Molecular and cellular rhythms in excitatory and inhibitory neurons in the mouse prefrontal cortex

While studies have shown that there are rhythms in gene expression in the prefrontal cortex (PFC), the contribution of different cell types and potential variation by sex has not been determined. Of particular interest are excitatory pyramidal cells and inhibitory parvalbumin (PV) interneurons, as interactions between these cell types are essential for maintaining the excitation/inhibition balance. Here, we identify cell-type specific rhythms in the translatome of PV and pyramidal cells in the mouse PFC and assess rhythms in PV cell electrophysiology. We find that while core molecular clock genes are conserved and synchronized between cell types, pyramidal cells have nearly twice as many rhythmic transcripts as PV cells (35% vs. 18%). Rhythmic transcripts in pyramidal cells also show a high degree of overlap between sexes, whereas in PV cells, rhythmic transcripts are largely distinct between sexes. Additionally, we find sex-specific effects of phase on action potential properties in PV cells. This study demonstrates that rhythms in gene expression and electrophysiological properties in the PFC vary by both cell type and sex. Moreover, the biological processes associated with rhythmic transcripts may provide insight into the unique functions of rhythms in these cells, as well as their selective vulnerabilities to circadian disruption.