Acute adaptive changes in food intake pattern following olfactory ablation in rats.

We determined whether acute compensatory feeding pattern changes after bulbectomy persist on a chronic basis, or whether physiological adaptation occurs to normalize acute changes. Rats were randomized to olfactory bulbectomy or sham operation; all had jugular vein catheterization. Food intake, meal number and size were studied during infusion of parenteral nutrients providing 100% daily caloric intake (PN-100) to minimize post-ingestive effects. Rats were randomly assigned to acute (from day 14 after operation, PN-100 infused for 4 days, followed by 4 days of saline infusion) or chronic study (PN-100 infused for 4 days from day 40, followed by 4 days of saline infusion). After olfactory ablation, acutely decreased meal size was offset by increased meal number, but 40 days after, baseline differences between meal size and number no longer existed. No qualitative differences in response to PN-100 were noted between acute and chronic groups. Findings suggest a functional adaptation of food intake regulatory mechanism between 14 and 40 days after bulbectomy.