OPTICAL VISUALISATION OF HEAT PRODUCTION IN BROWN ADIPOCYTES UPON ADRENERGIC STIMULATION

Abstract

Identification of brown adipose tissue in adults has led to significant interest in targeting this metabolically active tissue for treatment of obesity and diabetes. Improved methods for the direct measurement of heat production, as the signature function of brown adipocytes (BAs), would be of substantial benefit to these ongoing efforts. Here, I report the first application of a thermosensitive fluorescent dye, ERthermAC, to monitor thermogenesis in mouse and human BAs. ERthermAC accumulates in the endoplasmic reticulum of cells and displays a marked change in fluorescence intensity in response to adrenergic stimulation, corresponding to temperature change. ERthermAC fluorescence intensity profiles are congruent with mitochondrial depolarisation events visualised by JC-1 probe. Moreover, the averaged fluorescent intensity changes across a population of cells correlated well with dynamic changes such as thermal power, oxygen consumption, and extracellular acidification rates. These findings suggest ERthermAC as a promising new tool for studying thermogenic function in BAs.