光周期对蛋鸡 GnRH-I，GnRH-Ra mRNA表达和卵巢发育的影响

摘要

60 ISA brown layers at 75 day-old were randomly divided into long light group ( LL) and short light group ( SL) , the experiment lasted 70 days. SL constant light / dark:8 h/16 h; LL set of initial light / dark:8 h/16 h, A weekly increase of 0. 5 h, the light / dark reaches 13 h/11 h. Six layers were selected randomly in each group at 105-day-old and 136-day-old respectively to observe the effects of photoperiods on GnRH-I mRNA, GnRH-Ra mRNA expres-sion and ovarian development in layers. The results indicated that GnRH-I mRNA expression abundance in LL was sig-nificantly higher than that of SL (P<0. 05) the age at the136-day-old, and significantly higher than that of LL and SL ( P<0. 01) at 105-day-old. The GnRH-Ra mRNA expression in SL at 136-day-old was significantly decreased than that of 105-day-old (P<0. 05), the expression abundance of GnRH-Ra mRNA in LL was significantly higher than that of SL (P<0. 05). At the136 -day-old, ovary weight, ovary index in LL was significantly higher than that of SL (P<0. 01). Therefore, the long photoperiods obviously up-regulated GnRH-I mRNA expression in layers ' hypothalamus before start laying, to promote the ovarian development, the short photoperiods significant down-regulation GnRH-Ra mRNA expres-sion in pituitary and cause delay of ovarian development.%60只75日龄ISA褐蛋鸡随机分成长光组( LL)和短光组( SL),试验期70 d。短光组恒定光/暗：8 h/16 h；长光组起始光/暗：8 h/16 h,每周增加0.5 h,最长光/暗达到13 h/11 h。分别于105和136日龄每组取6羽蛋鸡采样,观察光周期对蛋鸡GnRH-I mRNA,GnRH-Ra mRNA表达以及卵巢发育的影响。结果表明：136 d长光组GnRH-I mRNA表达的丰度显著高于短光组(P<0.05),且极显著高于105 d长光组和短光组的表达(P<0.01)。136 d短光组GnRH-Ra mRNA表达较105 d显著下降(P<0.05),长光组GnRH-Ra mRNA的表达丰度显著高于短光组(P<0.05)。136 d长光组的卵巢重、卵巢指数极显著高于短光组(P<0.01)。以上说明,长光明显上调开产前蛋鸡下丘脑GnRH-I mRNA的表达,促进卵巢的发育；短光则明显下调垂体GnRH-Ra mRNA的表达,致使卵巢发育延缓。