Brief exposure to testosterone is sufficient to induce sex differences in the rabbit masseter muscle

Michael M. Reader, Gail Schwartz, Arthur W. English

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

In order to evaluate whether testosterone is responsible for inducing long-lasting sex differences in myosin heavy chain gene expression in the rabbit masseter muscle, we castrated young adult animals and administered supra-physiologic doses of testosterone for 3 or 6 weeks duration. Biopsies were taken from the masseter muscles of these animals at the time of castration and 3, 6 and 9 weeks later. Both immunoblot and immunohistochemical analyses of the myosin heavy chain (MyHC) isoform content of these muscle samples were performed. Exposure to testosterone for either duration resulted in a dramatic decrease in the content of the cardiac alpha MyHC isoform and a comparable increase in the content of the IIa MyHC isoform. The decrease in the cardiac alpha MyHC isoform content persisted for as long as 6 weeks after the end of treatment, but the increase in the content of the IIa MyHC isoform declined to normal during this time. Significant numbers of fibers were found containing both the cardiac alpha (and slow) and the IIa isoforms. Several fibers were encountered that contained both IIa and, presumably, the IIx isoform. Thus, a brief exposure to testosterone during postnatal maturation is able to produce a long lasting myosin heavy chain isoform switch that is similar in magnitude to that found during normal development.

Original languageEnglish (US)
Pages (from-to)210-217
Number of pages8
JournalCells Tissues Organs
Volume169
Issue number3
DOIs
StatePublished - Jul 28 2001

Keywords

  • Androgens
  • Fiber type
  • Masseter
  • Myosin heavy chain
  • Temporomandibular joint

ASJC Scopus subject areas

  • Anatomy
  • Histology

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