Absorption and excretion of simmondsin after different administration routes in rats

Adult rats received simmondsin by intragastric intubation (ig) or intraperitoneal injection (ip) or mixed in with food (MF). Food intake inhibition was noted after administration by any of these routes, starting within minutes after ig or MF administration and continuing for +/-2 h in the former case and for 20 h in the latter. Following ip administration, food intake inhibition started after approximately 0.5 h and continued for about 2 h and was followed by a hyperphagic period. Simmondsin was measurable in the blood, but the concentration did not correlate with the anorexic effect. Only a fraction of the ingested or ip-administered simmondsin was excreted unmodified in the urine or feces. Ip administered simmondsin was detectable in the feces, indicating passage from the blood into the gut. The presence of simmondsin in the proximal gut seems to be necessary for the induction of anorexia.