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Optical reversal of halothane-induced immobility in C. elegans
Vinod K Singaram1, Benjamin H Somerlot, Scott A Falk
1Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Current Biology : CB
|December 6, 2011
Summary
Volatile anesthetics like halothane cause immobility by altering neuronal resting membrane potential (RMP). Optogenetic manipulation of RMP in C. elegans neurons reverses or enhances halothane-induced immobility.
Area of Science:
- Neuroscience
- Anesthesiology
- Molecular Biology
Background:
- Volatile anesthetics (VAs) induce reversible neurological effects like loss of consciousness and immobility.
- The precise mechanism of action for VAs remains largely unknown in neuroscience.
- Genetic studies suggest ion channels regulating neuronal resting membrane potential (RMP) influence anesthetic sensitivity.
Purpose of the Study:
- To investigate the hypothesis that halothane, a volatile anesthetic, induces immobility by altering neuronal RMP.
- To explore the role of leak channels in setting RMP and their impact on anesthetic sensitivity.
Main Methods:
- Utilized Caenorhabditis elegans as a model organism.
- Employed optogenetic tools (channelrhodopsin-2 and halorhodopsin) to manipulate RMP in cholinergic neurons.
- Introduced mutations in leak channels affecting RMP.
- Tested sensitivity to halothane and isoflurane under manipulated conditions.
Main Results:
- Halothane-induced immobility was reversed by depolarizing cholinergic neurons using channelrhodopsin-2.
- Hyperpolarizing cholinergic neurons with halorhodopsin increased sensitivity to halothane.
- C. elegans sensitivity to halothane varied 25-fold with RMP manipulation or leak channel mutations.
- Isoflurane-induced immobility was unaffected by these treatments, ruling out nonspecific effects.
Conclusions:
- Neuronal resting membrane potential (RMP) and associated leak channels are critical determinants of halothane-induced general anesthesia.
- Findings provide mechanistic insights into how volatile anesthetics affect neuronal excitability.
- Optogenetic and genetic approaches offer powerful tools to dissect anesthetic mechanisms.
