INDUCTION OF THE SYNTHESIS OF HSP27 AND ALPHA-B-CRYSTALLIN IN TISSUES OF HEAT-STRESSED RATS AND ITS SUPPRESSION BY ETHANOL OR AN ALPHA(1)-ADRENERGIC ANTAGONIST

The levels of hsp27 and alpha B crystallin in various tissues of Fats that had been subjected to heat stress were determined by specific immunoassays. When rats were immersed in a water bath at 42 degrees C for 20 min, the levels of hsp27 in most tissues, including central nervous tissue, liver, lung, spleen, adrenal glands, and hypophysis, had increased dramatically 8 to 16 h after the treatment. alpha B crystallin was also induced at high levels in the liver and adrenals, but not much was induced in the central nervous tissue. The increases in the levels of both hsp27 and alpha B crystallin in response to heat stress were markedly inhibited when ethanol or an alpha(1)-adrenergic antagonist, prazosin, was administered before, but not after, the stress period. The expression of mRNA for hsp27 was suppressed in the livers of rats that had received ethanol or prazosin. A beta-adrenergic antagonist, propranolol, and an alpha(2)-adrenergic antagonist, yohimbine, did not inhibit induction of the synthesis of the two proteins. Accumulation of hsp70 after heat stress, at least in the liver, was inhibited by ethanol or prazosin in a similar manner to that of hsp27, as detected on Western blot analysis. These results suggest that the induction of hsp27 and alpha B crystallin, as well as of hsp70, in tissues of heat-stressed rats is controlled by a physiological process(es) that is sensitive to ethanol and prazosin, and is operative for a short time during the application of heat stress.