We investigated the effects of early environmental stimulation on spreading depression in the cerebral cortex of male Wistar adult (90 day old) well-nourished (23% protein diet) and early malnourished (8% protein) rats. Environmental stimulation was performed during the suckling period or after weaning. Control rats were housed in a standard environment. Environmental stimulation after weaning produced a reduction of body weights in well-nourished rats, and an increase in wet, but not dry brain weights, in malnourished rats. Environmental stimulation during suckling was associated with reduced spreading depression velocities in the malnourished, but not in the well-nourished group. In well-nourished rats stimulated during suckling, spreading depression velocities in the occipital and parietal regions of the same hemisphere were significantly different, the occipital area presenting lower values than the parietal region. The results indicate that environmental conditions prevailing during brain development can alter electrophysiological parameters of spreading depression of adult rats, the suckling period being more susceptible to such environmental conditions and the occipital cortex being more affected than the parietal region. Data also suggest that the nutritional status can influence brain spreading depression responses to environmental stimulation, malnourished rats being more effected than the well-nourished ones.
Intestinal protein absorption was studied in undernourished albino Swiss mice with acute schistosomiasis mansoni. Undernutrition was induced by feeding mice with the Regional Basic Diet (RBD) ingested by human populations in Northeast Brazil, an experimental model previously developed in our laboratory. Weaning mice were infected with 40 cercariae and compared to undernourished non-infected mice and/or to infected mice fed a balanced control diet. Apparent and True Protein Absorption Coefficients were determined by nitrogen balance during five consecutive days ending at the 63rd day of the trial (acute phase of murine schistosomiasis). Fecal metabolic nitrogen (FMN) was determined after administration of a non-protein diet and was also calculated through linear regression. Our results showed a reduced protein absorption in non-infected RBD-fed mice as compared to mice fed a casein control diet. Infection with Schistosoma mansoni had apparently no effect on intestinal protein absorption in well-nourished mice. However, infection seemed to interfere with protein absorption in under-nourished animals, since the lowest absorption ratios have been detected among RBD-fed infected mice. A brief discussion is made on the advantages of using the method of linear regression for the determination of FMN.
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