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Drug-induced Sensitization of Adenylyl Cyclase: Assay Streamlining and Miniaturization for Small Molecule and siRNA Screening Applications
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Drug-induced Sensitization of Adenylyl Cyclase: Assay Streamlining and Miniaturization for Small Molecule and siRNA Screening Applications

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Desensitization and down-regulation of the 5-hydroxytryptamine1B receptor in the opossum kidney cell line

R C Pleus1, D B Bylund

  • 1Department of Pharmacology, University of Nebraska Medical Center, Omaha.

The Journal of Pharmacology and Experimental Therapeutics
|April 1, 1992
PubMed

Insights

Serotonin 5-HT1B receptors in opossum kidney cells desensitize and down-regulate upon agonist exposure. This homologous desensitization affects adenylyl cyclase activity and receptor levels.

Area of Science:

  • Pharmacology
  • Cell Biology
  • Neuroscience

Background:

  • The 5-hydroxytryptamine (serotonin; 5-HT)1B receptor is a key mediator in various physiological processes.
  • This receptor is known to be negatively coupled to adenylyl cyclase via a Gi protein.

Purpose of the Study:

  • To investigate the desensitization and down-regulation of the 5-HT1B receptor in opossum kidney cells.
  • To determine the impact of serotonin (5-HT) exposure on receptor function and expression.

Main Methods:

  • Opossum kidney cell monolayers were preincubated with serotonin (5-HT).
  • Functional desensitization was assessed by measuring changes in forskolin-stimulated cyclic AMP production.
  • Receptor down-regulation was quantified using the radioligand [125I]iodocyanopindolol.

Main Results:

  • Preincubation with 5-HT induced homologous desensitization of 5-HT1B receptors, evidenced by a rightward shift in dose-response curves and reduced maximal inhibition of cyclic AMP production.
  • Desensitization was concentration- and time-dependent, with maximal effects observed after 3 hours.
  • Significant receptor down-regulation (up to 40%) was observed after 20 hours of exposure to 10 microM 5-HT.

Conclusions:

  • Agonist exposure leads to homologous desensitization of 5-HT1B receptors, impacting their functional response.
  • Down-regulation of 5-HT1B receptors occurs following prolonged agonist stimulation.
  • These findings align with the known mechanisms of desensitization and down-regulation for receptors coupled to adenylyl cyclase inhibition.

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