Prior use of 3-hydroxy-3-methyl-glutaryl-coenzyme a reductase inhibitor, simvastatin fails to improve outcome after experimental intracerebral hemorrhage

Abstract

Objective: Contrary to some clinical belief, there were quite a few studies regarding animal models of intracerebral hemorrhage (ICH) in vivo suggesting that prior use of statins may improve outcome after ICH. This study reports the effect of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG CoA) reductase inhibitor, simvastatin given before experimental ICH.

Methods: Fifty-one rats were subjected to collagenase-induced ICH, subdivided in 3 groups according to simvastatin treatment modality, and behavioral tests were done. Hematoma volume, brain water content and hemispheric atrophy were analyzed. Immunohistochemical staining for microglia (OX-42) and endothelial nitric oxide synthase (eNOS) was performed and caspase-3 activity was also measured.

Results: Pre-simvastatin therapy decreased inflammatory reaction and perihematomal cell death, but resulted in no significant reduction of brain edema and no eNOS expression in the perihematomal region. Finally, prior use of simvastatin showed less significant improvement of neurological outcome after experimental ICH when compared to post-simvastatin therapy.

Conclusion: The present study suggests that statins therapy after ICH improves neurological outcome, but prior use of statins before ICH might provide only histological improvement, providing no significant impact on neurological outcome against ICH.

Keywords: Inflammation; Intracerebral hemorrhage; Neuroprotection; Outcome; Rat; Statins.

Fig. 1

Behavioral tests. The modified limb placing test (A) and the corner turn test (B) reveal that the post-simvastatin treated group shows better neurological outcome on behavioral tests when compared with other two groups, but there is no significant neurological improvement in the pre-simvastatin treatment group; bars represent mean and standard deviation (SD); n=9 per each group; ^*p<0.05; Kruskal-Wallis test. ICH: intracerebral hemorrhage.

Fig. 2

Hematoma volume, brain water content and hemispheric atrophy. Measurement of hematoma volume (A) shows no difference between two groups. Analysis of brain water content (B) reveals that prophylactic adminstration of simvastatin decreased brain edema after ICH, albeit not statistically significant (p=0.309). Measurement of hemispheric atrophy (C) shows that there was a significant decrease of atrophy in the post-simvastatin treated group compared with others; n=4 per each group; bars represent mean and SD; ^*p<0.05; Mann-Whitney U test or Kruskal-Wallis test. SD: standard deviation.

Fig. 3

Immunohistochemistry for OX-42 around the hematoma. OX-42 positive microglia were clustered around the hematoma in the pre- (A) and post-simvastatin treated rats (B). The numbers of OX-42 are decreased by pre-simvastatin treatment. Quantitative analysis (C) shows a significant reduction in OX-42 positive cells in pre-simvastatin treated group than in the vehicle-treated group; n=4 per each group; magnification ×100; bars represent mean and SD; ^*p<0.05; Mann-Whitney U test. SD: standard deviation.

Fig. 4

Perihematomal cell death. Caspase-3 assay (merged images) shows that less abundant caspase-3 positive cells (orange-tinged color) were observed around the blood clot in the pre-simvastatin treated rats (A) than in the vehicle-treated rats (B). Quantitative analysis (C) shows less caspase-3 positive cells in the pre-simvastatin treated rats than in the vehicle-treated rats; n=4 per each group; bars represent mean and SD; ^*p<0.05; Mann-Whitney U test. SD: standard deviation.