A Study Of Leptin/Kisspeptin/GnRH On The Male Reproductive Decline Caused By High-fat Diet Induced Obesity In Testes Of Mice

Objective: To explore the role of the testicular leptin,kisspeptin and GnRH in testosterone decline in diet-induced obese mice by detecting leptin,testosterone and estrogen in serum and determining expression of Ob-R,Kisspeptin/GPR-54 and GnRH/GnRH-R in testes of C57BL/6J mice.Methods: Male C57BL/6J mice were randomly divided into normal-diet and high-fat diet groups.After 19 weeks,mice in the high-fat diet-fed group were further divided by body weight gain into diet-induced obesity(DIO)and diet-induced obesity resistant(DIO-R)group.The body weight was measured and the plasma was obtained.The epididymis adipose mass,perirenal fat and the testes were removed immediately to weigh.The effect of obesity on the reproductive organs in male mice was observed by measuring sperm count and spermatozoid motility,relative to testis and epididymis weight,testosterone levels,and pathologic changes.Leptin,testosterone and estrogen in serum were detected by ELISA method.The pathological changes occurred in testis were investigated after stained with hematoxylin and eosin.Leptin receptor(Ob-R),Kiss1,GPR-54,GnRH and GnRH-R mRNA were measured by real-time PCR.Expression of Ob-R,kisspeptin,GPR-54,GnRH and GnRH-R protein was determined by Western blotting.Results: From the second week of high-fat feeding,the mice in the DIO group began to gain weight.At the end of 19 weeks,the body weight of DIO group was significantly higher compared to that of control group and the DIO-R group(P<0.05).Body fat and percentage of body fat in the DIO group and the DIO-R group were significantly higher compared to those of the control group(P < 0.05).Testis and epididymis relative coefficients of the DIO group were significantly lower than the control group(P<0.05).The relative epididymal fat and retroperitoneal fat weight of the DIO group were higher than control group(P<0.05).The sperm motility of DIO group and DIO-R group were lower than the control group(P<0.05).Morphological analyses of the testes in the DIO group showed that the testicular structure was aberrant.Compared with the control group,the arrangement of seminiferous epithelia was sparse in the DIO group.Serum leptin andestrogen levels of DIO and DIO-R group were significantly increased compared to the control group(P < 0.05).Serum testosterone levels of DIO and DIO-R groups were significantly decreased compared to the control group(P<0.05).The levels of Ob-R,Kiss1,GPR-54 and GnRH gene expression in the DIO and DIO-R groups were significantly decreased compared to the control group(P<0.05).The levels of Ob-R,kisspeptin,GPR-54 and GnRH protein in the DIO and DIO-R groups were significantly decreased compared to the control group(P < 0.05).The levels of GnRH-R gene expression and protein in the groups showed no difference.Conclusion: These lines of evidence suggest that downregulation of Ob-R,Kisspeptin/GPR-54 and GnRH in the murine testis may contribute to male hypogonadism caused by high-fat diet-induced obesity.