Protective effects of nicorandil against cerebral injury in a swine cardiac arrest model

Mechanism of action and neuroprotective role of nicorandil in ischemic stroke

Nicorandil is a dual mechanism anti-anginal agent that acts as a nitric oxide (NO) donor and a potassium (K+) channel opener. Recent studies have evaluated the effect of nicorandil on ischemic stroke. Neurons have a low tolerance to hypoxia and therefore the brain tissue is significantly vulnerable to ischemia. Current approved treatments for ischemic stroke are tissue plasminogen activators and clot retrieval methods. The narrow therapeutic time window and lack of efficacy in restoring the dying neurons urge researchers to develop an alternative approach. In the terminal stages of anoxia, K+ channels induce hyperpolarization in various types of neuronal cells, leading to decreased neuronal activity and the preservation of the brain's energy. Nicorandil can open these K+ channels and sustain the hyperpolarization phase, which may have a neuroprotective effect during hypoxia. Additionally, we review how nicorandil can improve overall stroke outcomes through its anti-inflammatory, anti-oxidative, and edema-reducing effects. One of the major components evaluated in stroke patients is blood pressure. Studies have demonstrated that the effect of nicorandil on blood pressure is related to both its K+ channel opening and NO donating mechanisms. Since both hypertension and hypotension need correction before stroke intervention, it's crucial to consider the role of nicorandil and its impact on blood pressure. Previously published studies indicate that the right dosage of nicorandil can improve cerebral blood flow without significant changes in hemodynamic profiles. In this review, we discuss how nicorandil may contribute to better stroke outcomes based on previously published literature and laboratory findings.

Cardiac Arrest Induced by Asphyxia Versus Ventricular Fibrillation Elicits Comparable Early Changes in Cytokine Levels in the Rat Brain, Heart, and Serum

Background

Current postresuscitative care after cardiac arrest (CA) does not address the cause of CA. We previously reported that asphyxial CA (ACA) and ventricular fibrillation CA (VFCA) elicit unique injury signatures. We hypothesized that the early cytokine profiles of the serum, heart, and brain differ in response to ACA versus VFCA.

Methods and Results

Adult male rats were subjected to 10 minutes of either ACA or VFCA. Naives and shams (anesthesia and surgery without CA) served as controls (n=12/group). Asphyxiation produced an ≈4‐minute period of progressive hypoxemia followed by a no‐flow duration of ≈6±1 minute. Ventricular fibrillation immediately induced no flow. Return of spontaneous circulation was achieved earlier after ACA compared with VFCA (42±18 versus 105±22 seconds; P<0.001). Brain cytokines in naives were, in general, low or undetectable. Shams exhibited a modest effect on select cytokines. Both ACA and VFCA resulted in robust cytokine responses in serum, heart, and brain at 3 hours. Significant regional differences pinpointed the striatum as a key location of neuroinflammation. No significant differences in cytokines, neuron‐specific enolase, S100b, and troponin T were observed across CA models.

Conclusions

Both models of CA resulted in marked systemic, heart, and brain cytokine responses, with similar degrees of change across the 2 CA insults. Changes in cytokine levels after CA were most pronounced in the striatum compared with other brain regions. These collective observations suggest that the amplitude of the changes in cytokine levels after ACA versus VFCA may not mediate the differences in secondary injuries between these 2 CA phenotypes.

The KATP channel opener, nicorandil, ameliorates brain damage by modulating synaptogenesis after ischemic stroke

With population growth and aging, more and more patients with cerebral infarction have varying degrees of disability. ATP-sensitive potassium (KATP) channels regulate many cellular functions by coupling metabolic status with cell membrane electrical activity. Nicorandil (N-(2-hydroxyethyl)-nicotinamide nitrate) is the first KATP channel opener approved for clinical use. It has been reported that it might exert protective effects on the cerebral infarction by increasing cerebral blood flow and reducing inflammation. However, only a few studies explored its role in synaptogenesis. We made the rat model of middle cerebral artery occlusion (MCAO). Nicorandil was administered to rats via oral administration immediately after the surgery at a dose of 7.5 mg/kg and then daily for the next days. Infarct volume, cerebral edema, neurological deficits, cognitive impairment, and the level of Synaptophysin (SYP)、Growth associated protein-43 (GAP43) and neuronal nuclear antigen (NeuN) levels were measured to evaluate the effect of nicorandil. Our data showed that nicorandil treatment could decrease brain damage, improve learning and memory, and increase SYP、GAP43 and NeuN level. Taken together, we propose that nicorandil, as an opener of the KATP channel, provides a neuroprotective role in MCAO by promoting synaptic connections.

Impact of intracoronary nicorandil before stent deployment in patients with acute coronary syndrome undergoing percutaneous coronary intervention

The present study aimed to clarify the effect of bolus intracoronary nicorandil on inflammatory, oxidative and adherent indicators in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). This randomized controlled trial (RCT) was performed to detect the inflammation and oxidative stress in intracoronary blood both before and after PCI. In total, 65 consecutive patients undergoing PCI were classified into a nicorandil therapy group (n=32) or a placebo group (n=33). All procedures were performed at Shandong University Qilu Hospital, China, during the period from March, 2016 to May, 2017. Intracoronary blood from patients who received nicorandil therapy during PCI showed no change in soluble CD40 ligand (sCD40L) concentration (1.86±0.08 vs. 1.90±0.09 ng/ml, P=0.12) but a significant increase was noted in the control group (1.87±0.17 vs. 2.82±0.26 ng/ml, P<0.01). This indicated a relative reduction in sCD40L level after PCI in the nicorandil group. We further demonstrated an increase in superoxide dismutase (SOD) activity (29.37±0.81 vs. 31.03±0.60 U/ml, P<0.001) and a reduction in lipid peroxidation (3.84±0.99 vs. 4.23±0.13 U/ml, P=0.001) in the nicorandil group but observed no change in the placebo group. ICAM-1 levels showed no change in the nicorandil group (69.54±6.89 vs. 72.01±8.25 ng/ml, P=0.83) but a significant increase in the control group after PCI in intracoronary blood (56.57±4.96 vs. 76.81±6.88 ng/ml, P=0.002). No changes were found in hs-CRP, TNFα and sVCAM-1 levels in coronary blood for both groups before and after PCI in ACS patients. Our findings demonstrate that intracoronary bolus nicorandil therapy has a significant effect on the inhibition of inflammatory indicators and oxidative stress in patients with ACS during PCI. This suggests a possible medical application of nicorandil for reducing inflammation and oxidative stress.