Liraglutide ameliorates cerebral ischemic injury in diabetic rats by regulating microglia/macrophage polarization through inhibition of NOX2 expression

Abstract

Objective To investigate the effects of liraglutide (Lir) on microglia/macrophage polarization and on the expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX2) in the ischemic brain tissue of diabetic rats with focal cerebral ischemia. Method Seventy-five rats were randomly and equally divided into 5 groups: cerebral ischemia (CI) group, diabetes+cerebral ischemia (DCI) group, insulin treatment (Ins) group, Lir treatment (Lir) group, and NOX2 agonist tetrabromocinnamic acid (TBCA) + Lir group (TBCA). On the 3rd day after cerebral ischemia, the neurological deficit scores of the rats were evaluated, and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining was adopted to measure the cerebral infarct volume in each group. The co-labeling of CD16/32 and CD206 with Iba1 on microglia/macrophages were detected by immunofluorescence double-label staining, and the protein expression of NOX2, TNF-α, IL-1β, IL-10 and TGF-β were determined using Western blotting. Results As compared with the DCI group, the neurological deficit scores were decreased, and the cerebral infarction volume was reduced in the Lir group. The cell number of Iba1+/CD16/32+ microglia/macrophage (M1 type) was declined, with down-regulated expression of TNF-α, IL-1β and NOX2 in the Lir group, while the number of Iba1+/CD206+ microglia /macrophage (M2 type) was increased, with improved levels of IL-10 and TGF-β (all P < 0.05). However, the above effects were reversed by the treatment of NOX2 agonist TBCA (P < 0.05). Conclusion The neuroprotective effects of Lir on cerebral ischemic injury may be related to the inhibition of NOX2 expression and promotion of microglia/macrophages conversion to M2 type.

Keywords

• liraglutide
• cerebral ischemia
• diabetes
• microglia/macrophage
• polarization
• nox2