Objective:

To explore the HMGB1-TLR4-mediated neuroinflammatory mechanism in a rat model of IESS induced by prenatal stress combined with NMDA, and to evaluate the effects of anti-HMGB1 neutralizing antibody and ACTH on epileptic seizures and neuroinflammation.

Approach:

• Study Design: Pregnant Sprague-Dawley rats were randomly divided into prenatal stress (PS) and non-prenatal stress (NPS) groups. PS rats received cold water immersion and hot air drying, while NPS rats were reared normally. On postnatal day 12 (P12), offspring in the PS group were intraperitoneally injected with NMDA to establish the IESS model, and the NPS group was assigned to blank control (BC) and negative control (NC) subgroups.
• Intervention: Model rats were randomly divided into ACTH, anti-HMGB1, ACTH+anti-HMGB1, normal saline, and untreated groups. After intervention on P13, NMDA was re-administered, and seizure latency and severity score were recorded.
• Measurement: At the end of the experiment, the expression of HMGB1 and TLR4 in brain tissue was detected, HMGB1 co-localization was observed, and the levels of iNOS, Arg1 and cytokines (IL-1β, IL-2R, IL-8, TNF-α) were measured.

Key Findings:

• Prenatal stress combined with NMDA successfully established a stable IESS model in young rats.
• The expression of HMGB1, TLR4, iNOS, IL-1β, IL-2R, IL-8, and TNF-α was significantly upregulated, while Arg1 was markedly downregulated.
• Treatment with ACTH, anti-HMGB1, and their combination prolonged seizure latency, reduced seizure severity, downregulated HMGB1 and TLR4 expression, suppressed HMGB1 levels in neurons, astrocytes and activated microglia, inhibited iNOS and proinflammatory cytokines, and promoted Arg1 expression, with the combined intervention showing the optimal efficacy.

Interpretation:

Prenatal stress combined with NMDA activates the HMGB1/TLR4 pathway and neuroinflammation in IESS rats.

Conclusion:

ACTH and anti-HMGB1 treatments, alone or in combination, alleviate neuroinflammation in the rat model.