Characterization of the peroxisome proliferator activated receptor coactivator 1 alpha (PGC 1alpha) expression in the murine brain.

The peroxisome proliferator activated receptor coactivator 1 alpha (PGC-1alpha) is a nuclear transcriptional coactivator that is expressed in brown adipose tissue, brain, heart and kidney as well as cold-exposed skeletal muscle. In liver, white and brown adipose tissue, PGC-1alpha expression is regulated in a manner suggesting a role in energy homeostasis. To characterize PGC-1alpha expression in the rodent brain and to determine brain PGC-1alpha regulation, we used in situ hybridization histochemistry in C57Bl/6J mice and Sprague-Dawley rats. We found that PGC-1alpha is widely expressed in brain areas, including in the olfactory bulb, cerebral cortex, the diagonal band of Broca, the medial septal nucleus, reticular thalamic nucleus, the striatum and globus pallidus, the hippocampus, the substantia nigra, the mesencephalic nucleus of the trigeminal nerve, the cochlear nucleus and the superior olivary complex. In contrast, PGC-1alpha expression was absent in the hypothalamus. To evaluate PGC-1alpha expression under different physiologic states in these various brain areas, we examined expression with fasting, leptin treatment and cold exposure (4 h at 4 degrees C) and found no change, nor was expression changed in the brain of the leptin-deficient ob/ob mice and the hyperleptinemic UCP-DTA mice. Hence, PGC-1alpha is widely expressed in the rodent brain, but is not regulated by states of caloric deficiency, leptin, obesity or cold exposure. Its functional role in the brain requires further study.