Muscle regeneration |
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Authors: | H Sommerland M Ullman E Jennische A Skottner A Oldfors |
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Institution: | (1) Department of Pathology, Sahlgren Hospital, S-413 45 Göteborg, Sweden;(2) Department of Histology, Sahlgren Hospital, S-413 45 Göteborg, Sweden;(3) Kabi Vitrum AB, Stockholm, Sweden |
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Abstract: | Summary Against the background of the importance of growth hormone (GH) for normal muscle growth, a study was performed to investigate whether lack of GH after hypophysectomy affects the cell proliferation and the local production of insulin-like growth factor-I (IGF-I) in the early stages of muscle regeneration in adult rats. The level of IGF-I in the serum of hypophysectomised rats was reduced to about 30% of that of controls. The incorporation of methyl-3H]thymidine into the regenerating muscle showed a peak 6 days after the operation and then gradually declined to the end of the period of study 30 days after initiation of regeneration by ischemic necrosis. The DNA content rose to a maximum level after 6–8 days, and remained high after 30 days. There was no major difference in the incorporation of 3H]thymidine in regenerating muscle of hypophysectomised and control rats, but the DNA concentration in the regenerating muscles of hypophysectomised rats was significantly reduced after 30 days. There was a corresponding reduction in the number of nuclei per muscle fibre, indicating that hypophysectomy has a small effect on the cell proliferation during the early stages of muscle regeneration. Immunohistochemical demonstration of IGF-I in the regenerating muscle revealed the transient presence of immunoreactive material in satellite cells and myotubes after 6 to 8 days of regeneration but no immunoreactivity after 30 days. No obvious difference was observed between hypophysectomised and control rats, indicating that the endogenous production of IGF-I in regenerating skeletal muscle can occur independently of GH.Supported by the Swedish Medical Research Council (Project no. 7122 and 7120) |
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Keywords: | Skeletal muscle Regeneration Growth factors Growth hormone Rat |
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