注射ACTH对断奶母猪卵泡促黄体素受体表达及卵泡液中类固醇激素合成的影响

[目的] 为了探讨应激对断奶母猪繁殖障碍的影响机制，本试验以促肾上腺皮质激素（ACTH）注射所致的应激模型来研究应激对断奶母猪卵泡液中类固醇激素合成及卵泡促黄体素受体表达的影响。[方法] 对10头苏淮断奶母猪进行颈静脉插管手术，随机均分为对照组与ACTH处理组（n=5）。手术第3天开始以每次间隔8 h给ACTH处理组母猪注射ACTH （1 IU？kg-1），对照组母猪注射生理盐水，连续注射7 d。利用ELISA方法检测受试母猪卵泡液中类固醇激素及血浆中皮质醇的含量变化；利用荧光定量PCR测定胆固醇侧链裂解酶（CYP11A1）、17α-羟化酶（CYP17A1）、芳香化酶（CYP19A1）、类固醇激素合成急性期调节蛋白（StAR）、3β羟基类固醇脱氢酶（3β-HSD）、促黄体素受体（LHR）等基因的表达；利用免疫组化法检测CYP17A1、CYP19A1、LHR和3β-HSD蛋白的表达。[结果] 人工注射ACTH后40%的受试母猪出现排卵障碍；其血浆中皮质醇的含量极显著升高（P<0.01）；母猪卵泡液中雌二醇、雄烯二酮含量均显著下降（P<0.05）；CYP17A1、CYP19A1、LHR和3β-HSD基因表达量降低，其编码的蛋白CYP17A1、CYP19A1、LHR和3β-HSD表达量也明显下降。[结论] ACTH注射所致应激过程中，受试母猪的皮质醇含量升高可导致类固醇合成酶的基因、蛋白表达量明显下降，从而影响类固醇激素的合成及卵泡的发育。类固醇激素合成降低及LHR的低表达影响断奶母猪的正常排卵。
[Objectives] To investigate the mechanism of ovulation failure caused by stress in weaned sows, the effects of adrenocorticotropic hormone (ACTH)injection on the steroidogenesis capacity in follicular fluid and the expression of luteinizing hormone receptor (LHR)in follicular wall were studied in weaned sows.[Methods] All ten tested sows (n=10)were fitted with jugular vein catheters on the weaning day and randomly divided into control group and ACTH treatment group (n=5). Three days after surgery, the sows were injected with 1 IU？kg-1 ACTH or 9 g？L-1 NaCl every 8 h and continued for 7 days. The follicular fluid concentrations of steroid hormones and plasma concentrations of cortisol were determined using ELISA kits. The mRNA translation levels of cytochrome P450 side-chain cleavage (CYP11A1), cytochrome P450 17α-hydroxylase (CYP17A1), cytochrome P450 aromatase (CYP19A1), steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD)and LHR were quantified by real-time quantitative PCR. The protein expressions of CYP17A1, CYP19A1, LHR and 3β-HSD were detected by immunohistochemistry.[Results] The results showed that 40% of the tested sows displayed ovulation failure after ACTH injection. Plasma concentrations of cortisol significantly increased (P<0.01)and follicular fluid concentrations of estradiol and androstenedione significantly were reduced (P<0.05). The transcriptional levels of CYP17A1, CYP19A1, LHR and 3β-HSD were reduced (P<0.05)and their corresponding protein expressions of CYP17A1, CYP19A1, LHR and 3β-HSD also decreased (P<0.05).[Conclusions] The results suggest that, during the process of stress induced by ACTH injection, the decline of genes and their corresponding proteins expressions of steroid synthesisases reduced by inductions of cortisol in plasma will influence the steroid hormone synthesis and follicle development. The normal ovulation