Stimulatory effect of Saireito on proopiomelanocortin gene expression in the rat anterior pituitary gland.

The effect of administration of Saireito, a Saiko agent, via a stomach cannula on adrenocorticotropin (ACTH) release and gene expression of proopiomelanocortin (POMC), the precursor for ACTH, in the anterior pituitary, as well as on the corticotropin-releasing factor (CRF) in the hypothalamus, was examined in pentobarbital anesthetized rats. Saireito decreased the hypothalamic CRF level due to an early release of CRF and stimulated ACTH release and POMC gene expression but did not increase CRF gene expression. These results suggest that Saireito does not stimulate CRF gene expression, although it does stimulate CRF release, which in turn stimulates POMC gene expression in the anterior pituitary and ACTH release.