Differential effects of chronic drug treatment on alpha3* and alpha7 nicotinic receptor binding sites, in hippocampal neurones and SH-SY5Y cells

Br J Pharmacol. 2001 Aug;133(8):1286-95. doi: 10.1038/sj.bjp.0704207.


1. The aim of this study was to compare the effects of chronic treatment (for 4 or 7 days) with nicotinic drugs and 20 mM KCl on numbers of surface alpha7 nicotinic AChR, identified by [(125)I]-alpha bungarotoxin (alpha-Bgt) binding, in primary hippocampal cultures and SH-SY5Y cells. Numbers of alpha3* nicotinic AChR were also examined in SH-SY5Y cells, using [(3)H]-epibatidine, which is predicted to label the total cellular population of predominantly alpha3beta2* nicotinic AChR under the conditions used. 2. All the nicotinic agonists examined, the antagonists d-tubocurarine and methyllycaconitine, and KCl, upregulated [(125)I]-alpha Bgt binding sites by 20 - 60% in hippocampal neurones and, where examined, SH-SY5Y cells. 3. Upregulation of [(125)I]-alpha-Bgt binding sites by KCl was prevented by co-incubation with the L-type Ca2+ channel blocker verapamil or the Ca2+-calmodulin dependent kinase II (CaM-kinase II) inhibitor KN-62. Upregulation of [(125)I]-alpha-Bgt binding sites by nicotine or 3,[(4-dimethylamino) cinnamylidene] anabaseine maleate (DMAC) was insensitive to these agents. 4. [(3)H]-Epibatidine binding sites in SH-SY5Y cells were not affected by KCl but were upregulated in a verapamil-insensitive manner by nicotine and DMAC. KN-62 itself provoked a 2 fold increase in [(3)H]-epibatidine binding. The inactive analogue KN-04 had no effect, suggesting that CaM-kinase II plays a role in regulating numbers of alpha3* nicotinic AChR. 5. These data indicate that numbers of alpha3* and alpha7 nicotinic AChR are modulated differently. Nicotinic agonists and KCl upregulate alpha7 nicotinic AChR through distinct cellular mechanisms, the latter involving L-type Ca2+ channels and CaM-kinase II. In contrast, alpha3* nicotinic AChR are not upregulated by KCl. This difference may reflect the distinct physiological roles proposed for alpha7 nicotinic AChR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaloids / pharmacology
  • Animals
  • Azocines
  • Bacterial Toxins / pharmacology
  • Binding Sites / drug effects
  • Bridged Bicyclo Compounds, Heterocyclic / metabolism
  • Bungarotoxins / metabolism
  • Cells, Cultured
  • Cyanobacteria Toxins
  • Dimethylphenylpiperazinium Iodide / pharmacology
  • Hippocampus / cytology
  • Hippocampus / drug effects*
  • Hippocampus / metabolism
  • Humans
  • Inhibitory Concentration 50
  • Marine Toxins / pharmacology
  • Microcystins
  • Neuroblastoma
  • Neurons / drug effects*
  • Neurons / metabolism
  • Nicotine / agonists
  • Nicotine / antagonists & inhibitors
  • Nicotine / metabolism
  • Nicotine / pharmacology
  • Nicotinic Agonists / pharmacology*
  • Nicotinic Antagonists / pharmacology*
  • Pyridines / metabolism
  • Quinolizines
  • Rats
  • Receptors, Nicotinic / metabolism*
  • Tubocurarine / pharmacology
  • Tumor Cells, Cultured
  • Up-Regulation / drug effects*
  • Verapamil / pharmacology
  • alpha7 Nicotinic Acetylcholine Receptor


  • Alkaloids
  • Azocines
  • Bacterial Toxins
  • Bridged Bicyclo Compounds, Heterocyclic
  • Bungarotoxins
  • Chrna7 protein, human
  • Chrna7 protein, rat
  • Cyanobacteria Toxins
  • Marine Toxins
  • Microcystins
  • Nicotinic Agonists
  • Nicotinic Antagonists
  • Pyridines
  • Quinolizines
  • Receptors, Nicotinic
  • alpha7 Nicotinic Acetylcholine Receptor
  • cytisine
  • Dimethylphenylpiperazinium Iodide
  • Nicotine
  • Verapamil
  • epibatidine
  • Tubocurarine