Studies on antinephritic effect of TJ-8014, a new Japanese herbal medicine, and its mechanisms (2): Effect on the release of corticosterone from adrenal glands.

In order to elucidate the mechanisms of the antinephritic action of TJ-8014, the effect of this drug on corticosterone release from the adrenal cortex was investigated by using normal rats and rats with original-type anti-GBM nephritis. When the serum corticosterone level was determined 5 hr after test drugs were given p.o. to normal rats, TJ-8014 at 0.5 and 2.0 g/kg significantly elevated the hormone level by 48% and 74%, respectively. Of the crude drugs that constitute TJ-8014, Bupleuri radix (SAIKO) and Glycyrrhizae radix (KANZOU) at 1.0 g/kg also significantly elevated the serum level. When TJ-8014 was given p.o. daily from the next day of anti-GBM serum injection to the 15th day, 2.0 g/kg/day of the drug inhibited the urinary protein excretion. In addition, TJ-8014 (2.0 g/kg/day) inhibited the decrease in the serum and adrenal corticosterone levels induced by nephritis. When corticosterone at 10 mg/kg was given s.c. daily from the next day of the anti-serum injection to the 10th day, it not only reduced proteinuria, but also inhibited glomerular histopathological changes. In contrast, metyrapone, a corticosterone synthetase inhibitor, at 100 mg/kg x 2/day, p.o., aggravated the nephritis. These results suggest that the antinephritic action of TJ-8014 may be partly due to the enhancement of the synthesis or release of corticosterone from the adrenal cortex.