Structural specificity of MIF-1 and Tyr-MIF-1 in augmenting GABA-stimulated benzodiazepine receptor binding.

The possibility of a linkage between endogenous peptides and the GABA-benzodiazepine system has been greatly strengthened by reports that the brain peptides MIF-1(Pro-Leu-Gly-NH2) and Tyr-MIF-1(Tyr-Pro-Leu-Gly-NH2) augment GABA-stimulated benzodiazepine binding. We evaluated the actions of fragments and analogs of these small peptides on GABA-stimulated benzodiazepine binding in mouse cortical brain membranes. Fragments of Tyr-MIF-1, several compounds related to MIF-1, or several analogs of Tyr-MIF-1 had no effect on binding. These results demonstrate the specificity of the effects of MIF-1 and Tyr-MIF-1 on GABA-stimulated benzodiazepine binding.