Levosimendan limits reperfusion injury in a rat middle cerebral artery occlusion (MCAO) model

Abstract

Background: Neuroprotective strategies in ischemic stroke are an important challenge in clinical and experimental research as an adjunct to reperfusion therapy that may reduce neurologic injury and improve outcome. The neuroprotective properties of levosimendan in traumatic brain injury in vitro, transient global brain ischemia and focal spinal cord ischemia suggest the potential for similar effects in transient brain ischemia.

Methods: Transient brain ischemia was induced for 60 min by intraluminal occlusion of the middle cerebral artery in 40 male Wistar rats under general anesthesia with s-ketamine and xylazine and with continuous monitoring of their blood pressure and cerebral perfusion. Five minutes before inducing reperfusion, a levosimendan bolus (24 μg kg -1) was administered over a 20 minute period. Infarct size, brain swelling, neurological function and the expression of inflammatory markers were quantified 24 hours after reperfusion.

Results: Although levosimendan limited the infarct size and brain swelling by 40% and 53%, respectively, no effect on neurological outcome or mortality could be demonstrated. Upregulation of tumor necrosis factor α and intercellular adhesion molecule 1 was significantly impeded. Cerebral blood flow during reperfusion was significantly reduced as a consequence of sustained autoregulation.

Conclusions: Levosimendan demonstrated significant neuroprotective properties in a rat model of transient brain ischemia by reducing reperfusion injury.

Figure 1

Flow of animals related to stage of experiment.

Figure 2

Effects of transient cerebral ischemia and reperfusion on hemodynamics. Changes of heart rate (A, HR) mean arterial pressure (B, MAP) and cerebral blood flow (C, CBF) are displayed. Levosimendan infusion over 20 min was started at 5 min before reperfusion (p values from variance analysis for repeated measurements and post hoc test: * p < 0.05 vs. control).

Figure 3

Effects of levosimendan treatment on the autoregulatory index. Values after transient MCAO (reperfusion) were compared to values before ischemia (baseline) (*** p < 0.001 vs. levosimendan).

Figure 4

Effect of levosimendan on cerebral infarct size. Differences between infarct volume of the striatal and cortical parts of each slice were illustrated (A). A representative slice (slice number 3) after staining with triphenyltetrazolium chloride from a control animal (B) and a levosimendan-treated animal (C). The arrows indicate sites of infarct size reduction (* p < 0.05 from analysis of variance for repeated measurements).

Figure 5

Additional effects of levosimendan treatment on neurological injury during MCAO. Differences between groups for brain swelling (A), serum levels of s-100ß (B) and neurological testing (C) after 24 hours were displayed (* p <0.05 vs. control; ** p < 0.01 vs. control).

Figure 6

Relative expression of inflammatory markers in the cortical penumbra at 24 hours after MCAO (* p < 0.05 vs. control; ^# p < 0.05 vs. RQ = 1).