ULTRASOUND-INDUCED EPILEPTIFORM ACTIVITY IN RATS TREATED WITH HEXACHLOROBENZENE

Hexachlorobenzene (HCB), an environmental contaminant, has caused spon taneous convulsions in infants and neonate rats born and breast-fed fr om exposed mothers as well as in weanling rats exposed for many weeks. This study aimed to determine if HCB causes epileptiform convulsions in adult rats. For th is purpose, a controlled stimulus was used. Fema le Sprague-Dawley rats received HCB (100 mg/kg in corn oil) by daily g avage; on days 7 to 13, rats were exposed to a short ultrasound stimul ation 24 hr after each administration. Ultrasound-induced epileptiform activity characterized by a burst of erratic running and leaping and tonic-clonic convulsions was observed in 0, 0, 10, 40, 90, 90 and 100% of rats having received a cumulative dose of 600, 700, 800, 900, 1000 , 1100 and 1200 mg/kg, respectively. A similar dose-response pattern w as obtained for tremors observed in HCB-treated rats. For a 800 mg/kg group left without further treatment, a three-fold increase in the per centage of rats with epileptiform activity was observed two days after the end of treatment. In summary, ultrasound stimulation has permitte d us to demonstrate in a reproducible manner that adult rats treated w ith HCB display epileptiform activity. (C) 1994 Intox Press, Inc.