Effects Of Acute Cold And Heat Stress On Physiological And Biochemical Indexes And HSP70 Family Gene Expression In Goats And Sheep

China's four seasons temperature change range is large,prone to temperature rise or drop phenomenon.At present,researches on cold and heat stress of goats and sheep mainly focus on chronic stress,while the effect of acute cold and heat stress on goats and sheep is rarely reported.This experiment studied the effects of acute cold and heat stress on the physiological,antioxidant,immune and HSP70 family gene expression in goats and sheep,aimed to explore the early response mechanism,and provide theoretical basis for the early monitoring and prevention of cold and heat stress.Exp.1 Effects of acute heat stress on physiological,biochemical indexes and HSP70 family gene expression in goatsFive?12±0.5?-month-old healthy female goats?F₁ of Boer goat×Guanzhong dairy goat?were selected and raised separately at Cage in an environment controlled chamber?temperature:20?,relative humidity:60%?,adaptation period lasted for 5 d.Three high-temperature treatments were set at 30?,34?and 38?,and five goats were treated with self-control.Each high-temperature maintained 12 h,and then gradually revert to suitable environment?20??,and kept on for 3.5 d.Blood samples were collected,then serum antioxidant indexes,immune indexes and the expression of HSP70 family genes?HSPA1A,HSPA6 and HSPA8?in blood lymphocytes were measured by colorimetric method,ELISA and RT-PCR,respectively.The results showed that:?1?Compared with that before stress,the respiratory rate?RR?and rectal temperature?RT?of goats significantly increased at 2-12 h of heat stress at different temperatures?P<0.05?,and the change was most obvious at 38?.There was no significant change in heart rate?HR??P>0.05?.RR and RT could return to normal level in a short time?8 h and 4h?after restoring the appropriate temperature?P>0.05?.?2?serum SOD,GSH-Px activities?30?,2 h?and T-AOC contents?34?,4 h?increased significantly?P<0.05?.The activities of SOD,GSH-Px and T-AOC decreased significantly?P<0.05?and the content of MDA increased significantly?P<0.05?when heat stress lasted for 8-12 h at 30?and 38?.?3?Heat stress at different temperatures significantly increased the contents of TNF-?,IL-1?and IL-2?P<0.05?.In addition,IgG content significantly increased at 30?for 8-12 h?P<0.05?,and IgG,IgM and IgA significantly decreased at 38?for 4-12 h?P<0.05?,and IL-4 significantly decreased at 12 h?P<0.05?.?4?The expression of HSPA1A mRNA increased significantly at 30?and 34?for 2-8h?P<0.05?,and at 38?for 2-12 h?P<0.05?,both of which showed a trend of first increasing and then decreasing.HSPA6 mRNA expression increased significantly at 30?and 38?for2 h?P<0.05?,and at 34?for 2-4 h?P<0.05?,and then returned to normal level?P>0.05?.HSPA8 mRNA expression increased significantly at 4-8 h of heat stress at different temperatures?P<0.05?.Exp.2 Effects of acute heat stress on physiological,biochemical indexes and HSP70 family gene expression in sheepEight?12±0.5?-month-old healthy female sheep?F₁ of Small Tail Han sheep×Hu sheep?were selected and raised separately at cage in heat-preserved sheep house?wind chill temperature:-7.14±2.53??.The adaptation period lasted for 7 d.At the 8th day,sheep were treated with acute cold stress for 12 h in outside?wind chill temperature:-27.40±3.12??.Blood samples were collected at different time points of cold stress and tissue samples before and after cold stress,the expression of HSP70 family genes?HSPA1A,HSPA6 and HSPA8?in different tissues?liver,kidney,spleen,heart,longissimus dorsi muscle and duodenum?were measured by RT-PCR method,Other experimental method were the same as that of Exp.1.The results showed that:?1?RR decreased significantly at 4-12 h of acute cold stress?P<0.05?.RH increased first and then decreased with the prolongation of cold stress time,and increased significantly at 2-12 h?P<0.05?.RT decreased significantly at 12 h?P<0.05?.?2?Acute cold stress decreased significantly serum SOD,GSH-Px activity and T-AOC content?P<0.05?,increased MDA content?P<0.05?.Increased significantly TNF-?,IL-1?,IFN-?and IL-2 content?P<0.05?,and decreased IL-4,IgG,IgM and IgA content?P<0.05?.?3?At 12 h.The expression of HSPA1A mRNA significantly increased in liver,kidney,heart and longissimus dorsi muscle?P<0.05?.HSPA6 mRNA expression significantly increased in the heart and longissimus dorsi muscle?P<0.05?.HSPA8 mRNA expression significantly increased in the longissimus dorsi muscle?P<0.05?and decreased in the spleen and duodenum?P<0.05?.Conclusions:?1?Temperature and time of acute cold and heat stress had different effects on goats and sheep.With appropriate high temperature?30?and 34??and short time heat stress,goats chould resist resist heat stress by regulating physiological parameters,increasing antioxidant enzyme activity,regulating immune factor activity and HSP70 gene expression to adapt to high temperature environment.But long time or extreme high temperature?38??heat stress or extreme low temperature?-27??cold stress chould destroy the body temperature balance,reduce antioxidant and immune functions and damage the health of the body.?2?HSPA1A was more sensitive to temperature and time of cold and heat stress in HSP70 family genes,and could be used as a biomarker for early cold and heat stress.