EFFECTS OF PRENATAL EXPOSURE TO AMPHETAMINE IN THE MEDIAL PREFRONTAL CORTEX OF THE RAT

This study was designed to investigate the effects of prenatal exposur e to amphetamine in the organization of the medial prefrontal cortex o f the rat, by an evaluation of growth, morphometric and neurochemical parameters. Pregnant Wistar rats were given 10 mg/kg body weight/day o f D-amphetamine sulfate, subcutaneously, from gestational days 8 to 22 . Control groups of pregnant rats were injected with saline, pair-fed or non-manipulated; litters were culled to eight pups (four males and four females), weighed every other day until postnatal day 30 and ever y week until day 90. The Gompertz model was used to study body weight evolution and the estimated growth parameters were not significantly d ifferent in the experimental groups. At postnatal days 14 and 30, the volumes of the prefrontal cortex, the fraction of neuropile occupied b y neurons and the number of neurons per unit surface area were determi ned. The number of neurons per unit volume of reference area was calcu lated using the stereological technique of the dissector. For neuroche mical analysis, the medial prefrontal cortex was dissected to measure the concentration of dopamine, serotonin and their metabolites. The al lometric relationship of forebrain/body growth pointed to a mechanism of sparing and compensatory growth in the amphetamine exposed group. T he changes found in the number of neurons per unit volume at postnatal day 14 show a catch-up at postnatal day 30. A decrease in serotonin l evels was found in the amphetamine group compared with the pair-fed co ntrol, which was reflected in the ratio of serotonin to its metabolite , 5-hydroxyindolacetic acid. These changes, whether permanent or trans itory, raise the possibility that some of the effects of prenatal expo sure to amphetamine may be due to modifications in the neurotransmitte r levels of serotonin. Copyright (C) 1996 ISDN.