[Effect of administration with chlorpyrifos on electroretinogram in rats]

Changes in electroretinograms (ERG) due to administration of chlorpyrifos were examined in rats. Male Wistar rats were intraperitoneally injected with chlorpyrifos (0.2 mmol/kg body weight), and their cholinesterase (ChE) activities and ERG were measured at various times after the injection. Amplitudes of A and B waves in ERG were more than 50% decreased and latencies of the waves were prolonged 10-20% from 5 h to 2 d after the injection. At the same time, activities of ChE in plasma, erythrocytes, brain and retinochoroid were remarkably decreased. However, the amplitudes and latencies recovered to the control level more rapidly than the ChE activities of the erythrocytes, brain and retinochoroid. Injection into rats of 0, 0.002, 0.01, 0.05 or 0.25 mmol/kg of chlorpyrifos showed that the chlorpyrifos-induced changes of ERG were dose-dependent, and that a level of 0.05 mmol/kg caused a 50% decrease in the A or B wave 5 h after the injection. These results indicate that chlorpyrifos caused abnormal ERG characterized by decreased amplitudes and prolonged latencies of A and B waves and that the abnormal ERG did not always correspond to the decreased retinochoroid or brain ChE activities.