RESUMO
As several other factors, nutritional deficiency and sensory input hyperactivation can influence the mammalian brain development. This work investigated the effects of repeated episodes of early peripheral electrostimulation (PE), associated or not with early malnutrition, on cortical spreading depression (CSD) propagation. From postnatal days 7-28, well-nourished and malnourished Wistar rat pups (whose mothers were fed a 23 and 8% protein diet, respectively) received daily sessions of repetitive PE (2 or 60 Hz-square-wave pulses, 1.5 ms duration, 10-40 V intensity), delivered by two electrodes attached to the left paws. At postnatal days 35-45, under anesthesia, KCl-elicited spreading depression was monitored at two cortical points of both hemispheres. In the well-nourished rats, 2 Hz, but not 60 Hz PE was associated with slower spreading depression propagation in the hemisphere contralateral to the stimulated body-side, as compared to the ipsilateral hemisphere. In the malnourished rats, this effect was found for both 2 and 60 Hz stimulation frequencies. In the sham-stimulated controls, which received similar paw-electrodes, but were not stimulated, no inter-hemispheric spreading depression differences were seen. The results indicate an impairing effect of early PE on spreading depression propagation, which is frequency-dependent and can be influenced by the animal's nutritional status. Data raise the question whether brain plasticity changes consequent to the interaction between sensory input activation and malnutrition would be involved in the here described spreading depression effects.