychopharmacology
April 1995
R L Barrett, J L Wiley, R L Balster et al.
While many previous studies have shown that a variety of cannabinoids substitute and cross-substitute for delta 9-tetrahydrocannabinol (THC) in drug discrimination procedures, few have systematically examined potential THC-like effects of non-cannabinoid compounds. The purpose of the present study was to delineate further the pharmacological specificity of THC discrimination. Rats were trained...
Psychopharmacology
April 1995
J E Sprague, D E Nichols
The effects of the MAO-B inhibitors, L-deprenyl and MDL-72974 on MDMA-induced serotonergic neurotoxicity in rats were examined. MDMA alone produced a significant decrease in the number of 5-HT uptake sites, measured as a decrease in the Bmax for binding of [3H]paroxetine, and in 5-HT and 5-HIAA levels in the striatum. L-Deprenyl and MDL-72974 attenuated this MDMA-induced decrease in...
Psychopharmacology
February 1, 1995
S I Dworkin, S Gleeson, D Meloni et al.
49 citations
The effects of ibogaine (40 and 80 mg/kg, i.p.), an indole alkaloid proposed for the treatment of drug abuse, were determined in three different groups of rats responding under an FR10 schedule of food, cocaine or heroin reinforcement. Ibogaine (80 mg/kg, i.p.) given 60 min before the start of the session resulted in a 97% decrease in the number of ratios completed under the food reinforcement...
Psychopharmacology
February 1995
T Morita, S Hitomi, S Saito et al.
To study the effects of repeated ketamine administration on central muscarinic acetylcholine receptors (mAchRs), ddY male mice were administered subcutaneous doses of 25 mg/kg ketamine every 3 days for a total of five times. Receptor binding assays of mAchR were carried out in the forebrain (FB), cerebellum (CB) and brainstem (BS), using [3H]quinuclidinyl benzilate ([3H]QNB) as a ligand. In...
Psychopharmacology
February 1, 1995
P J Armstrong, C Morton, W Sinclair et al.
In this six-period randomised double-blind study, 12 healthy volunteers inhaled mixtures of nitrous oxide at concentrations of 0% (placebo); 3%, 5%, 7%, 10%, and 15% in oxygen. Each concentration was inhaled for 55 min, each period being on a separate day. The order of treatments was randomised using a Latin-Square design. The effects of nitrous oxide were assessed using a battery of...
Psychopharmacology
December 1994
Hugh Series, P J Cowen, Trevor Sharp
Previous work has suggested that repeated treatment with substituted amphetamines including PCA, MDMA and d-fenfluramine produces a persistent neurodegeneration which is relatively selective for the fine serotoninergic terminals arising from the dorsal raphe nucleus. The aim of the present study was to investigate whether the acute releasing effect of d-fenfluramine might also be sensitive to...
Psychopharmacology
November 1, 1994
James C. Callaway, Mauno M. Airaksinen, Dennis J. Mckenna et al.
79 citations
The binding of [3H]citalopram to the platelet 5-hydroxytryptamine (5-HT) transporter was measured in a group of healthy male drinkers of ayahuasca, a psychoactive sacrament indigenous to Amazonia, and a group healthy male controls. An increased number of binding sites (Bmax) in the platelets of ayahuasca drinkers was found, while the dissociation constant (Kd) remained the same for both groups....