| Adiponectin,a special protein secreted by adipocytes,plays a critical role in increasing fatty acid oxidation,resisting inflammatory reaction and anti-diabetes etc.By binding to its specific receptors(AdipoR1 and AdipoR2),adiponectin activates AMPK,PPAR,p38MAPK signal pathway.Recently,various studies have demonstrated that adiponectin might be an important signal factor in the regulation of nutritional status and reproductive function.However,the distribution and function of adiponectin and its receptors have not been studied in sheep yet.In this study,2-month old ewe lambs were chose as the main research objects.First the expression of AdipoR1/2 genes in ewe lamb tissues were tested by qRT-PCR and the AdipoRl protein localization in the ovary and uterus were analyzed using IHC.Then,the effect of food restriction on the concentrations of adiponectin and reproductive hormones were detected by ELISA;the effect of food restriction on gene transcriptions for AdipoR1/2 and other genes related to reproduction in hypothalamic-pituitary-ovarian(HPO)axis were detected by qRT-PCR.These results provide evidences for the further study of adponectin system as the mediator of nutritional status and reproductive function in sheep.1.The tissue expression of AdipoR1/2 and the localization of AdipoRl in the ovary and uterus in the lambsTo investigate the expression of AdipoR1/2 in lamb tissues and localization of AdipoRl protein,six female two-month-old ewes were killed and sixteen tissues including hypothalamus,pituitary,one of the paired ovaries and uterus,pineal,retina,brain,cerebellum,pon,rhinencephalon,breast,heart,liver,spleen,kidney and skeletal muscle were collected and snap-frozen in liquid nitrogen.The other set of ovaries and uterus were fixed with paraformaldehyde.The expressions of AdipoR1/2 genes were detected using qRT-PCR.Results showed that the mRNA expression of AdipoRl in the skeletal muscle was the highest,and the expressions in the brain,cerebellum,retina,heart were in the middle,while the expressions in the other eleven issues were lower;mRNA expression of AdipoR2 in the liver was the highest and the expressions in the brain,cerebellum,retina,heart and ovaries were in the middle,while the expressions in the other ten issues were lower.AdipoR1 protein in the ovaries and uteri of lambs were detected by immunohistochemistry.Results showed AdipoR1 immunoreactivity was exclusively observed in the oocytes of all follicles in the ovary,and glandular epithelial cells and luminal epithelial cells of endometrium.All of these results provide the experimental basis to investigate the role of adiponectin in the reproductive process.2.Impact of food restriction on the expression of the adiponectin system and relative genes in the hypothalamic-pituitary-ovarian axis of pre-pubertal ewesTo investigate the expression of adiponectin system and patterns of genes in the hypothalamic-pituitary-ovarian(HPO)axis of food-restricted pre-pubertal ewes,eighteen female two-month-old ewes were assigned to 3 groups:the control group(C),the low-food restricted group(LR)and the high-food restricted group(HR),which was fed with 100%,70%and 50%of ad libitum food intake,respectively.The hypothalamus,pituitary,ovary and serum were collected after food restriction for 2 months.Results by ELISA showed that food restriction increased serum adiponectin and reduced LH,FSH,E2,P4 concentrations.Quantitative real time-PCR results showed that the gene transcriptions for AdipoR1/2 were enhanced in the HPO axis,while the expression of KISS-1,GPR-54 and GnRH in the hypothalamus,LH? and FSH in the pituitary and StAR in the ovary were reduced after food restriction.In conclusion,our present study demonstrates that adiponectin system might be involved in the regulation of energy balance and reproductive function. |
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