Abstract
Rats previously trained to climb a rope were injected daily with a marihuana extract; the drug initially impaired the performance but after 14 injections the animals became completely tolerant. The rats were then trained to press either one of the 2 bars of a Skinner box. On each day only one of the bars was activated to deliver the reward; 45 min before the experiment an injection of cannabis extract (left bar) or of control solution (right bar) was given. After 30 injections the animals learned which bar to press in order to obtain the reward, indicating that they were still using some effect of marihuana as a discriminative stimulus. This dissociation of learning produced in marihuana “tolerant” rats, (as measured by rope-climbing), indicates that tolerance is not complete. Furthermore, as dissociation of learning is not produced by peripheral effects of drugs, it is suggested that even after chronic treatment marihuana continues to act on the central nervous system.
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Work partially aided by FundaÇÃo de Amparo à Pesquisa do Estado de Sao PÃulo (FAPESP) and Conselho Nacional de Pesquisas (CNPq). Read before the Annual Meeting of the Brazilian Society of Pharmacology and Experimental Therapeutics, SÃo Paulo, May 1971.
With fellowship from FAPESP.
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Bueno, O.F.A., Carlini, E.A. Dissociation of learning in marihuana tolerant rats. Psychopharmacologia 25, 49–56 (1972). https://doi.org/10.1007/BF00422616
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DOI: https://doi.org/10.1007/BF00422616