title: Oestrogen receptor-alpha activation augments post-exercise myoblast proliferation.
abstract: OBJECTIVE
  Our laboratory has shown that oestrogen acts to augment myoblast (satellite cell) activation, proliferation and total number and that this may occur through an oestrogen receptor (OR)-mediated mechanism. The purpose of this study was to further investigate the mechanism of oestrogen influence on augmentation of post-exercise myoblast numbers through use of a specific OR-alpha agonist, propyl pyrazole triol (PPT).
  
  
  METHODS
  Ovariectomized rats were used (n = 64) and separated into four groups: sham, oestrogen supplemented, agonist supplemented, and a combined oestrogen and agonist supplemented group. These groups were further subdivided into control (unexercised) and exercise groups. Surgical removal of white vastus and soleus muscles was performed 72 h post-exercise. Muscle samples were immunostained for the myoblast markers Pax7 and MyoD.
  
  
  RESULTS
  A significant increase in total (Pax7-positive) and activated (MyoD-positive) myoblasts was found in all groups post-exercise. A further significant augmentation of total and activated myoblasts occurred in oestrogen supplemented, agonist supplemented and the combined oestrogen and agonist supplemented groups post-exercise in white vastus and soleus muscles relative to unsupplemented animals.
  
  
  CONCLUSIONS
  These results demonstrate that both oestrogen and the specific OR-alpha receptor agonist, PPT, can significantly and to similar degrees augment myoblast number and activation following exercise-induced muscle damage. This suggests that oestrogen acts through an OR-mediated mechanism to stimulate myoblast proliferation following exercise, with OR-alpha playing a primary role.
authors.affiliation: Department of Kinesiology & PE and Faculty of Science, Wilfrid Laurier University, Waterloo, ON, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Thomas
authors.forename: K
authors.initials: K
authors.lastname: Bunyan
authors.forename: P M
authors.initials: PM
authors.lastname: Tiidus
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D018482:Muscle, Skeletal / Q000378:metabolism*; D010052:Ovariectomy; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha