Effects of co-administration of metformin and evogliptin on cerebral infarct volume in the diabetic rat.

Patients with diabetes suffer more severe ischemic stroke. A combination of metformin and dipeptidyl peptide-4 inhibitors is commonly prescribed to treat diabetes. Therefore, we aimed to determine if pretreatment with a combination of metformin and evogliptin, a dipeptidyl peptidase-4 inhibitor, could reduce cerebral infarct volume in rats with streptozotocin-induced diabetes. After confirming diabetes induction, the rats were treated with vehicle, evogliptin, metformin, or evogliptin/metformin combination for 30 days. Then, stroke was induced by transient middle cerebral artery occlusion (tMCAO). Infarct volume, oxidative stress, levels of methylglyoxal-modified protein, glucagon-like peptide-1 receptor (GLP-1R), AMPK, and Akt/PI3K pathway-related proteins, and post-stroke pancreatic islet cell volume were evaluated. Compared to vehicle, only the co-administration group had significantly reduced infarct volume from the effects of tMCAO; the regimen also improved glycemic control, whereas the individual treatments did not. Co-administration also significantly reduced methylglyoxal-modified protein level in the core of the brain cortex, and the expression of 4-HNE and 8-OHdG was reduced. Co-administration increased p-Akt levels in the ischemic core and mitigated the suppression of Bcl-2 expression. Plasma GLP-1 and dipeptidyl peptidase-4 levels and brain GLP-1R expression remained unaltered. In the pancreas, islet cell damage was reduced by co-administration. These results reveal that metformin and evogliptin co-administration ameliorates cerebral infarction associated with prolonged glycemic control and pancreatic beta cell sparing. Other potential protective mechanisms may be upregulation of insulin receptor signaling or reduction of methylglyoxal-induced neurotoxicity. The combination of metformin and evogliptin should be tested further for its potential against focal cerebral ischemia in diabetes patients.

Therapeutic effect of mesenchymal stem cells in an animal model of Alzheimer's disease evaluated by ß-amyloid positron emission tomography imaging.

OBJECTIVE: We evaluated the effects of bone marrow-derived mesenchymal stem cells in a model of Alzheimer's disease using serial [18F]Florbetaben positron emission tomography. METHODS: 3xTg Alzheimer's disease mice were treated with intravenously injected bone marrow-derived mesenchymal stem cells, and animals without stem cell therapy were used as controls. Serial [18F]Florbetaben positron emission tomography was performed after therapy. The standardized uptake value ratio was measured as the cortex standardized uptake value divided by the cerebellum standardized uptake value. Memory function and histological changes were observed using the Barnes maze test and ß-amyloid-reactive cells. RESULTS: Standardized uptake value ratio decreased significantly from day 14 after stem cell administration in the bone marrow-derived mesenchymal stem cells-treated group (n = 28). In contrast, there was no change in the ratio in control mice (n = 25) at any time point. In addition, mice that received bone marrow-derived mesenchymal stem cell therapy also exhibited significantly better memory function and less ß-amyloid-immunopositive plaques compared to controls. CONCLUSION: The therapeutic effect of intravenously injected bone marrow-derived mesenchymal stem cells in a mouse model of Alzheimer's disease was confirmed by ß-amyloid positron emission tomography imaging, memory functional studies and histopathological evaluation.

Expression of Cellular Receptors in the Ischemic Hemisphere of Mice with Increased Glucose Uptake.

Many previous studies have shown reduced glucose uptake in the ischemic brain. In contrast, in a permanent unilateral common carotid artery occlusion (UCCAO) mouse model, our pilot experiments using 18F-fluorodeoxyglucose positron emission tomography (FDG PET) revealed that a subset of mice exhibited conspicuously high uptake of glucose in the ipsilateral hemisphere at 1 week post-occlusion (asymmetric group), whereas other mice showed symmetric uptake in both hemispheres (symmetric group). Thus, we aimed to understand the discrepancy between the two groups. Cerebral blood flow and histological/metabolic changes were analyzed using laser Doppler flowmetry and immunohistochemistry/Western blotting, respectively. Contrary to the increased glucose uptake observed in the ischemic cerebral hemisphere on FDG PET (p<0.001), cerebral blood flow tended to be lower in the asymmetric group than in the symmetric group (right to left ratio [%], 36.4±21.8 vs. 58.0±24.8, p=0.059). Neuronal death was observed only in the ischemic hemisphere of the asymmetric group. In contrast, astrocytes were more activated in the asymmetric group than in the symmetric group (p<0.05). Glucose transporter-1, and monocarboxylate transporter-1 were also upregulated in the asymmetric group, compared with the symmetric group (p<0.05, respectively). These results suggest that the increased FDG uptake was associated with relatively severe ischemia, and glucose transporter-1 upregulation and astrocyte activation. Glucose metabolism may thus be a compensatory mechanism in the moderately severe ischemic brain.

Cranial burr hole with erythropoietin administration induces reverse arteriogenesis from the enriched extracranium.

It is challenging to revitalize ischemic penumbra after an acute stroke with intracranial perfusion insufficiency. To evaluate whether cranial burr hole and erythropoietin (EPO) generate effective revascularization, we investigated the efficacy of the augmentation method for reverse arteriogenesis from the healthy extracranial milieu. An intracranial perfusion insufficiency was created through bilateral internal carotid artery ligation (bICAL) in Sprague-Dawley rats. We administered recombinant human EPO (5000 U/kg) or saline intraperitoneally for 3 days after bICAL. Mechanical barrier disruption (MBD) was performed through a cranial burr hole with small dural cracks in the right hemisphere. The ipsilateral hemisphere with MBD grossly showed vascular networks between the extra- and intra-cranial spaces 2 weeks after the MBD procedure. It also showed significantly increased vessels in the intracranial vasculature adjacent to the MBD region (p = 0.0006). The levels of pro-angiogenic and inflammatory factors with prominent markers of vessel permeability were also significantly increased (MBD-only vs. control; Tnf-α, p = 0.0007; Vegf, p = 0.0206). In the EPO-administered group, such elevations in inflammation were significantly mitigated (combined vs. MBD-only; Tnf-α, p = 0.0008). The ipsilateral hemisphere with MBD-EPO (vs. MBD-only) showed significantly increased vessels (RECA-1, p = 0.0182) and their maturation (RECA-1/α-SMA, p = 0.0046), with upregulation of tumor growth factor-ß1 (Tgf-ß1, p = 0.037) and matrix metalloproteinase-2 (Mmp-2, p = 0.0488). These findings were completely blocked by minocycline (MIC) administration during in vivo (Tgf-ß1, p = 0.0009; Mmp-2, p < 0.0001) and in vitro experiments (tube formation, p < 0.0001). Our data suggest that the MBD procedure (for angiogenic routes) and EPO administration (for an arteriogenic booster) are complimentary and can facilitate successfully "reverse arteriogenesis" in subjects with intracranial perfusion insufficiency.

Low Testosterone Level as a Predictor of Poststroke Emotional Disturbances: Anger Proneness and Emotional Incontinence.

BACKGROUND: The role of sex hormones in poststroke mood and emotional disturbances is unclear. We aimed to evaluate the impact of sex hormones on poststroke emotional disturbance, especially anger proneness (AP) and emotional incontinence (EI). We also investigated whether statins, which are widely used for stroke prevention, affect sex hormone levels or the presence of poststroke AP/EI based on the hypothesis that intensive treatment with statins would inhibit the synthesis of cholesterol, the preferred substrate of testosterone. METHODS: We prospectively enrolled 40 patients who experienced ischemic stroke at least 3 months prior to study enrollment. We performed clinical and laboratory evaluations, including hormone-level measurements and neuropsychological tests. Poststroke AP and EI were assessed using interviews, then patients were divided into 2 groups: AP/EI-present or absent. RESULTS: Of the 40 patients (30 men, mean age 58.8 years), 16 (40.0%) were classified as AP/EI-present group. AP/EI were not related to stroke severity or location; however, the testosterone level was significantly lower in patients with AP/EI than in those without AP/EI (2.1 ± 1.7 vs. 3.9 ± 2.5 ng/mL, P = .023). After adjusting for potential confounding variables, low testosterone levels were a significant independent predictor of AP/EI (odds ratio .68, 95% confidence interval .49-.96, P = .027). In contrast, sex hormone levels and AP/EI prevalence did not differ between statin users and nonusers. CONCLUSIONS: AP/EI were associated with low testosterone levels in patients with previous ischemic stroke, but statin use did not affect AP/EI prevalence.

Impact of varying levels of hyperglycemia on clinicoradiographic outcomes after endovascular reperfusion treatment.

We evaluated the effects of admission hyperglycemia with different cut-off levels on 3-month outcomes, infarct growth, and hemorrhagic transformation in acute stroke patients with large artery occlusion of anterior circulation who received endovascular treatment (EVT). Between January 2011 and May 2016, patients that underwent EVT with pre-procedural and post-procedural diffusion-weighted imaging were identified from a multicenter registry. Normoglycemia was defined as a glucose level ≤ 110 mg/dL, moderate hyperglycemia as >110 and ≤170 mg/dL, and overt hyperglycemia as >170 mg/dL. Its effects on poor outcomes (3-month modified Rankin Scale score 3-6), infarct growth, and parenchymal hematoma type 2 were analyzed. Of 720 patients encountered, 341 patients were eligible. There was a statistically significant difference in glycated hemoglobin levels between the normoglycemia/moderate hyperglycemia and overt hyperglycemia groups (p < 0.001). Moderate hyperglycemia (odds ratio 2.37 [95% confidence interval 1.26-4.45], p = 0.007) and overt hyperglycemia (2.84 [1.19-6.81], p = 0.019) were associated with poor outcomes. Post-procedural infarct volumes were significantly greater in hyperglycemic patients (padjusted = 0.003). Only overt hyperglycemia (9.28 [1.66-51.88], p = 0.011) was associated with parenchymal hematoma type 2. Overall hyperglycemia was associated with poor outcomes and infarct growth, whereas overt hyperglycemia was associated with parenchymal hematoma type 2.