The protective effect of risk factors against stroke severity

Exendin-4 reduces ischemic brain injury in normal and aged type 2 diabetic mice and promotes microglial M2 polarization

Exendin-4 is a glucagon-like receptor 1 agonist clinically used against type 2 diabetes that has also shown neuroprotective effects in experimental stroke models. However, while the neuroprotective efficacy of Exendin-4 has been thoroughly investigated if the pharmacological treatment starts before stroke, the therapeutic potential of the Exendin-4 if the treatment starts acutely after stroke has not been clearly determined. Further, a comparison of the neuroprotective efficacy in normal and aged diabetic mice has not been performed. Finally, the cellular mechanisms behind the efficacy of Exendin-4 have been only partially studied. The main objective of this study was to determine the neuroprotective efficacy of Exendin-4 in normal and aged type 2 diabetic mice if the treatment started after stroke in a clinically relevant setting. Furthermore we characterized the Exendin-4 effects on stroke-induced neuroinflammation. Two-month-old healthy and 14-month-old type 2 diabetic/obese mice were subjected to middle cerebral artery occlusion. 5 or 50 µg/kg Exendin-4 was administered intraperitoneally at 1.5, 3 or 4.5 hours thereafter. The treatment was continued (0.2 µg/kg/day) for 1 week. The neuroprotective efficacy was assessed by stroke volume measurement and stereological counting of NeuN-positive neurons. Neuroinflammation was determined by gene expression analysis of M1/M2 microglia subtypes and pro-inflammatory cytokines. We show neuroprotective efficacy of 50 µg/kg Exendin-4 at 1.5 and 3 hours after stroke in both young healthy and aged diabetic/obese mice. The 5 µg/kg dose was neuroprotective at 1.5 hour only. Proinflammatory markers and M1 phenotype were not impacted by Exendin-4 treatment while M2 markers were significantly up regulated. Our results support the use of Exendin-4 to reduce stroke-damage in the prehospital/early hospitalization setting irrespectively of age/diabetes. The results indicate the polarization of microglia/macrophages towards the M2 reparative phenotype as a potential mechanism of neuroprotection.

The impact of smoking on the severity of acute ischemic stroke

OBJECTIVES

This study investigated the impact of smoking on the initial severity of acute ischemic stroke and examined its subsequent outcome.

METHODS

Patient data was collected from the Stroke Registry in the Chang Gung Healthcare System (SRICHS). A total of 2650 patients admitted for acute ischemic stroke from January to December 2009 were included. Baseline characteristics were compared between smokers and non-smokers. Factors affecting the initial severity and the recovery from neurological deficit were examined by logistic regression analysis. The patients were further divided according to stroke mechanism for subgroup analysis.

RESULTS

The total number of smokers and non-smokers was 817 (31.9%) and 1833 (69.1%), respectively. Univariate analysis showed that smokers had lower NIHSS scores on admission than did non-smokers (P<0.001). In subgroup analysis, smokers with small-vessel occlusions frequently had higher NIHSS scores on admission than did non-smokers (P=0.001). However, smokers with cardioembolic stroke had lower NIHSS scores on admission as compared to non-smokers (P=0.024). No subgroup had smoking as a significant factor for neurological recovery during hospitalization.

CONCLUSIONS

Smoking correlated with higher NIHSS scores on admission for small-vessel occlusion. Conversely, it was associated with lower NIHSS scores on admission for cardioembolism.