FMRF-NH2-LIKE MAMMALIAN PEPTIDE PRECIPITATES OPIATE-WITHDRAWAL SYNDROME IN THE RAT

Yang et al. (14) have isolated from mammalian brain an octapeptide FLFQPQRF-NH2 (F-8-F-NH2) with certain antiopiate properties. Third ventricular injection of 2 μg of this peptide together with the aminopeptidase inhibitor bestatin precipitated an opiate-withdrawal syndrome in morphine-dependent but not in nondependent rats. Third ventricular injection in nondependent rats of 15 μg of the peptide together with bestatin induced a morphine-withdrawal-like behavioral syndrome. This syndrome was not produced by injection of bestatin or saline vehicle alone and was preventable by injection of 3.5 mg/kg morphine sulphate SC. © 1990.