Stress-Induced Phosphorylation of C-JUN-N-Terminal Kinases and Nuclear Translocation of Hsp70 in the Wistar Rat Hippocampus

Abstract

Glucocorticoids are key regulators of the neuroendocrine stress response in the hippocampus. Their action is partly mediated through the subfamily of MAPKs termed c-jun-N-terminal kinases (JNKs), whose activation correlates with neurodegeneration. The stress response also involves activation of cell protective mechanisms through various heat shock proteins (HSPs) that mediate neuroprotection. We followed both JNKs and Hsp70 signals in the cytoplasmic and nuclear compartments of the hippocampus of Wistar male rats exposed to acute, chronic, and combined stress. The activity of JNK1 was decreased in both compartments by all three types of stress, while the activity of cytoplasmic JNK2/3 was elevated in acute and unaltered or lowered in chronic and combined stress. Under all stress conditions, Hsp70 translocation to the nucleus was markedly increased. The results suggest that neurodegenerative signaling of JNKs may be counteracted by increase of nuclear Hsp70, especially under chronic stress.