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Oestrogen‐dependent satellite cell activation and proliferation following a running exercise occurs via the PI 3K signalling pathway and not IGF ‐1
Author(s) -
Mangan G.,
Bombardier E.,
Mitchell A. S.,
Quadrilatero J.,
Tiidus P. M.
Publication year - 2014
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.12317
Subject(s) - medicine , endocrinology , wortmannin , pi , soleus muscle , ovariectomized rat , chemistry , estrogen , phosphatidylinositol , signal transduction , biology , skeletal muscle , biochemistry
Aim The purpose of this study was to determine whether 17 β ‐estradiol (E2) enhances the activation, proliferation and differentiation of muscle satellite cells ( SC ) following eccentric exercise either via insulin‐like growth factor‐1 ( IGF ‐1) or through phosphatidylinositol 3‐kinase ( PI 3K) signalling. Methods This study used 64, 9‐week‐old, ovariectomized Sprague–Dawley rats that were divided into eight treatments groups based on oestrogen status (0.25 mg oestrogen pellet or sham), exercise status (90 min run @ 17 m min −1 , −13.5° or unexercised) and PI 3K signalling inhibition (0.7 mg wortmannin kg −1 body weight or DMSO control). Results Significant increases in total SC s were found in both soleus and white gastrocnemius muscles (immunofluorescent co‐localization of Pax7 + nuclei) 72 h following eccentric exercise ( P < 0.05). Oestrogen supplementation caused a further enhancement in total SC s in exercised rats ( P < 0.05). In animals where the PI 3K pathway was inhibited, regardless of oestrogen or exercise status, there was no significant enhancement of SC number in both the soleus or white gastrocnemius muscles. Interestingly, oestrogen supplementation lowered muscle levels of IGF ‐1 with this effect being most prominent in the soleus muscle. While IGF ‐1 was increased following exercise ( P < 0.05), oestrogen supplementation abrogated this increase back to sedentary levels. Conclusion These data suggest that the increase in SC population following exercise in oestrogen‐supplemented females may be mediated via PI 3K pathway signalling and not IGF ‐1.