Effects of systemic and intra-prefrontal cortex administrations of ethanol on spatial working memory in male rats

Introduction: Ethanol can induce a wide spectrum of neurophysiological effects via interaction with multiple neurotransmitter systems and disruption of the balances between inhibitory and excitatory neurotransmitters. Prefrontal cortex is involved in cognitive process including working memory and is sensitive to ethanol. Present study investigates the effects of intraperitoneal (i.p.) administration of multiple doses of ethanol and intra-prefrontal cortex (i.c.) administration of ethanol on spatial working memory performance. Methods: Adults male wistar rats (200-250g) were used. Rats in various groups received saline (i.p.), saline (i.c.), ethanol (10%, 20% and 30%, i.p.) and ethanol (30%, i.c.). Surgery for intra-prefrontal cortex cannulation was performed for i.c. administrations. The spatial working memory was assessed 15 and 30 minutes after i.p and 5 minutes after i.c. injections at first, second, and third day using the 8-shape maze apparatus. Results: Ethanol (10%, i.p.) had no significant effects, but 15 and 30 min after administrations of ethanol (20%, i.p.) (P<0.05), and 15 min after administration of ethanol (30%, i.p.) (P<0.001), spatial working memory performance decreased significantly. Only i.c. administration of ethanol 30% at the first day, diminished working memory performance (P<0.001). Conclusion: Because working memory was impaired in both intraperitoneal and intra-prefrontal cortex administration, therefore probably a part of spatial working memory deficits is related to effects of ethanol on prefrontal cortex and disruption of neuronal circuits involved in working memory in this region.