Effects of statins on ischemic stroke: neuroprotection and/or triggering of apoptotic damage?

Hyperlipidemia and statins affect neurological outcome in lumbar spine injury

The disabling pathophysiologic effects of lipid and neuroprotective effects of statins have recently been demonstrated for acute spinal cord injuries in animal models. This large scale population-based study aimed to investigate the effect hyperlipidemia and the use of statins in patients with lumbar spine injury. The National Health Insurance Research Database of Taiwan was used to identify patients with lumbar spine injury. A total of 2844 patients were grouped into three: no hyperlipidemia, hyperlipidemia using low-dose of statins (≤90 of the defined daily dosage (DDD)), and severe hyperlipidemia using high-dose of statins (>90 DDD). A Cox multiple regression model was used to compare the incidence rates of disability among the three groups. The results showed that patients with hyperlipidemia appeared a higher risk of permanent disability (adjusted HR = 1.38, p = 0.28). In subgroup analysis, patients with severe hyperlipidemia had a higher risk of disability (adjusted HR = 3.1, p < 0.004), whereas hyperlipidemia using low-dose statins had a similar risk of permanently disability (adjusted HR = 0.83, p = 0.661). Hyperlipidemia adversely affected the neurological outcomes of lumbar spinal injury. Statins may have the potential to reverse this higher risk of disability. However, this beneficiary effect of statins only existed in patients using a lower dose (≤90 DDD).

Neuroprotective effect of atorvastatin in spinal cord ischemia-reperfusion injury

OBJECTIVES

Prevention of the development of paraplegia during the repair of the damage caused by descending thoracic and thoracoabdominal aneurysms remains an important issue. Therefore, we investigated the protective effect of atorvastatin on ischemia-induced spinal cord injury in a rabbit model.

METHOD

Thirty-two rabbits were divided into the following four equally sized groups: group I (control), group II (ischemia-reperfusion), group III (atorvastatin treatment) and group IV (atorvastatin withdrawal). Spinal cord ischemia was induced by clamping the aorta both below the left renal artery and above the iliac bifurcation. Seventy-two hours postoperatively, the motor function of the lower limbs of each animal was evaluated according to the Tarlov score. Spinal cord and blood samples were obtained for histopathological and biochemical analyses.

RESULTS

All of the rabbits in group II exhibited severe neurological deficits. Atorvastatin treatment (groups III and IV) significantly reduced the level of motor dysfunction. No significant differences were observed between the motor function scores of groups III and IV at the evaluated time points. Light microscopic examination of spinal cord tissue samples obtained at the 72nd hour of reperfusion indicated greater tissue preservation in groups III and IV than in group II.

CONCLUSION

This study demonstrates the considerable neuroprotective effect of atorvastatin on the neurological, biochemical and histopathological status of rabbits with ischemia-induced spinal cord injury. Moreover, the acute withdrawal of atorvastatin therapy following the induction of spinal cord ischemia did not increase the neuronal damage in this rabbit model.

Simvastatin reduced ischemic brain injury and perfusion deficits in an embolic model of stroke

Simvastatin is cholesterol lowering agent and also a modulator of cytokine in the nervous system. The functional significance and neuroprotectiove mechanism of simvastatins in ischemic brain injury is controversial. The purpose of study is to evaluate the effect of simvastatin on ischemic brain injury and to investigate the perfusion capability of brain microvessels in the ischemic injury. This study included two series of experiments. In the first series, we studied if simvastatin is neuroprotective in an embolic model of stroke. The treatments began 2 weeks before middle cerebral artery (MCA) occlusion. Infarct volume was measured at 48 h post stroke. Neurological deficits were assessed at 2 h, 24 h and 48 h post stroke. Results showed that infarct volume in rats which received saline and simvastatin was 32.5 +/- 9.3% (mean +/- SD) and 18.7 +/- 6.5%, respectively. The infarct volume in the simvastatin group was significantly smaller than in the controls (P < 0.002). Treatment with simvastatin also improved neurological deficits and reduced brain edema significantly (P < 0.05). In the second series, we studied if simvastatin can improve microvascular reperfusions after ischemia. Perfusion deficits were detected at 8 h post stroke using Evens blue dye. Neurological deficits were assessed at 2 h and 8 h post stroke. Results showed that perfusion deficit in saline and simvastatin-treated groups were 58.7 +/- 8.7% and 23.4 +/- 7.5%, respectively. The perfusion deficit in simvastatin-treated group was decreased 61% (P < 0.01). These studies thus suggest that simvastatin is a protective agent in ischemic brain injury and this protective effect may be partially due to its action in the improvement of microvascular reperfusion.

Use of statins in CNS disorders

It is well established that 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors ("statins") reduce cholesterol levels and prevent coronary heart disease (CHD). Although a causal relation between elevated cholesterol levels and stroke has not been well defined, a number of large secondary prevention studies and meta-analyses have shown that statin therapy reduces stroke in patients with CHD and hypercholesterolemia. In addition to the vascular effects of statins (stabilization of atherosclerotic plaques, decreased carotid intimal-medial thickness), there are increasing data to suggest that these agents have additional properties that are potentially neuroprotective. These include endothelial protection via actions on the nitric oxide synthase system, as well as antioxidant, anti-inflammatory and anti-platelet effects. These actions of statins might have potential uses in other neurological disorders such as Alzheimer's disease and certain types of brain tumors.