Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Kinesiology and Physical Education

Faculty/School

Faculty of Science

First Advisor

Peter Tiidus

Advisor Role

Thesis Supervisor

Abstract

Estrogen has been shown to augment satellite cell activation, proliferation and total number and that this may occur through an estrogen receptor (ER) mediated mechanism. The purpose of this study was to investigate the role of ERs in the postexercise estrogen-induced augmentation of satellite cells in skeletal muscle of ovariectomized rats. Furthermore, the specific role of the ERα was examined through the use of an ERa agonist, propyl pyrazole triol (PPT). Ovariectomized rats were used (n=64) and separated into 4 groups: sham, estrogen supplemented, agonist supplemented and a combined estrogen and agonist supplemented group. These groups were further subdivided into control (unexercised) and exercise groups. Animals in the exercise group participated in an intermittent running protocol that involved animals running downhill on a motorized treadmill for 90 minutes. Surgical removal of white vastus and soleus muscles occurred 72 hours post-exercise. Muscle samples were immunostained for the satellite cell markers Pax7 and MyoD. Significant increases in total (Pax7-positive) and activated (MyoD-positive) satellite cells were found in all groups post-exercise. A further significant augmentation of total and activated satellite cells occurred in estrogen supplemented, agonist supplemented and the combined estrogen and agonist supplemented groups postexercise in white vastus and soleus muscles relative to unsupplemented animals. These results demonstrate that both estrogen and the ERα agonist, PPT, can significantly augment satellite cell number and activation following exercise-induced muscle damage. This suggests that estrogen acts through an ER-mediated mechanism to stimulate satellite cell activation and proliferation following exercise, with ERα playing a primary role.

Convocation Year

2009

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