The Study Of Kisspeptin/GPR54 System On The Reproductive Regulation In The Hen's Hypothalamus-Pituitary-Ovary Axis

Kisspeptin, a neuropeptide discovered in 2001, is encoded by the KISS-1 gene and hydrolyzed into Kisspeptin-54,Kisspeptin-14,Kisspeptin-13 and Kisspeptin-10 which are different lengths of amidate peptide. It was discovered as the natural endogenous ligand of G protein-coupled recepter 54(GPR54). GPR54, a retinol family, was found in 1999 when Lee was separating and identifying the rat's brain tissue. Kisspeptin was reported to have many important physiological roles mediated by its functional receptor GPR54 in inhibiting of tumor metastasis, effecting neuroendocrine, reproduction, placental formation, obesity, diabetes and cardiovascular disease and so on. There is no study reported about kisspeptin to chicken in present literatures. Therefore, the distribution of kisspeptin and GPR54 in hen's brain, and the LH, FSH and E2 levels in serum after kisspeptin injected into lateral ventricle in hen, the effect of kisspeptin on hypothalamus-Pituitary-ovary oxis in vitro and the measurement in ELISA were studied in present study with immunohistochemistry and ELISA, in order to provide the morphological and physiological experimental data for kisspeptin's role in regulating reproduction of hens.1 The localization of kisspeptin and GPR54 in hen's brainThe immunohistochemical results showed that, kisspeptin and GPR54 immunopositive neurons and fibers are widely distributed in the hen's diencephalon and telencephalon. The Kisspeptin immunoreactive neurons are mainly localized in the thalamus dorsolateral anterior nucleus,thalamus anterolateral nucleus,circular nucleus,Lateral septal nucleus,medial septal nucleus,hypothalamus anterolateral nucleus and hypothalamus anterolateral nucleus, and the GPR54 immunoreactive neurons are mainly localized in the hippocampus, neostriatum, archistriatum. paleostriatum. Kisspeptin immunoreactive fibers are mainly distributed in the hypothalamus anterointernal nucleus,hypothalamus anterolateral nucleus,lateral septal nucleus and medial septal nucleus. GPR54 immunoreactive fibers are mainly observed in the suprachiasmatic nucleus,thalamus anterolateral nucleus,dorsomedial nucleus of hypothalamus and thalamus dorsolateral nucleus. 2 The effects of kisspeptin on hormones release of hypothalamic explants, anterior pituitary and ovarian cells in vitro.The results showed that both high and low doses (1,100,1000 nM) of kisspeptin can significantly stimulate the GnRH release levels in hypothalamic explants (P<0.05) with a dose-dependent-type growth. During the pituitary and ovarian cells, only high dose (1000 nmol/L) of kisspeptin can significantly increased the release of LH,FSH and E2 (P<0.05). This investigation suggested that kisspeptin could directly stimulate the release of GnRH,LH,FSH and E2 from hypothalamus plants, the anterior lobe of pituitary and ovary cells.3 The effects of kisspeptin on serum LH,FSH and E2 level after injection of kisspeptin into the lateral ventricle of hens.The results by enzyme-linked immunosorbent assay showed that after injection of kisspeptin into the lateral ventricle of hens, the serum LH,FSH and E2 levels are raised and can reached the peak soonly, but the LH and FSH levels can keep on about 1 hour, while the E2 level can retain for 20 min only. Soon after, the E2 level breakdown to the original level.