Neuropeptide Y receptors from calf brain: effect of crude Conus venom preparations on [3H]NPY binding.
NPY receptors are identified in calf frontal cortex and hippocampus membrane preparations by binding of N-[propionyl-3H] neuropeptide Y. Saturation and competition binding data with PYY, NPY-(18-36) and NPY itself fit with a single class of sites: for the radioligand KD = 1.4 +/- 0.5 nM, Bmax = 434 +/- 180 fmol/mg protein in frontal cortex, KD = 0.7 +/- 0.2 nM, Bmax = 267 +/- 50 fmol/mg protein in hippocampus. Competition curves of the Y1-subtype selective agonist [Leu31, Pro34]NPY are biphasic in both membrane preparations: high affinity sites (i.e. Y1-subtype) amount to 80% in frontal cortex and 23% in hippocampus. The remaining sites are of the Y2-subtype. Out of 23 Conus venom preparations, 17 inhibit the binding of [3H]NPY in both membrane preparations, but only two of them (from Conus aulicus and C. pennaceus) do so with high potency (IC50 < 5 micrograms protein/ml). Only one venom preparation (from C. mercator) had weak discriminatory properties (IC50Y2/IC50Y1 = 6). Venom from C. anemone increased the [3H]NPY binding 5-fold and with an IC50 of 15-18 micrograms protein/ml. This binding occurred to the venom itself and was unrelated to the NPY receptors since it was equally potent when displaced by [Leu31, Pro34]NPY, NPY-(18-36), PYY and NPY.
Czerwiec
E
E
Department of Protein Chemistry, Free University of Brussels (V.U.B.), St Genesius Rode, Belgium.
de Backer
J P
JP
Vauquelin
G
G
Vanderheyden
P M
PM
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D005625:Frontal Lobe / Q000187:drug effects* / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D016015:Logistic Models; D008978:Mollusk Venoms / Q000494:pharmacology*; D009478:Neuropeptide Y / Q000378:metabolism*; D011869:Radioligand Assay; D017476:Receptors, Neuropeptide Y / Q000187:drug effects* / Q000378:metabolism; D014316:Tritium
D008978:Mollusk Venoms; D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y; D014316:Tritium