Nerve Growth Factor, Brain-Derived Neurotrophic Factor and Osteocalcin Gene Relationship in Energy Regulation, Bone Homeostasis and Reproductive Organs Analyzed by mRNA Quantitative Evaluation and Linear Correlation Analysis.

Nerve Growth Factor (NGF)/Brain-derived Neurotrophic Factor (BDNF) and osteocalcin share common effects regulating energy, bone mass, reproduction and neuronal functions. To investigate on the gene-relationship between NGF, BDNF, and Osteocalcin we compared by RT-PCR the transcript levels of and as well as of their receptors , and in brain, bone, white/brown adipose tissue (WAT/BAT) and reproductive organs of 3 months old female and male mice. Brain and bone were used as positive controls for NGF/BDNF and Osteocalcin respectively. The role of oxitocin() and its receptor() was also investigated. expression shows an opposite trend compared to . / expression is 50% higher in BAT than brain, in both genders, but lower in bone. In contrast, expression in bone is higher than in brain, but low in BAT/WAT. We found gene expressed in brain in both genders, but expression is low in brain and BAT/WAT. As expected, gene is expressed in bone. gene was markedly expressed in brain, in the ovaries and in fat and bone in both genders. is highly expressed in reproductive tissues and mRNA levels are respectively 300, 100, and 50% higher in testis/ovaries/uterus than in brain. In contrast, BDNF genes are not expressed in reproductive tissues. As expected, is expressed in testis but not in the ovaries/uterus. A significant correlation was found between the expression levels of the gene ligands and their receptors in brain, BAT and testis suggesting a common pathway of different genes in these tissues in either male and female. Changes in the expression levels of , or genes may mutually affect the expression levels of the others. Moreover, it may be possible that different ligands may operate through different receptor subtypes. and failed to show significant correlation. The up-regulation of / in BAT is consistent with NGF as an energy regulator and with BDNF regulating bone.