PHGDH and carnosinemia: Considering that high levels of carnosine are associated with neurological dysfunction and that the pathophysiological mechanisms involved in serum carnosinase deficiency remain poorly understood, we investigated the in vivo effects of carnosine on bioenergetics parameters, namely, respiratory chain complexes (I–III, II, and II-III), malate dehydrogenase, succinate dehydrogenase, and creatine kinase activities and the expression of mitochondrial-specific transcription factors (NRF-1, PGC-1α, and TFAM) in skeletal muscle of young Wistar rats.