Discovering The Developmental Origins of Obesity

The Polish Academy of Sciences in Olsztyn, Poland

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Assessing the molecular basis for thermogenesis of brown adipocytes in interscapular brown fat and inguinal fat

tn Emilia Pawel poster Paris June 2013INTRODUCTION
Two types of fat tissue with diametrically opposing functions are present in humans and other mammals: white adipose tissue (WAT), which stores fat, and brown adipose tissue (BAT), which burns fat to produce heat. White adipocytes are almost completely filled with one lipid droplet surrounded by a thin layer of cytoplasm with little mitochondria. Brown adipocytes, in contrast, contain several small lipid droplets and a cytoplasm rich in mitochondria. BAT may exist in organism as a discrete organ that initially has been found in newborns mammals or it may exists as diffuse highly variable population of brown adipocytes within white fat depots (brite cells). While phenotypes of Ucp1-/- mice indicate that interscapular BAT (iBAT) is required for body temperature regulation, the function of brite cells is uncertain, although it is possible that induction and activation of brite cells may contribute to the regulation of body weight. Although the brown adipocytes of iBAT and brite cells have different genetic and developmental origins, it is unknown whether these two types of brown adipocytes have similar thermogenic capacities, that is, do these brown adipocytes have identical or different thermogenic potentiality. This property may be important to the effectiveness of each type of brown adipocyte in contributing to energy balance in an organism.

In our study we have estimated thermogenic potential of iBAT cells and brite cells in the inguinal fat depot by estimating the proportion of UCP1 to components of the respiratory complex during induction at 4°C and then during involution at 29°C. This study has beenmade possible by the availability of inbred strain of mice – AXB8, with a high capacity for UCP1 expression in brite cells.