Neural Release of Brain Serotonin and Body Temperature

Abstract

FELDBERG^1,2 has suggested that brain amines are directly involved in the hypothalamic control of body temperature. In cats and dogs serotonin was found to cause a rise in temperature and norepinephrine a fall, whereas in the rabbit³ and sheep⁴ there is a fall with serotonin and a rise with norepinephrine. Moreover, serotonin antagonizes the normal decrease of temperature of animals under anaesthesia. All these results, however, have been obtained using exogenous amines. We have shown that there is a neurally mediated release of endogenous serotonin in rat brain when the caudal midbrain raphé region is stimulated electrically and we have found that a specific behavioural consequence of such stimulation is a failure of the normal physiological habituation to repetitive sensory stimuli⁵. We have also measured the effect on body temperature of neurally released endogenous serotonin both in awake, unrestrained and in anaesthetized rats.