The alpha2C-adrenoceptor modulates GABA release in mouse striatum

Area of Science:

• Neuroscience
• Pharmacology
• Molecular Biology

Background:

• The alpha(2C)-adrenoceptor is highly expressed in the striatum, but its function is unclear due to limited noradrenergic input.
• Understanding its role is crucial for deciphering striatal neurochemistry and function.

Purpose of the Study:

• To investigate the role of the striatal alpha(2C)-adrenoceptor in modulating GABA release.
• To elucidate the specific mechanisms and neuronal localization of alpha(2C)-adrenoceptor-mediated effects.

Main Methods:

• Utilized gene-targeted knockout mice (alpha(2C)-KO) and wild-type (WT) littermates.
• Electrically stimulated perfused brain slices pre-loaded with [(3)H]GABA.
• Administered alpha(2)-adrenoceptor agonist (UK14304) and antagonist (RX821002).
• Performed pharmacological monoamine depletion and tetrodotoxin experiments.

Main Results:

• In WT mice, UK14304 enhanced GABA release, while RX821002 decreased it.
• RX821002's effect was absent in alpha(2C)-KO mice, but UK14304's effect remained.
• Monoamine depletion abolished RX821002's effect in WT mice.
• RX821002 reduced GABA release in hippocampal slices from both WT and alpha(2C)-KO mice.
• RX821002 increased GABA release in striatal slices from both genotypes in the presence of tetrodotoxin.

Conclusions:

• Alpha(2A)- and alpha(2C)-adrenoceptors are located on distinct neurons in the striatum.
• Striatal alpha(2C)-adrenoceptor effects on GABA release are mediated by an endogenous catecholamine, potentially dopamine.
• The alpha(2C)-adrenoceptor's action of RX821002 does not occur on the GABAergic terminal itself.