Synergic effect of overweight and cold on uncoupling proteins expression, a role of alpha(2)/beta(3) adrenergic receptor balance?

The effect of cold exposure, being overweight and their interaction was investigated on the response of uncoupling proteins UCP1, UCP2 and UCP3 and the alpha(2)/beta(3) adrenergic receptor (AR) balance in brown adipose tissue (BAT), as well as the involvement of leptin gene expression in white adipose tissues, in control and overweight male rats of the dietary obesity model known as the post-cafeteria model. UCP1, UCP2 and UCP3 mRNAs were up-regulated by cold, with a synergic effect of cold exposure and being overweight on UCP1 mRNA levels (with the related UCP1 protein response), and with UCP2 mRNA showing a parallel response. Furthermore, the BAT alpha(2)/beta(3) AR ratio was diminished in overweight rats. The results suggest that the UCP1-dependent thermogenic capacity in BAT of post-cafeteria overweight rats has a more sensitive response to cold exposure and that UCP2 and UCP3 could be somehow involved in the thermogenic response but differentially regulated. Moreover, the diminished alpha(2)/beta(3) AR ratio in BAT could be one of the factors involved in the more sensitive response of overweight rats to cold in terms of BAT thermogenesis-related parameters.