| When the warm-blooded animal is stimulated by the external high temperature environment,the body will produce a heat stress response.Regardless of human or animal,prolonged exposure to high temperature environment leads to abnormal physiological metabolism of the body.In mammals（including humans）,the reproductive system is most susceptible to heat stress damage,resulting in redox reactions in testicular tissues,apoptosis of spermatogenic cells,and decreased semen quality,directly affecting the ability of mammals to breed.Heat stress protein（HSP）is a class of highly conserved proteins produced during heat stress.Heat shock proteins are activated when the body is stimulated by high temperatures or other physical or chemical signals.Among them,Hsp70 is the most representative protein in the heat shock protein family,which has the effect of protecting tissue cells.In this study,8 week old male ICR mice were randomly divided into 4 groups,divided into control group,heat stress group,low dose of baicalein(100 mg·kg-1),high dose of baicalein(400 mg·kg-1).Except for the control group and the heat stress group,continuous administration was carried out for 14 days.On the 7th day,except for the control group,the other three groups were subjected to scrotal heat stress for15 min in a water bath at 43℃ to construct a mouse scrotum heat stress model.On day 14,all mice were dissected and testicular tissue was taken.By observing testicular histomorphology and antioxidant protein immune response,total superoxide dismutase（SOD）activity,testicular lipid peroxidation（MDA）,heat shock protein Hsp70 expression,antioxidant enzymes and withering Indicators of expression levels of death-related genes were tested.The testicular coefficient of mice showed that the testicular coefficient of the heat stress group was significantly lower than that of the control group（P<0.05）.Compared with the heat stress group,the testicular coefficient of the mice in the baicalein group was significantly increased（P<0.05）.And with the increase of the dose,the effect is more obvious.Morphological observation of testicular tissue showed that compared with the control group,spermatogenic cells in the testis tissue of the heat-stressed group showed obvious apoptosis,vacuolization occurred in the intercellular space,and the number of sperm decreased.Compared with the heat stress group,the mouse testicular tissue cells were significantly improved,and the spermatogenic cells almost returned to normal.The results of oxidation-related indicators showed that compared with the control group,the total superoxide dismutase（SOD）activity in the testis of the heat-stressed group was significantly decreased（P<0.05）,and the propylene glycol（MDA）content was significantly increased（P<0.05）.The total SOD activity and MDA content in the testis of the baicalein group were similar to those in the control group,and the difference was significant compared with the heat stress group（P<0.05）.In order to explore the molecular mechanism of heat stress-induced oxidative damage in testis of mice,this experiment uses real-time fluorescent quantitative PCR detection and immunohistochemistry.The results showed that compared with the control group,the expression levels of SOD1 mRNA,SOD2 mRNA and GPx4 mRNA in the testis of the heat stress group were significantly lower（P<0.05）.Compared with the heat stress group,the expression levels of SOD1 mRNA,SOD2 mRNA and GPx4 mRNA in the testis of the baicalein group were significantly increased.The results of immunohistochemistry showed that compared with the control group,the immune response of SOD2,GPx1 and GPx4 protein in the testis of the heat stress group was significantly decreased.Compared with the heat stress group,the testicular SOD2 of the baicalein group was compared.Both GPx1 and GPx4 protein immune responses were significantly increased.The above results indicate that baicalein can promote the growth and development of mouse testis,protect tissue integrity,enhance the activity of antioxidant enzymes,inhibit lipid peroxidation,and achieve antioxidant effects.To explore the molecular mechanism of heat shock protein Hsp70 in testis,ELISA and real-time quantitative PCR were used.The results showed that compared with the control group,the Hsp70 protein content and Hsp70 mRNA gene expression level in the testis of the heat stress group were significantly lower（P<0.05）.Compared with the heat stress group,the Hsp70 protein activity and Hsp70mRNA gene expression in the testis of the baicalein group were significantly increased（P<0.05）.PCR results of apoptosis-related factors showed that compared with the control group,the expression of anti-apoptotic factor Bcl-xL mRNA in the testis of the heat-stressed group was significantly increased,and the expression levels of the apoptosis-inducing factors Bax mRNA and caspase3 mRNA were significantly lower.Low（P<0.05）.The expressions of Bcl-xL mRNA,Bax mRNA and caspase3mRNA in the testis of the baicalin group returned to normal levels,which were significantly different from those in the heat stress group（P<0.05）.The above results indicate that baicalein can promote the biological activity of heat shock protein Hsp70and inhibit the apoptosis of spermatogenic cells.The results of this experiment indicate that baicalein protects the reproductive system function of mice by reducing heat stress-induced testicular redox reaction,enhancing heat shock protein Hsp70 activity and inhibiting apoptosis. |
