The biology of adipose tissue in non-ruminants: renewed interests in oxido-reduction pathways

White adipose tissue (WAT) comprises large fat depots interspersed in the body and plays a major role in energy homeostasis. This primary function related to lipid metabolism and mainly ensured by cytosolic enzymes acting in lipid synthesis or triacylglycerol hydrolysis is well documented in the literature. WAT is also characterized by a low number of mitochondria compared with brown adipose tissue, a fat depot specialized in heat production. Therefore, the relevance of mitochondria in WAT metabolism and how their metabolism could impact whole-body energy homeostasis have received only limited interests, especially in species such as pigs lacking UCP1, the hallmark of brown adipocytes. Recently, several high-throughput studies have revealed that mitochondrial genes playing roles in fatty acid beta-oxidation, energy oxido-reduction or response to oxidative stress were regulated in WAT following genetically- and environmentally-induced variations in animal’s growth efficiency and body fat mass. Activities of some of the encoded enzymes were also modulated, suggesting actual modifications in adipocyte physiology. Moreover, the abundance of proteins acting in oxidation or antioxidant processes exhibited significant differences along WAT development in pig fetuses. Finally, experiments on porcine preadipose cells harvested from WAT showed that adipogenesis and reactive oxygen species production in adipocytes can be modulated by exogenous antioxidant substances. Thus, a renewed interest in mitochondrial oxido-reduction metabolism in WAT may be useful for a better control of adipose tissue features in animal production