Functional role of the preoptic area and anterior hypothalamus in thermoregulation in freely moving rats.
We recently reported that perfusion of tetrodotoxin (TTX) into the preoptic area and anterior hypothalamus (PO/AH), by using a microdialysis technique, induced an increase in body temperature (Tb) under normal and hot ambient temperatures (23 and 35 degrees C) in freely moving rats. However, the procedure had no effect on Tb under a cold ambient temperature (5 degrees C). The present study was designed to determine the mechanism(s) of increases in Tb after perfusion of TTX into the PO/AH, by measuring tail skin temperature (Ttail) as an index of heat loss, and heart rate (HR) and locomotor activity (Act) as indexes of heat production, under three ambient temperatures. Under normal ambient temperature (23 degrees C), perfusion of TTX induced significant hyperthermia with increased HR, Act and Ttail. In a hot environment (35 degrees C), perfusion of TTX induced a greater increase in Tb with increased HR but no change in Ttail and Act. In a cold environment (5 degrees C), perfusion of TTX had no effect on Tb with a slight increase in Act but no change in HR and Ttail. Our results suggest that the PO/AH may be involved in inhibition of heat production and excitation/inhibition of the tail vasomotor tone.
Ishiwata
Takayuki
T
Department of Biology, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan. ishiwata@comp.metro-u.ac.jp
Hasegawa
Hiroshi
H
Yazawa
Toru
T
Otokawa
Minoru
M
Aihara
Yasutsugu
Y
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D007032:Hypothalamus, Anterior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D017551:Microdialysis; D009043:Motor Activity / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012881:Skin Temperature / Q000187:drug effects; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013623:Tail; D013779:Tetrodotoxin / Q000494:pharmacology
D026941:Sodium Channel Blockers; D013779:Tetrodotoxin