I、Generation of reactive oxygen species mediates butein-induced apoptosis in neuroblastoma cellsII、Effects of parenteral arginine on immunity and oxidant- antioxidant homeostasis in rats with subacute peritonitis

• Main Authors: Ya-Hui Chen, 陳雅慧
• Other Authors: 許立松
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/85495957968096683382

博士 === 中山醫學大學 === 生化暨生物科技研究所 === 101 === I、Flavonoids exhibit chemopreventive and chemotherapeutic effects. Butein, a bioactive flavonoid isolated from numerous native plants, has been shown to induce apoptosis in human cancer cells. In the current study, the molecular mechanisms of butein action on cell proliferation and apoptosis of neuroblastoma cells were evaluated. Treatment with butein decreased the viability of Neuro-2A neuroblastoma cells in a dose- and time-dependent manner. The dose-dependent nature of butein-induced apoptosis was characterized by an increase in the sub-G1 phase population. Treatment with butein signifi¬cantly increased intracellular reactive oxygen species (ROS) levels and reduced the Bcl-2/Bax ratio, triggering the cleavage of pro-caspase 3 and poly-(ADP-ribose) polymerase (PARP). Pre-treatment with the antioxidant agent, N-acetyl cysteine (NAC), blocks butein-induced ROS generation and cell death. NAC also recovers butein-induced apoptosis-related protein alteration. In conclusion, butein-triggered neuroblastoma cells undergo apoptosis via generation of ROS, alteration of the Bcl 2/Bax ratio, and cleavage of pro-caspase 3 and PARP. Our results suggest that butein may serve as a potential therapeutic agent for the treatment of neuroblastoma. II、Background: Arginine deficiency and chronic inflammation may cause immune dysfunction. The authors previously showed that a pharmacological dose of parenteral arginine facilitates ornithine rather than nitric oxide production in subacute peritonitis. Beneficial effects of arginine on oxidative stress have been reported; however, arginine-induced excess production of nitric oxide (NO) needs to be concerned in inflammation. Herein, they investigated the effects of different doses of parenteral arginine supplementation on immunocytic subpopulation distribution and function. In addition, dose effects of parenteral arginine on lipid peroxidation (i.e., thiobarbituric acid reactive substances, TBARS) and activities of antioxidant enzymes in the circulation and organs/tissues were investigated.Materials: Male Wistar rats with cecal puncture-induced sub-acute peritonitis were infused with parenteral nutrition solutions containing 1.61, 2.85, 4.08, and 6.54% of total calories as arginine for 7 days, i.e., the CP, LA, MA, and HA groups, respectively. Distributions of T cells, B cells, and monocytes/macrophages and cytokine productions of peripheral blood lymphocytes (PBLs) and splenocytes were analyzed. In addition, levels of lipid peroxidation, antioxidants, antioxidant enzyme activity, and nitrotyrosine in the circulation and peritonitis- affected target organs/tissues also were analyzed. Healthy, orally-fed rats were as references.Results: There were no significant differences in circulating white blood cell numbers and serum tumor necrosis factor (TNF)-α and interferon (IFN)-γconcentrations among groups. Serum nitrate/nitrite (NOx) and interleukin (IL)-2 levels were significantly decreased by arginine in a dose-dependent manner. Animals supplemented with parenteral arginine had significantly decreased productions of concanavalin (Con) A- and lipopolysaccharide (LPS)-stimulated TNF-α in PBLs and splenocytes, spontaneous IL-6 and LPS-stimulated IFN-γin PBLs, and LPS-stimulated IL-6 in splenocytes. In addition, the LA group had significantly increased production of spontaneous IFN-γin PBLs and splenocytes. The HAgroup had significantly increased spontaneous TNF-α, and Con A stimulated IL-4 and IL-6 in PBLs. Parenteral arginine significantly attenuated sub-acute peritonitis-induced increases in TBARS in the muscle and thiol group in the kidneys, significantly increased cytochrome P450 in the liver, and significantly decreased TBARS in the kidneys. In addition, peritonitis- elevated NOx (i.e., nitrate and nitrite) and TBARS in the plasma and peritonitis-declined glutathione peroxidase (GPx) activity in the kidneys were significantly reversed in the MA and HA groups. However, the LA group had significantly increased plasma GPx activity and the MA group had significantly decreased lung NOx and increased muscle NOx compared to the CP group. Conclusion: Parenteral arginine administration at approximately 4% of total calories may alter PBLs and splenocytic immunity, and >6% of total calories might not be of benefit in rats with subacute peritonitis. Parenteral arginine at 4 to 6% of total calories may attenuate lipid peroxidation and increase activities of antioxidant enzymes; however, nitrosative stress might be elevated. These results suggest that parenteral arginine supplementation may modulate oxidant-antioxidant homeostasis in dose- and organ-dependent manners.