Demonstration that acid-ethanol extracts of rat adipose tissue contain an inhibitor of food intake in the mouse

The recent identification of the mouse obese (ob) gene, whose product is a ∼16 kd protein secreted from adipose tissue, and the demonstration that the administration of recombinant OB protein inhibits food intake have led us to report a 1979 pilot study demonstrating an extractable activity from rat adipose tissue that inhibited food intake in the normal mouse. Two hundred grams of rat adipose tissue and 40 gm of rat muscle were extracted with acid-ethanol. The aqueous phase was lyophilized, and a filtered solution of the crude powder was injected subcutaneously daily into normal male mice. Administration of the extract from adipose tissue, but not from muscle tissue, resulted in a significant reduction in food intake and slowing of the rate of increase in body weight over the 10-day experimental period. The quantity of extracted fat represented by the daily dose was equivalent to 1.65 gm of fat administered to a 24-gram mouse. In retrospect this acid-ethanol extractable activity was probably the native OB protein in normal rat adipose tissue.