Time course of short-term and long-term orexigenic effects of Agouti-related protein (86-132)

Agouti-related protein (AGRP) is a newly identified orexigenic peptide that acts as an endogenous antagonist of melanocortin receptors MC3 and MC4. Th e present study examined the time course of the orexigenic effects of synth etic AGRP (86-132). Intracerebroventricular infusion of 0.1 nmol AGRP (86-1 32) increased food intake by 450 +/- 81% at 2 h post-injection. A second in crease in non-cumulative food intake (512 +/- 135%) was observed at 6 h pos t-injection. Following a single dose of AGRP (86-132) (0.1 nmol) the increa sed food intake was sustained for 6 days, occurring in the light cycle of t he first 2 days and subsequently switching to the dark cycle of the last 4 days. These time course profiles indicate the complexity of the mechanisms involved in AGRP-induced feeding. NeuroReport 12:1281-1284 (C) 2001 Lippinc ott Williams & Wilkins.