Activation of the MAPK signaling pathway induces upregulation of pro-apoptotic proteins in the hippocampi of cold stressed adolescent mice.

Stress induces many non-specific responses in the hippocampus, especially during adolescence. Low environmental temperature is known to induce stress, but its influence on the hippocampus, especially in adolescent mice is not clear. We compared apoptotic-related protein levels and MAPK signaling pathway activation in hippocampal neurons of adolescent mice under low temperature conditions (4 °C for 12 h) with western blotting and immunohistochemistry. Western bolt results demonstrated that the levels of phospho-JNK, phospho-p38, and cleaved-caspase 3 significantly increased, while the ratio of Bcl-XL/Bax decreased, in the cold stress group. The results of immunohistochemistry (IHC) and Nissl staining demonstrated that the protein optical density of caspase 3 increased and Nissl bodies decreased in the cold stress group compared with controls. Thus, we conclude that cold exposure initiates activation of the MAPK signaling pathway and subsequently induces the upregulation of pro-apoptotic proteins in the hippocampi of adolescent mice. Overall our study reveals the relationship between cold stress and apoptosis in adolescent mice.