Related Experiment Videos
Delta opioid receptor mediates phospholipase C activation via Gi in Xenopus oocytes
T Miyamae1, N Fukushima, Y Misu
1Department of Pharmacology, Yokohama City University School of Medicine, Japan.
Abstract:
Cloned mouse delta-subtype opioid receptor (DOR1) was expressed in Xenopus oocytes to study the signal transduction. Opioid delta-agonists evoked a calcium-dependent chloride current in oocytes injected with mRNA derived from DOR1, together with that from the alpha subunit of Gi1. The delta-agonist-induced current was blocked by naltrindol, a delta-specific antagonist. The delta-agonist evoked no or very weak currents in oocytes with the alpha subunit of Gq or G(o). These findings indicate the functional coupling between the opioid delta-receptor and phospholipase C through an activation of Gi.
Insights
The opioid delta receptor (DOR1) activates phospholipase C via Gi1 protein, triggering a calcium-dependent chloride current in Xenopus oocytes. This signaling pathway is specific to delta-opioid agonists and Gi1 coupling.
Area of Science:
- Neuropharmacology
- Molecular Biology
- Cell Signaling
Background:
- The delta-subtype opioid receptor (DOR1) plays a role in various physiological processes.
- Understanding the signal transduction pathways of opioid receptors is crucial for drug development.
Purpose of the Study:
- To investigate the signal transduction mechanism of the cloned mouse delta-subtype opioid receptor (DOR1).
- To determine the specific G protein coupling involved in DOR1 activation.
Main Methods:
- Expression of DOR1 mRNA and G protein alpha subunits (Gi1, Gq, G(o)) in Xenopus oocytes.
- Measurement of opioid delta-agonist-induced currents using electrophysiology.
- Assessment of antagonist effects using naltrindol.
Main Results:
- Delta-opioid agonists evoked a calcium-dependent chloride current in oocytes expressing DOR1 and Gi1 alpha subunit.
- This agonist-induced current was blocked by the delta-specific antagonist naltrindol.
- Minimal or no current was observed when oocytes expressed Gq or G(o) alpha subunits, indicating Gi1 specificity.
Conclusions:
- The opioid delta-receptor functionally couples to phospholipase C through the activation of the Gi1 protein.
- This study elucidates a specific signaling pathway for DOR1 activation, highlighting its interaction with Gi1.