Aquaporin-9 as a biomarker for hydrocephalus: Insights from experimental rat models

Background: Hydrocephalus, characterized by ventricular enlargement often associated with elevated intracranial pressure, necessitates reliable biomarkers for accurate diagnosis. Aquaporin-9 (AQP-9), localized at the interface of cerebrospinal fluid (CSF) spaces and blood vessels, plays a critical role in brain water homeostasis but remains underexplored in the context of hydrocephalus. Further investigation into AQP-9 expression in CSF is essential to elucidate its potential as a diagnostic biomarker and its role in hydrocephalus pathophysiology. Methods: This experimental study utilized 10–12-week-old Sprague–Dawley rats (Rattus norvegicus) weighing 200–250 g, randomly assigned to three groups. CSF served as the primary unit of analysis. AQP-9 levels were quantified using the enzyme-linked immunosorbent assay Sandwich method, with CSF sampling conducted at 7-day intervals over 21 days. Results: AQP-9 levels were significantly elevated in hydrocephalic mice compared to controls, with the highest levels on day 21 (887.62 ± 88.72). CSF drainage resulted in a notable reduction in AQP-9 levels at all time points. Statistical analysis confirmed significant differences across groups (P < 0.05), with post hoc tests showing meaningful reductions in AQP-9 levels after drainage compared to hydrocephalic states. These findings suggest AQP-9 as a potential biomarker for hydrocephalus diagnosis and monitoring therapeutic response. Conclusion: AQP-9 shows promise as a biomarker for hydrocephalus, with levels reflecting disease progression and decreasing after CSF drainage. This highlights its potential for diagnosis and therapeutic monitoring, warranting further validation.