Pharmacological differences between immunoisolated native brain and heterologously expressed rat α4β2 nicotinic receptors

Anthony Truong, Xiaolei Xing, John R. Forsayeth, Linda P. Dwoskin, Peter A. Crooks, Bruce N. Cohen

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Native brain and heterologously expressed rat α4β2 nicotinic receptors (in Xenopus oocytes and CV-1 cells) were immunoisolated with the anti-α4 antibody mAb 299 and their pharmacological properties were compared using [3H](±)epibatidine, the novel N-alkylnicotinium analog N-n-octylnicotinium iodide (NONI), and the ganglionic antagonist trimethaphan (TRM). The equilibrium dissociation constant (Kd) for [3H](±)epibatidine binding to the native and heterologously expressed receptors ranged from 13 to 21 pM. The Hill coefficients for [3H](±)epibatidine binding to the native and expressed receptors ranged from 0.8 to 1.1 and were consistent with a single high-affinity site. NONI inhibited 30 pM [3H](±)epibatidine binding to the native and expressed receptors with similar potency (IC50 values of 6-7 μM). However, [3H](±)epibatidine dissociated 2-3 times more slowly from the native, than from the expressed receptors and TRM inhibited 30 pM [3H](±)epibatidine binding to the native receptors (IC50 value of 330 μM) less potently than it did to the receptors expressed in oocytes (IC50 value of 16 μM) or CV-1 cells (IC50 value of 55 μM). The differences between the native and expressed [3H](±)epibatidine dissociation rate constants and IC50 values for TRM were significant for both host cell types, although the values for the CV-1-expressed receptors were closer to the native ones than were those for the oocyte-expressed receptors. Thus, the epibatidine and trimethaphan binding sites in native and expressed α4β2 receptors appear to have significantly different structural or chemical properties.

Original languageEnglish
Pages (from-to)68-76
Number of pages9
JournalMolecular Brain Research
Volume96
Issue number1-2
DOIs
StatePublished - Nov 30 2001

Bibliographical note

Funding Information:
This research was supported by funds from the California Tobacco-Related Disease Research Program, award number 6KT-0208, and from the NIH, grants DA10934 and DA00399. We thank Dr. Jerry Sepinwall of Hoffman-LaRoche for providing us with the trimethaphan camsylate used in these experiments.

Keywords

  • Dissociation rate constant
  • N-n-Octylnicotinium iodide, NONI
  • Neuronal nAChR
  • Trimethaphan
  • [H](±)Epibatidine
  • α4β2 Nicotinic receptor

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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