| Abstrakt: |
Summary: This study was designed to examine the effects of early periods of nutritional restrictions on the cellular growth potential of skeletal muscle. Skeletal muscle growth and cell development of male Sprague-Dawley rats were examined at 25 and 100 days of age in controls (c) and three treatment groups. Each of the three treatments consisted of a 50% restriction of food intake for 21 days through gestation (GR), lactation (LR), and an early postweanling period (PWR, 25–46 days of age). At the conclusion of the restrictions, body weights of the GR, LR, and PWR groups were 85, 42, and 59% of the weights of their respective age controls. Rehabilitation to 100 days of age enabled the GR, LR, and PWR groups to achieve, respectively, 93, 86, and 93% of the control group body weight. At 25 and 100 days of age, muscle weights, muscle fiber number, mean fiber diameter, DNA content, and protein content were determined in the soleus and extensor digitorum longus (EDL) muscles. Soleus and EDL muscle weights, DNA contents, and protein contents from the GR and LR groups were significantly less than C group values at 25 days, and the LR group values were significantly less than those from the GR group. When expressed as % of control values at 100 days, muscle weights and DNA contents were respectively: GR soleus 91%, 92%; GR EDL 87%, 89%; LR soleus 84%, 86%; LR EDL 89%, 80%; PWR soleus 87%, 83%; and PWR EDL 94%, 91%. Soleus and EDL muscle fiber numbers were unchanged by the gestational, lactational, and postweanling restrictions at both 25 and 100 days; however, an age-related decrease in fiber number occurred in both muscles for all groups. Reduction in muscle weights resulted from changes in muscle fiber size rather than fiber number. The ability of muscles to recover from a nutritional restriction appears to directly relate to the ability to achieve a normal complement of muscle nuclei (DNA). |
