Dihydrocapsaicin (DHC) enhances the hypothermia-induced neuroprotection following ischemic stroke via PI3K/Akt regulation in rat

• Published in: Brain research 2017-09, Vol.1671, p.18-25
• Main Authors: Wu, Di, Shi, Jingfei, Elmadhoun, Omar, Duan, Yunxia, An, Hong, Zhang, Jun, He, Xiaoduo, Meng, Ran, Liu, Xiangrong, Ji, Xunming, Ding, Yuchuan
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis - drug effects; Apoptotic cell death; Body Temperature; Brain Injuries - drug therapy; Brain Ischemia - drug therapy; Capsaicin - analogs & derivatives; Capsaicin - metabolism; Capsaicin - pharmacology; Hypothermia - metabolism; Hypothermia, Induced - methods; Infarction, Middle Cerebral Artery - drug therapy; Infusions, Intra-Arterial - methods; Intra-arterial cold infusions (IACIs); Ischemia/reperfusion injury; Ischemic Attack, Transient - drug therapy; Male; Middle cerebral artery; Neuroprotection - drug effects; Neuroprotective Agents - metabolism; Pharmacological hypothermia; Phosphatidylinositol 3-Kinases - drug effects; Phosphatidylinositol 3-Kinases - metabolism; Proto-Oncogene Proteins c-akt - drug effects; Proto-Oncogene Proteins c-akt - metabolism; Rats; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury - drug therapy; Stroke - drug therapy
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2017.06.029

•We investigated the neuroprotective effects of pharmacological hypothermia and local hypothermia in rat MCAO models.•The combination of the above methods enhances the efficiency of hypothermia.•The combination of the above methods enhances efficacy of hypothermia-induced neuroprotection following ischemic stroke.•PI3K/Akt apoptotic pathway is a possible mechanism for the combination therapy. Hypothermia has demonstrated neuroprotection following ischemia in preclinical studies while its clinical application is still very limited. The aim of this study was to explore whether combining local hypothermia in ischemic territory achieved by intra-arterial cold infusions (IACIs) with pharmacologically induced hypothermia enhances therapeutic outcomes, as well as the underlying mechanism. Sprague-Dawley rats were subjected to right middle cerebral artery occlusion (MCAO) for 2h using intraluminal hollow filament. The ischemic rats were randomized to receive: 1) pharmacological hypothermia by intraperitoneal (i.p.) injection of dihydrocapsaicin (DHC); 2) physical hypothermia by IACIs for 10min; or 3) the combined treatments. Extent of brain injury was determined by neurological deficit, infarct volume, and apoptotic cell death at 24h and/or 7d following reperfusion. ATP and ROS levels were measured. Expression of p-Akt, cleaved Caspase-3, pro-apoptotic (AIF, Bax) and anti-apoptotic proteins (Bcl-2, Bcl-xL) was evaluated at 24h. Finally, PI3K inhibitor was used to determine the effect of p-Akt. DHC or IACIs each exhibited hypothermic effect and neuroprotection in rat MCAO models. The combination of pharmacological and physical approaches led to a faster and sustained reduction in brain temperatures and improved ischemia-induced injury than either alone (P