Sex-Specific Microglial Response to Ketamine Unveiled in Mouse Brains

Research published online on July 31, 2026, in the prestigious scientific journal *Nature* has uncovered significant sex-specific differences in how the brains of mice respond to ketamine anesthesia at a cellular level. The study focused on microglia, specialized immune cells residing within the central nervous system, which are crucial for maintaining brain health. These cells are known to play vital roles in processes such as synaptic pruning (the elimination of unnecessary neural connections), immune surveillance of the brain, and responding to injury or disease. The investigation observed that following administration of ketamine, a dissociative anesthetic widely used in both human and veterinary medicine for its anesthetic properties and increasingly explored for its rapid antidepressant effects, microglia exhibited distinct behaviors in male versus female mice. Specifically, in female mice, these microglia were seen to actively extend processes towards neurons. This directed interaction suggests a more engaged or perhaps restorative role for microglia in the female brain's response to ketamine-induced anesthesia compared to their male counterparts. The findings imply that the brain's innate immune system, mediated by microglia, operates in a sex-dependent manner when encountering ketamine. This differential engagement could signify divergent pathways for neural circuit modulation, repair, or adaptation in the aftermath of anesthetic exposure. The study's publication in *Nature*, a leading peer-reviewed journal renowned for its high-impact scientific discoveries, underscores the potential significance of these observations within the broader neuroscience and neuropharmacology communities. Understanding these sex-based variations is becoming increasingly critical as ketamine's therapeutic applications, particularly in treating conditions like treatment-resistant depression, continue to expand. The precise nature and functional implications of this microglial-neuronal outreach in female mice—whether it represents a protective mechanism, a restorative process, or a modulatory influence on neural plasticity—warrant further in-depth scientific inquiry. This research adds a crucial layer of complexity to our understanding of neuropharmacology, highlighting that biological sex can profoundly influence neurological processes and responses to pharmacological interventions, potentially paving the way for more personalized and effective therapeutic strategies tailored to sex-specific biological mechanisms. The article's digital object identifier (DOI) is 10.1038/d41586-026-02356-0.