EFFECTS ON TEMPERATURE OF SEROTONIN AND EPINEPHRINE INJECTED INTO THE LATERAL CEREBRAL VENTRICLE OF THE CAT

¹ Department of Pharmacology, Mead Johnson Research Center, Evansville, Indiana

Serotonin (30-500 µg), administered via the lateral cerebral ventricle to conscious cats caused an immediate fall in the rectal temperature, followed later by a hyperthermia. This biphasic nature of the temperature response to serotonin has not been previously reported. The serotonin hypothermia was dose-related and seemed to be the major effect. Epinephrine (12.5 and 62.5 µg), similarly administered, resulted in a decrease in temperature. The hypothermic effect after serotonin was at variance with that of other investigators (Feldberg and Myers, 1964). However, it was consistently reproducible in this laboratory. It is proposed that the hypothermia observed may be a secondary effect of a vasoconstrictive action of serotonin in the hypothalamic area.