A preovulatory surge (PS) of luteinizing hormone (LH) and progesterone triggers follicle ovulation, which is the first step of egg production and is orchestrated by the hypothalamo-pituitary-gonadal (HPG) axis. In the HPG axis, hypothalamic peptides, gonadotropin releasing hormone, and gonadotropin inhibitory hormone, control the production of follicle stimulating hormone and LH by the pituitary, which subsequently regulate ovarian production of estradiol and progesterone, respectively. The goal of this study was to characterize the HPG axis function of average egg producing hens by assessing plasma hormone profiles and hypothalamic, pituitary, and follicle gene expression outside and during the PS (n = 3 per group). Results were analyzed by a one-way ANOVA using the mixed models procedure of SAS. Plasma estradiol was not affected by the PS (P > 0.05), but plasma progesterone levels increased 8-fold during the PS when compared to basal progesterone levels (P < 0.05). HPG axis gene expression related to ovulation stimulation (e.g., GNRH, GNRHR, and LHB) was down-regulated during the PS; whereas gene expression related to follicle development (e.g., FSHB) was up-regulated during the PS. Additionally, in the hypothalamus and pituitary, estradiol receptor expression was up-regulated during the PS, whereas progesterone receptor expression was down-regulated during the PS. In the follicle cells, gene expression pertaining to progesterone (e.g., STAR), androgen (e.g., HSD17B1), and estradiol (e.g., CYP19A1) production was up-regulated during the PS. Prior to this study, the HPG axis had yet to be characterized during the PS in the turkey hen. This study showed that the PS significantly impacted gene expression in the hypothalamus, pituitary, and ovarian follicles. These results provide a foundation for further research into the regulation of ovulation and egg production in turkey hens.

中文翻译：

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火鸡母鸡排卵前激增过程中下丘脑-垂体-性腺轴基因表达的特征。

黄体生成激素（LH）和孕酮的排卵前激增（PS）触发卵泡排卵，这是产卵的第一步，并由下丘脑-垂体-性腺（HPG）轴进行编排。在HPG轴上，下丘脑肽，促性腺激素释放激素和促性腺激素抑制激素控制垂体的促卵泡激素和LH的生成，随后分别调节卵巢中雌二醇和孕酮的生成。这项研究的目的是通过评估PS内外和PS期间血浆激素谱和下丘脑，垂体和卵泡基因的表达来表征普通产蛋母鸡的HPG轴功能（每组n = 3）。使用SAS的混合模型程序通过单向方差分析对结果进行分析。血浆雌二醇不受PS的影响（P> 0.05），但与基础孕激素水平相比，血浆PS期间孕激素水平增加了8倍（P <0.05）。与排卵刺激有关的HPG轴基因表达（例如，GNRH，GNRHR和LHB）在PS期间被下调。而与卵泡发育相关的基因表达（例如，FSHB）在PS期间被上调。此外，在下丘脑和垂体中，雌激素受体的表达在PS期间被上调，而孕酮受体的表达在PS期间被下调。在卵泡细胞中，与孕酮（例如STAR），雄激素（例如HSD17B1）和雌二醇（例如CYP19A1）有关的基因表达在PS期间被上调。在这项研究之前，火鸡母鸡在PS期间尚未对HPG轴进行表征。这项研究表明PS显着影响下丘脑，垂体和卵巢卵泡中的基因表达。这些结果为进一步研究火鸡母鸡排卵和产蛋的规律提供了基础。