[Comparing the two neurobehavioral toxicological methods on the toxic effect of methyl mercury]

To compare the two experimental methods for testing neurobehavioral toxicological effects, methyl mercury chloride at the dosage of 0.00, 0.01, 0.05 and 2.00 mg/(kg.d) was force-fed to pregnant Wistar rats during the 6-9th day of conception. The offspring of the 4 groups were randomly selected for Y maze or operant behavior test at the age of 7 or 10 weeks, respectively. The reinforcements of the performance were electric shock for Y maze and food pellets for operant behavioral test. The results showed that no sex-dependent effects were observed both in maze and operant behavior tests. The performances of offspring in 3 exposure groups were worse than that of control group both in Y maze and operant behavior tests(P < 0.05). It was demonstrated that a clear dose-effect relationship in maze test on error time(rs = 0.257, P < 0.05), arrival time(rs = 0.216, P < 0.01); in operant behavior test on differential reinforcement of high rate (rs = -0.7273, P < 0.01), but not on differential reinforcement of low rate(rs = -0.2238, P > 0.05). It is concluded that prenatal methyl mercury exposure caused some negative effects on the development of nervous system. But the negative reinforcement by human operation in Y maze test could affect the results. The positive reinforcement and automatic monitoring in operant behavioral test gave more reliable results.