|
|
||||||||
Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
The
proportions of muscle fibers of different phenotype in the adult rabbit
masseter differ greatly in different sexes. These sex differences are
not apparent in young adults, but arise under the influence of
testosterone in the males. We examined whether this switch occurred
during a critical period of postnatal development. Testosterone was
administered to young adults 1, 2, or 4 mo after castration, and also
to adult females. Samples of masseter muscle were taken at four monthly
intervals after the onset of treatment and examined for the expression
of different myosin heavy chain (MyHC) isoforms by using a panel of
monoclonal antibodies. Despite the length of androgen deprivation,
treatment with testosterone produced a marked MyHC isoform switch from
-slow/
to IIa. This male proportion of fibers of different
phenotypes persisted well beyond the return of serum testosterone
levels to pretreatment levels. Thus brief exposure to testosterone
produces a permanent change in the proportions of masseter muscle
fibers of different phenotypes, and the capacity for this change is not
restricted to a critical period.
masticatory muscles; sexual dimorphism; testosterone; myosin heavy chain
This article has been cited by other articles:
![]() |
J.A.M Korfage, J.H. Koolstra, G.E.J. Langenbach, and T.M.G.J. van Eijden Fiber-type Composition of the Human Jaw Muscles--(Part 2) Role of Hybrid Fibers and Factors Responsible for Inter-individual Variation Journal of Dental Research, September 1, 2005; 84(9): 784 - 793. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. L. Tosi, B. D. Boyan, and A. L. Boskey Does Sex Matter in Musculoskeletal Health? The Influence of Sex and Gender on Musculoskeletal Health J. Bone Joint Surg. Am., July 1, 2005; 87(7): 1631 - 1647. [Full Text] [PDF] |
||||
![]() |
T. van Wessel, G. E. J. Langenbach, N. Kawai, P. Brugman, E. Tanaka, and T. M. G. J. van Eijden Burst characteristics of daily jaw muscle activity in juvenile rabbits J. Exp. Biol., July 1, 2005; 208(13): 2539 - 2547. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |