“…The significance of high levels of UCP2 mRNA in white fat and of UCP3 mRNA in skeletal muscle of hibernating squirrels is unknown [209]. Thermogenic hormones and factors such as 3,3h,5-tri-iodothyronine [57,178,179,[210][211][212][213], leptin [57,214,215], lipopolysaccharide and tumour necrosis factor-α [173,174,216,217] increase expression of the UCP2 and UCP3 genes in animals, suggesting a contribution to thermogenesis regulated by hormones or cytokines. Induction of UCP2 and UCP3 in tissues of rodents by lipopolysaccharide, interleukin-1β and other cytokines, and inhibition of the effect of lipopolysaccharide on UCP2 expression by a cyclo-oxygenase inhibitor [173], point to a possible role for the novel UCPs in the still unknown thermogenic mechanisms of fever.…”