Myosin heavy chain composition of tongue muscle in microphthalmic (mi/mi) mice before and after weaning

To elucidate the effects of teeth on muscle fibers in the tongue during the developmental. process, we examined the expression of muscle contractile proteins and the genes for those proteins in normal mice and microphthalmic (mi/mi) mice with impaired tooth eruption. The mice were observed during the growth period, including weaning, which is when feeding movements undergo major changes. Expression of the myosin heavy chain (MyHC)-2a protein, whose contraction speed is relatively stow, disappeared after weaning in normal mice, white it remained in high concentrations even after weaning in mi/mi mice. The presence of MyHC-2a after weaning in mice with no tooth eruption was attributed to a compensation for tack of proper masticatory function and sucking-like movements, as MyHC-2a is necessary for these movements. (c) 2006 Elsevier GmbH. All rights reserved.