Psychophysiological stress induces heat shock cognate protein 70 messengerRNA in the hippocampus of rats

Psychophysiological stress has been shown to increase 70,000 mol. wt heat s hock protein messenger RNAs with northern blotting in rats. However, its lo calization is unknown. With in situ hybridization, we tested our hypothesis that restraint water-immersion stress may induce heat shock cognate protei n 70 messenger RNA expression simultaneously with some morphological change s selectively in the hippocampus of rats. Stress for 6 h significantly incr eased heat shock cognate protein 70 messenger RNAs in the hippocampus, with maximal intensity in the CA(3) subfield of the Ammon's horn and to a lesse r extent in CA(2). Stress for 12 h significantly increased heat shock cogna te protein 70 messenger RNAs in the whole hemisphere including the cerebral cortex, the thalamus, the hypothalamus, and the hippocampus with the highe st density in CA(3). Heat shock cognate protein 70 messenger RNA in rats wi th stress for 6 h followed by recovery for 6 h significantly increased at C A(3) and CA(2) compared with the controls or rats stressed for 6 h without recovery. No overt histological changes were detected in neuronal or glial cells in the slides of hematoxylin-eosin or Cresyl Violet staining. These r esults show that psychophysiological stress induces heat shock cognate prot ein 70 messenger RNA in the most stress-vulnerable brain structure, hippoca mpal CA(3), probably for cytoprotection, (C) 1999 IBRO. Published by Elsevi er Science Ltd.