Neuro-immunohistochemical and molecular gene expression variations during hibernation and activity phases between Rana mascareniensis and Rana ridibunda.

Low temperatures and the lack of food during the winter lead the marsh frog Rana ridibunda and the grass frog Rana mascareniensis to hibernate in order to survive. The present study aimed to investigate the cytoarchitecture of brain sub-regions affected by the thermal cycle's fluctuations during the hibernation and activity period, besides the regional distribution quantitative expression of Na(+)/K(+)-ATPase and Pax6 transcriptional factor, the molecular gene expressions of some heat shock proteins, uncoupling protein, and metallothionein. The two frog species were isolated from the field during summer and hibernation time in winter.