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Biomedical subjects

L D Chait

Publications and source records attributed to L D Chait.

41 records · Page 3Linked to original sources
PubMed1978

The effects of acute and chronic phencyclidine on schedule-controlled behavior in the squirrel monkey.

The effects of acute and chronic administration of phencyclidine (PCP) were examined in five male squirrel monkeys trained to respond on a chain fixed-interval fixed-ratio schedule of food presentation. Acute PCP (0.01-0.60) mg/kg i.m.) produced dose-related decreases in response rate during both components of the schedule. Both components were equally affected by the drug. The effects of the drug on fixed-interval response rate were dependent on the control rate of responding in corresponding segments of the interval. After the initial dose-response determination, the subjects were placed on an individualized regimen of chronic PCP administration lasting from 82 to 126 days, beginning with daily injections for 2 days alternating with saline injections for 2 days, progressing to four injections daily. No evidence of physical dependence was seen upon withdrawal of the drug. Redetermination of the dose-response function for PCP (0.03-1.0 mg/kg i.m.) demonstrated a nearly 2-fold shift to the right of both the fixed-interval and fixed-ratio dose-response curves, indicating tolerance. In addition, the subjects' behavior recovered sooner from a dose of PCP (0.60 mg/kg i.m.) given after the chronic regimen than from the same dose given before the chronic regimen. The results demonstrate that tolerance can occur to the behavioral effects of PCP in the squirrel monkey.

Animals↗
PubMed1976

Tolerance to the cardiovascular effects of delta9-tetrahydrocannabinol in the rat.

1. Daily intraperitoneal injections of delta9-tetrahydrocannabinol (delta9-THC, 10 mg/kg) resulted in tolerance to the effects of the cannabinoid on body weight and body temperature within 1-2 weeks of treatment. 2. Tolerance failed to develop to the suppression of spontaneous motor activity produced by delta9-THC during 28 days of treatment with the cannabinoid (10 mg/kg, i.p. per day). 3. Following treatment with vehicle for 28 days, intravenous administration of delta9-THC in anaesthetized rats produced a transient pressor response followed by a sustained hypotension and bradycardia. 4. Tolerance to the hypotensive and negative chronotropic responses to intravenous delta9-THC was readily apparent in animals which had received daily intraperitoneal injections of delta9-THC (10 mg/kg) for 28 days. 5. Tolerance failed to develop to the pressor actions of intravenous delta9-THC after 28 days of preptreatment. 6. There was no difference in the pressor response to intravenous noradrenaline in vehicle-treated animals (1.0 ml/kg, i.p., per day for 28 days) and delta9-THC-treated animals (10 mg/kg, i.p., per day for 28 days).

Animals↗