Evaluation of bilirubin cytotoxicity and phototherapy in baby Gnnn rats by histochemical enzyme marking of Purkinje cells

Abstract

During the first few days of life homozygous Gunn rats are especially threatened by bilirubin toxicity. However, in this early period neurological signs and behavior do not indicate kernicterus clearly. Likewise, histological preparations stained by conventional procedures have failed to show the full extent of the nerve cell damage before 10 days after birth. Previous studies of our group have shown that histochemical demonstration of reduced activity of oxydative enzymes can be used as a sensitive detector for bilirubin encep' alopathy. This technique has now successfully been applied to 4 - 8 day Gunn rats. By rating the number of Purkinje cells according to their enzyme activity, we have been able to document the increased neurotoxicity induced by sulfonamides (300-600 mg per kg sulfadimethoxine) or other drugs competing with bilirubin for the binding sites of plasaa albumin, and the protective effect of phototherapy (Westinghouse F 20 T 12 BB special blue lamps, 400-500 nm: 3400 μ Watt per cm2 at aniaal level, 4 days). The survival rate decreased or increased from 88 % (controls) to 0 or 0 to ˜50 %, respectively, in the drug injected or drug injected plus illuminated animals.