Objective To investigate the pathogenesis of high-altitude cerebral edema (HACE) and develop new therapeutic strategies.

Methods Male Sprague-Dawley (SD) rats of 6 weeks old were selected and placed in a hypobaric chamber. The rats were exposed to the high-altitude environment of 7000 m above sea level for 3 days for HACE modeling. Whether the HACE model was successfully established in the rats was evaluated by measuring brain water content, the degree of disruption to the blood-brain barrier (BBB), and brain tissue Nissl staining. The experimental animals were divided into four groups, with 28 rats in each group. The blank control group was exposed to a normobaric and normoxic environment simulating the conditions at 500 m above sea level for 3 d. The other groups, including a model group (the HACE group), a bumetanide group (the positive control group), and a XH-6003 treatment group, were placed at an altitude of 7000 m above sea level and were injected with normal saline, bumetanide, and XH-6003, a new type of Na-K-2Cl cotransporter 1 (NKCC1) inhibitor, via the tail vein, respectively, twice daily for 3 d. The experimental animals were taken out of the hypobaric chamber for testing after 3 d. The primary outcome measures included brain water content, BBB permeability, changes in brain tissue morphology, and the expression levels of aquaporin-4 (AQP4) and NKCC1. The secondary outcome measures included behavioral changes, apoptosis, and oxidative stress markers.

Results The HACE rat model was successfully established. The model group exhibited increased brain water content (P < 0.0001), BBB disruption (P < 0.0001), impairment in learning skills and memory (P < 0.001), and anxiety/depression-like behaviors (P < 0.01). qPCR results showed significantly increased expression of NKCC1 and AQP4 in the brain tissue of the model group (P < 0.01). Pathology examination revealed neuronal and glial cell damage in the hippocampus of the model group (P < 0.01). Treatment with XH-6003, the NKCC1 inhibitor, reversed brain water content, BBB disruption, and neuronal and glial cell damage to a certain degree (P < 0.05), decreased the expression of NKCC1 and AQP4 in the brain tissue (P < 0.01), and inhibited apoptosis-related proteins. Among the oxidative stress indices, only glutathione (GSH) showed improvement (P < 0.001). Rats treated with XH-6003 showed functional improvement only in the time spent exploring novel objects, while other behavioral outcomes remained unchanged.

Conclusion HACE is associated with the activation of the NKCC1/AQP4 pathway. Inhibition of this pathway alleviates brain edema, BBB disruption, and neuronal and glial cell damage. These findings suggest that XH-6003 holds potential as a therapeutic strategy for HACE at the cellular and molecular levels, but its effects in improving HACE-related behavioral disorders warrant further investigation.