| Inhibin(INH)and Actvin(Act)belongs to TGFβ superfamily composed of follicular granulosa cells secrete dimers glycoprotein,INH by alpha subunit and beta subunits of dimers,Act consists of two beta subunits of dimers,both belong to the TGF beta family.INH is mainly expressed in granulocytes of large follicles,whose function is to inhibit the secretion of pituitary FSH,the expression of FSHR of follicular granulocytes and the development of follicles.Act is mainly expressed in granular cells of small follicles,whose main function is to promote the secretion of pituitary FSH,the expression of FSHR of follicular granule cells and the development of follicles.A large amount of previous work in/of the literature and research group showed that active and passive immunization with INH subunits could increase the concentration of FSH and Act in the blood of female animals,including pigs,and increase ovulation rate and litter number.However,the Act level of follicular secretion after ovulation is still higher in INH immunized animals than that in non-immunized animals,so the Act level remains higher in immunized animals after ovulation.However,in vitro test results showed that Act inhibits the secretion of progesterone(P4)in luteinized granulocytes,so INH immunity may inhibit the secretion of luteinized P4 by upregulation of Act level,affecting the pregnancy rate and delivery rate of animals in pigs,cattle and sheep.Early pregnancy injection of hCG can improve corpus luteum function and intrauterine environment,promote early embryo development,and ultimately improve pregnancy rate.Therefore,this paper intends to study whether INH combined with hCG can improve ovulation rate and number of offspring,and at the same time improve the pregnancy rate of sows.Animal experiments: the sows were randomly divided into three groups: control group(Con,n=56),separate group(T1,n=56)and combined group(T2,n=50).INH was immunized 7 days before weaning,5-7 days after weaning,and 1000 IU hCG was injected 5 days after breeding in the combined group.The oestrus rate of sows in the experimental group was slightly higher than that of the control group(89.29% in the control group,93.40% in the experimental group).The delivery rate of T1 group(76.78%)was 6.98% lower than that of the control group(82.14%),and the delivery rate of T2(86%)was 12.01% higher than that of T1 group.The litter size of the T1 and T2 groups was 0.85 and 0.7,while the litter size was 0.96 and 0.69.The results showed that INH alone could promote follicle development and number of offspring,but could also reduce the rate of delivery.HCG injection can reverse the adverse effect of INH on fetal rate.Cell experiment: the preliminary experiment confirmed that 10 MB forskolin treatment for 48 h can make the luteinization of granule cells.After that,10 ng/mL Act and 100 IU/mL hCG were added to continue to process luteinized granule cells for 48 h.The medium was collected for the determination of P4.RNA was extracted from cells to detect the relative expression levels of key genes StAR,Cyp11a1 and 3 glom-hsd in progesterone secretion,as well as the key genes VEGF,PEDF and P27 kip in luteinization and cell cycle.Cells were collected for protein extraction,and Cyp11a1 and 3 cyton-hsd were detected by Western Blot.The results showed that progesterone secretion of granulocytes treated by forskolin increased significantly,and the secretion of progesterone increased by 20 times to 2000 ng/mL from the background,suggesting that foskolin can induce luteinization of granulocytes.Corresponding to the secretion of progesterone,the expression of StAR,Cyp11a1 and 3 hypoxic-hsd increased by 8 times,4 times and 10 times after treatment with foskolin.After treatment with Act,progesterone secretion in luteinized granulosa cells decreased by 35%,but the gene expression of StAR,Cyp11a1 and 3 cage-hsd decreased to the level before luteinization.When treated separately by hCG,the expression of StAR and 3 actin-hsd can be further increased,while the expression of Cyp11a1 is significantly reduced compared with luteinized granulosa cells.After the simultaneous treatment of hCG and Act,hCG can partially alleviate the inhibition of Act on the expression of StAR and Cyp11 a genes,and completely reverse the inhibition of Act on the expression of 3cage-hsd.The expression trend of StAR,Cyp11a1 and 3β-hsd was the same as that of genes.The above in vivo and in vitro results showed that INH combined injection of hCG can improve ovulation rate and number of offspring,as well as pregnancy rate.The application of this novel breeding control technology will effectively improve the economic benefits of breeding pig production and greatly promote the development of China’s pig industry. |
