Saireito (a Chinese herbal drug)-stimulated secretion and synthesis of pituitary ACTH are mediated by hypothalamic corticotropin-releasing factor

Administration of Saireito, a Saiko agent (a Chinese herbal drug), via a stomach cannula stimulates ACTH release and proopiomelanocortin, the precursor for ACTH, gene expression in the rat anterior pituitary. To study whether Saireito-stimulated secretion and synthesis of ACTh are mediated by hypothalamic corticotropin-releasing factor (CRF), we examined the effect of passive immunization of endogenous CRF by i.v. administration of CRF antiserum on Saireito-increased plasma ACTH levels and proopiomelanocortin gene expression in the rat anterior pituitary, under pentobarbital anesthesia. CRF antiserum inhibited Saireito-induced plasma ACTH levels and proopiomelanocortin mRNA levels in the anterior pituitary. This result indicates that Saireito stimulates CRF neurons to increase CRF release, which stimulates secretion and synthesis of ACTH.