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Sexual dimorphism of murine masticatory muscle function
David W Daniels1, Zuozhen Tian, Elisabeth R Barton
1Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
Objective:
To determine if gender distinctions of force generating capacity existed in murine masticatory muscles.
Design:
In order to investigate the effect of sex on force generating capacity in this muscle group, an isolated muscle preparation was developed utilising the murine anterior deep masseter. Age-matched male and female mice were utilized to assess function, muscle fibre type and size in this muscle.
Results:
Maximum isometric force production was not different between age-matched male and female mice. However, the rate of force generation and relaxation was slower in female masseter muscles. Assessment of fibre type distribution by immunohistochemistry revealed a three-fold decrease in the proportion of myosin heavy chain 2b positive fibres in female masseters, which correlated with the differences in contraction kinetics.
Conclusions:
These results provide evidence that masticatory muscle strength in mice is not affected by sex, but there are significant distinctions in kinetics associated with force production between males and females.
