A Study Of The Effect Of Leptin-Kisspeptin/α-MSH-GnRH On Pubertal Development In High-Fat Diet-Induced Obesity Male Mice

Objective:Current reports on the effects of obesity on male puberty are inconsistent.Studies have shown that obesity may lead to early or later puberty in boys,while the relevant mechanisms are not clear.We tried to explore the effect of obesity on the pubertal development of male mice and its relationship with Leptin-Kisspeptin/α-MSH-GnRH by checking the time of preputial separation,the pathological changes of testicular tissue,serum neutral hormone levels and hypothalamus Ob-R,Kisspeptin,GPR54,POMC（α-MSH）,MC4R,GnRH gene and protein expression.Methods:12 C57BL/6J male and 24 female mice were selected.One week after adaptive feeding,they were combined by 1:2.Select 24 male pups randomly divided into high-fat group（HFD）and control（CON）group,n=12 per group.The mother mice in the HFD were fed high-fat-diet immediately after parturition,and the offspring continued to be given high-fat feed after weaning.The female mice and offspring in the control group were fed ordinary diet for a total of 45 days.We detected the preputial separations time;separated and weighed of mouse organs and adipose tissue.Light microscope and electron microscope were used to observe the pathological changes of testis;ELISA method were used to detect serum levels of Leptin,LH,FSH,E2,T;immunohistochemical pathology were used to detect the hypothalamus GnRH protein expression;Western blot method were used to detect the protein expression of hypothalamic Ob-R,Kisspeptin,GPR54,α-MSH,MC4R;Real-time quantitative PCR method were used to detect hypothalamic Ob-R,Kiss-1,GPR54,POMC,MC4R and GnRH gene expression.Results:1.From the first day of high-fat-diet after weaning,the weight of the mice in the HFD group increased.On the 45^thday,the weight of the mice in the HFD group was significantly higher than that in the CON group（P<0.05）;On the 45^thday,the body fat and lean mass of the mice in the HFD group were significantly higher than those in the CON group（P<0.05）;Perirenal fat,perirenal fat index,peritesticular fat,and peritesticular fat index of HFD group mice significantly increased compared with CON group（P<0.05）;2.The preputial separation days of the HFD group mice was significantly earlier than that of the CON group mice（P<0.05）;Compared with the CON group,the sperm count,sperm motility and sperm deformity rate of the HFD group all increased（P<0.05）;3.Light microscope:we found that the arrangement of spermatogenic cells in the seminiferous tubules of the HFD group mice was disordered.Electron microscope:we found that there were more mitochondria and smaller nucleoli in the testicular leydig cells of mice in the HFD group.There are a large number of lipid droplets in the cell,which is significantly more than the CON group.The nuclear membrane of spermatocytes in the testis of the HFD group was blurred compared with that of the CON group.4.Compared with the CON group,serum leptin and testosterone in the HFD group increased significantly（P<0.05）;Compared with the CON group,the FSH and LH decreased significantly（P<0.05）;5.Compared with the CON group,Ob-R,Kisspeptin,MC4R,GPR54,GnRH protein levels of hypothalamus decreased in the HFD group mice（P<0.05）.Compared with the CON group,Ob-R,Kiss-1,MC4R,GPR54,GnRH mRNA levels of hypothalamus decreased in the HFD group mice,POMC mRNA level increased（P<0.05）.Conclusion:A early onset of puberty was found in obese male mice;Sperm deformity rate increased and pathological damage was found in testicular leydig cells in obese male mice.Puberty developmental damage was found in obesity male mice;Androgen level increased in obese male mice,which may lead to the early onset of puberty;the expression of Ob-R,Kisspeptin,GPR54,MC4R and GnRH decreased in obese male mice which may result in the puberty developmental damage in obesity male.