Blockade of nicotinic receptor-mediated release of dopamine from striatal synaptosomes by chlorisondamine and other nicotinic antagonists administered in vitro

Br J Pharmacol. 1994 Feb;111(2):406-13. doi: 10.1111/j.1476-5381.1994.tb14749.x.


1. Central nicotinic receptor function examined in vitro, by measuring nicotine-induced [3H]-dopamine release from rat striatal synaptosomes. 2. The agonists (-)-nicotine, acetylcholine, 1,1-dimethyl-4-phenylpiperazinium (DMPP) and cytisine (10(-7)-10(-4) M) all increased [3H]-dopamine release in a concentration-dependent manner. Cytisine did not produce a full agonist response, compared to the other agonists. 3. The actions of nicotine, acetylcholine and cytisine were largely dependent on external Ca2+. In contrast, DMPP (10(-5) and 10(-4) M) evoked a marked release of [3H]-dopamine even in the absence of Ca2+. Nevertheless, in the presence of external Ca2+, responses to DMPP were completely blocked by the nicotinic antagonists chlorisondamine and mecamylamine (5 x 10(-5) M); in the absence of external Ca2+, blockade was only partial. 4. Chlorisondamine, mecamylamine and dihydro-beta-erythroidine (10(-8)-10(-4) M) produced a concentration-dependent block of responses to nicotine (10(-6) M). Approximate IC50 values were 1.6, 0.3 and 0.2 x 10(-6), respectively. Chlorisondamine and mecamylamine blocked responses to nicotine (10(-7)-10(-4) M) insurmountably, whereas dihydro-beta-erythroidine behaved in a surmountable fashion. 5. The occurrence of use-dependent block was tested by briefly pre-exposing the synaptosomes to nicotine during superfusion with antagonist, and determining the response to a subsequent nicotine application. Consistent with a possible channel blocking action, brief pre-exposure to agonist increased the antagonist potency of chlorisondamine (approximately 25 fold). No significant use-dependent block was detected with dihydro-beta-erythroidine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / physiology
  • Chlorisondamine / pharmacology*
  • Dihydro-beta-Erythroidine / pharmacology
  • Dimethylphenylpiperazinium Iodide / pharmacology
  • Dopamine / metabolism*
  • Ganglionic Stimulants / pharmacology
  • In Vitro Techniques
  • Male
  • Mecamylamine / pharmacology
  • Neostriatum / drug effects
  • Neostriatum / metabolism*
  • Nicotine / antagonists & inhibitors*
  • Nicotine / pharmacology
  • Nicotinic Antagonists*
  • Potassium / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Nicotinic / metabolism
  • Synaptosomes / drug effects
  • Synaptosomes / metabolism*


  • Ganglionic Stimulants
  • Nicotinic Antagonists
  • Receptors, Nicotinic
  • Dihydro-beta-Erythroidine
  • Dimethylphenylpiperazinium Iodide
  • Mecamylamine
  • Nicotine
  • Chlorisondamine
  • Potassium
  • Calcium
  • Dopamine