A method of inducing global cerebral ischemia

Metformin improves anxiety-like behaviors through AMPK-dependent regulation of autophagy following transient forebrain ischemia

Stroke is one of the main threats to the public health worldwide. Metformin, an anti-diabetic drug, is an activator of AMP-activated protein kinase (AMPK). Metformin plays an important role on improving behavior in neurodegenerative diseases through diverse pathways. In the current study we aimed to investigate the probable effects of metformin on anxiety and autophagy pathway in global cerebral ischemia. Rats were divided into seven groups; Sham, ischemia (I/R), metformin (met), compound c (CC), CC+ischemia, met+ischemia, met+CC+ischemia. Metformin was pretreated for 2 weeks and CC administrated half an hour before global cerebral ischemia. Blood glucose, body weight, sensorimotor scores, elevated plus maze and open field test were evaluated after ischemia. Autophagy related factors were measured by Western blot and immunofluorescent assay in hippocampus of rats. Based on our results, pretreatment of rats by metformin improved sensory motor signs, anxiolytic behavior and locomotion in ischemic rats. CC injection in I/R rats attenuated the therapeutic effects of metformin. Autophagy factors such as light chain 3B, Atg7, Atg5-12 and beclin-1 decreased in ischemic rats compared to the sham group (P < 0.001 in all proteins). Level of autophagic factors increased in metformin pretreated rats compared to global cerebral ischemia (P < 0.001 in all proteins). These data indicated that the beneficial role of metformin in behavior and autophagy flux mediates via AMPK. Our results recommended that metformin therapy could improve psychological disorders and movement disability following I/R and profound understanding of AMPK-dependent autophagy would enhance its development as a promising target for intracellular pathway.

Neuroprotective effects of quercetin in a mouse model of brain ischemic/reperfusion injury via anti-apoptotic mechanisms based on the Akt pathway

The present study provided experimental evidence for the neuroprotective effects of quercetin using a rat model of global brain ischemic/reperfusion (I/R) injury. Pre‑treatment with quercetin (5 or 10 mg/kg orally (p.o.); once daily) induced a dose‑dependent reduction in I/R‑induced hippocampal neuron cell loss, with 10 mg/kg/day being the lowest dose that achieved maximal neuroprotection. Administration of 10 mg/kg quercetin over at least 3 days prior to I/R was required to improve the survival rate of I/R rats. Fluorescence‑assisted cell sorting, hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling indicated neuronal cell loss in the CA1 hippocampus. Rats that had undergone transient global cerebral ischemia for 15 min followed by 1 h of reperfusion exhibited a significant increase in reactive oxygen species (ROS) production in the hippocampus. The I/R‑induced ROS overproduction in the hippocampus at 1, 12 and 24 h following I/R was significantly decreased by quercetin pre‑treatment. Western blot analysis revealed that the neuroprotective effects of quercetin (5 and 10 mg/kg/day, p.o.) were associated with an upregulation of the I/R‑induced suppression of B‑cell lymphoma‑2 (Bcl‑2), Bcl extra large and survivin expression as well as phosphorylation of Bcl‑2‑associated death promoter. Furthermore, the neuroprotective effects of quercetin (5, 10 mg/kg/day) in the brain were associated with an upregulation of Akt signaling. These findings suggested that the inhibition of I/R‑induced brain injury by quercetin likely involves a transcriptional mechanism to enhance anti‑apoptotic signaling.