Liu Yue-Hua, Jia Shan-Shan, Hou Yu-Xia
Department of Orthodontics, School of Stomatology, Tongji University of China, 399 Yanchang Zhong Road, Shanghai 200072, China.
Angle Orthod. 2009 May;79(3):509-14. doi: 10.2319/031608-149.1.
To test the hypothesis that ovariectomy has no effects on contractile, histochemical, or biochemical properties of the rat genioglossus (GG).
Eight-week-old female Sprague-Dawley rats were randomly assigned into three groups: normal group (Normal), sham-operated group (Sham), and ovariectomized group (OVX). Four weeks later, genioglossal electromyography activity (EMGgg) and contractile properties were measured, including relative integrated EMG (iEMG), maximal twitch tension, 70%-decay time, and fatigue index (FI). Then rats were sacrificed and paired GG were removed for further analysis. Adenosine-triphosphatase (ATPase) staining was performed to determine the percent fiber-type distribution and to identify cross-sectional area (CSA) of muscle fibers. Myosin heavy chain (MHC) phenotypes were determined by gel electrophoresis.
Ovariectomy reduced EMG activity and contractile properties of the GG. Following ovariectomy, the CSA of type IIA and the proportion of MHCIIA decreased significantly. The MHC isoform composition of GG transferred from relative slow-twitch to fast-twitch isoform, following the order MHCIIB --> MHCIIX --> MHCIIA. Sham operation had no effect on any of the parameters.
The hypothesis is rejected. The contractile properties of the GG are sensitive to ovariectomy. These changes were, at least in part, associated with changes in the amount and type of contractile protein expressed.
验证卵巢切除术对大鼠颏舌肌（GG）的收缩、组织化学或生化特性无影响这一假设。
将8周龄雌性Sprague-Dawley大鼠随机分为三组：正常组（Normal）、假手术组（Sham）和去卵巢组（OVX）。四周后，测量颏舌肌肌电图活动（EMGgg）和收缩特性，包括相对积分肌电图（iEMG）、最大抽搐张力、70%衰减时间和疲劳指数（FI）。然后处死大鼠，取出成对的颏舌肌进行进一步分析。进行三磷酸腺苷酶（ATPase）染色以确定纤维类型分布百分比并识别肌纤维的横截面积（CSA）。通过凝胶电泳确定肌球蛋白重链（MHC）表型。
卵巢切除术降低了颏舌肌的肌电图活动和收缩特性。卵巢切除术后，IIA型肌纤维的CSA和MHCIIA的比例显著降低。颏舌肌的MHC同工型组成从相对慢肌型转变为快肌型，顺序为MHCIIB --> MHCIIX --> MHCIIA。假手术对任何参数均无影响。
该假设被否定。颏舌肌的收缩特性对卵巢切除术敏感。这些变化至少部分与所表达的收缩蛋白的数量和类型的变化有关。
