Effect of intravenous administration of apolipoprotein A-IV on patterns of feeding, drinking and ambulatory activity of rats

To characterize the anorectic effect of apolipoprotein A-IV (apo A-IV), we examined the effect of apo A-IV on the patterns of feeding, drinking and ambulation of rats fed ad libitum. A single dose of 200, 135 or 60 micrograms was infused intravenously through a chronically indwelling right atrial catheter just before the dark period. Apo A-IV suppressed food intake by decreasing meal size, but did not affect the interval between meals, the speed of eating, or the latency to eat the first meal after infusion. The anorectic effect of apo A-IV was dose-dependent and was effective for about 3 h after the infusion. The anorectic effect of apo A-IV is specific because inactivation of apo A-IV abolishes its anorectic effect. The anorectic effect of apo A-IV is not shared by apo A-I. Apo A-IV had no effect on drinking behavior or ambulatory activity. The results seem to indicate that apo A-IV specifically decreases the meal size, which supports our hypothesis that apo A-IV may act as a physiological signal for satiation after the ingestion of a lipid meal.