Figure 4.

Ghrelin administration normalizes skeletal muscle morphology in R6/2 mice. Skeletal muscle (femoris) morphology was evaluated in R6/2 mice after ghrelin or vehicle administration for 4 weeks and compared with WT littermates. Muscle tissues were stained with hematoxylin and eosin and images were captured under bright-field conditions with a 10x objective. The scale bar at the bottom right in each panel represents 50 μm. Representative images illustrating longitudinal skeletal muscle from WT treated with vehicle (a), R6/2 treated with vehicle (b), and R6/2 treated with ghrelin (c). The skeletal muscle morphology of vehicle treated R6/2 mice had a convoluted shape and non-muscular infiltrations were found, instead of the parallel aligned fibers seen in vehicle treated wildtype littermates. An improvement was seen after 4 weeks of ghrelin treatment in R6/2 mice, and the morphology was comparable to wildtype littermates. A morphology score (d) was given to longitudinal skeletal muscle (femoris) indicating presence of convoluted shape, muscle fibre degeneration and grade of non-muscular infiltrations. We found a significant increase in score in vehicle treated R6/2 mice compared to WT mice, normalized following ghrelin administration. Minimal Feret’s diameter (e) was measured of cross sectional skeletal muscle (femoris) and the variation coefficient was calculated (f) in R6/2 mice and WT littermates after 4 weeks of treatment with either ghrelin or vehicle. There was a significant decrease in diameter and a trend towards higher diameter variability in R6/2 mice compared to WT mice after 4 weeks of vehicle treatment, but no improvement was seen following ghrelin treatment. Although skeletal muscle diameter and variability was not improved by ghrelin administration, the variability in ghrelin treated R6/2 mice showed no significant difference compared to WT littermates. Data represent mean ± SEM n = 3 animals/ group. Statistical significance was determined by One-way ANOVA: *p < 0.05, ***p < 0.001