Sex-Specific Hippocampal Phosphoproteomic Features Associated with Stress-Induced Phenotypes in Mice Exposed to Chronic Restraint Stress.

Chronic stress significantly contributes to anxiodepression, with marked sex differences in hippocampal dysfunction. This study investigated the interplay between sex and stress phenotype in shaping hippocampal phosphorylation landscapes in a chronic restraint stress model of anxiodepression. Hippocampal phosphoproteomes of female and male mice, classified as anxiodepression-susceptible (AD-Sus) and insusceptible (Insus), were analyzed using 4D label-free quantitative proteomics. Distinct phosphorylation profiles associated with sex and phenotype were identified, with the corresponding phosphoproteins primarily linked to the MAPK signaling pathway. Females exhibited significant enrichment in the thyroid hormone signaling pathway and long-term potentiation. In contrast, males showed notable enrichment in the serotonergic synapse pathway, which suggests a sex-specific difference in serotonin-mediated emotional responses. GABAergic synapses were more prevalent in the Insus group than in the AD-Sus group, while the cGMP-PKG signaling pathway was enriched in both female and male AD-Sus groups. MAPK1 was identified as the kinase with the highest number of phosphorylated substrates across all groups, indicating its potential central role. Key phosphorylation targets included Stmn1 (S38) and Pdha1 (S232) in the female AD-Sus and Insus groups, and Stmn1 (S38) and Mapt (T523) in the female and male Insus groups. The Insus group exhibited additional kinases linked to numerous substrates, indicating a more complex kinase regulation mechanism compared to the AD-Sus group, where MAPK1 played a more pronounced role. Our findings demonstrate distinct sex- and phenotype-specific phosphorylation patterns, highlighting novel molecular mechanisms underlying stress-induced anxiodepression and resilience.