Myotrophic effects of muscle extracts obtained at different intervals after denervation

A study was made of the myotrophic effects of denervated muscle extracts on normal Wistar rat soleus muscle. Extracts obtained 1 h, 2, 4 and 7 days after sectioning of the sciatic nerve were administered intraperitoneally over five consecutive days. Soleus muscles were routinely processed for morphological and morphometrical analysis using light microscopic techniques. Quantitative differences were observed in the effects of different extracts on total muscle area, fibre cross-sectional area, mean minimum diameter and number of fibres/ area. The greatest myotrophic response was elicited by extracts obtained at 2 and 4 days; differences with respect to controls and extracts obtained at 1 day were significant (P < 0.05) for all parameters studied. Statistically significant differences (P < 0.05) were also recorded for fibre cross-sectional area and mean minimum diameter between the 2- and 4-day groups and the 7-day group. It may thus be concluded that the time elapsing between denervation and extract obtention influences the effect of the extract on normal rat muscle.