Paczoska-Eliasiewicz H E, Gertler A, Proszkowiec M, Proudman J, Hrabia A, Sechman A, Mika M, Jacek T, Cassy S, Raver N, Rzasa J
Department of Animal Physiology, University of Agriculture, Kraków, Poland.
Reproduction. 2003 Dec;126(6):739-51.
Thirty-four-week-old laying hens received injections of recombinant chicken leptin to assess the role of leptin in avian ovarian function. In the first experiment, the hens (n=60) were divided into three groups: (i). fed ad libitum; (ii). fasted; and (iii). fasted + leptin. Hens were fasted for 5 days and those treated with leptin received 250 microg leptin kg-1 body weight twice a day, i.p. In the second experiment, the hens (n=72) were divided into four groups: (i). fed ad libitum; (ii). fasted; (iii). fasted + leptin given only during fasting (5 days); or (iv). fasted and leptin given during both fasting and 5 days of re-feeding (10 days). LH was measured in blood plasma, and progesterone and oestradiol were measured in blood plasma and the ovary by radioimmunoassay. Apoptosis was examined in the walls of the three largest yellow hierarchical follicles (F3-F1; F3<F2<F1; 25-35 mm) by the TdT-mediated dUTP nick-end labelling method. Results showed that the injections of leptin during fasting: (i). delayed cessation of egg laying; (ii). attenuated regression of yellow hierarchical follicles; (iii). altered ovarian steroidogenesis; and (iv). abolished the fasting-induced apoptosis in the wall of F3-F1 follicles during the first 2 days of fasting and partially attenuated apoptosis after 5 days of fasting. Prolongation of leptin injections into the re-feeding period considerably delayed the restoration of the ovary. Expression of leptin receptor in laying hens was determined by RT-PCR. The highest expression of leptin receptor was observed in the hypothalamus. Lower receptor mRNA expression was found in the hypophysis, whereas the lowest expression was observed in the ovary. Within the ovary, a relatively high expression of leptin receptor was found in the stroma with cortical follicles <1 mm, the wall of white (1-8 mm) and small yellow follicles (>8-12 mm), and the granulosa layer of F3 follicles. The expression of leptin receptor in the granulosa layer of F2 and F1 follicles was barely detectable. This was in contrast to a much higher expression of leptin receptor maintained in the theca layer of F3-F1 follicles. The present results indicate that in chickens leptin might be involved in the adaptation to starvation due to attenuation of follicular apoptosis. The presence of leptin receptors in the ovary indicates the possibility of a peripheral effect of the hormone.
对34周龄的产蛋母鸡注射重组鸡瘦素，以评估瘦素在禽类卵巢功能中的作用。在第一个实验中，将母鸡（n = 60）分为三组：（i）自由采食；（ii）禁食；（iii）禁食 + 瘦素。母鸡禁食5天，接受瘦素治疗的母鸡每天腹腔注射250μg瘦素/ kg体重，共两次。在第二个实验中，将母鸡（n = 72）分为四组：（i）自由采食；（ii）禁食；（iii）仅在禁食期间（5天）给予瘦素；或（iv）在禁食和再喂食5天（10天）期间均给予瘦素。通过放射免疫分析法测定血浆中的促黄体生成素（LH），并测定血浆和卵巢中的孕酮和雌二醇。通过TdT介导的dUTP缺口末端标记法检测三个最大的黄色等级卵泡（F3 - F1；F3 < F2 < F1；25 - 35mm）壁中的细胞凋亡。结果表明，禁食期间注射瘦素：（i）延迟产蛋停止；（ii）减轻黄色等级卵泡的退化；（iii）改变卵巢类固醇生成；（iv）在禁食的前两天消除了F3 - F1卵泡壁中由禁食诱导的细胞凋亡，并在禁食5天后部分减轻细胞凋亡。在再喂食期间延长瘦素注射时间会显著延迟卵巢的恢复。通过RT - PCR测定产蛋母鸡中瘦素受体的表达。瘦素受体的最高表达在丘脑下部观察到。在垂体中发现较低的受体mRNA表达，而在卵巢中观察到最低表达。在卵巢内，在皮质卵泡<1mm的基质、白色（1 - 8mm）和小黄卵泡（>8 - 12mm）的壁以及F3卵泡的颗粒层中发现相对较高的瘦素受体表达。在F2和F1卵泡的颗粒层中几乎检测不到瘦素受体的表达。这与在F3 - F1卵泡的膜层中维持的高得多的瘦素受体表达形成对比。目前的结果表明，在鸡中，瘦素可能由于卵泡细胞凋亡的减弱而参与对饥饿的适应。卵巢中瘦素受体的存在表明该激素可能具有外周效应。
