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The Role of κ Opioid Receptor in Brain Ischemia
Journal article   Open access   Peer reviewed

The Role of κ Opioid Receptor in Brain Ischemia

Chunhua Chen, Chunhua Xi, Xuan Liang, Jingyuan Ma, Diansan Su, Ted Abel and Renyu Liu
Critical care medicine, Vol.44(12), pp.e1219-e1225
12/2016
DOI: 10.1097/CCM.0000000000001959
PMCID: PMC5203937
PMID: 27495821
url
http://doi.org/10.1097/CCM.0000000000001959View
Open Access

Abstract

Our previous studies indicated that highly selective κ opioid receptor agonists could protect the brain, indicating an important role of κ opioid receptor agonist in brain ischemia. In this study, we investigated the role and related mechanisms of κ opioid receptor agonists in brain ischemia in a middle cerebral artery occlusion mouse model. Animal model. Laboratory. The middle cerebral artery occlusion model was established by 120 minutes of ischemia followed by 24-hour reperfusion in male adult mice. Various doses of salvinorin A, a highly selective and potent κ opioid receptor agonist, were administered intranasally 10 minutes after initiation of reperfusion. Norbinaltorphimine (2.5 mg/kg, IP) as a κ opioid receptor antagonist was administered in one group before administration of salvinorin A (50μg/kg) to investigate the specific role of κ opioid receptor. Infarct volume, κ opioid receptor expression, and Evans blue extravasation in the brain, and neurobehavioral outcome were determined. Immunohistochemistry and western blot were performed to detect the activated caspase-3, interleukin-10, and tumor necrosis factor-α levels to investigate the role of apoptosis and inflammation. κ opioid receptor expression was elevated significantly in the ischemic penumbral area compared with that in the nonischemic area. Salvinorin A reduced infarct volume and improved neurologic deficits dose-dependently. Salvinorin A at the dose of 50 μg/kg reduced Evans blue extravasation, suggesting reduced impairment of the blood-brain barrier and decreased the expression of cleaved caspase-3, interleukin-10, and tumor necrosis factor-α in the penumbral areas. All these changes were blocked or alleviated by norbinaltorphimine. κ opioid receptors were up-regulated and played a critical role in brain ischemia and reperfusion. κ opioid receptor activation could potentially protect the brain and improve neurologic outcome via blood-brain barrier protection, apoptosis reduction, and inflammation inhibition.
Naltrexone - analogs & derivatives Receptors, Opioid, kappa - antagonists & inhibitors Apoptosis - drug effects Mice, Inbred C57BL Receptors, Opioid, kappa - agonists Brain Ischemia - metabolism Male Brain Ischemia - physiopathology Blotting, Western Receptors, Opioid, kappa - physiology Naltrexone - pharmacology Animals Reperfusion Injury - prevention & control Brain Ischemia - drug therapy Diterpenes, Clerodane - pharmacology Mice Disease Models, Animal

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