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Bicuculline blocks nicotinic acetylcholine response in isolated intermediate lobe cells of the pig

Z W Zhang1, P Feltz

  • 1Institut de Physiologie (UA309 CNRS), Université Louis Pasteur, Strasbourg, France.

British Journal of Pharmacology
|January 1, 1991
PubMed

Insights

Bicuculline inhibits acetylcholine responses in pig pituitary cells by directly blocking the receptor-ionophore complex. This effect is dose-dependent and partially competitive, offering insights into neurotransmission.

Area of Science:

  • Neuropharmacology
  • Cellular Neuroscience

Background:

  • Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission.
  • The intermediate lobe (IL) of the pituitary gland expresses nAChRs involved in hormone release.

Purpose of the Study:

  • To investigate the effect of bicuculline on acetylcholine (ACh)-evoked responses in porcine IL cells.
  • To characterize the mechanism of bicuculline's interaction with the ACh receptor-ionophore complex.

Main Methods:

  • Patch-clamp electrophysiology was used to record whole-cell currents.
  • Dose-response relationships and voltage-dependence were analyzed.
  • Competitive inhibition was assessed.

Main Results:

  • Bicuculline reduced ACh-evoked whole-cell currents (IACh) in all tested IL cells.
  • The blockade was dose-dependent, with a half-maximal inhibitory concentration (IC50) of 43.8 microM.
  • Bicuculline exhibited partial competitive inhibition and slight voltage-dependence at hyperpolarized potentials.

Conclusions:

  • Bicuculline directly interacts with the ACh receptor-ionophore complex in porcine IL cells.
  • This interaction inhibits nicotinic neurotransmission in the pituitary intermediate lobe.

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