Heat Stress Damage In Mice By Lycopene Research On Protection Mechanism

Objective: To explore the damage and mechanism of heat stress on reproductive function of male mice,as well as the protective effect of lycopene on heat stress injury of testis in mice and the possible mechanism.Methods:Using randomized controlled experiments,60 healthy male Kunming mice aged 7-8 weeks were randomly divided into 6 groups: normal control group(CON),heat stress group(HS),lycopene group(LYC 10 mg / kg BW),low dose lycopene +heat stress group(L-LYC 10 mg / kg BW),medium dose lycopene + heat stress group(M-LYC 20 mg / kg BW),and high dose lycopene + heat stress group(H-LYC40 mg /kg BW).Lycopene was administered by gavage,and a heat stress model was established by placing the testis in a 43-℃ water bath for 20 min.Mice were sacrificed 24 h after a hot bath.Body weight and testis and epididymis were measured,and testis and epididymis indexes were calculated;sperm suspension of epididymis were collected for sperm number and motility analysis;hematoxylin-eosin staining microscope for histopathological changes in testicular tissue and epididymis;lipid peroxide(MDA)and antioxidant enzyme(SOD);and protein expression levels of Nrf2,NQO 1 and HO-1 in testis in different treatment groups.Results:(1)Compared with normal control group,the body weight,epididymis and epididymal index of mice after heat stress treatment had no significant decrease(P >0.05),but the testicular weight and index of mice were significantly decreased(P <0.01).After three different doses of lycopene treatment,the testis weight and testis index decreased significantly(P < 0.05).Compared with the control group,the sperm motility rate and number of mice after heat stress treatment were significantly decreased(P < 0.05),and the sperm motility rate and number of mice after three doses of lycopene administration group were significantly increased(P < 0.05).Compared with the normal control group,the number of spermatogenic cells in the spermatogenic tubules of testis in the heat stress group was reduced,the arrangement of spermatogenic cells at all levels was disordered,and the number and density of spermatogenic cells in the epididymis were significantly reduced.Lycopene administration could partially alleviate the above pathological injuries caused by heat stress on testis and epididymis of mice.(2)Compared with normal control group,MDA in heat stress group was significantly increased(P < 0.01),SOD was significantly decreased(P < 0.01),and protein expressions of Nrf2,NQO1 and HO-1 were significantly decreased(P < 0.05).Three doses of tomato red could significantly reduce MDA levels in testicular tissue of mice after heat stress(P < 0.01).The expression levels of Nrf2,NQO1 and HO-1 were significantly increased when SOD level was increased(P < 0.01)(P < 0.05).Conclusion: Lycopene can alleviate the damage of testicular and epididymis caused by heat stress and improve the quality of sperm.Its protective mechanism is related to lycopene can alleviate the oxidative stress damage of heat stress through the Nrf 2 /ARE signaling pathway and improve the antioxidant capacity of testis.