Developmental Changes Of The GnRH, GTH, GH And Their Receptors In Goat Lambs’ Pituitary-Ovary Axis

Gonadotrophin (GTH),gonadotropin-releasing hormone (GnRH), growth hormone (GH)and Ghrelin plays a key role in mammalian reproductive regulation, their physiologicalregulatory function mainly are mediated through binding receptors, FSHR and LHR, GnRHR,GHR. Therefore, studying the expression and distribution of these hormones and theirreceptor in pituitary and ovary during postnatal development, is base of understanding how toaffect the pituitary-ovarian axis during their reproductive development regulation.We studied the expression of GTH, GnRH and GH, and their receptors in pituitary-ovarian axis of female Jining goat aged from day0(D0) to day180(D180) at the level ofprotein and mRNA using the methods of IHC, RT-PCR and Western-blot; detected thelocalization and mRNA expression of these hormones and receptors.. The results show that,The content of serum estrogen (E2) had significant differences from D0to D180day.Progesterone (P) had similar changing trend with E2, the level of them were high at D0,dropped significantly at D30, and appeared two peak at the D90and D180respectively, andthe level of P at rised sharply D120.. The level of FSH was also increased on D0and D90;With E2, the change trend of LH was similar with that of E2, appeared peak at D90. The peakof E2, FSH, and LH levels appeared at D90may be one of the reasons of early estrus in jininggrey goats.2. FSH, LH, Ghrelin, GnRH, GnRHR, GH, GHR, AR positive cells and their mRNAwithin the anterior pituitary all showed specific distribution and expression from D0to D180.immunoreactive positive cells showed regional distribution, and positive reactivity increasedwith age. Pituitary GH, Ghrelin and LH distribution in cells and mRNA expression have thesame change trend, with the characteristic of significant peak at the D60(p <0.05), followedby D30, D90, this hints at the stage of D30-90, the pituitary gland can regulate the function ofitself and ovary through a lot of synthetic secretion of the hormones in pituitary cells, it maybe the material basis for the early sexual maturity in jining grey goats.GnRHR, GHR, AR mRNA expression in pituitary gland and ovary had a little ofchanges between the D60and D180, indicating these hormone receptors were relativelyconstant in postnatal and sexual maturity stage, the effect of these hormones on pituitarygland and ovary may depends on the level of themselves.The Ghrelin-ip, GnRH-ip cell andmRNA expression in pituitary and ovary may be the result of "requirements" of pituitary and ovary. The expression of AR-ip cells in pituitary and ovary also indicate that androgen has afunction of regulation for pituitary and ovary.The distribution of FSHR, LHR, Ghrelin and GHR positive cells in ovaries appearedbigger difference with different ages, especially in postbirth. The immunoreactivityconcentrated in irregular primordial follicle oocytes just postborn, but also appeared in aminority of secondary follicle with growth, on phase of D30to D180are often distributed in1-2growing follicles. When secondary follicle appears atresia, Ghrelin, GHR positive cellswere distributed evenly with style of a circular permutation in the follicular wall. GHR, andLHR,FSHR,GHR,GnRHR,GnRH is positive on the smooth muscle of artery walls withinovary, and Ghrelin showed strong positive surrounding connective tissue of artery walls.Amount of mRNA expression of several substances showed similar changing trend with theresults of immnohistochemistry stain.In summary, FSH, LH, GH, Ghrelin, GnRH, GnRHR immunoreactivity cells and theirmRNA expression in anterior pituitary during postnatal was closely related to the growthstage, several kinds of hormones can synergistically regulate the function and activity ofpituitary and ovary. Distribution differences of FSHR,LHR,Ghrelin,GnRHR and GHR inovary illustrate that the regulation for follicular development vary with the body growth,whether the translation of these hormone receptor mRNA associate with folliculardevelopment. Pituitary and ovary can produce Ghrelin, GnRH through the way of autocrine orparacrine.