Influence of dopamine on flash visual evoked potentials (FVEP) in prenatally mercury intoxicated rats.

The female adult white Wistar rats were given tap water (control) or 50 ppm of methylmercury chloride (MMC) ad libitum throughout their pregnancies. Newborn rats drank mother's milk during the first 21 days after delivery and then only tap water. The study was carried out on three-month old offsprings of white Wistar rats. The flash visual evoked potentials (FVEP) were recorded before and after injecting of 10 microl 0.9% saline, 50 or 100 nmols of dopamine (DA) into the lateral brain ventricle by method used before in our laboratory. The amplitude of the first deep negative (N(1)) peak significantly increased to 109-114% after both doses of DA in the control group and to 138-139% in mercury-treated animals. The amplitude of the next positive (P(1)) wave decreased to 94% and 86% in the control group after 50 and 100 nmols of DA, respectively. In Hg-treated group after 50 nmols of DA, the value dropped down to 91%, but increased to 109% after 100 nmols of DA. The increasing of DeltaN(1)P(1) was observed in the control group to 112% after 50 nmols and to 109% after 100 nmols of DA and in Hg-exposed rats, respectively, to 127% and to 129%. The described changes were statistically significant (p < 0.05). The N(1) and P(1) latencies were prolonged in the control group after both doses of DA. In Hg-treated group, the prolongation of N(1) latency was recorded, while the P(1) latency was not changed. We concluded that prenatal Hg intoxication disturbed the effect of DA on FVEP.