Expression of Bcl-2 and Bad in hippocampus of status epileptic rats and molecular mechanism of intervened recombinant human erythropoietin.

Injury of hippocampal neurons in status epilepticus (SE) SD rats kindled by pentylenetetrazol (PTZ) were studied, and the changes of apoptosis neurons, protein expression of Bad and Bcl-2 alone and combined application of phosphatidyl inositol 3-kinase (PI3K) inhibitor LY294002 and recombinant human erythropoietin (rHuEpo) were evaluated for the possible mechanisms of rHuEpo. The SE rats kindled by the PTZ were randomly divided into normal control group [normal saline (NS)], model group (PTZ + NS), rHuEpo treated group (PTZ + rHuEpo), LY294002 treated group (PTZ + LY294002 + rHuEpo) and LY294002 control group (rHuEpo + PTZ + DMSO). Apoptosis of hippocampal neurons was detected by TUNEL method; expression of phosphorylation protein kinase B (p-PKB/p-Akt), Bcl-2 and Bad were detected by immunohistochemistry; the expression of Bcl-2 mRNA, Bad mRNA in hippocampal neurons of rats were detected through reverse transcription polymerase chain reaction (RT-PCR); the expression of Akt, p-Akt and Bcl-2, Bad protein in hippocampal neurons of rats were detected by western blotting. The amount of apoptotic neurons was less in the rHuEpo treated group and the LY294002 control group than in the LY294002 treated group (P<0.05). The expression of p-Akt protein and Bcl-2 protein increased while the Bad protein decreased significantly in the rHuEpo treated group and the LY294002 control group compared with the LY294002 treated group (P<0.05). The expression of Bad protein and Bad mRNA in hippocampus increased while the p-Akt, Bcl-2, Bcl-2 mRNA decreased significantly in the LY294002 treated group compared with the rHuEpo treated group (P<0.05). The PI3K/Akt signaling pathway is one of the pathways of rHuEpo neuroprotective effects and was confirmed from both the of positive and negative aspects. rHuEpo regulates the expression of mitochondrial apoptotic pathway related factors Bad and Bcl-2 to inhibit apoptosis and promotes neuronal survival.

Reduction of DNA damage induced by titanium dioxide nanoparticles through Nrf2 in vitro and in vivo.

Titanium dioxide nanoparticles (Nano-TiO2) are widely used to additives in cosmetics, pharmaceutical, paints and foods. Recent studies have demonstrated that Nano-TiO2 induces DNA damage and increased the risk of cancer and the mechanism might relate with oxidative stress. The aim of this study was to evaluate the effects of Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2), an anti-oxidative mediator, on DNA damage induced by Nano-TiO2. Wildtype, Nrf2 knockout (Nrf2(-/-)) and tert-butylhydroquinone (tBHQ) pre-treated HepG2 cells and mice were treated with Nano-TiO2. And then the oxidative stress and DNA damage were evaluated. Our data showed that DNA damage, reactive oxygen species (ROS) generation and MDA content in Nano-TiO2 exposed cells were significantly increased than those of control in dose dependent manners. Nrf2/ARE droved the downstream genes including NAD(P)H dehydrogenase [quinine] 1(NQO1), heme oxygenase 1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC) expression were significantly higher in wildtype HepG2 cells after Nano-TiO2 treatment. After treatment with Nano-TiO2, the DNA damages were significantly increased in Nrf(-/-) cells and mice whereas significantly decreased in tBHQ pre-treatment cells and mice, compared with the wildtype HepG2 cells and mice, respectively. Our results indicated that the acquired of Nrf2 leads to a decreased susceptibility to DNA damages induction by Nano-TiO2 and decreasing of risk of cancer which would provide a strategy for a more efficacious sensitization of against of Nano-TiO2 toxication.

[Effect of recombinant human erythropoietin on hippocampal p-Akt and caspase-9 expressions in rats with status epilepticus and the mechanism].

OBJECTIVE: To observe the effect of recombinant human erythropoietin (rhuEPO) on p-Akt and caspase-9 expressions in the hippocampus of rats with status epilepticus (SE) and explore the neuroprotective mechanism of rhuEPO. METHODS: Adult male SD rats were randomized into control, PTZ, rHuEPO, LY294002 group, and DMSO groups and treated with normal saline (NS), PTZ, PTZ+rHuEPO, PTZ+LY294002+rHuEPO, and PTZ+DMSO+rHuEPO, respectively. The behavioral and electroencephalogram (EEG) changes of the rats were recorded, and the expressions of p-Akt and caspase-9 were detected using immunohistochemistry. The hippocampal expression of caspase-9 mRNA was detected using RT-PCR, and the expressions of Akt and p-Akt proteins were determined with Western blotting. RESULTS: The p-Akt-positive cell and p-Akt protein expression increased significantly while the caspase-9-positive cell and caspase-9 mRNA expression decreased in rHuEPO group as compared with those in PTZ group (P<0.05). LY294002 treatment prior to rHuEPO injection significantly abolished the effects of rHuEPO on caspase-9 and p-Akt immunohistochemical positivity and caspase-9 mRNA and p-Akt protein expressions (P<0.05). CONCLUSION: Administration of rHuEPO activates the PI3K/Akt signaling pathway in SE rats and increases the expression of p-Akt protein to regulate the expression of caspase-9, a regulatory factor of the mitochondrial-dependent apoptotic pathway, and therefore provides anti-apoptotic and neuroprotective effects.