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Med Sci Sports Exerc. 2019 May 16. doi: 10.1249/MSS.0000000000002040. [Epub ahead of print]

The Effect of Growth Restriction on Voluntary Physical Activity Engagement in Mice.

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1
Department of Kinesiology, Michigan State University, East Lansing, MI.

Abstract

INTRODUCTION:

The purpose of this study was to determine the effect of growth-restriction on the biological regulation of physical activity.

METHODS:

Using a cross-fostering, protein restricted nutritive model, mice were growth-restricted during either gestation (GUN; N=3 litters) or postnatal life (PUN; N=3 litters). At 21 days of age, all mice pups were weaned and fed a non-restrictive healthy diet for the remainder of the study. At 45 days of age mice were individually housed in cages with free moving running wheels to assess physical activity engagement. At day 70, mice were euthanized, and the nucleus accumbens was analyzed for dopamine receptor 1 expression. Skeletal muscle fiber type and cross-sectional area of the soleus, extensor digitorom longus, and diaphragm were analyzed by immunohistochemistry. The soleus from the other hind leg was evaluated for calsequestrin 1 and annexin A6 expression.

RESULTS:

The PUN female mice (15,365 ±8,844 revolutions·day-1) had a reduction (P=0.0221) in wheel revolutions per day as compared to the GUN (38,667±8648 revolutions·day-1) and CON females (36,421.0± 6,700 revolutions·day-1). PUN female mice also expressed significantly higher Drd1compared (P=0.0247) to the other groups. PUN female soleus had a higher expression of calsequestrin 1, along with more Type IIb fibers (P=0.0398).

CONCLUSION:

Growth-restriction during lactation reduced physical activity in female mice by reducing the central drive to be active and displayed a more fatigable skeletal muscle phenotype.

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