Voltage-sensitivity at the human dopamine D2S receptor is agonist-specific

Area of Science:

• Pharmacology
• Neuroscience
• Molecular Biology

Background:

• G protein-coupled receptors (GPCRs) mediate cellular responses to diverse stimuli.
• Agonist potency at some GPCRs has been shown to be voltage-sensitive.
• Electrophysiology in Xenopus oocytes is a common method to study GPCR function.

Purpose of the Study:

• To investigate whether voltage-sensitivity of agonist potency is a general feature of all agonists at the dopamine D(2S) receptor.
• To determine if different agonists exhibit distinct voltage-dependent behaviors at the same GPCR.

Main Methods:

• Utilized electrophysiology assays in Xenopus oocytes.
• Employed G protein-coupled potassium channels as a functional readout.
• Tested the voltage-sensitivity of various agonists at the dopamine D(2S) receptor.

Main Results:

• Demonstrated agonist-specific voltage-sensitivity at the dopamine D(2S) receptor.
• Dopamine potency decreased with depolarization, while beta-phenethylamine, p-, and m-tyramine potencies were voltage-insensitive.
• Certain N,N-dipropyl-2-aminotetralin compounds also exhibited voltage-sensitive behavior.

Conclusions:

• The voltage-sensitivity of agonist potency at the dopamine D(2S) receptor is not uniform across all agonists.
• This agonist-selective voltage-sensitivity is not explained by differential G protein subtype activation or effector ratios.
• This study provides the first evidence of distinct voltage-sensitive and voltage-insensitive agonist behaviors at a single GPCR.