Characteristics of learning and memory impairment induced by delta9-tetrahydrocannabinol in rats.
We investigated the characteristics of delta9-tetrahydrocannabinol (THC)-induced impairment of learning and memory using an 8-arm radial maze task, a water maze, a visual discrimination task with 2 figures and a passive avoidance test in rats. THC (6 mg/kg, i.p.) impaired spatial memory in the standard task of the 8-arm radial maze. THC (4-6 mg/kg, i.p.) selectively impaired working memory in a reference and working memory task of the 8-arm radial maze. Even at a dose of 10 mg/kg, THC did not impair spatial memory in the water maze. In addition, THC at a dose of 6 mg/kg, which had inhibitory effects in the 8-arm radial maze, did not affect performance in the visual discrimination task. These results indicate that at low doses (2-6 mg/kg), THC may not produce visual function abnormalities. THC impaired retrieval (6 mg/kg, i.p.) as well as acquisition (10 mg/kg, i.p.) in the passive avoidance test. The consolidation process was also impaired by i.c.v. injection (100 microg), but not i.p. injection (6-10 mg/kg) of THC. These results suggest that THC-induced impairment of spatial memory is based on the selective impairment of working memory through its effects on acquisition and retrieval processes.
Mishima
K
K
Department of Physiology and Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Japan.
Egashira
N
N
Hirosawa
N
N
Fujii
M
M
Matsumoto
Y
Y
Iwasaki
K
K
Fujiwara
M
M
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects; D013759:Dronabinol / Q000037:antagonists & inhibitors / Q000633:toxicity*; D006213:Hallucinogens / Q000037:antagonists & inhibitors / Q000633:toxicity*; D007276:Injections, Intraventricular; D007859:Learning Disabilities / Q000139:chemically induced* / Q000523:psychology; D018782:Maze Learning / Q000187:drug effects; D008569:Memory Disorders / Q000139:chemically induced* / Q000523:psychology; D008570:Memory, Short-Term / Q000187:drug effects; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010862:Pilocarpine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D000077285:Rimonabant; D012601:Scopolamine / Q000494:pharmacology
D006213:Hallucinogens; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010880:Piperidines; D011720:Pyrazoles; D010862:Pilocarpine; D013759:Dronabinol; D012601:Scopolamine; D000077285:Rimonabant