抄録
The preoptic area (POA) of the hypothalamus is known to be the primary locus for body temperature regulation. Bilateral microinjections of GABA (300 mM, 100 nl) or the GABAA receptor agonist muscimol (100 μM, 100 nl) into the POA increased the rate of whole body oxygen consumption (VO2) and body core (colonic) temperature of urethane-chloralose-anesthetized, artificially ventilated rats. The GABA-induced thermogenesis reflected mainly nonshivering thermogenesis, because it was suppressed by pretreatment with intravenous administration of the β-blocker propranolol and was not affected significantly by that with the muscle relaxant. Then, the involvement of GABA in cold-induced thermogenesis was examined. Non-noxious cooling stimuli were delivered to the shaved back of rats by contact with a plastic bag containing 28°C water. Cooling of the skin increased the VO2, which response was also suppressed by pretreatment with propranolol but not by that with the muscle relaxant. Bilateral microinjections of the GABAA receptor antagonist bicuculline (500 μM, 100 nl), but not those of vehicle saline, into the POA blocked the thermogenic response elicited by cooling of the skin. These results suggest that GABA and GABAA receptors in the POA mediate cold-induced nonshivering thermogenesis. [Jpn J Physiol 54 Suppl:S231 (2004)]
