去卵巢对大鼠颏舌肌肌电及其肌纤维型的影响

Effects of ovariectomy on electromyography and phenotype in rat genioglossus

目的检测雌性大鼠去卵巢后颏舌肌肌电及肌纤维组织化学特征变化,探索雌激素影响上气道稳定性的机制。方法30只雌性SD大鼠随机分成3组:正常组、假手术组、去卵巢组。手术6周后,采用插入式双极针电极引导大鼠颏舌肌肌电,检测各实验动物颏舌肌的肌电强度;采用颏舌肌肌球蛋白ATP酶组织化学染色法,检测各组大鼠颏舌肌肌纤维的分类及其面积,并分析比较各组间差异。结果假手术组颏舌肌的肌电强度与正常组相比无显著性差异(P>0.05),去卵巢组颏舌肌的肌电强度较正常组明显降低(P<0.05)。正常雌性大鼠颏舌肌由Ⅱ型肌纤维构成,其中ⅡA为(40.27±1.01)%,ⅡB/ⅡX为(59.73±1.01)%;假手术组和正常组大鼠颏舌肌肌纤维构成和面积无显著性差异;去卵巢组颏舌肌肌纤维构成比例与正常组相比较无显著性变化(P>0.05),但ⅡA型肌纤维面积较正常组有明显减小(P<0.05)。结论去卵巢后大鼠颏舌肌肌电减弱可能与其ⅡA型肌纤维减小有关,雌激素可能通过影响颏舌肌肌功能对上气道稳定性发挥保护作用。

Objective To investigate the effects of ovariectomy on genioglossus （GG） electromyography and myofibre phenotype in female rats and to explore the proposal mechanisms underling ovarian hormone protecting to the potency of upper airway （UA）. Methods 30 female Sprague-Dawley rats were randomly assigned to three groups： normal group （NORMAL）, sham group （SHAM） and ovariectomized group （OVX）. Six weeks later, electromyography activity of the genioglossus （EMGgg） was obtained from inserted bipolar electrodes. The integrated EMG （iEMG） was analyed. Genioglossus was stained with ATPase staining. The fibre phenotype composition and cross sectional area （CSA） of type Ⅱ A and Ⅱ B/Ⅱ X fibres were measured. Results EMGgg had no significant variety between the normal and sham group （.P〉0.05）. Compared to normal group, iEMG was significantly decreased in OVX group （P〈0.05）. GG myofibres were composed of Ⅱ phenotye, including Ⅱ A （40.27±1.01）% and Ⅱ B/Ⅱ X （.59.73±1.01）%, fibres composition and CSA of types Ⅱ A and ⅡB/Ⅱ X had no significant variety between the normal and sham group. Compared to normal group, fibres composition had no significant variety in OVX group （P〉0.05）, but the CSA of type Ⅱ A was significantly decreased （P〈0.05）. Conclusion The decreased EMGgg of ovariectomized rat maybe relates to the decrease of CSA in type Ⅱ A fibre. Ovarian hormone may protect the patency of upper airway through affecting muscle function of UA dilator.