Muscle type from which satellite cells are derived plays a role in their damage response.

The aim of this study was to evaluate the response of satellite cells to muscular atrophies which possess different pathological characteristics and which were induced by distinct damages. Right lower limbs of rats were exposed to denervation or disuse and later its tibialis anterior (TA) or soleus (SOL) muscles were analyzed. After confirming their functional impairments indicated by common but distinct pathological and electrophysiological characteristics, the quantitative polymerase chain reaction analysis of Pax7 and Pax3 expressions and the number of Pax7+ve and Pax3+ve cells were analyzed sequentially at day 0, day 7, and day 14. TA muscles of both denervation- and disuse-induced atrophy models showed persisted low level of Pax7 expression from day 7 (0.91 ± 0.23 and 0.31 ± 0.07, P = 0.06, n = 6) through day 14 (1.09 ± 0.15 and 0.4 ± 0.09 [P < 0.05]). On the other hand, significant elevations were observed in Pax3 expression in both atrophy models (2.73 ± 0.46 and 2.75 ± 0.26 [P < 0.05]) at day 7. Similar to TA muscle, resembled pattern of Pax7 and Pax3 expression changes were observed between the SOL muscles of denervation- and disused-atrophy models. These trends were further confirmed by the changes in Pax7+ve and Pax3+ve cell numbers of TA and SOL muscles in both atrophy models. Despite the distinct pathological findings, similar patterns in the changes of Pax3 and Pax7 expressions and the changes of Pax7+ve and Pax3+ve cell numbers were observed between the denervation- and disuse-induced atrophy models and this commonality was admitted among the muscle type. Therefore, we claim that the muscle regeneration orchestrated by satellite cells was governed by the muscle type in which satellite cells reside.

Effects of Tuina on Muscle-specific microRNA and Factors Related with Proliferation and Differentiation of Muscle Satellite Cells in Denervation-induced Atrophy in Rats / 中国康复理论与实践

Objective:To investigate the effects and mechanism of Tuina on denervation-induced atrophy. Methods:A total of 42 Sprague-Dawley rats were randomly divided into sham group (n = 6), model group (n = 18) and Tuina group (n = 18). The model group and Tuina group freed and excised right tibia nerve about one centimeter, while the sham group freed the right tibia nerve only. From the second day after operation, Tuina group accepted Tuina on the injured area, while the sham group and the model group were only fixed without any intervention. Six rats were sacrificed on the 14th, 21st and 28th day after operation in the model and Tuina groups, and the sham group was sacrificed on the 28th day after operation. The gastrocnemius muscles were measured wet weight ratio. The diameter and area of muscle cells were measured under HE staining. The expression of Pax7, MyoD, MyoG, microRNA-1, microRNA-133a and microRNA-206 in the gastrocnemius muscles were detected with reverse transcription real-time quantitative polymerase chain reaction. Results:Compared with the sham group, the wet weight ratio, the area of muscle cells (except the 14-day-Tuina group) and the diameter of muscle cells decreased at each time point in the model group and Tuina group (P < 0.05); compared with the model group, the wet weight ratio, muscle cell diameter and muscle cell area increased at each time point in Tuina group (P < 0.05). Compared with the sham group, the expression of Pax7 increased in the 14-day-model group (P < 0.05) and decreased in the 28-day-model group (P < 0.05), and it increased at each time point (except 28-day) in Tuina group (P < 0.05); compared with the model group, the expression of Pax7 increased at each time point in Tuina group (P < 0.05). Compared with the sham group, the expression of MyoD and MyoG increased at each time point in the model group and Tuina group (P < 0.05); compared with the model group, the expression of MyoD and MyoG increased at each time point (except 14-day) in Tuina group (P < 0.05). Compared with the sham group, the expression of microRNA-1 and microRNA-133a decreased, and microRNA-206 increased in the model group and Tuina group at 21-day (P < 0.05); compared with the model group, the expression of microRNA-1, microRNA-133a and microRNA-206 increased in Tuina group (P < 0.05). Conclusion:Tuina may activate the Pax7/MyoD/MyoG pathway by increasing the expression of muscle-specific microRNA, to promote the proliferation and differentiation of muscle satellite cells, and delay denervation-induced atrophy.

Effects of Electroacupuncture on Autophagy-related Gene Expression in Skeletal Muscle in Denervated Rats / 中国康复理论与实践

@#Objective To explore the effects and mechanism of electroacupuncture(EA)on denervation-induced atrophy. Methods A total of 21 male Sprague-Dawley rats were divided into sham group(n=7),model group(n=7)and EA group (n=7).The latter two groups were cut off their right sciatic nerve.Since one day after modeling,EA group accept-ed electroacupuncture at right Zusanli(ST36)and Huantiao(GB30)for eight weeks.Then,the gastrocnemius of all the rats were obtained,and measured the wet mass ratio.Cross-sectional area(CSA)and fiber diameter were measured after HE staining. The expression of autophagy-related gene ULK1, Atg13, Beclin1, Atg14, Atg7, Atg12,Atg5 and Atg16L1 were tested with reverse transcription real-time quantitative polymerase chain reaction. Results Compared with the sham group,the wet mass ratio,CSA and fiber diameter of gastrocnemius were lower signifi-cantly in the model group and EA group(P<0.001),and they were more in EA group than in the model group(P<0.05).Compared with the sham group,the mRNA expression of ULK1,Atg13,Beclin1,Atg14,Atg7,Atg12,Atg5 and Atg16L1 was more significantly in the model group (P<0.001), and they decreased in EA group compared with those of the model group(P<0.05). Conclusion Electroacupuncture can inhibit the overexpression of autophagy-related gene in denervated rats,which may steady skeletal muscle cells to delay atrophy.