Psychopharmacology
April 1, 2000
S C Dulawa, K A Scearce-Levie, R Hen et al.
26 citations
Prepulse inhibition (PPI) is the normal reduction of the startle response which occurs when an abrupt startling stimulus is preceded by a weak pre-stimulus and is decreased in several neuropsychiatric disorders. The role of the serotonin 1B (5-HT(1B)) receptor in modulating PPI was investigated using 5-HT-releasing agents in wild-type (WT) and 5-HT1B knockout (1BKO) mice. Whether the...
Pharmacology, biochemistry, and behavior
March 1, 2000
Z A Martinez, N D Halim, J L Oostwegel et al.
NMDA antagonists and dopamine (DA) agonists produce neuropathological and/or behavioral changes in rats that may model specific abnormalities in schizophrenia patients. In adult rats, NMDA antagonists and DA agonists disrupt sensorimotor gating-measured by prepulse inhibition (PPI)-modeling PPI deficits in schizophrenia patients. In addition, high doses of NMDA antagonists produce limbic system...
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
July 1, 1999
Z A Martinez, G D Ellison, Mark A. Geyer et al.
Phencyclidine (PCP), a non-competitive NMDA antagonist with actions at multiple other central nervous system receptors, can cause both acute and lasting psychoses in humans, and has also been used in cross-species models of psychosis. Acute exposure to PCP in rats produces behavioral changes, including a loss of prepulse inhibition (PPI) of the startle reflex, which parallels the loss of PPI...
Neuron
March 1, 1999
R. Grailhe, C. Waeber, S. Dulawa et al.
In order to determine the distribution and function of the 5-HT5A serotonin receptor subtype, we generated knockout mice lacking the 5-HT5A gene. Comparative autoradiography studies of brains of wild-type (wt) and 5-HT5A knockout (5A-KO) mice revealed the existence of binding sites with high affinity for [125I]LSD that correspond to 5-HT5A receptors and that are concentrated in the olfactory...
Behavioural Pharmacology
November 1, 1998
Euphrosyne Gouzoulis‐mayfrank, Karsten Heekeren, B. Thelen et al.
79 citations
Schizophrenic patients exhibit deficits in indices of sensorimotor gating, such as habituation and prepulse inhibition (PPI) of the startle reflex. Hallucinogenic drug-induced states are putative models for the early and acute stages of schizophrenic and schizophrenia-spectrum disorders. Hallucinogenic drugs have been shown to disrupt PPI and/or retard habituation of the startle reflex in...
Psychopharmacology
January 1994
K M Krebs, M A Geyer
Like hallucinogenic 5-HT2 agonists, LSD (d-lysergic acid diethylamide) produces characteristic decreases in locomotor activity and investigatory behaviors of rats tested in a novel environment. Because LSD is an agonist at both 5-HT1A and 5-HT2 receptors, however, the respective influences of these different receptors in the behavioral effects of LSD remain unclear. In particular, the paucity...
European Journal of Pharmacology
April 7, 1992
C W Callaway, Mark A. Geyer
35 citations
This study examined the behavioral effects in rats of intracerebral administration of S(+)-3,4-methylenedioxymethamphetamine (S-MDMA) using an automated holeboard and open-field apparatus. Administration of S-MDMA into the nucleus accumbens septi produced locomotor hyperactivity. Although the stimulant effects of S-MDMA administered systemically are antagonized by fluoxetine pretreatment, the...
Psychopharmacology
1991
C W Callaway, M P Johnson, L H Gold et al.
70 citations
Derivatives of amphetamine are potent releasers of both dopamine (DA) and serotonin (5-HT), but the relative contributions of DA and 5-HT release to the behavioral effects of these drugs have not been established. Previously, S-(+)3,4-methylenedioxymethamphetamine (S-(+)MDMA) was found to produce locomotor hyperactivity in rats which was dependent on 5-HT release. The present study found that...
Psychopharmacology
1991
S M Mittman, M A Geyer
Rats tested for 1 h in the Behavioral Pattern Monitor (BPM) after injection of the mixed serotonergic agonist d-lysergic acid diethylamide (LSD) exhibit a behavioral profile similar to that produced by various hallucinogenic 5HT-2 agonists. The characteristic effects of the hallucinogens include suppression of locomotor and exploratory behavior and a preferential decrease in entries into the...
Journal of Pharmacology and Experimental Therapeutics
August 1, 1990
C. Callaway, L. Wing, Mark A. Geyer et al.
Methylenedioxymethamphetamine (MDMA) is a phenylethylamine with novel mood-altering properties in humans. MDMA shares the dopamine-releasing properties of amphetamine but has been found to be a more potent releaser of serotonin (5-HT). The present study undertook to determine the relative roles of dopamine and 5-HT release in MDMA-induced locomotor hyperactivity. S-(+)MDMA produced...
Psychopharmacology
March 1, 1990
Lauren L. Wing, Gregory S. Tapson, Mark A. Geyer
99 citations
In rats tested during their first exposure to a Behavioral Pattern Monitor chamber, acute injections of the 5HT-2 agonists mescaline, quipazine, 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), or 2,5-dimethoxy-4-ethylamphetamine (DOET) produced an inhibition of locomotor and investigatory behavior during the first 30 min of the test session. This suppression of...
Psychopharmacology
1989
S M Mittman, M A Geyer
Behavioral profiles composed of both locomotor activity and investigatory behavior were established for the 5HT-1A agonists 8OHDPAT, buspirone, gepirone, and ipsapirone using rats tested in a Behavioral Pattern Monitor. Typically these compounds dose-relatedly decreased horizontal locomotion and investigatory activity during the first half of the 1-h test session. Time-course studies revealed...
Progress in neuro-psychopharmacology & biological psychiatry
1985
L M Adams, M A Geyer
A previously proposed animal model of lysergic acid diethylamide's (LSD) effects in humans was tested for its applicability to other hallucinogens, 2,5-dimethoxy-4-methyl amphetamine (DOM) and N,N-dimethyltryptamine (DMT). Both "free" and "forced" exploration tests in a behavioral pattern monitor were used to determine the effects of these hallucinogens on the normal tendencies of rats to avoid...
Psychopharmacology
June 1, 1982
Lynne M. Adams, Mark A. Geyer
A free exploration test was used to examine the effects of LSD on investigatory responding and locomotor activity in a novel environment. Rats were injected with 20–30 μg/kg LSD or saline prior to being placed in a home cage. After 10 min, a door was opened permitting entry into a larger holeboard chamber where crossovers, rearings, hole pokes, and routes of locomotion were monitored. When...
Psychopharmacology
September 1979
M A Geyer, R K Light, G J Rose et al.
The disruption of the temporal distribution of investigatory responses by rats in a novel hole-board following lysergic acid diethylamide-25 (LSD), as described in a companion paper (Geyer and Light, 1979), was found to be a characteristic effect of a variety of hallucinogens. Similar effects were produced by indoleamine hallucinogens, such as LSD, N,N-dimethyltryptamine, and psilocin, and by...
Pharmacology Biochemistry and Behavior
February 1, 1979
Mark A. Geyer, Gary J. Rose, Lyle R. Petersen
7 citations
To test the possible involvement of serotonin-containing cells of the midbrain in mediating the effects of mescaline on startle responding, electrolytic lesions were made in either the dorsal or median raphe nucleus in rats. Decreases in either striatal or hippocampal tryptophan hydroxylase activity confirmed the effectiveness of the lesions. One week later, startle was measured in response to...
Journal of Pharmacology and Experimental Therapeutics
December 1, 1978
Mark A. Geyer, Lyle R. Petersen, Gary J. Rose et al.
69 citations
Tactile startle responding by male Sprague-Dawley rats given 60 presentations of air-puff stimuli (37.5 psi) was measured after the intraperitoneal administration of graded doses of hallucinogens and other psychoactive drugs. Among the drugs tested were the indoleamine-derived compounds, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine and psilocin, and the phenylethylamine-derived...
Pharmacology, biochemistry, and behavior
1975
Mark A. Geyer, J D Warbritton, D B Menkes et al.
34 citations
Rat startle responses to air puffs were monitored in a stabilimeter during the intraventricular infusion of various doses of 5-hydroxytrptamine (5-HT) or the putative hallucinogenic congener of 5-HT, 5-hydroxy-N, N-dimethyltrytamine (5-HDMT) or saline. Qualitativity opposite effects were observed, with 5-HT producing a dose-dependent decrease in responsivity and 5-HDMT increasing the magnitude...