ISSN:
1432-2072
Keywords:
Marijuana (Cannabis)
;
l-δ 8-trans-Tetrahydrocannabinol (δ 8-THC)
;
Behavioral Pharmacology
;
Tolerance
;
“Reverse Tolerance” (Sensitivity)
;
Differential Reinforcement of Low Rates of Responding (DRL)
;
Rats
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effects have been observed of chronic daily intraperitoneal injections of a marijuana (cannabis) constituent, δ 8-tetrahydrocannabinol (δ 8-THC), on the temporally-spaced lever pressing of rats maintained under a DRL (differential reinforcement of low rates of responding) schedule of water reinforcement. A different chronic dose was given to each of four rats. During the test session following the first drug injection, the two rats which received the lower doses (5.62 or 10.0 mg/kg) showed lengthy periods of no lever pressing, and the two rats receiving the higher doses (17.8 or 31.6 mg/kg) showed almost no lever pressing. In the case of the lower doses, the response rate between the long pauses was increased. With repeated injections, tolerance developed to the drug-induced cessation of responding at all dose levels, but increased sensitivity to the response rate-increasing effect was observed, particularly with the 10.0 and 17.8 mg/kg doses. These behavioral effects were probably not mediated by drug-induced changes in body temperature regulation. The increased sensitivity to the rate-increasing effect of the marijuana constituent with repeated injection may be related to the “reverse tolerance” to marijuana's psychological effects that has been reported in man.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00426107
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