Esketamine steers microglia away from inflammatory state via NMDAR2A in cell study

Esketamine, a non-competitive antagonist of the N-methyl-D-aspartate receptor (NMDAR), suppressed the shift of BV2 microglial cells toward the pro-inflammatory M1 phenotype in a new cell-culture study published in Molecular Biology Reports. The effect depended on a specific receptor subtype, NMDAR2A, while the closely related NMDAR2B subtype was not involved. According to the study's authors, polarization toward the M1 phenotype contributes to the initiation and progression of neuroinflammatory diseases primarily through the release of pro-inflammatory cytokines that exacerbate central nervous system-associated injury.

NMDAR activation has previously been implicated in microglial overactivation and cytotoxicity, and testing whether blocking these receptors could modulate microglial polarization was the stated aim of the work. The research team, which included Hui Li, Xiaoyuan Zhang, Yushan Luo, Wen Hu, Yang Liu, Yimin Ren and Xiaohua Zou, used BV2 microglial cells as an in vitro model. To probe the drug's molecular targets, they combined several standard laboratory approaches: small interfering RNA to knock down specific gene products, Western blotting to measure protein signaling, enzyme-linked immunosorbent assay to quantify secreted cytokines, and immunofluorescence staining to visualize polarization markers.

They also applied inhibitors and agonists to manipulate two signaling pathways of interest, the mammalian target of rapamycin (mTOR) pathway and the brain-derived neurotrophic factor (BDNF)-tyrosine kinase receptor B (TrkB) pathway. The results showed a coherent signaling chain. By inhibiting NMDARs, esketamine enhanced phosphorylation of mTOR and activated the BDNF-TrkB signaling pathway.

In parallel, the drug attenuated the M1 polarization that lipopolysaccharide, a bacterial endotoxin used to provoke inflammatory responses in the cell culture, would otherwise induce in the BV2 cells. Pro-inflammatory cytokine expression fell accordingly, indicating that the phenotypic shift away from M1 was accompanied by a measurable reduction in the inflammatory output of the cells. The most striking finding was the receptor selectivity.

When the researchers dissected which NMDAR subtype mediated the anti-inflammatory effect, the answer was primarily NMDAR2A, while the NMDAR2B subtype was not involved. This subtype-specific result emerged from the combination of pharmacological modulation and small interfering RNA knockdown within the same cell model. The authors conclude that esketamine suppressed pro-inflammatory microglial polarization by selectively modulating the NMDAR2A subtype, leading to activation of the mTOR signaling pathway and enhancement of the BDNF-TrkB signaling pathway.

In their framing, the drug's influence on microglial inflammation runs through a defined molecular route rather than a nonspecific dampening of cell activity. Several caveats are essential when interpreting these findings. The entire study was conducted in BV2 cells, an immortalized mouse microglial cell line, and the M1 polarization was provoked artificially with lipopolysaccharide.

The published material does not include data from primary microglia, animal models, or human subjects, so no conclusions about therapeutic benefit in any neurological or psychiatric condition can be drawn from this work alone. For now, the finding stands as a carefully mapped molecular observation in a cell-culture system: one drug, one receptor subtype, and a measurable shift in how microglia respond to an inflammatory trigger. Whether the NMDAR2A-dependent, mTOR- and BDNF-TrkB-linked pathway described here holds up in more physiological models remains to be tested by future research.

Subject of Research: Esketamine's suppression of M1 microglial polarization in BV2 cells through NMDAR2A, mTOR and BDNF-TrkB signaling

Article Title: Targeting NMDAR2A in microglia: esketamine suppresses M1 polarization in BV2 cells

Article References: Li, H., Zhang, X., Luo, Y., Hu, W., Liu, Y., Ren, Y., & Zou, X. (2026). Targeting NMDAR2A in microglia: esketamine suppresses M1 polarization in BV2 cells. Molecular Biology Reports, 53(1), Article 1782. https://doi.org/10.1007/s11033-026-12874-9

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12874-9

Keywords: esketamine, microglia, NMDAR2A, M1 polarization, BV2 cells, neuroinflammation, mTOR, BDNF-TrkB, cytokines, cell culture study, NMDAR antagonist, Molecular Biology Reports