SINGLE PRE-TRAINING GLUCOSE INJECTION INDUCES MEMORY FACILITATION IN RODENTS PERFORMING VARIOUS TASKS - CONTRIBUTION OF ACIDIC FIBROBLAST GROWTH-FACTOR

Effects of a pre-training intraperitoneal glucose injection on learnin g and memory were tested using two tasks: passive avoidance and Morris water maze. In the former task, mice that had received glucose 2 h pr ior (but not 1, 3, or 5 h prior) to a trial that combined acquisition with passive avoidance of foot shock showed a significantly increased retention latency when tested 24 h later. Thus, this effect was rime-d ependent, and it was also found to be dose-dependent by further experi ment. In contrast, 2-deoxy-D-glucose and fructose had no such effect. In the Morris water maze task, glucose injection 2 or 3 h before a blo ck of trials enhanced the spatial memory performance of mice. These gl ucose-induced memory-facilitation effects were abolished by an intrace rebroventricular injection of anti-acidic fibroblast growth factor ant ibody 30 min before the glucose injection, suggesting a critical role for endogenous acidic fibroblast growth factor in this facilitatory ef fect. Furthermore, continuous intracerebroventricular infusion of acid ic fibroblast growth factor in rats significantly increased retention latency (when tested repeatedly on successive days using a passive avo idance task). Our earlier studies demonstrated that brain acidic fibro blast growth factor is produced in the ependymal cells of the cerebrov entricular system, and is released into the cerebrospinal fluid follow ing either a meal or a (intraperitoneal or intracerebroventricular) gl ucose injection. This released acidic fibroblast growth factor also di ffuses into the brain parenchyma, and is taken up by neurons in the hi ppocampus, hypothalamus, and elsewhere in the brain some 2 h after the meal or glucose injection. These and the present findings indicate (i ) that pre-training glucose injection improves memory performance, and (ii) that acidic fibroblast growth factor, especially by its action w ithin the hippocampus, is involved in this enhancement process. (C) 19 98 IBRO. Published by Elsevier Science Ltd.