Effect of constitutive inactivation of the myostatin gene on the gain in muscle strength during postnatal growth in two murine models

INTRODUCTION: The effect of constitutive inactivation of the gene encoding myostatin on the gain in muscle performance during postnatal growth has not been well characterized. METHODS: We analyzed 2 murine myostatin knockout (KO) models, (i) the Lee model (KO(Lee) ) and (ii) the Grobet model (KO(Grobet) ), and measured the contraction of tibialis anterior muscle in situ. RESULTS: Absolute maximal isometric force was increased in 6-month-old KO(Lee) and KO(Grobet) mice, as compared to wild-type mice. Similarly, absolute maximal power was increased in 6-month-old KO(Lee) mice. In contrast, specific maximal force (relative maximal force per unit of muscle mass was decreased in all 6-month-old male and female KO mice, except in 6-month-old female KO(Grobet) mice, whereas specific maximal power was reduced only in male KO(Lee) mice. CONCLUSIONS: Genetic inactivation of myostatin increases maximal force and power, but in return it reduces muscle quality, particularly in male mice. Muscle Nerve 55: 254-261, 2017