An anorectic proteoglycan of membrane origin.
The endogenous substance(s) involved in the regulation of food intake has been isolated from serum, urine and feces. In the present study, a similar type of anorexigenic proteoglycan was isolated from human rat erythrocyte membranes and rat liver membranes. Membranes were suspended in 2.0% deoxycholate and allowed to stand at 25 degrees C for 30 min. The suspension was treated with 5% TCA, supernatant was collected, dialyzed and concentrated. TCA-soluble proteins were fractionated on Sephadex G-150. The active second peak fractions were further purified on DEAE-Sephadex A-25. Biologically active substance reduced the appetite in rats significantly when given intraperitoneally. The proteoglycan (50 kDa) consisted of 70-85% carbohydrate. Similar properties of plasma and membrane anorectic substance further indicated its membrane origin. We believe that this anorectic proteoglycan is anchored to cell membranes and released into the blood circulation to regulate the food intake.