Sex differences in cell type-specific transcriptional programs and GPCR signaling in the human subgenual anterior cingulate cortex

Psychiatric conditions show marked sex differences in disease onset, symptom presentation, and response to treatments. Understanding how sex differences manifest across molecularly distinct neuronal populations in individuals without psychiatric conditions may help explain sex-dependent variation in neural circuit function and treatment response. Here, we examined molecularly distinct cell types within the subgenual anterior cingulate cortex (sgACC) of non-psychiatric subjects. Using RNA sequencing data previously generated from laser-capture microdissected neurons, we investigated sex differences in gene expression and co-expression networks in excitatory pyramidal neurons (layers 2/3 and 5/6) and somatostatin (SST)-, parvalbumin (PVALB)-, and vasoactive intestinal peptide (VIP)-expressing inhibitory interneurons (N=10 males, 9 females). We identified sex differences in transcriptomic profiles, biological pathways, and co-expression network connectivity. PVALB cells showed stronger overall female transcriptional enrichment, while SST cells exhibited male-enriched transcriptional signatures. Weighted gene co-expression network analysis identified PVALB and SST modules more connected in males and females, respectively, which included hub genes involved in immune, extracellular matrix, and bioenergetic processes. Since G protein-coupled receptors (GPCRs) are viable therapeutic targets, we examined sex differences in GPCR transcripts. Across all GPCR-cell-type combinations, CHRM2 in PVALB cells showed the second strongest sex difference (enriched in females). To test the functional relevance of this difference, we used patch-clamp electrophysiology in mouse prefrontal cortex. M2 receptor activation increased maximal firing rates in PVALB cells from female but not male mice. Collectively, our findings demonstrate cell type-specific sex differences in the sgACC corresponding to functional differences in neuromodulator signaling, with potential implications for treatment response.