Changes in ingestive behavior, serum glucose and free fatty acids concentrations in rats following intracerebroventricular injection of spermine.

We examined the changes in ingestive behavior, serum glucose (Glc) and free fatty acids (FFA) concentrations in male rats following intracerebroventricular (i.c.v.) injection of spermine (SPM). In satiated rats, over a 53.3 nmol of SPM suppressed feeding and drinking behavior in a dose-dependent manner. The median suppressive dose was 90.8 nmol for feeding behavior and 68.3 nmol for drinking behavior. Spermidine also suppressed ingestive behavior but the potency was appreciable weak compared to that of SPM, and the occurrence of the maximal suppression was observed 2-3 days later than that of SPM. The most significant anorexia and adipsia induced by SPM appeared between 16 and 36 hr after i.c.v. administration. SPM (180 nmol) produced a biphasic increase in serum Glc concentration. The 1st peak was at 1 hr and the other peak was 24 hr after the dosing. The same dose of SPM elevated serum FFA concentrations gradually, and the maximal increase appeared 24 hr after the injection. As less than a 120 nmol dose of SPM did not alter serum Glc and FFA concentrations, there seems to be no causal relation between SPM-induced anorexia, and changes in serum Glc and FFA concentrations. Nevertheless, the findings that a very small dose of SPM produced anorexia and adipsia support the possibility that SPM may play some functional role in the brain.