The enhancing effects of hippocampal infusions of glucose are not restricted to spatial working memory

Extensive evidence shows that hippocampal infusions of glucose enhance spontaneous alternation (SA) performance or reverse deficits in this task. The current experiments determined whether the enhancing effects of hippocampal infusions of glucose are restricted to spatial working memory. Specifically we tested whether hippocampal infusions of glucose would reverse deficits in an emotional reference memory task (continuous multiple trial inhibitory avoidance [CMIA]) produced by septal infusions of the γ-aminobutyric acid agonist muscimol. Male Sprague-Dawley rats were given septal infusions of vehicle or muscimol (0.15 nmol: SA; 5 nmol: CMIA) combined with hippocampal infusions of vehicle or glucose (50 nmol) 15 min prior to assessing SA or CMIA training. CMIA retention was tested 48 h later. Muscimol infusions decreased percent alternation scores and avoidance retention latencies. Importantly, hippocampal infusions of glucose reversed the deficits produced by the septal muscimol infusions on both tasks. These findings show for the first time that hippocampal glucose infusions also influence emotional memory, indicating that the enhancing effects of glucose generalize to memory tasks that vary in motivational and cognitive demand.