The effect of berberine on bilirubin excretion in the rat.

Berberine-containing herbs have been used in folk medicine to relieve neonatal jaundice. In the present investigation, the acute and chronic effects of berberine on bilirubin excretion were studied in rats. Acute doses of berberine were found to increase the secretion of bilirubin in experimental hyperbilrubinemia without affecting the UDP-glucuronyltransferase activity and BSP clearance. Continuous treatment abolished this effect. This apparent tolerance could be attributed to the inhibitory action of chronic berberine treatment on UDP-glucuronyltransferase activity, but the mechanism of this inhibition was not elucidated. Liver microsomal protein concentration, ethylmorphine N-demethylation, and BSP clearance were unchanged.