Normobaric hyperoxia retards the evolution of ischemic brain tissue toward infarction in a rat model of transient focal cerebral ischemia

The purpose of this study was to investigate the effect of Ghrelin on the polarization of microglia/ macrophages after cerebral ischemia (CI) in rats. 60 wild-type SD rats were randomly divided into sham group, CI group, CI+Ghrelin group, 20 rats in each group. The modified Longa suture method was used to establish the middle cerebral artery occlusion (MCAO) model in rats. Before surgery, Ghrelin was injected subcutaneously (100μg/kg, twice a day) for 4 consecutive weeks. After modeling, neurological function scores were performed with three behavioral experiments: mNSS score, Corner test, and Rotarod test, to evaluate the recovery of neurological function after Ghrelin treatment. At the same time, the brain tissues were collected and stained with 2,3,5-triphenyltetrazolium chloride (TTC) to detect the cerebral infarct volume. RT-qPCR was used to detect the expression of TNF-α and IL-1β in the ischemic brain tissue, and the TUNEL staining was used to detect the apoptosis of brain tissue. Flow cytometry was used to detect the percentage of M1 type microglia/macrophages which were isolated by trypsin digestion of fresh cerebral cortex. Then, the Western blotting and immunofluorescence method were used to detect the phosphorylation level of AKT (P-AKT) and AKT. Compared with the CI group, the neurological function of the rats in the CI+Ghrelin group was dramatically improved, and the cerebral infarction area was dramatically reduced. At the same time, the expression of TNF-α and IL-1β in the ischemic brain tissue of rats in the CI+Ghrelin group decreased, and the apoptotic cells in the brain tissue also decreased. Compared with the CI treatment group, the activation of M1 microglia/macrophages in the cortex of the ischemic side of the infarct and the peri-infarct area in the CI+Ghrelin group was dramatically inhibited. At the same time, the ratio of P-AKT/AKT of the brain tissue in the CI+Ghrelin group was dramatically higher than that of the CI group. In the rat cerebral ischemia model, Ghrelin can promote the repair of brain damage and the recovery of neurological function after ischemia. Its mechanism may be related to activating AKT to selectively reduce M1 microglia/macrophages, reducing inflammation and cell apoptosis in brain tissue.

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Inflammatory cell populations in early neuroinflammation in the core and peri-ischemic lesions of rat brain after transient focal cerebral ischemia: A morphometric study

10.7287/peerj.preprints.26510v1 ◽

2018 ◽

Author(s):

Emoke Horvath ◽

Alex Oradan ◽

Liviu Chiriac ◽

Minodora Dobreanu ◽

Előd-Ernő Nagy ◽

...

Keyword(s):

Cerebral Ischemia ◽

Rat Model ◽

Inflammatory Cell ◽

Focal Cerebral Ischemia ◽

Artery Occlusion ◽

The Core ◽

Transient Focal Cerebral Ischemia ◽

Cox 2 ◽

Cerebral Artery Occlusion

Background and Objective: Clinical and experimental observations emphasize the role of inflammation as a direct risk factor for stroke. To better characterize the inflammation, we have conducted a detailed histological analysis of the inflammatory cell population after transient middle cerebral artery occlusion in a rat model. Methods: Fifteen adult Wistar male rats were divided randomly into test (n=10) and sham (n=5) groups. In the ischemic group, transient focal cerebral ischemia was induced with an intraluminal filament technique. Histologic lesions of the ischemic core and the surrounding penumbra zone were evaluated, based on a complex algorithm. Representative morphological changes in the core and the penumbra zone were compared. Immunohistochemistry was performed for leukocytes markers (CD15, CD68, CD3), leukocyte-released effectors (MMP-9 and COX-2), and FXIII (possibly involved in microglia and macrophage activation) Results: Neuronal vacuolation and degeneration were significantly more in the core lesion, whereas cellular edema and inflammatory infiltrate were increased in the penumbra. CD68, CD3, FXIII and Cox-2 expression were significantly higher in the penumbra than in the core (p=0.026; p=0.006; p=0.002; and p<0.001). Discussion: In the rat model of middle cerebral artery occlusion, inflammatory mechanisms, microglia/macrophage cells, and T-lymphocytes likely play an important role in the penumbra. The deterioration of neurons is less in the penumbra than in the core. Appreciation of the role of the inflammatory cells and mechanisms involved in stroke might lead to measures to inhibit the injury and save brain volume.

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