Impaired learning in adulthood following neonatal delta9-THC exposure.
Cannabis is one of the most commonly used illicit drugs during pregnancy, but little is known about the lasting effects of early-life exposure to this drug. In this study, male Wistar rat pups were treated daily with (-)-delta9-tetrahydrocannabinol (THC; 5 mg/kg, s.c.) or its vehicle between postnatal days (PND) 4 and 14. Drug administration during this early postnatal period in rats is analogous to the third trimester of gestation in humans, which is a major period of synaptogenesis. Rats were subsequently tested drug-free during young adulthood (PND 56) using a two-component food-motivated double Y-maze test. Each trial included distinct spatial discrimination and delayed alternation components, which permitted the simultaneous assessment of reference memory and working memory. Rats were tested for 30 trials/day, 5 days/week for 5 weeks. Results revealed no significant differences between THC- and vehicle-treated rats in the spatial discrimination task. However, compared to vehicle-treated rats, THC-treated rats committed significantly more errors, and required significantly longer to obtain 80% correct over two consecutive days in the delayed alternation task. Results suggest that neonatal THC exposure leads to a specific and lasting deficit in learning in adulthood, which is likely due to impaired working memory function.
O'Shea
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School of Psychology, University of New England, Armidale, New South Wales, Australia.
Mallet
P E
PE
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D013759:Dronabinol / Q000494:pharmacology*; D005260:Female; D007859:Learning Disabilities / Q000139:chemically induced / Q000503:physiopathology; D008297:Male; D018782:Maze Learning / Q000187:drug effects* / Q000502:physiology; D008568:Memory / Q000187:drug effects / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D013759:Dronabinol