[Background]: Brown adipose tissue (BAT), a highly innervated and irrigated tissue, is responsible for the adaptive response to cold, activating thermogenesis. Heat production in BAT is achieved by inducing the mitochondrial uncoupling protein (UCP-1) expression and the production of fatty acids generated by lipolysis. This response to cold is regulated by the release of noradrenaline from the innervating nervous system. [Objectives]: We have studied the effect of cold exposure on BAT of heterozygous animals for tyrosine hydroxylase (Th), the limiting enzyme of the catecholamines synthesis pathway. Analysis of BAT during late stages of embryonic development and perinatal stages should give us information of the importance of this mutation in development of this target tissue. [Results]: Staining with H&E showed some differences in the histology of tissue with a more “compact” appearance in TH+/- mice. Analysis by immunohistochemistry and western blot confirmed the lower expression of TH in the BAT of the TH +/- mice. The catecholamine levels measured by ELISA showed a decreased in the dopamine and noradrenaline BAT content of TH +/- animals in response to cold. However, the reduced of catecholaminergic response to cold of the TH+/- BAT did not result in a diminished cold adaptation. The TH+/- mice showed similar Ucp1 induction after cold exposure to those of the wild type mice. In addition, we found that some key genes in the BAT browninig, such as Prdm16 and Fgf21, were increased in TH+/- mice in thermoneutrality conditions. Similarly to the BAT, the inguinal white adipose tissue (iWAT) of TH+/- mice responds normally to cold. [Conclusion]: We are studying the compensatory mechanisms that allow normal UCP-1 expression in TH +/- mice BAT despite the lower expression of TH and catecholamines compared to wild type animals. The analysis of other important tissue during thermogenesis, the iWAT, could help us to understand these mechanisms and the browning process.

Resumen del póster presentado presentado al CIBERDEM Annual Meeting, celebrado en Cerdanyola del Vallès, Barcelona (España) del 11 al 13 de mayo de 2016.-- et al.

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