性成熟启动时间不同的母鸡瘦素及其受体mRNA表达的差异

Comparison of leptin and leptin receptor mRNA expression between pullets of different timing for sexual maturation

为探讨瘦素(leptin)及其受体在禽类性成熟启动过程中的作用,试验采用120羽60日龄伊莎蛋母鸡,随机均分为2组,分别饲养于光照逐渐延长(以光/暗为8 h/16 h为起点每周增加0.5 h光照,简称长光照组)和恒定的短光照(光/暗为8 h/16 h,简称短光照组)条件下,记录体重变化与性成熟时间。长光照组和短光照组母鸡分别于136和151日龄时开产。在136日龄时,每组取10只鸡宰杀后取血液、脂肪和下丘脑组织,分别检测血清leptin水平、脂肪leptin mRNA与下丘脑leptin受体mRNA的表达。结果表明:136日龄时,长光照组和短光照组母鸡血清雌二醇(E2)和leptin水平均无显著差异(P>0.05,n=10)。相对定量RT-PCR结果显示:136日龄时,长光照组母鸡脂肪leptin mRNA表达丰度极显著高于短光照组(P<0.01,n=10),但下丘脑leptin受体mRNA的表达水平无显著差异(P>0.05,n=10)。以上结果提示:15 d的性成熟时间差异并不伴随产蛋母鸡血清leptin及下丘脑leptin受体mRNA表达水平的显著变化,而脂肪leptin mRNA表达水平与血清leptin蛋白水平的不一致性则提示循环leptin的其他组织来源。

In order to elucidate the role of leptin in the onset of sexual maturation in birds, 120 ISA pullets at 60 day-old （ D60 ） were allocated randomly into two groups, the long light （LL） group raised under artificial light regimes with incrementally increased light phase （L/D from 8 h/16 h to 14 h/10 h over 12 weeks） and the short light （SL） group raised on consistent short light （L/D is 8 h/16 h） from D60. Pullets in LL group reached sexual maturation 15 days earlier than those in SL group, reaching 5% egg production in the flock on D136 and D151 , respectively. The serum levels of estrogen, leptin and leptin receptor mRNA expression in hypothalamus showed no significant differences between two groups on D136. However, leptin mRNA in adipose tissue was significantly higher in LL than in SL （P 〈0.01, n = 10）. The results suggested that 15 days difference of sexual maturation in laying hens was not accompanied with significant changes of plasma leptin concentration and leptin receptor mRNA in hypothalamus. Additionally, the inconsistent changes of plasma leptin concentration and leptin mRNA expression in adipose tissue imply other sources of circulation leptin in domestic fowl.