卵巢激素释放的突然停止与肌肉收缩功能的下降有关,然而,逐渐的卵巢衰竭对整个周期的肌肉收缩性的影响,早期和晚期更年期仍不清楚。在这项研究中,使用4-乙烯基环己烯二环氧化物(VCD)诱导的卵巢衰竭小鼠模型来检查肌肉机械功能的时程变化。在40(围绝经期早期)评估雌性小鼠的足底屈肌(VCD:n=10;CON:n=8),80(围绝经期晚期),初次VCD注射后120天(更年期发作)和176天(更年期晚期)。在频率范围(10-200Hz)上建立转矩-频率关系。针对相对载荷(最大等距扭矩为10-80%)引起等渗动态收缩,以确定扭矩-速度-功率关系。然后,小鼠使用间歇性100Hz等距收缩进行疲劳任务,直到扭矩下降60%。抽搐的恢复,在任务失败后10分钟跟踪10Hz和100Hz扭矩。此外,来自指短屈肌的完整肌纤维经历了疲劳任务(在70Hz下重复50次),然后监测10和100Hz的Tetanic[Ca2]10分钟。VCD小鼠在所有时间点均表现出比对照低16%的抽搐扭矩。除了抽搐扭矩,10Hz扭矩和10Hz破伤风[Ca2+],在恢复过程中,VCD相对于疲劳前显示出更大的值,在恢复过程中,对照组和VCD小鼠之间没有观察到显着差异。这些结果表明,逐渐的卵巢衰竭对体内肌肉机械功能的损害很小,在疲劳恢复期间,主要观察到低频刺激的微小变化。
The abrupt cessation of ovarian hormone release is associated with declines in muscle contractile function, yet the impact of gradual ovarian failure on muscle contractility across peri-, early- and late-stage menopause remains unclear. In this study, a 4-vinylcyclohexene diepoxide (
VCD)-induced ovarian failure mouse model was used to examine time course changes in muscle mechanical function. Plantar flexors of female mice (
VCD: n = 10; CON: n = 8) were assessed at 40 (early perimenopause), 80 (late perimenopause), 120 (menopause onset) and 176 (late menopause) days post-initial
VCD injection. A torque-frequency relationship was established across a range of frequencies (10-200 Hz). Isotonic dynamic contractions were elicited against relative loads (10-80% maximal isometric torque) to determine the torque-velocity-power relationship. Mice then performed a fatigue task using intermittent 100 Hz isometric contractions until torque dropped by 60%. Recovery of twitch, 10 Hz and 100 Hz torque were tracked for 10 min post-task failure. Additionally, intact muscle fibres from the flexor digitorum brevis underwent a fatigue task (50 repetitions at 70 Hz), and 10 and 100 Hz tetanic [Ca2+] were monitored for 10 min afterward.
VCD mice exhibited 16% lower twitch torque than controls across all time points. Apart from twitch torque, 10 Hz torque and 10 Hz tetanic [Ca2+], where VCD showed greater values relative to pre-fatigue during recovery, no significant differences were observed between control and
VCD mice during recovery. These results indicate that gradual ovarian failure has minimal detriments to in vivo muscle mechanical function, with minor alterations observed primarily for low-frequency stimulation during recovery from fatigue.