Related Experiment Videos
Cannabinoids modulate potassium current in cultured hippocampal neurons
S A Deadwyler1, R E Hampson, B A Bennett
1Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157.
Receptors & Channels
|January 1, 1993
Summary
Cannabinoid analogs modulate potassium A currents (IA) in hippocampal neurons by affecting their voltage dependence. These effects are mediated by G-protein-coupled receptors, influencing neuronal excitability.
Area of Science:
- Neuroscience
- Molecular Pharmacology
Background:
- The functional significance of newly discovered G-protein-coupled cannabinoid receptors in the brain remains to be fully elucidated.
- The hippocampus, a brain region with high cannabinoid receptor density, is crucial for cognitive functions.
Purpose of the Study:
- To investigate the electrophysiological effects of potent cannabinoid analogs on cultured hippocampal neurons.
- To determine the role of G-protein-coupled receptors in mediating cannabinoid actions on neuronal currents.
Main Methods:
- Whole-cell patch clamp recordings were used to measure voltage-dependent potassium currents, specifically the potassium A current (IA).
- Cultured hippocampal neurons were exposed to various cannabinoid analogs (CP 55,244, CP 55,940, levonantradol, WIN 55,212-2).
- Pertussis toxin and GTP-gamma-S were employed to probe the involvement of G-proteins.
Main Results:
- Cannabinoid analogs significantly altered the voltage dependence of IA in a concentration-dependent manner.
- Cannabinoids decreased IA inactivation, increasing its activation near resting membrane potentials.
- These effects were blocked by pertussis toxin and mimicked by GTP-gamma-S, indicating G-protein mediation.
- The potency of analogs in modulating IA correlated with their binding affinity and GTPase activity.
Conclusions:
- Cannabinoid effects on IA in hippocampal neurons are mediated via G-protein-coupled receptors.
- This modulation of IA voltage dependence may counteract depolarizing events, influencing neuronal excitability.