Tumor necrosis factor‐alpha antagonist administration recovers skeletal muscle dysfunction in ovariectomized rats

Skeletal muscles deteriorate after ovariectomy. Molecular pathway of this deterioration has not been defined. Tumor necrosis factor (TNF)‐alpha activation is assumed to trigger muscle atrophy and administration of its antagonist is hypothesized to recover this atrophy in rats. Slow‐twitch soleus and fast‐twitch extensor digitorum longus muscle functions were investigated in intact, ovariectomized (OVX), and OVX plus 10 µg/g/week TNF‐alpha antagonist administered female rats. Maximum isometric twitch and tetanic contraction responses were lower in the OVX groups. Maximum isometric twitch amplitudes recovered in the extensor digitorum longus but not in the soleus muscles after TNF‐alpha antagonist administration. The decrease in responses to tetanic stimulations recovered in the OVX–TNF group at frequencies higher than 20 Hz in both muscle types. OVX animals body weight was 21% higher than intact animals. Muscle weight to body weight ratios of the OVX groups were higher than the control group which recovered after TNF‐alpha antagonist administration. Findings suggest that the functional loss in OVX rat muscles is TNF‐alpha pathway dependent. Skeletal muscle atrophy and function after OVX recovered by TNF‐alpha antagonist administration. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:275–280, 2011