Estrogen Receptor (ER) Mediated Recovery Of Atrophic Muscle Following Hind Limb Unweighting (HLU)

PURPOSE: to determine if the recovery of atrophic muscle (mass and contractile function) is ER mediated. METHODS: Mature 4 mos old female C57/BL6 mice (n=70) were divided into sham ovariectomy (OVX) and OVX groups. All but 10 sham controls were HLU for 4 wks. One third of the HLU mice were studied immediately after unweighting, one third were studied after 3 days of recovery following HLU and the final third were studied after 3 days of recovery and 3 days of injections with ICI 182780, an E2 antagonist that blocks both ER alpha and beta. Contractile tension was determined in soleus, plantaris, gastrocnemius and tibialis anterior. RESULTS: HLU significantly reduced muscle mass and contractile force in all 4 muscles studied. In Sham OVX, recovery resulted in a significant (p