The aim of this study was to investigate the molecular mechanisms of arginine (Arg) on follicular development of acute feed-restricted ewes during the luteal phase. From day 6 of the estrous cycle, 24 multiparous Hu sheep were randomly assigned into three groups: control group (a maintenance diet; n = 6), feed restriction group (0.5 maintenance diet, saline infusion; n = 9) and Arg treatment group (0.5 maintenance diet, infusion with 155 μmol of Arg-HCl/kg body weight; n = 9). The intravenous administrations were performed three times per day from day 6 to day 15 of the estrous cycle. At the end of treatment, the hypothalamus and pituitary were collected, as well as the follicular fluid (FF) and granulose cells (GCs) in the ≥2.5 mm follicles. The transcription level of NPVF was significantly increased, and the expression level of GNRH was significantly decreased in the hypothalamus with feed restriction. In addition, feed restriction significantly decreased the number of ≥2.5 mm follicles in the ovaries. In the ≥2.5 mm follicles, feed restriction significantly increased estradiol (E2) level in FF and the expression levels of steroidogenesis related genes (STAR, 3BHSD and CYP19A1) in GCs, while significantly decreased the expressions of FSHR and cell proliferation related genes (YAP1, CCND1 and PCNA) in GCs. Moreover, the activities of glucose metabolism enzymes (PFKP and G6PDH) were significantly decreased in GCs of the ≥2.5 mm follicles with feed restriction. Interestingly, as a precursor of nitric oxide, Arg supplementation can rescue the effects of feed restriction on follicular development by enhancing glucose metabolism and cell proliferation of GCs, and alleviating the abnormal E2 secretion in the ≥2.5 mm follicles, accompanied with recovering the expressions of NPVF and GNRH in the hypothalamus. These findings will be helpful for understanding the role of nutrition and Arg in sheep follicular development.

中文翻译：

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精氨酸输注在黄体期挽救限食胡羊的卵巢卵泡发育

本研究的目的是研究精氨酸 (Arg) 在黄体期对急性饲料受限母羊卵泡发育的分子机制。从发情周期的第 6 天起，将 24 只经产胡羊随机分为三组：对照组（维持饮食；n = 6）、限料组（0.5 维持饮食，盐水输注；n = 9）和精氨酸治疗组（0.5 维持饮食，输注 155 μmol Arg-HCl/kg 体重；n = 9）。从动情周期的第6天至第15天每天进行3次静脉内给药。在治疗结束时，收集下丘脑和垂体，以及≥2.5 mm卵泡中的卵泡液（FF）和颗粒细胞（GCs）。NPVF 的转录水平显着增加，GNRH在下丘脑中的表达水平显着降低。此外，饲料限制显着减少了卵巢中≥2.5 mm 的卵泡数量。在≥2.5 mm的卵泡中，限饲显着增加FF雌二醇（E2）水平和GCs类固醇生成相关基因（STAR、3BHSD和CYP19A1）的表达水平，同时显着降低FSHR和细胞增殖相关基因（YAP1）的表达, CCND1 和 PCNA) 在 GC 中。此外，葡萄糖代谢酶（PFKP 和 G6PDH）的活性在 ≥ 2.5 mm 卵泡的 GCs 中显着降低，并限制饲料。有趣的是，作为一氧化氮的前体，Arg补充剂可通过增强GCs的糖代谢和细胞增殖，缓解≥2.5 mm卵泡E2分泌异常，同时恢复下丘脑NPVF和GNRH的表达，从而挽救限食对卵泡发育的影响。这些发现将有助于了解营养和精氨酸在绵羊卵泡发育中的作用。