Enhanced antiopiate activity and enzyme resistance in peptidomimetics of FMRFamide containing (E)-2,3-methanomethionine.

FMRFamide is a molluscan peptide that has shown antiopiate activity in a number of mammalian test systems. The current study determined the antiopiate potency of FMRFamide and two conformationally constrained peptidomimetics of FMRFamide containing stereoisomers of (E)-2,3-methanomethionine. Morphine abstinence signs were observed after varying doses (0.

Tyr-MIF-1 precipitates abstinence syndrome in morphine-dependent rats.

The endogenous neuropeptide Tyr-MIF-1 (Tyr-Pro-Leu-Gly-amide) has been shown to counteract various opiate actions. In the current study, third ventricular injection of 35 micrograms Tyr-MIF-1 protected by the enzyme inhibitor bestatin precipitated an abstinence syndrome in morphine-dependent rats, but not in opiate-naive rats. The results raise the possibility that Tyr-MIF-1 might participate in opiate dependence and opiate abstinence syndrome.

Enhanced antiopiate activity in peptidomimetics of FMRFamide containing Z-2,3-methanomethionine.

FMRFa is a molluscan peptide that has shown antiopiate activity in a number of mammalian test systems. The current study determined the antiopiate potency of FMRFa and two conformationally constrained peptidomimetics of FMRFa containing stereoisomers of Z-2,3-methanomethionine. Morphine abstinence signs were observed after varying doses (0.