Behavior and nitrergic activity in experimental models of combined methyl mercury and ethanol intoxication during brain development has not been studied in detail. The present study examined behavioral changes and NADPH-diaphorase histochemical activity in the hippocampus, cerebellum and striatum, resulting from ethanol (EtOH) and methyl mercury (MeHg) intoxication of pregnant female rat offspring. Open field (OF), elevated plus maze (EPM), forced swim (FS), and inhibitory avoidance tests (IA), were used to examine locomotion, anxiety, depression and memory. After behavioral tests brains of 2 months old subjects were processed for NADPH-d histochemistry and densitometry of the neuropil of the hippocampus, striatum and cerebellum. Female rats were given EtOH 22.5% w/v (6.5 g/kg per day, by gavages) during the gestational period until the 21st post-natal day. At day 15th of pregnancy, they received 8 mg/kg of MeHg. EtOH and MeHg experimental groups reduced the frequency and time spent in the open arms in the EPM test. MeHg increased locomotor activity and immobility at FS test, whereas EtOH+MeHg showed a greater reduction in the frequency and time spent in the open arm at EPM and smaller latency in the IA trials. Dentate gyrus nitrergic activity was reduced in the polymorphic layer of the MeHg, but increased in EtOH in both polymorphic and molecular layer of dentate gyrus and in the lacunosum molecular of CA1. Nitrergic activity was increased in all striatal segments of EtOH, in the anterior region in EtOH+MeHg but reduced in most regions of the striatum in the Hg.
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