This study investigated the effects of pre- and postnatal conditions of protein deficiency followed to nutritional rehabilitation in the morphology of skeletal muscle. Twelve Wistar male rats were distributed in two groups: nourished (N), with normal protein diet and undernourished (U), with low protein diet. The respective diet was maintained until animals completed 21 days of life. After that, part of group U (n = 4) received normal protein diet, forming a third group, renourished group (R). Forty-two-day-old animals were euthanized and we performed histopathological and morphometric analysis of the soleus muscle. Analysis stained in hematoxylin and eosin (H&E) of the group N revealed polygonal and equidistant muscle fibers, with normal distribution in muscle fascicles. However, D group had rounded and disorganized fibers with different distances between them in muscle fascicles. R group presented muscle fibers with several formats, polygonal and rounded, and some muscle fascicles starting the reorganization process. In N group, analysis of the connective tissue showed predominance of type I collagen and a lower amount collagen type III, both well organized. Whereas U group had a predominance of disorganized type III collagen, in R group, there was return of type I collagen, but partially organized. Muscle fiber area of U (163.18 ± 52.55 μm2) and R (381.79 ± 26.62 μm2) groups was smaller than N (1229.2 μm2 ± 61.12 μm2). Muscle fibers density of groups U (3369 ± 1226 fibers/mm2) and R (1979 ± 28 fibers/mm2) was larger than N (830 ± 113 fibers/mm2). The nutritional rehabilitation in the present study showed an attempt of reorganization of the muscle tissue.
Keywords: connective tissue; dietary proteins; metabolism; morphology; skeletal muscle; undernutrition.