Department of Neurology, Henry Ford Hospital, Detroit, MI 48202, United States.
J Neurol Sci. 2011 Oct 15;309(1-2):96-101. doi: 10.1016/j.jns.2011.07.008. Epub 2011 Jul 29.
Niaspan, an extended-release formulation of niacin (vitamin B3), has been widely used to increase high density lipoprotein (HDL) cholesterol and to prevent cardiovascular diseases and stroke. We have previously demonstrated that Niaspan (40 mg/kg) administered at 2h after stroke induces neuroprotection, while low dose Niaspan (20mg/kg) does not reduce infarct volume. Tissue plasminogen activator (tPA) is an effective therapy for acute stroke, but its use remains limited by a narrow therapeutic window. We have previously demonstrated that intravenous administration of tPA 4h after stroke in rats does not reduce infarct volume. In this study, we tested whether combination treatment with low-dose Niaspan (20mg/kg) and tPA administered 4h after embolic stroke in a rat model reduces infarct volume and provides neuroprotection.
Adult male Wistar rats were subjected to embolic middle cerebral artery occlusion (MCAo) and treated with low-dose Niaspan (20mg/kg) alone (n = 7), tPA (10mg/kg) alone (n = 7), combination of low-dose Niaspan and tPA (n = 7), or saline control (n = 9), 4h after stroke. A battery of functional outcome tests was performed. Rats were sacrificed at 7 days after MCAo and lesion volumes were measured. To investigate the underlying mechanism of combination treatment neuroprotective effect, deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), cleaved caspase-3, tumor necrosis factor alpha (TNF-alpha), and toll-like receptor 4 (TLR-4) immunostaining were performed.
Combination treatment with low-dose Niaspan and tPA significantly improved functional outcome compared to the saline control group (p<0.05), while treatment with Niaspan or tPA alone did not significantly improve functional outcome compared to saline control group. Additionally, combination treatment significantly reduced infarct volume compared to saline control group (p = 0.006) and infarct volume was significantly correlated with functional outcome (p = 0.0008; r = 0.63). Monotherapy with Niaspan or tPA did not significantly decrease infarct volume compared to saline control group. Combination treatment reduced apoptosis as measured by significant reduction in the number of TUNEL-positive cells and cleaved caspase-3 expression in the ischemic brain compared to saline control group (p<0.05). Combination treatment also significantly reduced the expression of TNF-alpha and TLR-4 in the ischemic brain compared to Niaspan, tPA and saline treatment groups (p<0.05). A significant interaction between Niaspan and tPA on the TNF-alpha expression was detected (p<0.05), indicating a synergy effect in the combination treatment group.
Treatment of stroke with combination of low-dose Niaspan and tPA at 4h after embolic stroke reduces infarct volume, improves neurological outcome and provides neuroprotection. The neuroprotective effects of combination treatment were associated with reduction of apoptosis and attenuation of TNF-alpha and TLR-4 expression.
烟酸（维生素 B3）的缓释制剂尼可司汀（Niaspan）已被广泛用于提高高密度脂蛋白（HDL）胆固醇水平，预防心血管疾病和中风。我们之前的研究表明，中风后 2 小时给予尼可司汀（40mg/kg）可诱导神经保护，而低剂量尼可司汀（20mg/kg）则不能减少梗死体积。组织型纤溶酶原激活物（tPA）是急性中风的有效治疗方法，但由于治疗窗口狭窄，其应用仍然受到限制。我们之前的研究表明，在大鼠中风后 4 小时给予静脉内 tPA 不能减少梗死体积。在这项研究中，我们测试了在栓塞性大脑中动脉闭塞（MCAo）大鼠模型中，低剂量尼可司汀（20mg/kg）与 tPA 联合治疗是否可以减少梗死体积并提供神经保护。
成年雄性 Wistar 大鼠接受栓塞性大脑中动脉闭塞（MCAo）并接受低剂量尼可司汀（20mg/kg）单独治疗（n = 7）、tPA（10mg/kg）单独治疗（n = 7）、低剂量尼可司汀与 tPA 联合治疗（n = 7）或生理盐水对照治疗（n = 9），在中风后 4 小时。进行了一系列功能预后测试。大鼠在 MCAo 后 7 天处死，并测量病变体积。为了研究联合治疗神经保护作用的潜在机制，进行了脱氧核苷酸转移酶介导的 dUTP 缺口末端标记（TUNEL）、cleaved caspase-3、肿瘤坏死因子-α（TNF-α）和 Toll 样受体 4（TLR-4）免疫染色。
与生理盐水对照组相比，低剂量尼可司汀和 tPA 的联合治疗显著改善了功能预后（p<0.05），而尼可司汀或 tPA 单独治疗与生理盐水对照组相比，功能预后没有显著改善。此外，与生理盐水对照组相比，联合治疗显著减少了梗死体积（p = 0.006），梗死体积与功能预后显著相关（p = 0.0008；r = 0.63）。与生理盐水对照组相比，尼可司汀或 tPA 单独治疗并未显著减少梗死体积。与尼可司汀、tPA 和生理盐水治疗组相比，联合治疗显著减少了缺血大脑中的 TUNEL 阳性细胞数量和 cleaved caspase-3 表达，从而减少了细胞凋亡（p<0.05）。与尼可司汀、tPA 和生理盐水治疗组相比，联合治疗还显著降低了缺血大脑中的 TNF-α和 TLR-4 表达（p<0.05）。在 TNF-α表达方面检测到尼可司汀和 tPA 之间存在显著的相互作用（p<0.05），表明联合治疗组存在协同作用。
在栓塞性中风后 4 小时给予低剂量尼可司汀和 tPA 联合治疗可减少梗死体积、改善神经功能预后并提供神经保护。联合治疗的神经保护作用与细胞凋亡减少以及 TNF-α和 TLR-4 表达减弱有关。
