性激素对雄性大鼠颏舌肌功能及性激素受体基因表达的影响

Effects of sex hormones on genioglossal muscle activities,estrogen and androgen receptor expression in adult rat

目的定量检测雌激素受体(estrogen receptor,ERα、ERβ)及雄激素受体(androgenreceptor,AR)在雄性大鼠颏舌肌细胞中的表达,并分析性激素水平对雄性大鼠颏舌肌功能与 ERα、ERβ及 AR 基因表达的影响,探索性激素影响上气道稳定性的机制。方法成年雄性 SD 大鼠34只,其中10只采用实时荧光定量聚合酶链反应(fluorescent quantitative reverse transcription-polymerasechain reaction,FQ RT-PCR)分析颏舌肌中 ERα、ERβ及 AR mRNA 的表达。其余24只随机分为对照组、雌激素组(每次肌肉注射苯甲酸雌二醇0.1 mg/kg,2次/周)和雄激素组(每次肌肉注射丙酸睾酮2.5 mg/kg,2次/周)。4周后引导大鼠颏舌肌肌电,检测肌肉收缩功能,并采用 Western blot 法分析 ERα、ERβ及 AR 蛋白的表达情况。结果相对于管家基因(glyceraldehyde 3-phosphatedehydrogenase,GAPDH),颏舌肌细胞中 AR mRNA 转录水平为(295.80±127.20),ERα mRNA 为(2042.00±921.57),ERβ mRNA 为(65.96±29.57),ERα mRNA 与 ERβ mRNA 的比值为(36.83±19.66)。ERα mRNA 的转录水平明显高于 ERβ mRNA(P<0.01)。性激素干预后,与对照组相比,雌激素组颏舌肌的肌电活动明显增强(P<0.01),单次收缩、强直收缩最大张力,强直收缩力衰退速率无明显变化;雌激素组颏舌肌组织中 ERα明显增高(P<0.05)。相比对照组,雄激素组颏舌肌的肌电活动减弱(P<0.05),单次收缩、强直收缩最大张力略有增加(P>0.05),强直收缩力衰退速率明显加快(P<0.05),颏舌肌组织中 ERα无明显变化,而 AR 及 ERβ明显减少(P<0.05)。结论大鼠颏舌肌细胞中 ER、AR 均有 mRNA 转录,ER 的表达以 ERα为主。雌激素增强雄性大鼠颏舌肌的肌电活动,上调颏舌肌组织中 ERα基因的表达;而雄激素减弱颏舌肌的肌电活动,降低颏舌肌抗疲劳性,并下调 AR 及 ERβ基因的表达。

Objective To explore gene expression of estrogen receptor （ERα, ERβ） and androgen receptor （AR） in geniogtossal muscle （GG） of adult male rats, and to investigate the effects of sex hormones on GG activities, ERα,ERβ and AR expression. Methods GG samples were collected from 10 healthy adult male rats. Total RNA were extracted and subjected to fluorescent quantitative reverse transcription-polymerase chain reaction （ FQ RT-PCR） for quantitative measurement of ERα, ERβ and AR mRNAs. The other 24 male rats were randomly divided into 3 groups： control group, estrogen group （intramuscular injection of estrogen 0.1mg/kg, twice a week） and androgen group （intramuscular injection of androgen 2.5 mg/kg, twice a week）. The electromyographic activities （EMG） and contract tension of GG were investigated after 4-week treatment. The expression of ERα, ERβ and AR was assessed by Western blot. Results The mRNA expression ratios of AR/GAPDH, ERα/GAPDH, ERβ/GAPDH and ERα/ERβ were （295. 80 ± 127.20）, （2042. 00 ± 921.57 ）, （ 65.96 ± 29. 57 ） and （ 36. 83 ± 19. 66 ）, respectively. The mRNA level of ERα was significantly higher than that of ERβ（ P 〈 0. 01 ）. Compared with the control group, the EMG of GG was intensified in the estrogen group （ P 〈 0. 01 ）. GG contractility did not change significantly （ P 〉 0. 05 ） , and ERα expression in GG was up-regulated by estrogen （ P 〈 0. 05 ） ; while in the androgen group, the EMG of GG was weakened （ P 〈 0. 05 ）. Pt and P0 were slightly increased （ P 〉 0. 05 ） and the decline rate of P0 was markedly quickened （P 〈 0.05）. AR and ERβ expressions were down-regulated by androgen （P 〈 0. 05 ）. Conclusions Both AR and ER were expressed in GG of adult male rats, and ERa was expressed more abundantly than ERβ. Estrogen could greatly improve activities of GG and stimulate the expression of ERα. Whereas, androgen could restrain activities of GG, impair its fatigue resistance capacity and inhibit the expression of AR and ERβ.