Acute Hyperglycemia Does Not Affect Brain Swelling or Infarction Volume After Middle Cerebral Artery Occlusion in Rats

Acute Hyperglycemia Exacerbates Hemorrhagic Transformation after Embolic Stroke and Reperfusion with tPA: A Possible Role of TXNIP-NLRP3 Inflammasome

OBJECTIVES

Acute hyperglycemia (HG) exacerbates reperfusion injury after stroke. Our recent studies showed that acute HG upregulates thioredoxin-interacting protein (TXNIP) expression, which in turn induces inflammation and neurovascular damage in a suture model of ischemic stroke. The aim of the present study was to investigate the effect of acute HG on TXNIP-associated neurovascular damage, in a more clinically relevant murine model of embolic stroke and intravenous tissue plasminogen activator (IV-tPA) reperfusion.

MATERIALS AND METHODS

HG was induced in adult male mice, by intraperitoneal injection of 20% glucose. This was followed by embolic middle cerebral artery occlusion (eMCAO), with or without IV-tPA (10 mg/kg) given 3 h post embolization. Brain infarction, edema, hemoglobin content, expression of matrix metalloproteinase (MMP-9), vascular endothelial growth factor A (VEGFA), tight junction proteins (claudin-5, occluding, and zonula occludens-1), TXNIP, and NOD-like receptor protein3 (NLRP3)-inflammasome activation were evaluated at 24 h after eMCAO.

RESULTS

HG alone significantly increased TXNIP in the brain after eMCAO, and this was associated with exacerbated hemorrhagic transformation (HT; as measured by hemoglobin content). IV-tPA in HG conditions showed a trend to decrease infarct volume, but worsened HT after eMCAO, suggesting that HG reduces the therapeutic efficacy of IV-tPA. Further, HG and tPA-reperfusion did not show significant differences in expression of MMP-9, VEGFA, junction proteins, and NLRP3 inflammasome activation between the groups.

CONCLUSION

The current findings suggest a potential role for TXNIP in the occurrence of HT in hyperglycemic conditions following eMCAO. Further studies are needed to understand the precise role of vascular TXNIP on HG/tPA-induced neurovascular damage after stroke.

Post-stroke Hyperglycemia in Non-diabetic Ischemic Stroke is Related With Worse Functional Outcome: A Cohort Study

OBJECTIVE

To investigate long-term and serial functional outcomes in ischemic stroke patients without diabetes with post-stroke hyperglycemia.

METHODS

The Korean Stroke Cohort for Functioning and Rehabilitation (KOSCO) is a large, multi-center, prospective cohort study of stroke patients admitted to participating hospitals in nine areas of Korea. From KOSCO, ischemic stroke patients without diabetes were recruited and divided into two groups: patients without diabetes without (n=779) and with post-stroke hyperglycemia (n=223). Post-stroke hyperglycemia was defined as a glucose level >8 mmol/L. Functional assessments were performed 7 days and 3, 6, and 12 months after stroke onset.

RESULTS

There were no significant differences in baseline characteristics between the groups, except in the age of onset and smoking. Analysis of the linear correlation between the initial National Institutes of Health Stroke Scale (NIHSS) score and glucose level showed no significant difference. Among our functional assessments, NIHSS, Fugl-Meyer Assessment (affected side), Functional Ambulatory Category, modified Rankin Scale, and Korean Mini-Mental State Examination (K-MMSE) showed statistically significant improvements in each group. All functional improvements except K-MMSE were significantly higher in patients without post-stroke hyperglycemia at 7 days and 3, 6, and 12 months.

CONCLUSION

The glucose level of ischemic stroke patients without diabetes had no significant correlation with the initial NIHSS score. The long-term effects of stress hyperglycemia showed worse functional outcomes in ischemic stroke patients without diabetes with post-stroke hyperglycemia.