GLUCOSE ATTENUATES COLD-INDUCED IMPAIRMENT OF DELAYED MATCHING-TO-SAMPLE PERFORMANCE IN RATS

Administration of glucose has been shown to enhance performance in a v ariety of test situations in which memory is impaired by some amnestic treatment. In the present study, the effects of glucose were examined on a working-memory deficit produced when rats performed a delayed ma tching-to-sample (DMTS) task while being exposed to ambient cold air. In the DMTS task, the rats were required to respond on one of two leve rs cued by an illuminated light above the lever on the front wall of a n operant chamber. Following a variable delay ranging from 1 to 16 sec , both lights were illuminated and the rats were required to correctly respond on the lever previously cued for a food reward. They responde d on the back wall lever during the delay interval to prevent position bias. Glucose (10-500 mg/kg) or saline, administered (i.p.) in a mixe d sequence, were given 1 h before a 75-min session in which the rats p erformed the DMTS task (180 trials). During test sessions, the ambient air temperature was either 23-degrees-C or 2-degrees-C. Administratio n of glucose during exposure to 23-degrees-C did not systematically af fect matching accuracy or other performance measures. In the rats pret reated with saline, exposure to 2-degrees-C produced a downward shift in the delay gradient in that matching accuracy was impaired at all de lay intervals when compared with performance at 23-degrees-C. Glucose produced dose-dependent improvement of matching accuracy with short, b ut not long, interpolated delays. Selective modulation of cold-induced impairment of working memory at the short delays suggests that glucos e preferentially enhances stimulus acquisition during exposure to cold stress.