Sex Differences in Single Neuron Function and Proteomics Profiles Examined by Patch-Clamp and Mass Spectrometry in the Locus Coeruleus of the Adult Mouse

ABSTRACT: Aims: This study aimed to identify and characterize the intrinsic properties of locus coeruleus (LC) noradrenergic neurons in male and female mice using a genetic approach. We also sought to investigate sex-specific differences in membrane properties, action potential generation, and protein expression profiles to understand the mechanisms underlying neuronal excitability variations. Methods: Utilizing a genetic mouse model by crossing Dbhcre knock-in mice with tdTomato Ai14 transgenic mice, LC neurons were identified using fluorescence microscopy. Neuronal properties, including capacitance, action potential frequency, and rheobase, were assessed using patch-clamp recordings. Spontaneous and evoked activity between sexes was compared. Proteomic analyses of individual LC neuron soma was conducted using mass-spectrometry to discern protein expression profiles. Results: Female LC noradrenergic neurons displayed greater membrane capacitance than those in male mice. Male LC neurons demonstrated greater spontaneous and evoked action potential generation compared to females. Male LC neurons exhibited a lower rheobase and achieved higher peak frequencies with similar current injections. Proteomic analysis revealed inherent differences in protein expression profiles between sexes, with male mice displaying a notably larger unique protein set compared to females. Notably, pathways pertinent to protein synthesis, degradation, and recycling, such as EIF2 and glucocorticoid receptor signaling, showed reduced expression in females. Conclusions: Male LC noradrenergic neurons exhibit higher intrinsic excitability compared to those from females. The discernible sex-based differences in excitability could be ascribed to varying protein expression profiles, especially within pathways that regulate protein synthesis and degradation. This study lays the groundwork for future studies focusing on the interplay between proteomics and neuronal function examined in individual cells.

INSTRUMENT(S): Orbitrap Eclipse

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Brain, Neuron

SUBMITTER: Jingyun Lee  

LAB HEAD: Osvaldo Delbono

PROVIDER: PXD045844 | Pride | 2024-05-24

REPOSITORIES: Pride