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

PLoS One. 2014 Aug 7;9(8):e103114. doi: 10.1371/journal.pone.0103114. eCollection 2014.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / metabolism
  • Brain Ischemia / pathology
  • Brain Ischemia / prevention & control*
  • Diabetes Mellitus, Experimental
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Drug Evaluation, Preclinical
  • Exenatide
  • Gene Expression Profiling
  • Infarction, Middle Cerebral Artery
  • Male
  • Mice, Inbred C57BL
  • Microglia / metabolism
  • Microglia / pathology*
  • Neuroprotective Agents / pharmacology*
  • Peptides / pharmacology*
  • Phenotype
  • Stroke / drug therapy*
  • Stroke / pathology
  • Time Factors
  • Venoms / pharmacology*

Substances

  • Biomarkers
  • Neuroprotective Agents
  • Peptides
  • Venoms
  • Exenatide

Grants and funding

This study was supported by 1)Novo Nordisk foundation [Grant number 5421]. http://www.novonordiskfonden.dk/en/grantrecipients?field_date_value%5Bvalue%5D&field_date_value_1%5Bvalue%5D&field_related_center_tid=All&keys=&page=1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 2) Diabetesfonden [Grant number DIA2013-010]. http://www.diabetesfonden.se/Forskning/Beviljade-projekt/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 3)European foundation for the study of diabetes [(EFSD/Lilly European Diabetes Research Programme)grant number: 94174]. www.EuropeanDiabetesFoundation.org. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 4) AFA Insurance [grant number 110067].http://www.afaforsakring.se/Forskning/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 5)Diabetes Research and Wellness Foundation [grant number 0245/2010W]. http://diabeteswellness.se/Research/2010%C3%A5rsforskningsanslag/tabid/841/language/en-US/Default.aspx. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 6)the Swedish Heart and Lung Foundation [grant number:20130523. http://www.hjart-lungfonden.se/Forskning/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 7) This work has also been supported by grants from: Konung Gustaf V:s och Drottning Victorias Frimurarestiftelse,The Swedish Research Council, the Swedish Society of Medicine and by the foundations Bergvalls, Syskonen Svensson, Thuring, Lagerman, Osterman, Stohne, Åhlén, STROKE Riksförbundet, Tornspiran, Gamla Tjänarinnor. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.