N,N'-Alkane-diyl-bis-3-picoliniums as nicotinic receptor antagonists: inhibition of nicotine-evoked dopamine release and hyperactivity

J Pharmacol Exp Ther. 2008 Aug;326(2):563-76. doi: 10.1124/jpet.108.136630. Epub 2008 May 6.

Abstract

The current study evaluated a new series of N,N'-alkane-diyl-bis-3-picolinium (bAPi) analogs with C6-C12 methylene linkers as nicotinic acetylcholine receptor (nAChR) antagonists, for nicotine-evoked [3H]dopamine (DA) overflow, for blood-brain barrier choline transporter affinity, and for attenuation of discriminative stimulus and locomotor stimulant effects of nicotine. bAPi analogs exhibited little affinity for alpha4beta2* (* indicates putative nAChR subtype assignment) and alpha7* high-affinity ligand binding sites and exhibited no inhibition of DA transporter function. With the exception of C6, all analogs inhibited nicotine-evoked [3H]DA overflow (IC50 = 2 nM-6 microM; Imax = 54-64%), with N,N'-dodecane-1,12-diyl-bis-3-picolinium dibromide (bPiDDB; C12) being most potent. bPiDDB did not inhibit electrically evoked [3H]DA overflow, suggesting specific nAChR inhibitory effects and a lack of toxicity to DA neurons. Schild analysis suggested that bPiDDB interacts in an orthosteric manner at nAChRs mediating nicotine-evoked [3H]DA overflow. To determine whether bPiDDB interacts with alpha-conotoxin MII-sensitive alpha6beta2-containing nAChRs, slices were exposed concomitantly to maximally effective concentrations of bPiDDB (10 nM) and alpha-conotoxin MII (1 nM). Inhibition of nicotine-evoked [3H]DA overflow was not different with the combination compared with either antagonist alone, suggesting that bPiDDB interacts with alpha6beta2-containing nAChRs. C7, C8, C10, and C12 analogs exhibited high affinity for the blood-brain barrier choline transporter in vivo, suggesting brain bioavailability. Although none of the analogs altered the discriminative stimulus effect of nicotine, C8, C9, C10, and C12 analogs decreased nicotine-induced hyperactivity in nicotine-sensitized rats, without reducing spontaneous activity. Further development of nAChR antagonists that inhibit nicotine-evoked DA release and penetrate brain to antagonize DA-mediated locomotor stimulant effects of nicotine as novel treatments for nicotine addiction is warranted.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Behavior, Animal / drug effects*
  • Biological Transport, Active
  • Blood-Brain Barrier / metabolism
  • Corpus Striatum / drug effects
  • Corpus Striatum / metabolism
  • Discrimination Learning / drug effects
  • Dopamine* / metabolism
  • Male
  • Molecular Structure
  • Motor Activity / drug effects
  • Nerve Tissue Proteins / metabolism
  • Nicotine / pharmacology*
  • Nicotinic Antagonists / chemistry
  • Nicotinic Antagonists / pharmacokinetics
  • Nicotinic Antagonists / pharmacology*
  • Picolines / chemistry
  • Picolines / pharmacokinetics
  • Picolines / pharmacology*
  • Plasma Membrane Neurotransmitter Transport Proteins / metabolism
  • Protein Binding
  • Rats
  • Rats, Inbred F344
  • Rats, Sprague-Dawley
  • Receptors, Nicotinic / metabolism*
  • Structure-Activity Relationship

Substances

  • N,N'-dodecane-1,12-diyl-bis-3-picolinium dibromide
  • Nerve Tissue Proteins
  • Nicotinic Antagonists
  • Picolines
  • Plasma Membrane Neurotransmitter Transport Proteins
  • Receptors, Nicotinic
  • Slc6a8 protein, rat
  • Nicotine
  • Dopamine