Abstract
We sought to clarify the role of brain polyamines on stress-induced hyperthermia (SIH), a model of anticipatory anxiety, after single injection of diazepam, polyamine or 14-days injections of α-difluoromethylornithine (DFMO), a specific inhibitor of polyamine synthesis. In addition, polyamine levels in the hippocampus and hypothalamus were measured after putrescine or DFMO treatments. Male C57BL/6J mice are subjected to two sequential rectal temperature measurements with a 10-min interval. The first measurements is the basal temperature (T1) and the second is the stress-enhanced temperature (T2) and the difference (delta-T=T2-T1) is regarded as SIH. In control mice, delta-T was nearly 1°C. Pretreatment with diazepam dose-dependently inhibited the SIH. Similarly, putrescine blocked delta-T although T1 was decreased, dose-dependently. Furthermore, spermidine and spermine also lowered delta-T and T1 at the doses lower than putrescine. In contrast, DFMO had no effect on T1 but it increased delta-T. Pretreatment with putrescine or DFMO increased or decreased brain putrescine levels, respectively. These results suggest that endogenous brain putrescine and other polyamines might have an anxiolytic-like effect under stressful conditions. [J Physiol Sci. 2007;57 Suppl:S178]
