| Objective: To observe the effects of high-fat diet and exercise on the expression of kiss-1-GPR54 signal pathway in hypothalamic and gonadotrophin during the developmental stages of male rats,and analyze the change of kiss-1-GPR54 signal pathway and its downstream factors after high-fat diet and exercise,and explore the effect of energy balance on the development of male rats and clarify its mechanism.Methods: 3 weeks male SD rats were given high fat diet and exercise intervention(60%-70% VO2 max intensity exercise intervention,1 h / time,5 times / week).Rats were divided into control group(group C),high-fat diet control group(group H)and control exercise group(group CE),high-fat diet exercise group(group HE),Each group was divided into 3 weeks group,5 weeks group,6 weeks group and 8 weeks group according to the time point.,abdominal aorta blood,hypothalamic,testicular were collected.The morphological changes of testicular were observed by hematoxylin-eosin staining;the serum levels of luteinizing hormone(LH),follicle stimulating hormone(FSH)were measured by Elisa and serum testosterone(T)were measured by chemiluminescence immunoassay;The mRNA expression of kiss-1,GPR54,PLC,IP3 R and GnRH in the hypothalamus was detected by RT-qPCR;the co-localization and amount of kiss-1 and GPR54 in the hypothalamus were observed by immunofluorescence double labeling and protein expressions of GnRH by immunohistochemical staining which in the corresponding point of weeks of age.Results:(1)The mRNA expression levels of kiss-1,GPR54,PLC and IP3 R in the hypothalamus during the development of rats was showed a trend of first rising in the hypothalamus of male rats increased from 3weeks,which was peaked at 6 weeks of age and then decreased at 8weeks.However,GnRH mRNA and serum LH were higher at 3wk and 8wk,lower at pre-puberty and puberty stages;With the development of HPG axis and the increasing number of spermatids and Leydig cells in testis,the level of serum T in rats gradually increased at each developmental stage and increased significantly after the testis matured.(2)After high-fat diet intervention,the mRNA and protein expressions of kiss-1 and GPR54 in the hypothalamus of all developmental stages were increased,the expression levels of PLC mRNA and IP3 R mRNA were significantly decreased,but the variation tendency and peak appearance time of kiss-1,GPR54,PLC and IP3 R mRNA were not changed;the expression level of GnRH in the hypothalamus did not increase significantly until maturity.Serum LH levels in all developmental stages increased with the increase of kiss-1-GPR54 signal pathway;lipid deposition was appeared in testis tissue,decrease of Leydig cells and decrease of serum T level serum testosterone secretion is inhibited.(3)After exercise intervention,the level of kiss-1 and GPR54 protein in all development stages were decreased,the expression levels of PLC and IP3 R mRNA were mainly affected by high-fat diet intervention,little affected by exercise intervention;the trend of GnRH during development stages is not completely consistent with the kiss-1-GPR54 signaling pathway,the expression level of GnRH in the hypothalamus did not decrease significantly until maturity;although serum FSH tended to decrease,but the variation tendency and peak appearance time of kiss-1-GPR54 signaling pathway was not changed;changes in the expression level of mRNA was significantly correlated with body weight,exercise intervention stimulates the increase of body weight and length in 6weeks rats,while kiss-1mRNA increases with the increase of body weight and length;exercise intervention can reduce lipid deposition in testes and the testicular index,elevate serum testosterone levels of rats with high-fat diet at different developmental stages.Conclusion:(1)The kiss-1-GPR54-PLC-IP3 R signaling pathway in the hypothalamus during the development of rats was showed a trend of first rising and then decreasing,which was peaked at 6 weeks of age;However,the expression level of hypothalamus-pituitary-gonadal hormone and the change trend of kiss-1-GPR54 signaling pathway were not identical.(2)Although high fat diet intervention can induce the expression of kiss-1-GPR54 signaling pathway in hypothalamic and serum gonadotropin level increase,GnRH trends not fully consistent with the kiss-1-GPR54 signaling pathway,after the maturity period there was a significant rise;lipid deposition was appeared in testis tissue and serum T levels are suppressed.(3)Although exercise intervention could inhibit the expression of kiss-1-GPR54 signal pathway and serum gonadotrophin in hypothalamus,it did not affect the time of puberty onset in male rats.The trend of GnRH did not change completely with kiss-1-GPR54 signaling pathway consistent,the expression level of GnRH in the hypothalamus did not decrease significantly until maturity;exercise intervention can reduce lipid deposition in testes and the testicular index,and increase the number of Leydig cells and the level of serum T in the high-fat diet rats. |
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