Chronic effect of saikosaponin on adrenal and thymus growth in normal and dexamethasone-treated rats.

Abstract

The effects of repeated intraperitoneal administration of total saikosaponin or saikosaponin d from Bupleuri Radix on the wet weight of the adrenals and thymus, and on the resting level of plasma corticosterone were determined in intact or hypophysectomized rats. Total saikosaponin or saikosaponin d increased the relative weight of the adrenals with respect to the initial body weight, decreased the relative weight of the thymus, and did not affect the resting evening level of plasma corticosterone in normal intact rats. A moderate, but not high, dose of saikosaponin administered with dexamethasone antagonized the atrophic effect of dexamethasone on the adrenals. Moderate and high doses of saikosaponin acted synergistically on dexamethasone-induced atrophy of the thumus, but it did not significantly affect the resting dexamethasone-depressed level of plasma corticosterone. In hypophysectomized rats, a high dose of saikosaponin d did not affect the weight of either the adrenals or the thymus, whereas exogenous adrenocorticotropin markedly increased the adrenal weight but not the thymus weight, and dexamethasone did not decrease the adrenal weight but markedly decreased the thymus weight.