Effects Of Adiponectin On Hypothalamus Reproductive Endocrine Of Wannanhua Pigs

Wannanhua pig is the local breed in Huangshan, China, which has the characteristics of early maturity, high reproduction rate, disease resistance and high-quality pork. Adiponectin (Adp) is one of the most abundant adipokines mainly secreted by adipose tissues and had closely relationship with the reproduction particularly. In order to understand the interrelationship between the Adp and the hypothalamo-pituitary-gonadal (HPG) axis in Wannanhua pigs, we measured serum levels of Adp and reproductive related hormones and the mRNA expression of these genes. In addition, the effects of recombinant adiponectin (rAdp) on cultured hypothalamic cells of mice were also studied in this paper in order to discover the influence of adiponectin on hypothalamus reproductive endocrine.1The developmental patterns and correlation of Adiponectin, Adiponectin receptors, GnRH and GnⅢ in the hypothalamus of Wannanhua pigsFive Wannanhua boars and five Wannanhua gilts at birth,30,45,90and180days of age were selected. The concentration of serum adiponectin, GnRH and GnIH at different days of age were detected by ELISA, while the developmental patterns and gender differences of Adp, AdpR1, AdpR2, GnRH and GnIH/mRNA expression in hypothalamus were detected by Real-time fluorescent quantitative PCR(FQ-PCR). The results showed as follows:(1) The Adp, GnRH and GnIH level in serum were significantly changed with age increasing. At30days of age, the Adp content was lower than other days (P<0.01) while the GnRH and GnIH content were higher than other days (P<0.05or P<0.01).(2) In hypothalamus, the mRNA expression of Adp was very low, while AdpR1, AdpR2mRNA had relatively steady expression levels at different stages of growth (P>0.05) and the mRNA expression of AdpR1were significantly higher than AdpR2at any days of age. The GnRH and GnIH mRNA expression in hypothalamus declined generally with age increasing, which at the bottom at45d or90d respectively. While the GnRH mRNA expression in hypothalamus of the gilts at birth was significantly higher than other days (P<0.05),(3) With the comparison between different genders, we can find that AdpR1mRNA expression at birth and AdpR2and GnRH mRNA expression at30days of boars were significantly higher than those of gilts (P<0.05).(4) The analysis of correlation: There was significant negative correlation between the AdpR1and GnRH mRNA in hypothalamus (P<0.05). The Adp and GnRH level in serum were inversely correlated (P<0.05) in gilts; The serum GnRH and GnIH content were significant correlation (P<0.01) both in boars and in gilts.The results indicated that the adiponectin may suppress production of GnRH in hypothalamus by endocrine pathway and mediated by AdpRl during the development of Wannanhua pigs and the suppression was mainly found in gilts.2Effect of rAdp on GnRH and GnIH gene expressions in cultured hypothalamic cells of mice.Hypothalamic cells were isolated abacterially from hypothalamus at18d fetal mice. Hypothalamic cells were cultured after some treatment. Cells treated with rAdp five days after subculture. FQ-PCR methods were used to detect the expression of AdpRl, AdpR2, GnRH and GniH mRNA in cells after4h and24h rAdp treatment. The results showed as follows:(1) Effect of rAdp on AdpR mRNA expression in cultured hypothalamic cells of mice:AdpR2mRNA levels decreased significantly after4h treatment of2μg/ml rAdp, while others gene expressions had no significant difference with rAdp treatment in hypothalamic cells. In addition, AdpRl mRNA levels were significantly higher than AdpR2mRNA expression (P<0.01).(2) Effect of rAdp on GnRH and GnIH mRNA expression in cultured hypothalamic cells of mice:In hypothalamic cells, GnRH and GnIH mRNA levels decreased significantly after24h treatment of10μg/ml rAdp (P<0.01). The rAdp had no effects on the mRNA expression of GnRHand GnIH after4h treatment.In hypothalamic cells, rAdp may inhibit the GnRHand GnIH mRNA expression, and its action is mainly mediated by AdpR1. Regulation of adiponectin on GnRH and GnIH has a certain dose-effect and time-effect.