Objective To investigate the effects of the increase of intracellular free calcium on afferent discharges of isolated soleus muscle spindle in rats.Methods Twelve rats were randomly divided into three groups:the 2.0ion group,the 5.0ion group,and the dimethyl sulfoxide(DMSO) group.The isolated soleus muscle spindle of rats in 3 groups were separated.After incubation with 2μmol/L ionomycin in 2.0ion group and 5 μmol/L ionomycin in 5.0ion group respectively,the changes of free calcium concentration in soleus muscle spindle were observed by laser scanning confocal microscopy.The air-gap technique was used to observe the afferent discharge activities of rats' isolated soleus muscle spindle,and the changes of the afferent discharge activities in 3 groups were observed after treated with DMSO,2μmol/L,or 5 μmol/L Ionomycin respectively.Results Ionomycin (2 and 5 μmol/L) could significantly increase the level of resting calcium in intrafusal muscle of rats' soleus muscle,and the effect was concentration dependent (P＜0.01).Ionomycin (2 and 5 μmol/L) could significantly reduce the afferent discharges of single muscle spindle of soleus muscle (P＜0.05).5 μmol/L ionomycin could prolong the periodic interval of spontaneous discharge of single muscle spindle (P ＜ 0.05),and there was no significant changes on evoked discharges of muscle spindle after the adding of Succinylcholine chloride(Sch) with concentration of 50 mg/L.Conclusion Increased free calcium concentration in rat soleus muscle spindle can inhibit afferent discharges of muscle spindle.

实验观察了后肢制动一周大鼠离体单一比目鱼肌肌梭自发放电和由氯化琥珀胆碱(Succinylcholine chloride,Sch)所致的诱发放电的变化,并观测了三磷酸腺苷对肌梭传入放电的影响.实验采用空气隔绝法记录离体单一肌梭电生理活动,分别给予3种浓度(1、2和3 mg/kg)的三磷酸腺苷灌流肌梭,并记录其自发放电和氯化琥珀胆碱所致的诱发放电的情况.结果显示,后肢制动7 d大鼠比目鱼肌离体单一肌梭自发放电较正常明显减少(P<0.05),氯化琥珀胆碱所致的诱发放电未见明显增多,给予1 mg/kg三磷酸腺苷灌流肌梭后,肌梭自发及诱发放电未见明显改变,给予2和3 mg/kg三磷酸腺苷灌流其自发放电明显增加(P<0.05),诱发放电仅在给予3 mg/kg的三磷酸腺苷灌流肌梭后明显增加(P<0.05).提示三磷酸腺苷可提高后肢制动大鼠离体单一肌梭自发及诱发放电,起到对抗肌萎缩的作用.研究为大鼠肌梭生理的研究及废用性肌萎缩的实验研究提供了有意义的资料.

采用激光扫描共聚焦显微镜技术,观察大鼠后肢制动一周比目鱼肌梭内肌细胞内静息Ca2+的变化,并以Na2 ATP作为对抗措施,观察其对后肢制动大鼠梭内肌细胞Ca2+的影响.结果显示后肢制动一周,大鼠比目鱼肌梭内肌细胞Ca2+浓度明显升高,而经Na2 ATP注射后,大鼠后肢制动一周梭内肌细胞Ca2+浓度升高不明显.提示Na2 ATP可对抗后肢制动所致的梭内肌细胞钙超载.为大鼠肌梭生理的研究及钙离子与废用性肌萎缩的实验研究提供了有意义的资料.

观察了含有不同钙离子浓度的细胞外液对大鼠离体单一比目鱼肌肌梭自发放电的影响.实验分为低钙改良任氏液组和高钙改良任氏液组,首先采用空气隔绝法记录大鼠离体单一比目鱼肌肌梭自发放电情况,然后分别以相应改良任氏液灌流肌梭,并记录其自发放电和氯化琥珀胆碱所致的诱发放电的情况.给予低钙改良任氏液灌流肌梭后,其自发放电频率增加(P<0.01),自发放电的周期间隔缩短(P<0.01),给予氯化琥珀胆碱后诱发放电未见明显增加;给予高钙改良任氏液灌流肌梭后,其自发放电频率减少(P<0.01),自发放电的周期间隔延长(P<0.05),给予氯化琥珀胆碱后诱发放电未见明显增加.提示含有较低钙离子浓度的细胞外液可增加大鼠离体单一比目鱼肌肌梭自发放电,含有较高钙离子浓度的细胞外液可抑制该肌梭自发放电.为大鼠肌梭生理的研究及钙离子与失重性肌萎缩的实验研究提供了有意义的资料.

应用Ca2+导入剂Ionomycin建立大鼠比目鱼肌梭内肌细胞钙超载模型.实验采用激光扫描共聚焦显微镜技术,观察给予不同浓度Ca2+导入剂Ionomycin后,大鼠比目鱼肌梭内肌细胞内静息Ca2+的变化.实验结果显示给予2μmol/L Ionomycin灌流后,梭内肌细胞内Ca2+浓度缓慢升高(P<0.01),达峰后(2.67±0.43)min,MFI最大增值降低50％;给予5μmol/L Ionomycin灌流后,梭内肌细胞内Ca2+浓度迅速升高(P<0.01),达峰后(6.26±0.87)min,MFI最大增值降低50％.提示给予2μmol/L Ionomycin灌流肌梭可以形成短期的钙超载,给予5μmol/L Iono-mycin则可以建立稳定的大鼠比目鱼肌梭内肌细胞钙超载模型.为大鼠肌梭生理的研究及钙离子与失重性肌萎缩的实验研究提供了有意义的资料.

Ca2+触发了肌肉的收缩,参与肌细胞活动的调节,钙稳态的维持对肌肉收缩功能具有重要作用.模拟失重条件下肌细胞钙稳态失衡与肌球蛋白表型的转换及骨骼肌收缩功能减弱关系密切.针对钙稳态的维持及模拟失重条件下的钙稳态失衡与肌萎缩的关系及其可能的机制进行了综述.

目的:探讨高频正弦波振动(HFV)对骨骼肌在废用状态时细胞凋亡的对抗作用.方法:建立废用动物模型,改进振动仪的关键技术,采用短时间歇式振动的方法,结合电镜观察、免疫组化染色法和TUNEL法检测,观察HFV对制动大鼠比目鱼肌(SOL)湿重体重比、肌纤维横截面积、肌纤维超微结构的变化、Bcl-2和Bax的表达情况.结果:(1)制动后大鼠SOL湿重体重比为30.22±2.68,下降了36.43%.肌纤维的横截面积为3789.56±95.14μm2,下降了37.77%.HFV组相对制动组的SOL湿重体重比及横截面积均有所增加(P<0.05);(2)电镜可见制动后梭外肌病变明显,核内染色质团块状凝集.梭内肌部分肌膜溶解消失,细胞核变形.振动组的梭外肌Z线结构比较清晰,梭内肌纤维结构未见明显改变;(3)制动后大鼠SOL中Bcl-2阳性表达率为20%,明显低于对照组的表达情况(P<0.05).制动后Bax阳性表达率为80%,明显高于对照组的表达情况(P<0.05).制动后AI为20%,明显高于对照组(P<0.05).HFV组相对制动组的Bcl-2阳性表达率均有所增加,Bax阳性表达率以及AI有所降低(P<0.05).结论:改进后的抗肌萎缩振动仪操作性较强,对制动大鼠废用性肌萎缩的凋亡进程有抑制作用.

Objective:To determine peripheral neural adaptations to 2-week immobilization and whether muscle vibration intervention during immobilization would attenuate the negative adaptations induced by immobilization.Methods:Twenty-four subjects with one hind limb immobilized by plaster were divided into the immobilization group and the immobilization with muscle vibration group.Mechanical vibrations with constant low amplitude (0.3 mm) were applied with a constant frequency of 100 Hz on the soleus muscle of the subjects in vibration group during the immobilization period.The conduction velocity of tibial nerve and the latencies of M wave and H-reflex of soleus were observed before and after 2-week immobilization.Results:After 2 weeks of immobilization, conduction velocity of tibial nerve did not change with immobilization in either group (P>0.05).Significant increases in latency of M wave (P=0.000) and H wave (P=0.000) were found in the immobilization group, but no changes were observed in conduction through the spinal reflex loop (H minus M-wave latencies) (P=0.256).No significant changes occurred in the immobilization with muscle vibration group.Conclusion:These findings suggest that limb immobilization induces plastic changes in peripheral neural function, as evidenced by the increases in M-wave and H reflex latency and that such alterations was prevented by the intervention of muscle vibration during the immobilization period.

目的 探讨不同浓度氯化琥珀胆碱(suxamethonium chloride,Sch)对大鼠比目鱼肌离体单一肌梭传入放电的影响.方法 采用空气隔绝法记录大鼠比目鱼肌离体单一肌梭传入放电,分别给予25 mg/L、50mg/L、75 mg/L、100 mg/L、125 mg/L Sch灌流后,观察大鼠比目鱼肌离体单一肌梭传入放电的变化.结果 1)给予25 mg/L Sch灌流后,大鼠比目鱼肌离体单一肌梭传入放电较灌流前无明显变化;2)分别给予50 mg/L、75 mg/L Sch灌流后,肌梭传入放电较灌流前明显增多(P＜0.01);3)给予100 mg/L Sch灌流后,肌梭传入放电较灌流前无明显变化;4)给予125 mg/L Sch灌流后,肌梭传入放电较灌流前明显减少(P＜0.05).结论 一定浓度的氯化琥珀胆碱(50～ 75 mg/L)可特异性地兴奋肌梭,使大鼠比目鱼肌离体单一肌梭传入放电明显增多;氯化琥珀胆碱浓度过高(≥125mg/L)反而会抑制大鼠比目鱼肌离体单一肌梭的传入放电.

Objective To investigate the changes in the afferent discharge activities of the sensory nerve endings in muscle spindles of rats with hindlimb immobilization. Methods Plaster cast was used immobilize the hindllimbs of rats. Using air-gap technique, the spontaneous discharge of the muscle spindles and its responses to perfusion with succinylcholine (0.05 mg/ml) and suspension in an extended position were observed in isolated muscle spindles from rats with hindlimb immobilization for 3, 7, and 14 days. Results The muscle spindles of rat soleus showed a sharp decrease in spontaneous discharge frequency (P<0.01) and response to succinylcholine perfusion after 3 days of hindlimb immobilization (P<0.05). Significant changes of the firing rate in an extended position was observed in rats after a 14-day immobilization (P<0.01). The duration of individual spikes was significantly prolonged following hindlimb immobilization (P<0.01). Conclusion Muscle spindle discharges decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of the muscle spindle.

目的 观察后肢制动早期大鼠比目鱼肌梭内肌纤维形态结构的改变.方法 以后肢制动建立后肢脱负荷动物模型,将实验动物分为正常对照组、后肢制动3天组和后肢制动7天组.分离各组大鼠单一肌梭,用透射电子显微镜技术观察大鼠比目鱼肌梭内肌纤维的超微结构.结果 后肢制动3天后,梭内肌纤维内线粒体明显增生肿胀;7天后,梭内肌纤维直径明显减小,细胞核发生明显的退行性改变.结论 后肢脱负荷早期可造成梭内肌纤维形态结构发生明显的退行性改变,梭内肌纤维肌梭超微结构的这种改变,必然会影响肌梭的功能活动,可能是引起废用性肌萎缩发生的重要因素之一.

To study the effects of 14 days of simulated weightlessness on ionotropic glutamate receptors (iGluRs) immunoreactivity in the Interpositus nuclear neurons of rat, immunohistochemistry ABC staining method was used.Results showed that the numbers of NMDAR-1, AMPAR-2 and KAR-2 immunoreactive neurons in the interposed cerebellar nucleus were all obviously increased after 14 days of tail-suspension ( P<0.05).The findings suggested that weightlessness induces an obvious increase in the activation of neuro-nal circuit in the interposed cerebellar nucleus.

It has been reported that the threshold to activate 'silent' or inactive descending facilitation of nociception is lower than that of descending inhibition. Thus, the development of pain therapy to effectively drive descending inhibition alone, without the confounding influences of facilitation is a challenge. To address this issue we investigated the effects of intramuscular stimulation with a heating-needle on spinal nociception, assessed by measuring nociceptive paw withdrawal reflex in rats. Additionally, involvement of the thalamic 'nociceptive discriminators' (thalamic mediodorsal (MD) and ventromedial (VM) nuclei), and opioid-mediated mechanisms were further explored. Descending facilitation and inhibition were elicited by 46°C noxious heating-needle stimulation, and were regulated by thalamic MD and VM nuclei, respectively. In contrast, innocuous heating-needle stimulation at a temperature of 43°C elicited descending inhibition modulated by the thalamic VM nucleus alone. Microinjection of μ/δ/κ-opioid receptor antagonists β-funaltrexamine hydrochloride/naltrindole/nor-binaltorphimine, into the VM nucleus attenuated the 46°C intramuscular heating-needle stimulation-evoked descending inhibition, whereas treatment of the MD nucleus with β-funaltrexamine hydrochloride significantly decreased the descending facilitation. By contrast, descending inhibition evoked by 43°C heating-needle stimulation was only depressed by naltrindole, as opposed to μ- and κ-opioid receptor antagonists, which failed to influence descending inhibition. The present study reveals distinct roles of μ-opioid receptors in the function of thalamic MD and VM nuclei,which exert facilitatory and inhibitory actions on nociception. Furthermore, innocuous, but not noxious, intramuscular heating-needle stimulation targeting δ-opioid receptors is suggested to be a promising avenue for the effective inhibition of pain.

<正>中、长期航天飞行会使人体多个器官系统发生一系列病理生理性变化[1,2],特别是下肢抗重力肌会出现明显的肌肉萎缩[3]。肌肉萎缩不仅会影响航天员在太空的飞行时间和工作效率,而且还会影响航天员返回地面后的再适应能力。美国、俄罗斯曾在此方面进行了大量的研究,也研制了多种防护措施,但由于不清楚失重导致肌肉萎缩的确切机制,这些措施的效果都不尽理想。因此,阐明失重所致肌肉萎缩的发生机制具有十分重要的理论意义。长期以来,国内外学者对失重性肌萎缩的发生机制进行了广泛而深入的研究,并取得了一定的进

Objective To observe the effect of cordyceps extracting solution(CS) on the afferent discharge frequency of rats muscle spindle.Methods The endotracheal intubation and the external jugular vein intubation under anaesthesia were performed for 20 female SD rats,then the nerve filaments of soleus muscle were isolated in vivo to observe the influence from the CS on muscle spindle afferents.Results After administration of 50 mg·kg-1,100 mg·kg-1,and 150 mg·kg-1 CS,the spontaneous discharge of soleus muscle spindle in rats increased significantly.The effect of CS on muscle spindle afferents was dose-dependent.Conclusion CS can effectively increase afferent discharge of soleus muscle spindle of rats.

Capsule restricts the further study on muscle spindle function and the involved mechanism. The aim of this study was to establish the isolation method of intrafusal fibres from the isolated rat muscle spindle. Intrafusal fibres were harvested from muscle spindle of soleus muscle in rats using neutrase-collagenase digestion. A variety of incubation mediums have been tested to find out an appropriate medium of intrafusal fibers in vitro. Trypan blue staining was used to detect cell death, and patch clamp was used to record resting potential. The results showed that the intrafusal fibres incubated with amine acid-saline solution were almost all dead. DMEM could maintain good condition of the fibres, but excess CO2 ventilation would induce cellular swelling or even death. While Leiboviz's 15 (L-15) medium can guarantee 1-2 h of physiological condition of the intrafusal fibres. Coverslips treated with gelatin, polylysine and serum was the better interfaces for the intrafusal fibres to adhere easily, compared with regularly treated coverslip. The resting potential of intrafusal fibres was (-45.3 ± 5.1) mV, consistent with others obtained from in vivo muscle spindle from cats and frogs. These results suggest that the isolation method of the intrafusal fibres has been successfully established in the present study, providing a new approach in better understanding of muscle spindle activities and the involved mechanism.

One of the most important and urgent issues in the field of space medicine is to reveal the potential mechanism underlying the disused muscle atrophy during the weightlessness or microgravity environment. It will conduce to find out effective methods for the prevention and treatment of muscle atrophy during a long-term space flight. Increasing data show that muscle spindle discharges are significantly altered following the hindlimb unloading, suggesting a vital role in the progress of muscle atrophy. In the last decades, we have made a series of studies on changes in the morphological structure and function of muscle spindle following simulated weightlessness. This review will discuss our main results and related researches for understanding of muscle spindle activities during microgravity environment, which may provide a theoretic basis for effective prevention and treatment of muscle atrophy induced by weightlessness.

Objective To study the antagonistic effects of cordyceps(CS) on atrophy of disused muscle of rats under immobilization.Methods Models of disused muscles were established by immobilizing rat hindlimbs.Changes of myosin heavy chain(MHC) expression in intrafusal and extrafusal fibers in soleus muscle were detected.The morphology and the constituent ratio of skeletal muscle fibers were observed.Results ① After the 14-day hindlimb immobilization,the soleus muscle fibers showed an evident shift toward a decreased percentage of type Ⅰ fibers,but an increased percentage of type Ⅱ.The expression of MHC in muscle spindle was increased.② Compared with those in the immobilization group,the soleus muscle fibers in the CS group showed an evident shift toward increased SOL wet weight/weight ratio and cross-section of muscle fibers,and an increased percentage of type Ⅰ fibers,and an decreased percentage of type Ⅱ fibers.The change of MHC expression in muscle spindle was inconspicuous.Conclusion HFV is effective in antagonizing atrophy of rat disused muscle.

Recently, we hypothesized that supraspinal structures may have important functions in discriminating between noxious mechanically and heat mediated nociception through distinct functions: facilitation and inhibition. In this study, conducted in conscious rats, we explored the role of different thalamic nuclei: the mediodorsal (MD) nucleus, the central medial (CM) nucleus, the submedius (SM) nucleus, the ventralmedial (VM) nucleus and the ventral posterolateral (VPL) nucleus, in the descending control of secondary and contralateral mechanical hyperalgesia and heat hypoalgesia occurring in intramuscularly hypertonic (HT, 5.8%) saline-induced muscle nociception. We found that the MD nuclei participated in the descending facilitation of mechanical hyperalgesia, and that the VM nuclei were specifically involved in the descending inhibition of heat hypoalgesia. Neither descending facilitation nor descending inhibition was affected after electrolytic lesion of the thalamic CM, SM, and VPL nuclei. This descending facilitatory and inhibitory modulation of nociception was strengthened by glutamate, and weakened by GABA, microinjected into the thalamic MD and VM nuclei. It is suggested that (1) thalamic MD nucleus and VM nucleus form two distinct endogenous systems in the control of noxious mechanically and heat evoked responses, and (2) the strengthening of descending inhibition and the weakening of descending facilitation by means of up regulation and down regulation of appropriate receptor expression in the VM and MD nuclei may provide a new strategic policy in treating pathological pain.

Introduction: The purpose of this study was to evaluate the electrophysiological changes observed in dorsal root ganglion (DRG) neurons in a simulated weightlessness rat model and to assess the mechanisms involved in these changes. Methods: The simulated weightlessness model was created by hindlimb unloading (HU). Whole-cell patch-clamp recordings, conduction velocity measurement, and ultrastructural observation were performed. Results: In the HU rats, the action potentials had a longer duration and slower falling rate, but there was no significant effect on amplitude or rate of rise. HU also induced lowering of rheobase and of the threshold potential, making the cells more excitable. The conduction velocities in the proximal branches of ganglion cells were also decreased, and some degenerative changes in the myelin sheath were noted. Conclusions: This study provides evidence of plasticity of DRG neurons induced by HU. The changes observed might contribute to impaired motor performance in rats submitted to HU. Muscle Nerve 45: 6569, 2012