Characterization of a System to Study the Uncoupling Protein Expression in Brown Adipocyte Primary Cultures

Abstract

Brown adipose tissue at birth is the main tissue involved in the neonatal thermogenesis. The brown fat mitochondria have a highly specialized protein called “uncoupling protein” which is the major component of the inner membrane and only present in this tissue. This protein is a carrier for protons and allows the re-entry of protons extruded by the respiratory chain, thus dissipating the proton-electrochemical gradient as heat (1). Synthesis of the uncoupling protein in vivo at birth is essentially controlled by the sympathetic fibers, releasing noradrenaline, stimulated by neonatal hypothermia. This acute effect is mimiced by the injection of isoproterenol (2). The possibility of the use of primary cultures of brown adipose tissue as a model to study the short-term and long-term regulation of uncoupling protein expression remains to be established. Thus, we report here the successful culture of brown adipocytes from rat fetuses in the last day of gestation to investigate the genetic expression of the uncoupling protein under several experimental conditions.