The effect of continuous intracerebroventricular infusion of satietin on ingestion, activity and body weight of rats.

Satietin is a putative satiety agent when given either peripherally or intracerebroventricularly (ICV). In the present study male Sprague Dawley rats were fitted with chronic third ventricle cannulas. After recovery, Alzet seven day osmotic pumps were inserted subcutaneously and tubing was connected to the cannula. Rats were then infused ICV with saline or semi-purified human satietin (25 micrograms/day; 1 microliter/hr). In the satietin group, daily chow intake was reduced (p less than 0.05) on days 1 and 2, recovered to control levels on days 4 and 5 and again declined (p less than 0.05) on days 6-8. During this latter period the satietin treated animals appeared ill. The satietin group's water intake paralleled food consumption, whereas the groups' water/food intake ratios did not differ. Satietin infusions decreased (p less than 0.01) the rats' body weight 42 grams by day 4, whereas the control group's weight remained constant. Even during the period where the satietin group's food intake returned to control levels they continued to lose weight. Running wheel activity was reduced throughout the satietin infusion period even when food and water ingestion had returned to control levels. The data suggest that semi-purified human satietin, when tested in rats, is an anorexogenic agent, however, its continuous use quickly produces tolerance and later what may be a cross-species allergic reaction (due to the satietin itself or a contaminant). The appropriateness of testing semi-purified satietin in the rat model is questioned.