الفهرس 
Age-related muscle atrophy (sarcopenia) in different speciesOnly 14 pages are availabe for public view
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Abstract
The purpose of this study was to investigate the age-related histological, biochemical, and molecular changes occurring in the gastrocnemius muscles during aging. Albino male rats (N = 56) were divided into 4 groups as follows: the 1st group is 14 rats of 1 month-old weighting 28.37±2.52 g, the 2nd group is 14 rats of 5 month-old weighting 156.42 ± 5.56 g, the 3rd group is 14 rats of 10 month-old weighting 211.45 ± 12.14 g and the 4th group is 14 rats of 15 month-old weighting 336.14 ± 29.39 g). furthermore, Each group was subdivided into 2 subgroups each consist of 7 rats, the first subgroups fed a laboratory regular diet (Protein 25%, Fat 5.0%, Carbohydrate 47.5%, Crude fiber 5.3%, Ash 7.0%), and the second subgroups fed a Lab. regular diet + quercetin which was administrated intraperitoneally (i.p.) at a dose of 200 mg/kg body weight for 2 weeks. The rats were housed in cages in controlled environmental conditions (22-25°C), with a 12-12 h light-dark cycle. The results showed that aging significantly decreased the catalase activity and increased MDA levels, while insignificantly change SOD activity, GSH and protein levels. Moreover, it significantly decreased the relative expression of AMPKα2 and Bcl2 genes while significantly increased the relative expression of both of NF-Kb and Bax genes. At the histological level, hyalinization, fragmentation and hyalinization of the muscles fibers were determined with aging. At the immunohistochemical level, an increase in the caspase 3 expression were noticed. The prevous changes were re-evaluated after short-term supplementation of quercetin at a save dietary supplement dose (200 mg/kg body weight for three times/ week for 2 weeks). Chapter 6 80 Summary and Conclusion The results showed that:- 1- The daily weight gain in quercetin subgroups was higher than that of the control subgroups by 148%, 237%, 275% & 114%, at the 1st, 5th, 10th and 15th month of age, respectively. 2- Catalase content in quercetin subgroups increased at the 5th, 10th and 15th month by 5.3%, 57.8%. 66.9% when compared with their control subgroups respectively. 3- GPx activity showed a non-significant change (p ≥ 0.05) at the 5th, 10th and 15th month of age when compared with the control rats that have one-month age and didn’t receive quercetin. 4- SOD activity showed a non-significant increase (p ≥ 0.05) at the 1st month while showed a significant increase (p ≤ 0.05) at the 5th, 10th and 15th when compared with the control rats at the 1st month and didn’t recieve quercetin. Interestingly, quercetin treatment showed a non-significant increase (p ≥ 0.05) in the SOD activity at the 1st, and 15th month when compared with their control sugroups at the same age, respectively. 5- GSH content showed a non-significant increase (p ≥ 0.05) at the 1st and 5th month while showed a significant increase (p ≤ 0.05) at the 10th and 15th when compared with the rats at the 1st month that did not receive quercetin, respectively. Interestingly, quercetin treatment showed a non-significant increase (p ≥ 0.05) in the GSH content at the 1st, 5th and 15th month when compared with their control subgroups at the same age, respectively. 6- MDA levels showed a significant decrease (p ≤ 0.05) at the 5th, 10th and 15th month comparing with the control subgroup including rats at the 1st month that didn’t recieve quercetin. Interestingly, when compared quercetin-treated subgroups with their control Chapter 6 81 Summary and Conclusion subgroups at the same age, a significant change (p ≤ 0.05) in the MDA content was noticed. 7- The total protein showed a non-significant change (p ≥ 0.05) at the 5th, 10th and 15th month while showed a non-significant change (p ≥ 0.05) only at the 1st month when compared with the rats at the 1st month of age that didn’t receive quercetin, respectively. Furthermore, the total protein concentration at the 5th, 10th and 15th month showed a non-significant change (p ≥ 0.05) when compared with their control subgroups at the same age, respectively. GENE EXPRETION - Significant (p ≤ 0.05) upregulation of AMPKα2 gene expression level at the 1st, 5th, 10th and 15th months of age as compared with the control subgroups at the same age, respectively. The expression levels of AMPKα2 gene were equal to 6.28 ± 0.37, 4.72 ± 0.25 and 1.55 ± 0.08 fold change at the 1st, 5th, 10th and 15th months of age, respectively. - Significant (p ≤ 0.05) upregulation of Bcl2 gene expression levels at the 1st, 5th, 10th and 15th month of age as compared with the control subgroups at the same age, respectively. The expression levels of Bcl2 were equal to 3.41 ± 0.2, 2.60 ± 0.14, 1.91 ± 0.1 and 1.37 ± 0.08 fold change, respectively. - Significant (p ≤ 0.05) downregulation of of NF-κB gene expression levels at the 1st, 5th, 10th and 15th months of age as compared with the control subgroups at the same age, respectively. The expression levels of NF-κB gene were equal to 0.31 ± 0.01, 0.50 ± 0.01, 0.71 ± 0.06 and 0.88 ± 0.05 fold change at the 1st, 5th, 10th and 15th months of age, respectively. - Significant (p ≤ 0.05) downregulation of Bax gene expression level at the 1st, 5th, 10th and 15th months of age when compared with the control subgroups at the same age, respectively. The expression levels of Bax Chapter 6 82 Summary and Conclusion genes were with 0.06 ± 0.01, 0.08 ± 0.01, 0.15 ± 0.02 and 0.65 ± 0.03 fold change at the 1st, 5th, 10th and 15th month of age, respectively. HISTOPATHOLOGICAL CHANGES After quercetin administration, rats gastrocnemius fibers appeared with normal structure and muscles’ myolysis, infiltration and fragmentation were rarely observed at both 1st and 5th month of age. At both 10th and 15th month of age, focal hyalinization of the muscle fibers was still determined while most fibers appeared with normal appearance CASPASE 3 IMMUNOSTAINING -Examination of rats gastrocnemius muscle sections at the 1st, 5th, 10th and 15th month of age showed a significant (p ≤ 0.05) decrease in the immunohistochemical expression of caspase 3 compared with what was observed at the same age without quercetin administration in the control subgroups, respectively.