EFFECT OF COMBINATIONS OF INSULIN, GLUCOSE AND SCOPOLAMINE ON RADIAL-ARM MAZE PERFORMANCE

Previous research has shown that glucose is an effective agent in faci litating memory performance and in attenuating scopolamine-induced amn esia. Although insulin has not been shown to facilitate unimpaired mem ory, a previous study has demonstrated that insulin can also attenuate scopolamine-degraded memory. The present study was designed to determ ine how different combinations of insulin, glucose and scopolamine aff ect memory. It involved nine rats whose memory was assessed through pe rformance in a win-shift radial arm maze task under different drug tre atments. A 2 x 2 x 2 (insulin x glucose x scopolamine) within-subjects design with a 5-h drug test interval was employed. Scopolamine disrup ted memory performance, and both glucose and insulin-counteracted this disruption. Combining the glucose and insulin treatments did not incr ease their ability to attenuate scopolamine deficits but slightly decr eased this effect. Glucose tended to enhance memory, even in the absen ce of scopolamine, whereas insulin had no effect on memory in the abse nce of scopolamine. Blood glucose levels were measured and did not ind icate changes caused by drug treatments. The memory effects may have b een due to the acetylcholine-agonist actions of glucose and insulin, a n interpretation consistent with previous research findings. (C) 1997 Elsevier Science Inc.