Pharmacological stimulation of brain carnitine palmitoyl-transferase-1 decreases food intake and body weight

Abstract

Inhibition of brain carnitine palmitoyl-transferase-1 (CPT-1) is reported to decrease food intake and body weight in rats. Yet, the fatty acid synthase (FAS) inhibitor and CPT-1 stimulator C75 produces hypophagia and weight loss when given to rodents intracerebroventricularly (icv). Thus roles and relative contributions of altered brain CPT-1 activity and fatty acid oxidation in these phenomena remain unclarified. We administered compounds that target FAS or CPT-1 to mice by single icv bolus and examined acute and prolonged effects on feeding and body weight. C75 decreased food intake rapidly and potently at all doses (1–56 nmol) and dose dependently inhibited intake on day 1. Dose-dependent weight loss on day 1 persisted through 4 days of postinjection monitoring. The FAS inhibitor cerulenin produced dose-dependent (560 nmol) hypophagia for 1 day, weight loss for 2 days, and weight regain to vehicle control by day 3. The CPT-1 inhibitor etomoxir (32, 320 nmol) did not alter overall day 1 feeding. However, etomoxir attenuated the hypophagia produced by C75, indicating that CPT-1 stimulation is important for C75's effect. A novel compound, C89b, was characterized in vitro as a selective stimulator of CPT-1 that does not affect fatty acid synthesis. C89b (100, 320 nmol) decreased feeding in mice for 3 days and produced persistent weight loss for 6 days without producing conditioned taste aversion. Similarly, intraperitoneal administration decreased feeding and body weight without producing conditioned taste aversion. These results suggest a role for brain CPT-1 in the regulation of energy balance and implicate CPT-1 stimulation as a pharmacological approach to weight loss.