Proteomics analysis of hypothalamic response to energy restriction in dairy cows.

The hypothalamus is the central regulatory unit that balances a number of body functions including metabolic rate, hunger, and satiety signals. Hypothalamic neurons monitor and respond to alterations of circulating nutrients and hormones that reflect the peripheral energy status. These extracellular signals are integrated within the cell at the ATP:AMP ratio and at the level of ROS, triggering gene expression associated with glucose and lipid metabolism. In order to identify new molecular factors potentially associated with the control of energy homeostasis, metabolic adaptation, and regulation of feed intake, hypothalami from ad libitum fed and energy restricted cows were characterized using 2-DE and MALDI-TOF-MS. Among 189 different protein spots identified, nine proteins were found to be differentially expressed between groups. Beside the 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase, stress-induced phosphoprotein-1, heat shock protein 70 kDa-protein-5, dihydropyrimidinase-related protein-2, [Cu-Zn]-superoxide dismutase, ubiquitin carboxy-terminal hydrolase-L1, and inorganic pyrophosphatase were found to be up-regulated, whereas glyceraldehyde 3-phosphate dehydrogenase and aconitase-2 were down-regulated in the restricted group. In conclusion, differentially expressed proteins are related to energy and nucleotide metabolism and cellular stress under conditions of dietary energy deficiency. These proteins may be new candidate molecules that are potentially involved in signaling for maintaining energy homeostasis.