Molecular variability elicits a tunable switch with discrete neuromodulatory response phenotypes

Area of Science:

• Neuroscience
• Computational Biology
• Molecular Biology

Background:

• Single-cell studies reveal significant molecular variability in cellular responses.
• Understanding this variability is crucial for deciphering cellular signaling and function.
• Electrophysiological excitability and neuromodulation are key neuronal functions influenced by molecular composition.

Purpose of the Study:

• To investigate the impact of molecular variability in cell signaling components and ion channels on neuronal electrophysiological excitability and neuromodulation.
• To computationally model the interplay between neuropeptide receptor expression, ion channel expression, and neuronal response dynamics.

Main Methods:

• A computational approach integrating neuropeptide receptor-mediated signaling with electrophysiology was employed.
• Simulated a neuronal population with varied expression levels of neuropeptide receptors and ion channels within physiological ranges.
• Analyzed electrophysiological responses to neuropeptide stimuli and categorized responses into distinct phenotypes using multivariate statistical methods.

Main Results:

• Distinct neuronal response patterns emerged, with low neuropeptide receptor levels increasing excitability and high levels decreasing it.
• A narrow receptor level range, termed a separatrix, differentiated these response patterns.
• The position of the separatrix was influenced by the expression levels of multiple ion channels, indicating a complex interaction.

Conclusions:

• Neuronal responses to neuromodulation are highly dependent on the complex interplay between receptor and ion channel expression levels.
• Receptor expression and the cell's biophysical state interact with specific relative contributions to determine neuronal excitability.
• This study enhances the understanding of how molecular expression variability shapes cellular responses to neuromodulation.