Evaluation of Morphological Changes in Muscle Fibers and Neuronal Terminals of Motor Neurons in Male Rats from Childhood to Old Age

The aim of this study was to investigate the effect of time and age on morphological changes in male rats.

For conducting this study, 15 male Wistar rats in three age groups of 2 weeks (150-100 g), 6 weeks (250-220 g) and 96 weeks (320-280 g) were kept in Pasargad Tissue and Gene Laboratory in Tehran City for six weeks and 48 hours later they were dissected and the soleus muscles was extracted. Cross-sectional area and number of muscle fibers were measured by light microscopy. Immunohistochemical method was used to measure sema3a and NCAM proteins of muscle fibers. To determine the differences between the groups, one-way analysis of variance with Tukey post hoc test was used at the significant level of p≤0.05. Statistical analysis was performed by Prism5 software.

The results showed that there was a significant difference in the cross section of muscle fibers between the three age groups: children and young people (p=0.01), children and the elderly (p=0.049), and finally young people and the elderly (p=0.049). There was also a significant decrease in the number of muscle fibers in the age group of elderly compared to children and elderly to young people (p≤0.001). Moreover, sema3a protein expression increased significantly over time between the age groups of children and young (p≤0.048), children and elderly (p=0.0001) and finally young and elderly (p=0.0001). NCAM protein expression significantly reduced in three age groups: children and young people (p=0.048), children and controls (p=0.0001), and young and elderly people (p=0.001).

The results showed that with increasing growth from childhood to youth, hypertrophy increases and decreases in old age, in addition the process of hyperplasia will decrease with age. In addition to proteins involved in axonal growth due to growth decrease and neurodegenerative proteins also increase.