Binding profile of benextramine at neuropeptide Y receptor subtypes in rat brain areas

Binding studies in rat whole brain, frontoparietal cortex and brainstem membrane preparations revealed that benextramine displayed [3H]neuropeptide Y specific binding from a low and a high affinity site with IC50 values in the μM (36 ± 2, 4.4 ± 1.4 and 300 ± 120 μM, respectively) and the pM (29.3 ± 12.1, 0.35 ± 0.11 and 0.42 ± 0.03 pM, respectively) range, whereas in rat hippocampus benextramine displaced [3H]neuropeptide Y specific binding from one site only with an IC50 value of 22.8 ± 5.7 μM. With the exception of frontoparietal cortex binding assay, benextramine was not able to completely inhibit [3H]neuropeptide Y specific binding revealing the presence of a benextramine nonsensitive third binding site. Benextramine pretreatment followed by membrane washing demonstrated that benextramine inhibited irreversibly both high and low affinity sites. © 1994.