Lipopolysaccharide-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Intravenous injection of lipopolysaccharide (LPS, 1 μg/kg) elicited triphasic thermogenic and tachycardic responses with the peaks at ∼60, 100, and 130 min in urethane-chloralose-anesthetized rats. The colonic temperature increased monophasically by 0.9–2.2 °C. Repeated bilateral microinjections of a GABAA receptor antagonist, bicuculline methiodide, into the preoptic area (POA) of the hypothalamus at 40, 80, and 120 min abolished all phases of the LPS-induced responses, which were also blocked by pretreatment with indomethacin, but not by vagotomy. These results suggest that the LPS-induced febrile responses are mediated by a GABA-receptive mechanism in the POA.