Treatment of acute focal cerebral ischemia with propranolol

Increased Renal Dysfunction, Apoptosis, and Fibrogenesis Through Sympathetic Hyperactivity After Focal Cerebral Infarction

Sympathetic nervous system plays an important role in secondary injury of diseases. Accumulating evidence has observed association between ischemic stroke and renal dysfunction, but the mechanisms are incompletely clear. In this study, we investigated whether sympathetic hyperactivity can cause the development of renal dysfunction, apoptosis, and fibrogenesis after focal cerebral infarction. To determine the renal consequences of focal cerebral ischemia, we subjected a mice model of transient middle cerebral artery occlusion (tMCAO) and examined systolic blood pressure, heart rate, renal structure and function, serum catecholamine, and cortisol levels, and the expression of active caspase-3 bcl-2, bax, and phosphorylated p38 MAPK after 8 weeks. We also analyzed the relationship between insular cortex infarction and acute kidney injury (AKI) in 172 acute anterior circulation ischemic stroke (ACIS) patients. Transient right middle cerebral artery occlusion induced sympathetic hyperactivity, renal dysfunction, upregulation of apoptosis, and fibrogenesis in kidneys of mice. Metoprolol treatment relieves the development of renal injury. Study in stroke patients demonstrated that insular cortex infarction, especially the right insular cortex infarction, is an independent risk factor of AKI. Focal cerebral ischemia in mice leads to the development of renal injury driven by sympathetic hyperactivity. Right insular cortex infarction is an independent risk factor of AKI in older patients. Understanding the brain-kidney interaction after stroke would have clinical implications for the treatment and overall patient outcome.

Analytic Review: Ischemic Cerebrovascular Disease: Diagnosis and Management

Ischemic stroke is the most common cause of neurologic morbidity and mortality. The proper management of a stroke patient is dictated by the underlying pathophysiology. An ischemic stroke may occur as a result of restricted flow or thrombosis from atherosclerosis, artery-to-artery embolization, cardiac-to-brain embolization, or disorders of coagulation, to mention a few of the most common causes. Determining the relevant cause of stroke is made more difficult by the coexistence of many possible factors such as hypertension, atherosclerosis, and cardiac disease. Nevertheless, judgments are based on the clinical presentation, computed tomographic scans, cerebral angiograms, and results of echocardiography and electrocardiographic monitoring.

Therapy of the ischemic stroke patient is aimed primarily at preserving areas of potentially recoverable ischemic brain. This is accomplished by correcting or avoiding circumstances that can promote further impairment of ischemic brain. These include proper management of blood pressure, cardiac function, oxygenation, and fluid balance. The role of anticoagulation, hemodilution therapy, and other proposed forms of therapy is often unclear.

Autonomic dysfunction in acute ischemic stroke: an underexplored therapeutic area?

Impaired autonomic function, characterized by a predominance of sympathetic activity, is common in patients with acute ischemic stroke. This review describes methods to measure autonomic dysfunction in stroke patients. It summarizes a potential relationship between ischemic stroke-associated autonomic dysfunction and factors that have been associated with worse outcome, including cardiac complications, blood pressure variability changes, hyperglycemia, immune depression, sleep disordered breathing, thrombotic effects, and malignant edema. Involvement of the insular cortex has been suspected to play an important role in causing sympathovagal imbalance, but its exact role and that of other brain regions remain unclear. Although sympathetic overactivity in patients with ischemic stroke appears to be a negative prognostic factor, it remains to be seen whether therapeutic strategies that reduce sympathetic activity or increase parasympathetic activity might improve outcome.

Long-term and spatial memory effects of selective β1-antagonists after transient focal ischaemia in rats

BACKGROUND

Although various reports have shown that β-antagonists provide neuroprotective effects after cerebral ischaemia, their effect on spatial memory after transient focal ischaemia is not known. We investigated the treatment of β1-antagonists on neurological outcome spatial memory for 1 month after focal cerebral ischaemia in rats.

METHODS

Male rats randomly received an i.v. infusion of saline 0.5 ml h(-1), esmolol 200 μg kg(-1) min(-1), or landiolol 50 μg kg(-1) min(-1). Infusion was initiated 30 min before middle cerebral artery occlusion and continued for 24 h. The infarct areas in the hippocampus and striatum were measured after the final retention trial and neurological examinations.

RESULTS

Neurological deficit scores in the landiolol- and esmolol-treated rats were significantly lower than in the control rats at 1, 4, 7, and 11 days after ischaemia (P<0.05). Using the Morris water maze to assess spatial memory, we found that escape latency and swimming path length to the platform were significantly shorter in the landiolol-treated rats, compared with the saline-treated rats at 4 and 11 days after ischaemia (P<0.05). The mean (SD) infarct area was 19.1 (8.0)% in the striatum and 18.6 (10.0)% in the hippocampus of the landiolol-treated rats, and 16.8 (14.0)% and 16.8 (15.0)% in the striatum and hippocampus, respectively, of esmolol-treated rats. This was significantly less than in control rats [striatum 31.7 (14.0)% and hippocampus 29.8 (13.0)%, P<0.05].

CONCLUSIONS

The current study indicates that although esmolol and landiolol provided long-term neuroprotection in terms of histological outcome, they had no effect on neurological outcome and spatial memory retention.

Neuroprotective effects of selective β-1 adrenoceptor antagonists, landiolol and esmolol, on transient forebrain ischemia in rats; a dose-response study

Although selective beta-1 adrenoceptor antagonists are known to provide neuroprotective effects after brain ischemia, dose-response relationships of their neuroprotective effects have not been examined. The present study was conducted to evaluate whether the degree of brain protection against transient forebrain ischemia would be influenced by different doses of selective beta-1 adrenoceptor antagonists, esmolol and landiolol, in rats. Adult male S.D. rats received intravenous infusion of saline 0.5 ml/h, esmolol 20, 200, 2,000 μg/kg/min, or landiolol 5, 50, 500 μg/kg/min. Infusion was initiated 30 min prior to ischemia and continued for 24h. Ten-minute forebrain ischemia was induced by hemorrhagic hypotension and occlusion of the bilateral carotid arteries. Neurological and histological examinations were performed. Neurological deficit scores at 1, 4 and 7 days were lower, and the number of intact neurons in CA1 hippocampal region was larger in the rats treated with esmolol and landiolol after ischemia, compared with saline-treated rats (P<0.05), whereas no difference was found among different doses of esmolol and landiolol. These results suggested that selective beta-1 adrenoceptor antagonists improved neurological and histological outcomes following forebrain ischemia in rats, irrespective of their doses.

Pre-stroke use of beta-blockers does not affect ischaemic stroke severity and outcome

BACKGROUND AND PURPOSE

It is unclear whether pre-stroke beta-blockers use may influence stroke outcome. This study evaluates the independent effect of pre-stroke use of beta-blockers on ischaemic stroke severity and 3 months functional outcome.

METHODS

Pre-stroke use of beta-blockers was investigated in 1375 ischaemic stroke patients who had been included in two placebo-controlled trials with lubeluzole. Stroke severity was assessed by either the National Institute of Health Stroke Scale (NIHSS) or the European Stroke Scale (ESS). A modified Rankin scale (mRS) score of >3 at 3 months was used as measure for the poor functional outcome.

RESULTS

Two hundred and sixty four patients were on beta-blockers prior to stroke onset, and 105 patients continued treatment after their stroke. Pretreatment with beta-blockers did not influence baseline stroke severity. There was no difference in stroke severity between nonusers and those on either a selective beta(1)-blocker or a non-selective beta-blocker. The likelihood of a poor outcome at 3 months was not influenced by pre-stroke beta-blocker use or beta-blocker use before and continued after stroke onset.

CONCLUSIONS

  Pre-stroke use of beta-blockers does not appear to influence stroke severity and functional outcome at 3 months.

Posttreatment but not pretreatment with selective beta-adrenoreceptor 1 antagonists provides neuroprotection in the hippocampus in rats subjected to transient forebrain ischemia

BACKGROUND

beta-Adrenoreceptor antagonists provide neuroprotection against focal cerebral ischemia, but the effects of these antagonists on experimental global cerebral ischemia are unknown. That is, the effect of beta-adrenoreceptor antagonism in vulnerable brain regions after ischemic insult has not been examined. Therefore, we investigated the neuroprotective effects of preischemic or postischemic administration of propranolol (a nonselective beta-adrenoreceptor antagonist), esmolol, and landiolol (selective beta-adrenoreceptor 1 antagonists) against forebrain ischemia in rats.

METHODS

IV administration of saline 10 microL . h(-1), propranolol 100 microg . kg(-1) . min(-1), esmolol 200 microg . kg(-1) . min(-1), or landiolol 50 microg . kg(-1) . min(-1) in male Sprague-Dawley rats was started 30 minutes before or 60 minutes after 8-minute bilateral carotid artery occlusion combined with hypotension (35 mm Hg) under isoflurane (1.5%) anesthesia. All drugs were administered continuously until 5 days after reperfusion, and the animals were evaluated neurologically and histologically after this 5-day period.

RESULTS

Preischemic treatment with propranolol, esmolol, or landiolol failed to provide neuroprotection against forebrain ischemia in the hippocampus. Rats treated with propranolol tended to have a worse score for motor activity and a higher mortality rate (up to 64%), but the differences with other groups were not statistically significant. Postischemic treatment with esmolol and landiolol, but not with propranolol, reduced neuronal injury after forebrain ischemia. However, motor activity did not differ among rats treated postischemically with any of the beta-adrenoreceptor antagonists or saline.

CONCLUSIONS

Postischemic treatment with esmolol and landiolol provided neuroprotection in the hippocampus in rats subjected to bilateral carotid artery occlusion combined with hemorrhagic shock, whereas treatment with propranolol failed to show neuroprotection. We suggest that concomitant beta-blockade and shock might work as a systemic depressant, rather than a neuroprotectant, resulting in exacerbation of cerebral ischemia.

Postischemic brain injury is attenuated in mice lacking the beta2-adrenergic receptor

BACKGROUND

Several beta-adrenergic receptor (betaAR) antagonists have been shown to have neuroprotective effects against cerebral ischemia. However, clenbuterol, a beta(2)AR agonist, was shown to have neuroprotective activity by increasing nerve growth factor expression. We used beta(2)AR knockout mice and a beta(2) selective antagonist to test the effect of loss of beta(2)ARs on outcome from transient focal cerebral ischemia.

METHODS

Ischemia was induced by the intraluminal suture method, for 60 min of middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. Neurological score was determined at 24 h reperfusion and infarct size was determined by cresyl violet or 2,3,5-triphenyltetrazolium chloride staining. beta(2)AR knockout mice and wild-type congenic FVB/N controls were studied, as well as 2 groups of wild type mice given either ICI 118,551 (0.2 mg/kg) or 0.9% saline intraperitoneally 30 min before MCAO (n = 10 per group). Changes in expression of heat shock protein (Hsp)72 after ischemia were examined by immunohistochemistry and western blots.

RESULTS

Compared with wild type littermates, infarct volume was decreased by 22.3% in beta(2)AR knockout mice (39.7 +/- 10.7 mm(3) vs 51.0 +/- 11.4 mm(3), n = 10/group, P = 0.034) after 60 min of MCAO followed by 24 h reperfusion. Pretreatment with a beta(2)AR selective antagonist, ICI 118,551, also decreased infarct size significantly, by 25.1%, compared with the saline control (32.8 +/- 11.9 mm(3) vs 43.8 +/- 10.3 mm(3), n = 10/group, P = 0.041). Neurological scores were also significantly improved in mice lacking the beta(2)AR or pretreated with ICI 118,551. After cerebral ischemia, total levels of Hsp72 and the number of Hsp72 immunopositive cells were greater in mice lacking beta(2) AR.

CONCLUSION

Brain injury is reduced and neurological outcome improved after MCAO in mice lacking the beta(2)AR, or in wild type mice pretreated with a selective beta(2)AR antagonist. This is consistent with a shift away from prosurvival signaling to prodeath signaling in the presence of beta(2)AR activation in cerebral ischemia. Protection is associated with higher levels of Hsp72, a known antideath protein. The effect of beta(2)AR signaling in the setting of cerebral ischemia is complex and warrants further study.

Beta-adrenoreceptor antagonists attenuate brain injury after transient focal ischemia in rats

Beta-adrenoreceptor antagonists experimentally reduce cardiac and renal injury after ischemia and are also clinically useful for myocardial infarction and severe burns. In addition, beta-adrenoreceptor antagonists provide neuroprotective effects after focal cerebral ischemia in experimental settings. We conducted the present study to compare the neuroprotective effects of several beta-adrenoreceptor antagonists in rat transient focal cerebral ischemia. Halothane-anesthetized normothermic adult male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion using the intraluminal suture technique confirmed by laser Doppler flowmetry. Rats received an IV infusion of saline 0.5 mL/h, propranolol 100 microg x kg(-1) x min(-1), carvedilol 4 microg x kg(-1) x min(-1), esmolol 200 microg x kg(-1) x min(-1), or landiolol 50 microg x kg(-1) x min(-1) (n = 6 in each group). Infusion was initiated 30 min before middle cerebral artery occlusion and continued for 24 h. Additional rats received esmolol 50 microg x kg(-1) x min(-1) or landiolol 10 microg x kg(-1) x min(-1) intrathecally (IT) via the cisterna magna (n = 5 in each group), according to the same experimental protocol. The neurological deficit score was evaluated at 22 h after reperfusion, and the brains were removed and stained with triphenyltetrazolium chloride for evaluation of infarct volume. Additional rats that received saline, esmolol, and landiolol IV (n = 6 in each group) were allowed to survive for 7 days followed by measurement of infarct size. Neurological deficit scores were smaller in rats treated with propranolol-IV, carvedilol-IV, esmolol-IV, landiolol-IV, esmolol-IT, and landiolol-IT compared with saline-treated rats (P < 0.05). Cortical and striatum infarct volumes were less in the rats receiving beta-adrenoreceptor antagonists via either IV or IT than in saline-treated rats (P < 0.05). We conclude that beta-adrenoreceptor antagonists improve neurological and histological outcomes after transient focal cerebral ischemia in rats independent of administration route.

Focal cerebral ischemia: pathophysiologic mechanisms and rationale for future avenues of treatment

Although approximately 500,000 patients suffer from a stroke each year in the United States, treatment of these patients to date has consisted primarily of prevention, supportive measures, and rehabilitation. The modification of experimental cerebral infarction by new pharmacologic agents, along with encouraging results from the restoration of blood flow to areas of focal ischemia in both laboratory and clinical trials, suggests that a more aggressive approach might be considered in selected patients with acute stroke.

Therapeutic progress--review XXIII. Are we making progress in the treatment of acute stroke?

The principal purpose of the treatment of acute stroke is to ensure that the quality of life of those affected is returned to as near normal as possible. Early nursing and physiotherapy are important components of effective management of acute stroke. It is not the intention of this review to examine these aspects which are so well described elsewhere (1). Instead, the theoretical and clinical bases for the various specific treatments advocated in recent years to reduce brain damage after ischaemic insult will be considered to serve as a guide for clinicians. Areas in this field where further research may prove rewarding are highlighted.