Mode of bilirubin deposition in the cerebellum of developing jaundiced Gunn rats.

Bucolome is known as a potent displacer of bilirubin from the blood into tissues. The effects of the drug on newborn rats with congenital jaundice (Gunn rats) were examined on postnatal days 7, 11, 15 and 21. A single subcutaneous injection of bucolome resulted in a rapid fall of the total plasma bilirubin concentration and the lowered level persisted as long as 23 h. Concomitantly with the drop, the cerebellar bilirubin level increased within 1 h. Although cerebellar bilirubin returned to the initial level after 24 h in rats treated with bucolome on days 7 and 21, it remained almost constant or rather increased during the period of 1-24 h in rats treated on days 11 or 15. In 15-day-old rats, localized yellow staining in the cerebellum 24 h after treatment was most apparent in the granule cell layer of the ventral part of the pyramis and the dorsal part of the uvula under the dissecting microscope. These observations suggest that the period most susceptible to bilirubin deposition lies around day 15 in the cerebellum of jaundiced Gunn rats.