| White adipose tissue is not only the main storage room of triglycerides,but also an endocrine organ.It releases many bioactive proteins,which are called adipokines.Adiponectin(AdipoQ)is a kind of adipokine hormone,which mainly comes from white adipose tissue.It is the most abundant adipokine in plasma.Its biological role is mainly through its two receptors,adiponectin receptor 1(AdipoR1)and 2(AdipoR2).In recent years,studies have found that it plays an increasingly important role in regulating reproductive function,especially the regulation of hypothalamic pituitary ovarian axis(HPO).Previous studies have shown that AdipoQ can have peripheral effects on ovary and uterus through its central effect on hypothalamus and pituitary,and direct effects on oocytes and embryos to affect the reproductive system.At present,there is little research on AdipoQ and AdipoRs in layer reproduction,especially on the HPO axis.In view of this,this experiment took Hy-Line laying hens as the research object to explore the biological role of AdipoQ and AdipoRs in laying hens’ reproduction,in order to provide a theoretical basis for improving poultry reproductive regulation.Experiment 1.Study on the relationship between AdipoQ and AdipoRs and HPO axis related reproductive gene expression and hormone secretion in laying hensIn this study,30 Hy-Line laying hens of 15W,20W,30W and 68W natural populations were selected and individually caged.The expression of HPO axis related reproductive genes and the secretion level of reproductive hormones in laying hens at different physiological stages,as well as the correlation between AdipoQ and AdipoRs and reproductive hormones were detected by qRT-PCR and ELISA.The results showed that AdipoQ mRNA was highly expressed in hypothalamus and low in ovary;Week age significantly affected the expression of AdipoQ in HPO axis,AdipoR1 in ovary and AdipoR2 in hypothalamus(P<0.05).At the same time,week age also affected the expression of some reproductive genes in HPO axis(FSHR,PGR,STAR and CYP11A1,etc.);In the follicles of laying hens at different developmental stages of 30W,AdipoQ was highly expressed in the pre grade and grade follicular membrane,and AdipoRl and 2 were highly expressed in the granular layer;Weeks of age had a significant effect on all HPO axis hormone indexes(P<0.05),and these indexes changed with the change of egg laying performance,showing a trend of first increasing(30W highest)and then decreasing with weeks of age;After correlation analysis,except for AdipoR1 and AdipoR2,there was significant(P<0.05)or very significant correlation between other indexes(P<0.01).The above results showed that there was a very significant correlation between AdipoQ and reproductive HPO axis related reproductive genes and hormone secretion in laying hens.Experiment 2.Effects of AdipoRon on HPO axis related reproductive gene expression,hormone level and potential signal pathway in laying hens during peak oviposition period30 Hy-Line laying hens at the peak of 30W laying were selected and individually caged.They were divided into 3 treatments,10 repetitions in each treatment and 1 chicken in each repetition.AdipoRon was injected at the dose of 0 mg/kg,5 mg/kg and 15 mg/kg to study the effects of different doses of treatment and different lengths of treatment(0,10,20,30,60 and 120 min)on reproductive related gene expression and hormone secretion.The results showed that different doses of AdipoRon and the time after treatment had significant effects on the contents of serum AdipoQ and AdipoRs and reproductive related hormones(P<0.05).AdipoQ,AdipoR1,AdipoR2,GnRH,LH,FSH and P4 increased significantly with the increase of injection dose of adiporon and the extension of time after injection,while E2 decreased,indicating that AdipoQ can cooperate with many reproductive hormones to promote laying at the peak of laying,and AdipoRon can promote laying through AMPK,ACC,p38MAPK and PPAR-α etc.The signal pathway plays its physiological function.Experiment 3.Effects of AdipoRon on follicular growth and yolk deposition in expected oviposition period36 Hy-Line laying hens in the expected oviposition period(15W)were selected and individually caged.They were divided into three treatments according to Omg/kg,5mg/kg and 15mg/kg.AdipoRon was injected continuously for 8 days.Each treatment had 12 repetitions and one chicken in each repetition.In addition,the follicles of late laying(68W)Hy-Line laying hens were cultured in vitro and subjected to different concentration gradients of AdipoRon(0,5,10,20)μg/ml)to detect the expression of reproductive related genes and yolk synthesis related genes.The results showed that AdipoRon could significantly promote the expression of GnRH,GnRHR,FSH and LH in the hypothalamic pituitary axis(P<0.05).In addition,it could also up regulate the expression of liver lipid production and transport genes VTG,OVR,apoB and MTP.At the same time,AdipoRon could also up regulate the expression of steroidogenic(STAR,CYP19A1,CYP17A1,CYP11A1),angiogenesis gene(VEGFA2,VEGFR1,VEGFR2,ANGPT1,ANGPT2)and yolk uptake genes PPAR-g and VLDLR in SWF at the expected and late laying stage(P<0.05).The results show that AdipoRon can promote the expression of ovarian steroidogenic genes in the expected and late egg laying period,and then promote the production of steroids.Then steroids act on follicles to promote follicular angiogenesis.Moreover,AdipoRon can up regulate the expression of yolk uptake and transport genes,liver lipid production and transport genes,and improve yolk deposition,So as to promote the maturation of egg laying function in the pre laying period and slow down the decline of egg laying function in the late laying period.In conclusion,in HPO axis,AdipoQ mRNA is highly expressed in hypothalamus and low in ovary.Weeks of age can affect the expression of AdipoQ on HPO axis;AdipoQ and AdipoRs were significantly correlated with reproductive HPO axis related reproductive genes and hormones in laying hens.At the peak of labor(30W),in vivo injection of AdipoRon can affect the expression of related genes and hormones on the HPO axis,and through the related signal pathways on the HPO axis(AMPK,ACC,p38MAPK,PPAR-α)play its physiological function.In the expected delivery period(15W),in vivo injection of AdipoRon can affect the expression of ovarian steroidogenic genes,promote follicular angiogenesis,up regulate liver lipid production and transport genes,improve yolk deposition,and promote the functional maturity of egg laying in the expected delivery period.In the later stage of egg laying(68 W),the addition of AdipoRon in vitro can affect the expression of ovarian steroidogenic genes,up regulate the expression of angiogenesis genes and yolk uptake genes in SWF,and then slow down the decline of laying function in the later stage of laying.In conclusion,AdipoQ plays an important role in reproductive regulation at different developmental stages of laying hens. |
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