Characterization of binding sites of a memory-enhancing peptide AVP(4–8) in rat cortical synaptosomal membranes

Abstract

The pentapeptide pGlu-Asn-Cyt-Pro-Arg [AVP(4–8), termed ZNC(C)PR in this article] has been found as a metabolite of arginine-vasopressin (AVP) in rat brain and has been shown to have potent memory-enhancing activity and to yield a series of biochemical events in brain tissues. [ 35S]ZNC(C)PR was chemically synthesized with high specific activity (232 Ci/mmol), and specific binding sites for ZNC(C)PR were located in synaptosomal membrane preparations of rat brain. We identified a specific binding site for ZNC(C)PR with a K d of 3.12 n M and B max of 31 fmol/mg protein in anterior cortical synaptosomal membranes in the presence of 5m M Ni 2+. A comparison of synthetic analogues of ZNC(C)PR competing with [ 35S]ZNC(C)PR for binding to anterior cortical receptor are presented. ZDC(C)PR, a 2-aspartyl substitute of the 2-asparaginyl residue in ZNC(C)PR, had the most potent competition, but AVP did not show significant ability to compete for the receptor with ZNC(C)PR.