Tissue Damages And Expression Of Hsp90 And Its Corresponding MRNA In The Heat-Stressed Broilers

One hundred AA broilers were divided into 5 groups at random and 20 broilers per group.After 30 days adaptive feeding under the normal condition,80 broilers were stressed by suddenly increasing environment temperature from(25±1)℃to(40±1)℃for 2,3,5, 10 h,respectively.On terminating the heat stress,each bird was sacrificed by decapitation. Heart,liver and kidney were chosed to investigate the study on heat-stressed tissue damages and expression of Hsp90 and its corresponding mRNA in broilers.By means of histopathology,immunohistochemistry,enzyme linked immunosorbent assay(ELISA) and fluorescence quantitative real-time polymerase chain reaction(FQ RT-PCR),the tissue pathological injuries,the distribution of Hsp90,expression of Hsp90 and its corresponding mRNA in the tissue of stressed broilers were studied.The results of histopathology and immunohistochemistry showed that the parenchymal cell damage of the heart,liver,kidney,lung,spleen and thymus of the broiler chickens gradually aggravated with stress prolonging in the period of 2-5 h after heat stressing,and the typical histopathological changes were granular degeneration,adipose degeneration, hyperemia and necrosis.The Hsp90-positive immunoreactivity was detected in both nucleus and cytoplasm of tissue.However,in all examined tissues,the nuclear signals of Hsp90 were the most prominent.And the Hsp90 signals in the places where tissues showed integrity were stronger than the other places.Strong Hsp90-positive immunoreactivity was also observed in the endothelial cells and the wall of heart blood vessels,the endothelial cells of the central vein and sinusoid of the liver,the epithelium cells of the glomerular capillary vessels and the endothelial cells and the wall of arteriolar blood vessels of the nephridial tissues,the endothelial cells and the wall of lung arteriolar blood vessels,the endothelial cells and the wall of spleen central arteriolar blood vessels of broiler.The results of ELISA and FQ RT-PCR showed that Compared to the control group,the results of ELISA showed that the expression of Hsp90 increased significantly(p＜0.01) in the heart,liver and kidney of heat-stressed broilers after exposure to high temperature for 2 h.Following a slight reduction(p＞0.05) of Hsp90 concentrations at 3 and 5 h in the treatment groups,the expression of Hsp90 in the heart(p＜0.01) and kidney(p＜0.05) exhibited further induction after 10 h of heat stress.In the liver(p＞0.05),however,the concentration of Hsp90 gradually decreased with increasing heat stress.Our results demonstrate that hsp90 mRNA expression in the heart,liver and kidney of broilers exhibits the same trend as Hsp90 protein expression in the heart and kidney of broilers during acute heat stress.In the initial stage of heat stressing,the levels of hsp90 mRNA and the concentration of Hsp90 significantly increased.Subsequently,the hsp90 mRNA and Hsp90 protein expression decline after 3 and 5 h of heat stress.As heat stress prolonged,the levels of hsp90 mRNA and the concentration of Hsp90 protein are observed to rise again after 10 h of heat stress.According to the above results,we get conclusions:There should be certain degree of correlation between the distribution and expression of Hsp90 and the histologic lesions of the tissue of the broiler chickens under stress state.The observation of histopathology of tissues and the distribution of Hsp90 showed that the region where tissues represent integrity,the signals were stronger than the other places.We can conclude that Hsp90 protect the cells from damage.High expression of Hsp90 was detected in the endothelial cells of blood vessels and the arteriolar wall of all examined organ tissues.This suggests that Hsp90 plays a role in the functioning of blood vessels.The variation of Hsp90 expression in the endothelial cells of blood vessel and the arteriolar wall may influence blood supply to some organs via regulation of vasoconstriction and vessel relaxation.As heat stress prolonged,the variable properties of Hsp90 concentration exhibit an oscillatory pattern,and the hsp90 mRNA transcription exhibits the same trend as Hsp90 protein expression at the same period.It demonstrated that the expression of Hsp90 and its corresonding mRNA are depend on the duration and temperature of heat stress,and it implied that the variation of Hsp90 expression and hsp90 mRNA transcription levels,might be hallmark to assessment stress damage.