Myosin heavy chain expression in peripheral muscles of Prairie Voles Microtus ochrogaster is not sexually dimorphic

Abstract

Previous research has reported skeletal muscle protein expression characteristics for laboratory strains of various rodents, such as rats and mice. However, we do not know the muscle protein expression or sexual dimorphism characteristics of skeletal muscle for other rodents such as voles, for which the behavior, morphology, and physiology have been documented. Myosin heavy chain (MHC) content in skeletal muscle is related to functional characteristics. This study investigated sex characteristics (male, n=6; female, n=8) for MHC expression for triceps brachii, tibialis anterior, gastrocnemius, and soleus muscles in prairie voles. Relative (%) MHC protein expression was determined via SDS-PAGE for types I, IIa, IId/x, and IIb MHC isoforms. Male voles had greater soleus wet weight and greater IIa MHC expression for tibialis anterior as compared to those of female voles. Skeletal muscle mass and MHC protein expression were not sexually dimorphic. Differences in circulating testosterone titers did not appear to influence these characteristics of mature peripheral skeletal muscle. Prairie voles, however, exhibited much more heterogeneity in MHC expression as compared to previous reports on rats, rabbits, and mice. It is likely that this is due to differences in the natural history and functional requirements of voles and other small mammals [Acta Zoologica Sinica 54 (1): 104 – 110, 2008].