EFFECTS OF PRENATAL COCAINE EXPOSURE IN THE PREFRONTAL CORTEX OF THE RAT - A MORPHOMETRIC EVALUATION

This work was undertaken in order to assess the organization of the pr elimbic area of the medial prefrontal cortex of rats exposed prenatall y to cocaine. Pregnant Wistar rats were assigned to the following grou ps: 1. Cocaine-60 mg/kg body wt/d sc, from gestational days 8-22; 2. S aline; 3. Pair-fed; and 4. Nonmanipulated. Male offspring were perfuse d on postnatal days 14 and 30. Six brains per group and per age were e mbedded in celloidin to calculate the volumes of the prelimbic area; s ections from the other six brains were embedded in resin and processed for electron microscopy. Using semithin sections (2 mu m) of layers I I-III and V-VI, the following parameters were calculated: 1. The fract ion of the neuropil occupied by neurons (V-V); 2. The packing (N-A) de nsity; and 3. The numerical (N-V) density. Qualitative alterations con sisted of dispersed profiles of degenerated neurons and dendrites in t he medial prefrontal cortex. No significant differences were found in the gross morphometric parameters when the cocaine group was compared with the other groups. A high interanimal variation was shown in the p relimbic volumes of postnatal day (PND) 14 cocaine-treated rats, and a decrease in volumes was detected at PND30. Although there are some al terations in the main afferent cortical target area for dopaminergic i nput, its gross morphometric parameters do not seem to be sufficiently affected to account for the behavioral alterations referred to as bei ng dependent on this brain region.