R-Ras3/(M-Ras) is involved in thermal adaptation in the critical period of thermal control establishment.

Neuroanatomically, the body temperature is balanced by the preoptic anterior hypothalamus (PO/AH) and controlled by thermosensitive neurons. Hot or cold exposure during the critical period of temperature control development causes a plastic change in the ratio between hot- and cold-sensitive cells and can modulate temperature tolerance. In this project, mRNA fingerprinting was used to identify the proteins involved in thermal adaptation in 3-day-old chicks. Fifteen genes were induced, among which were NADH dehydrogenase, protocadherin, anolase alpha, 14-3-3epsilon, and R-Ras3. The role of each of these genes is potentially interesting and requires detailed evaluation, but since the present working hypothesis assumed neuronal remodeling, we concentrated on the role of R-Ras3/(M-Ras), which is uniquely expressed in the brain and whose physiological role has not been described. In the present study, R-Ras3 expression during thermal conditioning was investigated by several molecular techniques and its mRNA was found to be induced in the PO/AH with a tenfold peak after 12 h of heat conditioning and a fourfold increase after 6 h of cold conditioning. To improve our understanding of thermal adaptation-related signal transduction, we screened for changes in the expression of transcription factors that were implicated with the Ras gene family, and found that both jun mRNA expression and Jun phosphorylation were induced after 30 min of temperature conditioning. Taken together, the present findings correlate the R-Ras3-jun pathway with thermal-control establishment.