United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Japan.
College of Agriculture, Ibaraki University, Ibaraki, Japan.
Endocrinology. 2022 Sep 1;163(9). doi: 10.1210/endocr/bqac112.
Leptin and insulin-like growth factor 1 (IGF-1) regulate follicle development and reproduction in vertebrates. This study investigated the role played by leptin and IGF-1 in primordial follicle activation in the ovary of 7-day-old chicks. Different doses of leptin were intraperitoneally administrated to female layer chicks, and further analyses were performed. While leptin administration did not affect hepatic leptin receptor (LEPR), growth hormone receptor (GHR), or IGF-1, the lower dose of leptin significantly increased the messenger RNA (mRNA) expression of IGF-1, IGF-1 receptor, and IGF-binding protein (IGFBP)-2 and attenuated anti-Müllerian hormone (AMH) gene expression in the ovary. Furthermore, the ovaries of the same age chicks were challenged with leptin and/or IGF-1 in vitro. Leptin at a lower dose increased the mRNA expression of IGF-1, LEPR, and leptin; 100 ng/mL leptin and 10 ng/mL IGF-1 alone or combined with leptin reduced IGFBP-2 mRNA expression. AMH gene expression was also reduced by all doses except 10 ng/mL leptin. Histological studies showed that a lower dose of leptin injection induced the primordial follicle growth in the ovary in vivo, and the number of primordial follicles was higher in all leptin treatments over control in vitro. Moreover, the luciferase assay revealed that leptin enhanced IGF-1 promoter activity in LEPR-expressing CHO-K1 cells. Collectively, these results indicate that leptin directly affects the IGF-1/IGFBP system and promotes primordial follicular growth in the ovary of early posthatch chicks. In addition, the follicular development by leptin-induced IGF-1 is, at least in part, caused by the suppression of AMH in the ovary.
瘦素和胰岛素样生长因子 1（IGF-1）调节脊椎动物的卵泡发育和生殖。本研究探讨了瘦素和 IGF-1 在 7 日龄鸡卵巢原始卵泡激活中的作用。向雌性蛋鸡腹腔内注射不同剂量的瘦素，并进行进一步分析。虽然瘦素给药不影响肝脏瘦素受体（LEPR）、生长激素受体（GHR）或 IGF-1，但较低剂量的瘦素显著增加了卵巢中 IGF-1、IGF-1 受体和 IGF 结合蛋白（IGFBP）-2 的信使 RNA（mRNA）表达，并减弱了抗缪勒管激素（AMH）基因表达。此外，还在体外用瘦素和/或 IGF-1 挑战相同年龄的鸡的卵巢。较低剂量的瘦素增加了 IGF-1、LEPR 和瘦素的 mRNA 表达；100ng/ml 瘦素和 10ng/ml IGF-1 单独或与瘦素联合使用可降低 IGFBP-2 mRNA 表达。除了 10ng/ml 瘦素外，所有剂量均降低了 AMH 基因表达。组织学研究表明，较低剂量的瘦素注射可诱导体内卵巢原始卵泡生长，并且所有瘦素处理的原始卵泡数量均高于体外对照。此外，荧光素酶检测表明，瘦素增强了 LEPR 表达的 CHO-K1 细胞中 IGF-1 启动子的活性。总之，这些结果表明，瘦素直接影响 IGF-1/IGFBP 系统，并促进早期出壳小鸡卵巢原始卵泡的生长。此外，瘦素诱导的 IGF-1 引起的卵泡发育至少部分是由于 AMH 在卵巢中的抑制。
