SPREADING DEPRESSION IS FACILITATED IN ADULT-RATS PREVIOUSLY SUBMITTED TO SHORT EPISODES OF MALNUTRITION DURING THE LACTATION PERIOD

Lactating rat darns were submitted to short episodes (1, 2 or 3 weeks) of nutritional restriction by receiving the ''regional basic diet'' ( RBD, with 8% protein) of low-income human populations of Northeast Bra zil. Their pups were then studied regarding the developmental effects on body and brain weights. When the rats reached adulthood, cortical s usceptibility to the phenomenon of spreading depression (SD) was evalu ated by performing electrophysiological recordings on the surface of t he cerebral cortex. SD was elicited at 20-min intervals by applying 2% 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 electroco rticogram and the slow potential change of SD. When compared to contro l rats fed a commercial diet with 23% protein, early malnourished rats showed deficits in body and brain weights (10% to 60% and 3% to 15%, respectively), as well as increases in velocity of SD propagation (10% to 20%). These effects were directly related to the duration of mater nal dietary restriction, with pups malnourished for 2 or 3 weeks prese nting more intense weight and SD changes than those malnourished for 1 week. The effects of 1-week restrictions on SD were less evident in t he pups malnourished during the second week of lactation and were more evident in pups receiving the RED 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.