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Bidirectional Influence of Limbic GIRK Channel Activation on Innate Avoidance Behavior
Baovi N Vo1, Ezequiel Marron Fernandez de Velasco2, Timothy R Rose1
1Graduate Program in Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455.
Summary
ML297, a G-protein-gated inwardly rectifying K+ (GIRK) channel activator, reduces avoidance behavior by inhibiting excitatory neurons in the ventral hippocampus (vHPC). This inhibition is necessary and sufficient for ML297's anxiolytic effects in male mice.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- G-protein-gated inwardly rectifying K+ (GIRK) channels modulate neuronal excitability.
- ML297 activates GIRK channels and reduces innate avoidance behavior in male mice.
- Cellular mechanisms of ML297's behavioral effects remain unclear.
Purpose of the Study:
- Investigate the neural circuits mediating ML297's suppression of innate avoidance behavior.
- Determine the role of ventral hippocampus (vHPC) and basolateral amygdala (BLA) in ML297's effects.
- Identify specific neuronal populations targeted by ML297.
Main Methods:
- Systemic and intracranial administration of ML297 in male C57BL/6J mice.
- Elevated plus maze (EPM), open-field, light-dark, and marble-burying tests.
- Viral genetic and chemogenetic manipulation of vHPC excitatory neurons (CA3 and DG).
- Assessment of neuronal activation via immunohistochemistry.
- Genetic ablation of GIRK channels in specific neuronal populations.
Main Results:
- Systemic ML297 suppressed EPM-induced neuronal activation in vHPC and BLA.
- Intracranial ML297 in vHPC mimicked systemic effects; intra-BLA administration had opposite effects.
- Inhibition of excitatory neurons in vHPC CA3 and DG subregions reduced avoidance behavior across multiple tests.
- Genetic ablation of GIRK channels in CA3/DG excitatory neurons blocked ML297's behavioral effects.
- Marble-burying test performance was unaffected.
Conclusions:
- Acute inhibition of excitatory neurons in the ventral CA3 and DG subregions of the vHPC is necessary for ML297's anxiolytic efficacy.
- This inhibition is sufficient to decrease innate avoidance behavior in male mice.
- Findings provide a cellular basis for ML297's therapeutic potential in anxiety disorders.
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