Therapeutic eﬀect of and mechanisms underlying the eﬀect of miR-195-5p on subarachnoid hemorrhage-induced vasospasm and brain injury in rats

Objectives There is much evidence suggesting that inﬂammation contributes majorly to subarachnoid hemorrhage (SAH)-induced cerebral vasospasm and brain injury. miRNAs have been found to modulate inﬂammation in several neurological disorders. This study investigated the eﬀect of miR-195-5p on SAH-induced vasospasm and early brain injury in experimental rats. Methods Ninety-six Sprague-Dawley male rats were randomly and evenly divided into a control group (no SAH, sham surgery), a SAH only group, a SAH + NC-mimic group, and a SAH + miR-195-5p group. SAH was induced using a single injection of blood into the cisterna magna. Suspensions containing NC-mimic and miR-195-5p were intravenously injected into rat tail 30 mins after SAH was induced. We determined degree of vasospasm by averaging areas of cross-sections the basilar artery 24h after SAH. We measured basilar artery endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase(iNOS), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphorylated NF-κB (p-NF-κB), inhibitor of NF-κB (IκBα) and phosphorylated-IκBα (p-IκBα). Cell death assay was used to quantify the DNA fragmentation, an indicator of apoptotic cell death, in the cortex, hippocampus, and dentate gyrus. Tumor necrosis factor alpha (TNF-α) levels were measured using sample protein obtained from the cerebral cortex, hippocampus and dentate gyrus. Results Prior to ﬁxation by perfusion, there were no signiﬁcant physiological diﬀerences among the control and treatment groups. SAH successfully induced vasospasm and early brain injury. MiR-195-5p attenuated vasospasam-induced changes in morphology, reversed SAH-induced elevation of iNOS, p-NF-κB, NF-κB, and p-IκBα and reversed SAH-induced suppression of eNOS in the basilar artery. Cell death assay revealed that MiR-195-5p signiﬁcantly decreased SAH-induced DNA fragmentation (apoptosis) and restored TNF-α level in the dentate gyrus. Conclusion In conclusion, MiRNA-195-5p attenuated SAH-induced vasospasm by up-regulating eNOS, down-regulating iNOS and inhibiting the NF-κB signaling pathway. It also protected neurons by decreasing SAH-induced apoptosis-related cytokine TNF-α expression in the dentate gyrus. Further study is needed to elucidate the detail mechanism underlying miR-195-5p eﬀect on SAH-induced vasospasm and cerebral injury. We believe that MiR-195-5p can potentially be used to manage SAH-induced cerebral vasospasm and brain injury. Abstract 27 There is much evidence suggesting that inflammation contributes majorly to subarachnoid 28 hemorrhage (SAH)-induced cerebral vasospasm and brain injury. miRNAs have been found to 29 modulate inflammation in several neurological disorders. This study investigated the effect of 30 miR-195-5p on SAH-induced vasospasm and early brain injury in experimental rats. 32 Ninety-six Sprague-Dawley male rats were randomly and evenly divided into a control 33 group (no SAH, sham surgery), a SAH only group, a SAH + NC-mimic group, and a SAH + 34 miR-195-5p group. SAH was induced using a single injection of blood into the cisterna magna. 35 Suspensions containing NC-mimic and miR-195-5p were intravenously injected into rat tail 30 36 mins after SAH was induced. We determined degree of vasospasm by averaging areas of cross-37 sections the basilar artery 24h after SAH. We measured basilar artery endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), nuclear factor kappa-light-chain-39 enhancer of activated B cells (NF- κ B), phosphorylated NF- κ B (p-NF- κ B), inhibitor of NF- κ B and phosphorylated-I κBα (p-I κBα). Cell death assay was used to quantify the DNA fragmentation, an indicator of apoptotic cell death, in the cortex, hippocampus, and dentate gyrus. were using sample protein obtained