摘要：The intestinal absorption of ten steroid hormones was evaluated in the rat small intestine, especially focusing on the interaction with intestinal P-glycoprotein (P-gp). Hydrocortisone, prednisolone, 6α-methylprednisolone, and dexamethasone (adrenocortical steroid hormones) all disappeared in a regional-dependent manner(duodenum>jejunum>ileum). The decreased rate of disappearance in the lower small intestine seemed to be due to the involvement of absorption barriers like P-gp. In contrast, all sex hormones including progesterone exhibited very high absorbability in the entire small intestine (duodenum=jejunum=ileum), possibly demonstrating the absence of restricted absorption by intestinal P-gp. Progesterone enhanced the rate of disappearance of vinblastine but did not affect 6α-methylprednisolone. In the presence of vinblastine and verapamil, on the other hand, the rate of disappearance of 6α-methylprednisolone increased significantly. It was demonstrated that there was a plural P-gp family, which had different substrate specificities, in the rat intestive and that steroid hormones interacted with them as substrates or inhibitors in a very complex manner.
关键词：steroid hormone;absorption;P-glycoprotein;rat small intestine;vinblastine;progesterone
