Htr2a Gene and 5-HT(2A) Receptor Expression in the Cerebral Cortex Studied Using Genetically Modified Mice

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Serotonin 5-HT(2A) receptors are crucial in the cerebral cortex, influencing mental disorders and hallucinogen effects.
• Specific cell-type expression of 5-HT(2A) receptors in the cortex remains largely uncharacterized.

Purpose of the Study:

• To identify and characterize the cell types expressing the Htr2a gene and 5-HT(2A) receptors in the mouse cerebral cortex.
• To map the laminar and regional distribution of 5-HT(2A) receptors.
• To investigate the functional impact of serotonin on identified interneuron populations.

Main Methods:

• Utilized EGFP-expressing BAC transgenic mice to track Htr2a gene expression.
• Employed 5-HT(2A) receptor knockout mice and immunohistochemistry to map receptor localization.
• Conducted electrophysiological recordings and immunohistochemistry to analyze GABAergic interneurons.

Main Results:

• Identified three main neuronal populations expressing Htr2a: layer V pyramidal cells, GABAergic interneurons, and subplate/Layer VIb cells.
• Revealed strong laminar expression of 5-HT(2A) receptors in the cortex, with an anteroposterior gradient matching layer V pyramidal cells.
• Demonstrated that most fast-spiking, parvalbumin-expressing GABAergic interneurons are excited by serotonin via 5-HT(2A) receptors.

Conclusions:

• Clarified the cellular distribution of 5-HT(2A) receptors in the cerebral cortex.
• Extended understanding of the role of specific cortical interneurons in serotonin signaling.
• Provided a foundation for further research into 5-HT(2A) receptor function in cortical circuits and related disorders.