Salvinorin A ameliorates cerebral vasospasm through activation of endothelial nitric oxide synthase in a rat model of subarachnoid hemorrhage

Objective This study aimed to demonstrate the potential of salvinorin A (SA) for cerebral vasospasm after subarachnoid hemorrhage (SAH) and investigate mechanisms of therapeutic effect using rat SAH model. Methods Salvinorin A was injected intraperitoneally, and the neurobehavioral changes were observed at 12 hours, 24 hours, 48 hours, and 72 hours after SAH. Basilar artery was observed by magnetic resonance imaging (MRI). The inner diameter and thickness of basilar artery were measured. The morphological changes and the apoptosis in CA1 area of hippocampus were detected. Endothelin‐1 (ET‐1) and nitric oxide (NO) levels were detected by ELISA kit. The protein expression of endothelial NO synthase (eNOS) and aquaporin‐4 (AQP‐4) was determined by Western blot for potential mechanism exploration. Results Salvinorin A administration could relieve neurological deficits, decrease the neuronal apoptosis, and alleviate the morphological changes in CA1 area of hippocampus. SA alleviated CVS by increasing diameter and decreasing thickness of basilar artery, and such changes were accompanied by the decreased concentration of ET‐1 and increased level of NO. Meanwhile, SA increased the expression of eNOS and decreased the expression of AQP‐4 protein in the basilar artery and hippocampus. Conclusions Salvinorin A attenuated CVS and alleviated brain injury after SAH via increasing expression of eNOS and NO content, and decreasing ET‐1 concentration and AQP‐4 protein expression.