Elevating serotonin levels in brain with 5-hydroxytryptophan produces hypothermia in rats.
The effect of the 5-hydroxytryptamine (5-HT) precursor 5-hydroxytryptophan (5-HTP) on the thermoregulatory responses of unanesthetized rats were assessed at three different ambient temperatures (Ta) of 8, 22 and 31 degrees C. Intraperitoneal administration of either 5-HTP alone or 5-HTP plus R04-4602 (the peripheral decarboxylase inhibitor) produced dose-dependent hypothermia at both Ta's of 8 and 22 degrees C. The hypothermia was brought about solely by a decrease in metabolic heat production at 8 degrees C Ta. At 22 degrees C Ta, the hypothermia was due to both a decrease in metabolic heat production and an increase in tail and footsole skin temperature. However, at 31 degrees C Ta, there were no changes in rectal temperature in response to either 5-HTP or 5-HTP plus R04-4602 application. The data suggest that an increase in 5-HT levels in brain decreases heat production and/or increase heat loss and leads to hypothermia in rats.
D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000818:Animals; D001545:Benserazide / Q000494:pharmacology; D001833:Body Temperature Regulation / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*
D012701:Serotonin; D001545:Benserazide; D006916:5-Hydroxytryptophan