Vorinostat Rescues Cognitive Deficits in a Neuroinflammatory Mouse Model: A Study of Sex Differences and the Underlying TLR4/NF-κB Mechanism.

With the acceleration of global aging, Alzheimer's disease (AD) poses a significant public health challenge, and effective treatments are still lacking. Neuroinflammation, particularly microglia-mediated inflammation, plays a central role in AD pathogenesis, with the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway being a key regulator. The histone deacetylase inhibitor (HDACi) Vorinostat (SAHA) has shown anti-inflammatory and neuroprotective potential in preclinical studies. Given the significant sex differences in AD incidence, pathology, and treatment response, this study aimed to systematically investigate the effects of SAHA on lipopolysaccharide (LPS)-induced neuroinflammation and cognitive dysfunction, analyzing its sex-specific effects and underlying mechanisms. An LPS-induced neuroinflammation model was established in male and female C57BL/6 mice via intraperitoneal injection (1 mg/kg) for 7 consecutive days, followed by SAHA (50 mg/kg) gavage intervention for 23 days. Cognitive function was assessed using Y-maze, novel object recognition, and passive avoidance tests. Hippocampal pathology was analyzed via hematoxylin-eosin (HE) staining and Nissl staining. Western blot and quantitative PCR (qPCR) were used to detect hippocampal expression of the TLR4/TRAF6/IKKα/NF-κB pathway, inflammatory factors (IL-6, IL-1β, TNF-α, iNOS), and neuroplasticity-related proteins (BDNF, p-CREB). In vitro experiments using LPS-stimulated BV2 microglia validated SAHA's anti-inflammatory mechanisms via CCK-8, Griess assay, qPCR, and Western blot. Results showed that LPS treatment significantly activated the TLR4/TRAF6/IKKα/NF-κB pathway, upregulated hippocampal pro-inflammatory factors, caused neuronal damage, and impaired learning and memory; these effects appeared more pronounced in female mice, though this observation is exploratory and requires cautious interpretation. SAHA treatment markedly alleviated LPS-induced inflammation, neuropathology, and cognitive deficits. Notably, SAHA appeared to produce differential effects across sexes: female mice showed potentially stronger and more comprehensive improvements in cognitive recovery, downregulation of inflammatory factors, and upregulation of BDNF and p-CREB compared to males, suggesting a possible sexually dimorphic response. In vitro experiments further confirmed that SAHA significantly reduced inflammation in LPS-stimulated BV2 microglia by inhibiting the TLR4/TRAF6/IKKα/NF-κB pathway. In conclusion, this study demonstrates that SAHA exerts neuroprotective effects by inhibiting the TLR4/NF-κB pathway, thereby improving cognitive impairment, and may have a more pronounced protective effect in females. These findings suggest SAHA is a promising drug for treating neuroinflammation-induced cognitive dysfunction and highlight the importance of considering sex as a biological variable in epigenetic therapy for precision medicine.