Spreading depression is facilitated in adult rats previously submitted to short episodes of malnutrition during the lactation period

RESUMO

Lactating rat dams were submitted to short episodes (1,2 or 3 weeks) of nutritional restriction by receiving the "regional basic diet" (RBD), with 8 percent protein) of low-income human population of Northeast Brazil. Their pups were then studied regarding the developmental effects on body and brain weights. When the rats reached adulthood, cortical susceptibility to the phenomenon of spreading depression (SD) was evaluated by performing electrophysiological recordings on the surface of the cerebral cortex. SD was elicited at 20-min intervals by applying 2 percent KCL for 1 min to a site on the frontal cortex and its occurrence was monitored at 2 sites in the parietal region by recording the electrocorticogram and the slow potential change of SD. When compared to control rats fed a commercial diet with 23 percent protein, early malnourished rats showed deficits in body and brain weights (10 percent to 60 percent and 3 percent to 15 percent, respectively), as well as increases in velocity of SD propagation (10 percent to 20 percent). these effects were directly related to the duration of maternal dietary restriction, with pups malnourished for 2 ou 3 weeks presenting more intense weight and SD changes than those malnourished for 1 week. The effects of 1-week restrictions on SD were less evident in the pups malnourished during the second week of lactation and were more evident in pups receiving the RBD during the third week. The results indicate that short episodes of early malnutrition during the suckling period can affect body and brain development, as well as the cortical susceptibility to SD during adulthood. The data also suggest that the third week of lactation is the period during which the brain is most sensitive to malnutrition, concerning the effects on SD.