IntroductionHeat stress (HS) can progress to heat stroke, a life-threatening condition. Aquaporin-4 (AQP4) has been implicated in HS-induced brain injury, but its role in heat acclimation (HA)-mediated protection remains unclear. This study investigated whether HA ameliorates HS-induced brain damage through AQP4.Methods9L/lacZ cells were randomly assigned to four groups: Control (37 °C, 5% CO₂), HA (39 °C, 5% CO₂, 2 h/day for 6 days), HS (43 °C, 5% CO₂, 2 h), and HA+HS (HA pretreatment followed