[Effect of repeated serotonin injections on temperature regulation in the rat]

The effect of repeated serotonine injections was investigated in thirty Wistar rats tested under normo-, hypo- und hyperthermic conditions. 7 mul of a 0.5% serotonine solution (5HT) were injected into the third ventricle at 1-hr intervals. Temperature responses such as oxygen consumption and rectal temperature were measured and the heat loss was calculated. Intraventricular serotonine produced cooling in all animals. The central mechanisms of heat production were inhibited and those of heat loss were activated. The serotonine responses were most pronounced in hypothermic rats and least effective in hyperthermic animals.