Long-lasting Effects of Early Environmental Stimulation on Cortical Spreading Depression in Normal and Early...

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.