ECLAMPSIA-LIKE SEIZURES AND ELECTROENCEPHALOGRAPHIC CHANGES IN PREGNANT RABBITS WITH ENDOTHELIN-1 INJECTIONS

To examine the possible role of endothelin and vasospasm in eclamptic seizures, we studied and analyzed the electroencephalograms (EEG) of e ndothelin-1 (ET-1)-treated pregnant, nonpregnant and sham control (dex trose-treated) rabbits. After multiple intravenous bolus injections of ET-1 (500 pmol/kg) or 5% dextrose in the rabbits, we recorded EEG dir ectly from the brain cortex and analyzed by Fast Fourier Transform (FF T). Water content was measured in the brain of all groups (n = 7). Rep eated seizures occurred in all of the pregnant and 2 of the nonpregnan t rabbits by variable doses of ET-1. FFT analysis showed remarkable ch anges in frequency and power arrays characterized by mild to severe fo rm of dysrhythmia, high-voltage spikes, high-voltage fast and slow wav es after ET-1 injections. Water content was increased in brain mass in ET-1-treated rabbits (p = 0.001) suggesting an ET-1-induced edema. Hi stologically we confirmed that ET-1 caused ischemic changes in brain t issues. However, ET-1 induced more pronounced changes in behavior, EEG , brain edema or ischemia in pregnant than in nonpregnant groups. The injections of exogenous ET-1 into the brain substances were strongly s uggested by immunohistochemical study with polyclonal antiendothelin a ntibody in brain tissue sections. Therefore, we assume that endothelin along with other vasoactive substances causes acute cerebral vasospas m and ischemia inducing EEG changes leading to ultimate clinical convu lsions in eclampsia.