Expression of heat shock protein 90 (Hsp90) and transcription of its corresponding mRNA in broilers exposed to high temperature.

1. In order to understand the distribution and variation of Hsp90 and its corresponding mRNA in the tissues of heat-stressed broilers, 100 experimental birds were heat stressed for 0, 2, 3, 5 and 10 h. 2. Both nuclear and cytoplasmic Hsp90-positive signals were observed in myocardial cells, hepatocytes and renal tubule epithelial cells. The expression of Hsp90 increased in the heart, liver and kidney of broilers after exposure to high temperature for 2 h. 3. Following non-significant reduction after 3 and 5 h in the treatment groups, the expression of Hsp90 in the heart and kidney, but not in the liver, increased again after 10 h of heat stress. In the heart and kidney, hsp90 mRNA transcription levels exhibited the same trend as the protein expression of Hsp90. 4. Induction of hsp90 mRNA and Hsp90 protein at an early stressing stage indicated that heat stress can directly stimulate and quickly initiate the transcription of hsp90 mRNA and translation of Hsp90 protein to protect cells. 5. Hsp90 was strongly expressed in endothelial cells and blood vessel walls, suggesting that there is a relationship between vasoconstriction and Hsp90 localisation, which influences blood flow regulation.