Abstract
The absorption, distribution, and excretion of 3H-labelled ecdysterone were studied in mice by means of autoradiographic technique. When administered intraperitoneally, ecdysterone was rapidly and easily absorbed into the blood and distributed to various organs (in particular, in the excretory organs such as the liver, gall bladder, intestine, and kidney) in which the radioactivity reached the maximal levels quite soon. Its clearance from the organs excluding the excretory organs was rather rapid, and the radioactivity specifically accumulated in the liver was gradually transported into the intestinal lumen via the gall bladder which showed the highest and continuous uptake. The glandular secretion of radioactivity into the gastric mucosa also partially contributes to its transportation from the blood to the digestive tract. After oral administration of 3H-ecdysterone, the absorption from the intestine was slow and limited and high radioactivity in the gastrointestinal tract was retained. The liver took up some radioactivity which attained a maximum soon after administration and gradually decreased due to the biliary excretion through the gall bladder in which the radioactivity hit the maximum level about 1 hr after administration and maintained a high level thereafter. Elimination of the administered ecdysterone from the body appears to be fast and its excretion pattern indicates that the excretion in the feces, mostly derived from the biliary excretion, is much more important than that in the urine after both intraperitoneal and oral administration.
