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

Previous work from our laboratory has demonstrated that estrogen will attenuate leukocyte infiltration into skeletal muscle following eccentric exercise. However the mechanisms by which estrogen exerts its effects are still uncertain. In experiment one, we investigated the role of estrogen receptor (ER) influence on muscle leukocyte infiltration following eccentric exercise through administration of the ER antagonist ICI 182,780 following downhill running in ovariectomized female rats with (E+) or without (E-) estrogen supplementation. At 24 hours post-exercise, soleus and white vastus muscles were removed and immunostained for HIS48 (neutrophil) and EDI (macrophage) positive cells. The increase in number of fibres positive for HIS48 in soleus and positive for EDI in the soleus and white vastus was significantly attenuated (p0.05) to those without ER antagonist. This suggests that the ability of estrogen to attenuate post-exercise leukocyte infiltration into skeletal muscle is not ER-mediated.

In experiment two, we examined the interaction effects of estrogen and progesterone on skeletal muscle in response to injury in ovariectomized female rats. At 24 hours post-exercise, soleus and white vastus muscles were removed and immunostained for HIS48 (neutrophil) and EDI (macrophage) positive cells. Leukocyte infiltration 24 hours post-exercise in the soleus (red) and white vastus muscles were significantly decreased in ovariectomized rats treated with progesterone alone relative to unsupplemented ovariectomized rats. Following exercise the percentage of leukocyte infiltration also decreased significantly with estrogen supplementation alone in both muscle types, 67-69% and 63-74% in neutrophils and macrophages, respectfully. Furthermore, the combination of estrogen and progesterone supplementation did not significantly alter the attenuation observed by estrogen alone. These results demonstrate that skeletal muscle in female rats benefited from both progesterone or estrogen treatment alone; effects of progesterone with estrogen following exercise were neither greater nor less than with estrogen alone.

Convocation Year

2008

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