甘肃鼢鼠骨骼肌低氧适应特征的研究

【作者】 熊晓毅；

【导师】 何建平；

【作者基本信息】 陕西师范大学 ， 生理学， 2010， 硕士

【摘要】 骨骼肌是哺乳动物运动系统的重要组织,哺乳动物通过骨骼肌舒缩来完成躯体运动。甘肃鼢鼠(Myospalax cansus)是我国黄土高原特有地下鼠,终身营严格地下生活,为适应地下低氧环境,其结构和功能都出现了很多变化特征。本文拟通过对低氧条件下甘肃鼢鼠和SD大鼠骨骼肌特征进行比较,旨在探讨甘肃鼢鼠骨骼肌低氧适应机制。研究结果如下：1.运用形态学方法对常氧、低氧2周和低氧4周后甘肃鼢鼠及SD大鼠骨骼肌形态结构进行比较研究,发现甘肃鼢鼠骨骼肌形态结构在常氧、低氧2周和低氧4周后变化不明显,肌纤维排列有序,肌膜完整且清晰,肌横纹规则整齐,形态大小一致,核较大,肌纤维呈圆柱状,排列整齐,胞浆染色均匀,核位于肌膜下.SD大鼠骨骼肌形态结构随低氧时间延长发生显著变化,低氧2周后,骨骼肌肌纤维明显萎缩,肌纤维间隙增大,结构较紊乱,胞浆染色较均匀。低氧4周后,骨骼肌肌纤维破裂,呈细丝状,不规则,大小不一致,肌纤维结构明显紊乱,部分区域可见单个肌纤维断裂,肌节紊乱；细胞排列紧密,界限不清,核较稀疏,染色质浓缩、靠近核膜。说明甘肃鼢鼠骨骼肌的正常结构和功能,对其适用低氧环境有着重要意义。2.利用紫外分光光度计对常氧、低氧2周及低氧4周甘肃鼢鼠和SD大鼠骨骼肌乳酸脱氢酶(LDH)活性进行测定。结果表明,常氧条件下甘肃鼢鼠雌雄间前肢和后肢LDH活性无显著性差异(P>0.05)；前后肢LDH活性有极显著差异(P<0.01),前肢LDH活性显著高于后肢；低氧2周及4周后,LDH活性均下降,但差异不显著(P>0.05)。SD大鼠低氧2周后,LDH活性升高,但与常氧相比无显著差异(P>0.05)。说明两种生活环境不同的啮齿动物,骨骼肌代谢在低氧适应过程中表现出不同的发展趋势,甘肃鼢鼠适应低下洞道生活,前肢适应挖掘活动,无氧代谢能力较强。同时,由于甘肃鼢鼠长期适应低下低氧,其LDH水平显著低于SD大鼠,并在低氧2周和4周,LDH水平变化不明显；SD大鼠在低氧适应2周和4周后LDH会有所升高,说明其无氧代谢水平有所升高。3用紫外分光光度计对常氧、低氧2周及4周甘肃鼢鼠和SD大鼠骨骼肌琥珀酸脱氢酶(SDH)活性进行测定。结果表明,常氧条件下,甘肃鼢鼠前后肢SDH活性无显著性差异(P>0.05)。低氧2周后,SDH活性降低,与常氧相比,无显著性差异(P>0.05)；低氧4周后,SDH活性升高,但与常氧和低氧2周相比均无显著性差异(P>0.05)。SD大鼠低氧2周后,SDH活性升高,但与常氧时相比,无显著性差异(P>0.05)；低氧4周后SDH活性进一步升高,但与常氧和低氧2周相比均无显著性差异(P>0.05)。说明两种啮齿动物骨骼肌在低氧适应过程中有氧代谢变化不明显。4.利用紫外分光光度计对常氧、低氧2周及4周甘肃鼢鼠和SD大鼠前后肢骨骼肌肌红蛋白(Mb)浓度进行测定。结果表明,常氧条件下,甘肃鼢鼠前后肢Mb浓度均无显著性差异(P>0.05),雌雄间前肢有极显著性差异(P<0.01)、后肢Mb浓度无显著差异(P>0.05)。低氧2周后,Mb浓度有极显著性升高(P<0.01)；低氧4周, Mb浓度降低,与常氧和低氧2周相比均有极显著性差异(P<0.01)；前肢雌雄间有极显著性差异(P<0.01),后肢无显著性差异(P>0.05)。SD大鼠低氧2周后,Mb浓度降低,但与常氧相比无显著差异(P>0.05)。低氧4周,Mb浓度进一步降低,但与常氧和低氧2周相比均无显著性差异(P>0.05)。甘肃鼢鼠前肢及后肢Mb浓度在常氧条件下,分别显著高于SD大鼠(P<0.05),低氧2周和低氧4周后,极显著高于SD大鼠(P<0.01)。说明甘肃鼢鼠骨骼肌中氧供应充足,即使在低氧环境中也能满足骨骼肌运动对氧气的需求。5.对常氧及低氧2周、4周的甘肃鼢鼠和SD大鼠体重进行测定。结果表明,甘肃鼢鼠雌、雄性体重在低氧过程中有所降低,但与常氧组均无显著差异(P>0.05)；SD大鼠雌性、雄性体重随低氧时间延长明显降低,与常氧组有极显著差异(P<0.01),与低氧2周组无显著差异(P>0.05)。说明甘肃鼢鼠在低氧环境中,能较快调动自身适应机能,维持其正常体重。总之,在低氧条件下,甘肃鼢鼠和SD大鼠体内各器官系统和身体机能的调节系统可能在不同水平产生适应性变化的整合,使骨骼肌的有氧代谢酶类和无氧酵解酶的活性发生不同变化。不同低氧条件下,甘肃鼢鼠骨骼肌各指标均较常氧对照组无显著性变化,基本保持在一个恒定水平。而SD大鼠各指标则在低氧应激到达一定程度时发生明显变化。说明甘肃鼢鼠长期生活在地下低氧环境中,对低氧刺激不敏感,在实验过程中可能会顺利启动自身整体协调的低氧适应机制,从而在各个器官稳定的情况下维持在低氧条件下的生存。更多还原

【Abstract】 Skeletal muscle is an important organization for movement system of mammalian, whose body movement is completed through the systole and diastolic of skeletal muscle. Gansu zokor is the unique specie of subterranean rodents in Loess Plateau, China, which lives under the ground all their life. To adapt the underground hypoxic environment, the structure and function of their body have come out many great changes. Through comparing the characteristics of skeletal muscle between Gansu zokor and SD rats under hypoxic conditions, would investigate the adaptation mechanism of Gansu zokor skeletal muscle under the hypoxia environment.The results are as follows:1. With morphologic methods, the differences of skeletal muscle between Gansu zokor and SD rats under different conditions (Normoxia, hypoxia 2 weeks, hypoxia 4 weeks)were compared. The results showed that the morphology of cansus skeletal muscle did not change significantly during the different time, the muscle fiber arranged orderly, muscle membrane completed and clear, muscle striations arrayed regular and straight in the same shape and size, the nuclear relative larger, muscle fiber cylindrical and arranged in order, cytoplasm uniform staining and the nuclear located under the muscle membrane.There is a significant difference on SD rats muscle morphology when the hypoxia conditions time prolonged. The muscle fiber was significantly atrophied under the hypoxia environment for 2 weeks, and the muscle fiber gap increased, more disordered structure, cytoplasm was uniform. After 4 weeks of hypoxia, skeletal muscle fiber breakdown as well as different in sized, muscle fiber structure was significant disorder, part of the areas appeared single muscle fiber rupture and sarcomere disorder, and cells closely arranged but not clearly, nuclear was scattered but chromatin condensed and closed to the nuclear membrane.It suggests that it is great important to study the normal skeletal muscle structure and function of cansus for their speciall physiological characteristics adapting hypoxic environment.2. The skeletal muscle lactate dehydrogenase (LDH) activity was measured between Gansu zokor and SD rat in normoxia and hypoxia 2 weeks, hypoxia 4 weeks, by UV spectrophotometer. The results showed that in normoxia between male and female cansus of the forelimbs and hindlimbs the LDH activity was not significantly different (P>0.05), the LDH activity was extremely significantly different (P<0.01) between the forelimbs and hindlimbs, and the LDH activity of forelimbs was significantly higher than the hindlimbs (P<0.05). After treatment with hypoxia for 2 weeks and 4 weeks, LDH activity decreased, but the difference was not significant (P> 0.05). After the SD rats treatment with hypoxia for 2 weeks, LDH activity increased, but the comparison with normoxia there was no significant difference (P> 0.05). It showed that the skeletal muscle metabolism of two different rodents lived in different environment showed different developmental trend in the process of hypoxia adaptation. Being adapted to tunnel life underground, forelimbs of Gansu zokor is used to dig and have more stronger anaerobic metabolism ability. Meanwhile, because of long life in the hypoxia environment underground, the LDH level was significantly lower than the SD rats, and after 2 weeks and 4 weeks under hypoxia, LDH levels did not change significantly. After the hypoxic adaptation for 2 weeks and 4 weeks LDH of SD rats will be increased, indicating the level of anaerobic metabolism rised.3. The skeletal muscle succinate dehydrogenase (SDH) activity was measured between Gansu zokor and SD rat in normoxia and hypoxia 2 weeks, hypoxia 4 weeks, with Using UV spectrophotometer. The results showed that under normoxic conditions, the SDH activity of forelimbs and hindlimbs of cansus was not significantly different (P> 0.05). After 2 weeks under hypoxia, SDH activities decreased and had no significant differences (P> 0.05) under normoxia. After 4 weeks under hypoxia, Gansu zokor SDH activity increased but no significant difference was showed among normoxia, hypoxia 2 weeks, and hypoxia 4 weeks (P> 0.05). After treatment under hypoxia for 2 weeks, SD rats SDH activity increased, but no significant difference by comparing with normoxia (P>0.05). After 4 weeks of hypoxic, SD rats SDH activity further increased but no significant difference by comparing with normoxia and hypoxia 2 weeks (P> 0.05). The study showed that two rodents skeletal muscle did not change significantly during aerobic metabolism in hypoxia.4. With UV spectrophotometer the skeletal muscle myoglobin (Mb) concentration was measured between Gansu zokor and SD rat in normoxia and hypoxia 2 weeks, hypoxia 4 weeks. The results showed that under normoxic conditions, Mb concentrations of forelimbs and hindlimbs of cansus were not significantly different (P> 0.05), the concentrations of forelimb between male and female were significantly different (P<0.01), and those of hindlimbs were no significant different (P> 0.05). After 2 weeks of hypoxia, Mb concentration was significant higher (P<0.01). After hypoxia for 4 weeks, Mb concentration decreased, showed highly significant differences by comparing with normoxia and hypoxia 2 weeks (P<0.01). The Mb concentration of forelimbs between male and female were significantly different (P<0.01), while those of hindlimbs have no significant difference (P> 0.05). After treatment under hypoxia for 2 weeks, SD rats Mb concentration decreased, but showed no significant difference (P>0.05) by comparing with normoxia. After hypoxia for 4 weeks, Mb concentration further decreased, but showed no significant difference (P>0.05) by comparing with normoxia and hypoxia 2 weeks. Mb concentration of forelimbs and hindlimbs of Myospalax cansus were higher than SD rats (P<0.05), and hypoxia for 2 and 4 weeks showed significantly higher than SD rats (P<0.01). The results indicated that Gansu zokor has special adapting mechanism for supplying oxygen to skeletal muscle, even in low oxygen environments during the movement.5 The body weight of normoxia and hypoxia 2 weeks, hypoxia 4 weeks of Gansu zokor and SD were measured. The results showed that body weight of cansus between male and female decreased during the hypoxia treatment, but there were no significantly different (P> 0.05) by comparing with normoxia. The body weight of both male and female SD rats decreased under hypoxia, but there were no significantly different (P> 0.05) by comparing with normoxia (P<0.01) and 2 weeks under hypoxia (P> 0.05). It suggested that Gansu zokor can quickly adapt the low oxygen environments in order to alter their own function to maintain the normal body weight.In conclusion, under the hypoxia environment, Gansu zokor and SD rats can use various organ systems and body regulation system to produce different adaptable mechanism in different levels, following that the enzymes activity of skeletal muscle for aerobic metabolism and anaerobic glycolysis were changed in order to complete body movement more effectively. Comparing with normoxia, the various indicators of skeletal muscle of Gansu zokor have no significant change and remain at a constant level. However, there were significant differences in the various indicators of SD rats when reaching a certain degree under the hypoxic stress. It indicates that Gansu zokor is insensitive to hypoxia stimulation because of living in the hypoxic environment for a long time. In the experiment they may start their own adaptation and coordination mechanism for hypoxic adaptation which makes each organ maintain stable to survive in such a hypoxic environment.更多还原