Changes in serotonin contents in brain affect metabolic heat production of rabbits in cold.
Elevating serotonin (5-HT) contents in brain with 5-hydroxytryptophan (5-HTP) reduced rectal temperature (Tre) in rabbits after peripheral decarboxylase inhibition with the aromatic-L-amino-acid decarboxylase inhibitor R04-4602 at two ambient temperatures (Ta), 2 and 22 degrees C. The hypothermia was brought about by both an increase in respiratory evaporative heat loss (Eres) and a decrease in metabolic rate (MR) in the cold. At a Ta of 22 degrees C, the hypothermia was achieved solely due to an increase in heat loss. Depleting brain contents of 5-HT with intraventricular, 5,7-dihydroxytryptamine (5,7-DHT) produced an increased Eres and ear blood flow even at Ta of 2 degrees C. Also, MR increased at all but the Ta of 32 degrees C. However, depleting the central and peripheral contents of 5-HT with p-chlorophenylalanine (pCPA) produced lower MR accompanied by lower Eres in the cold compared to the untreated control. Both groups of pCPA-treated and 5,7-DHT-treated animals maintained their Tre within normal limits. The data suggest that changes in 5-HT content in brain affects the MR of rabbits in the cold. Elevating brain content of 5-HT tends to depress the MR response to cold, while depleting brain content of 5-HT tends to enhance the MR response to cold.
D006916:5-Hydroxytryptophan / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001545:Benserazide / Q000008:administration & dosage / Q000494:pharmacology; D001831:Body Temperature; D001833:Body Temperature Regulation; D001921:Brain / Q000378:metabolism*; D003080:Cold Temperature; D004423:Ear / Q000098:blood supply; D007274:Injections, Intraperitoneal; D008297:Male; D011817:Rabbits; D012039:Regional Blood Flow; D012701:Serotonin / Q000378:metabolism*; D012881:Skin Temperature; D014666:Vasomotor System / Q000502:physiology
D012701:Serotonin; D001545:Benserazide; D006916:5-Hydroxytryptophan