The effects of hypoglycemia and ethanol on rat performance in the radial-arm maze

A deficit in blood glucose (BG) (hypoglycemia, HG) causes a characteristic array of physiological sequelae, symptoms and cognitive impairment in human subjects. However, the performance of hypoglycemic animal subjects in the standard paradigms of behavioral pharmacology has received little research attention. The primary purpose of these experiments was to determine the effect of insulin-produced HG on spatial working memory in rats trained in the radial-arm maze (RAM), using a noninterrupted (win-shift) procedure. A second aim was to further investigate possible interaction between HG and ethanol administration since potentiation between the drugs' depressant effects has been reported for rat spontaneous motor activity (SMA). Insulin administration (resulting in BG levels approximately 65% of control levels) was combined factorially with ethanol treatment in two experiments. HG significantly increased time required to complete RAM trials in both experiments, but did not impair accuracy of arm choice. In the second experiment, ethanol was administered only once to minimize development of tolerance, and under these conditions, ethanol at 1500 mg/kg impaired arm-choice accuracy and marginally potentiated HG-produced slowing of running time. The current results appear somewhat similar to previously reported effects of HG on reaction time in human subjects.