Acrolein inducesneurotoxicity in nigrostantal dopammeric system of rat brain

• Main Authors: Yi-Ting Wang, 王怡婷
• Other Authors: Anya Maan-Yuh Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/42185037372315130496

碩士 === 國立陽明大學 === 生理學研究所 === 103 === Clinical studies have shown elevated levels of acrolein, an α,β-unsaturated aldehyde with a potent oxidative activity, in the brain of patients with CNS neurodegenerative diseases. In my thesis, the neurotoxic effect of acrolein was investigated in brain of Sprague Dawley rats. Acrolein was applied via intranigral infusion of acrolein (15, 50,150 nmoles) and oral administration of acrolein (1 and 5 mg/kg/day, 14 days). In the first part of my study, 7 days after local infusion of acrolein, Western blot assay showed that acrolein elevated 4-HNE (a product of lipid peroxidation) and HO-1(a redox-regulated protein) levels as well as α-synuclein aggregation (a pathological hallmark of Parkinsonism) in the acrolein-infused substantia nigra (SN) of rat brain, indicating acrolein-induced oxidative stress. In addition to acrolein-induced reduction in tyrosine hydroxylase levels in the acrolein-infused SN, acrolein dose-dependently reduced striatal dopamine content using high-performance liquid chromatography coupled with electrochemical detection. Acrolein increased glial fibrillary acidic protein (a biomarker of activated astrocytes) and ED-1 levels (a biomarker of activated microglia) as well as activated caspase 1 (a hallmark of inflammasome), indicating that acrolein is capable of inducing neuroinflammation in the acrolein-infused SN. At the same time, acrolein activated caspase 3 and caspase 12, indicating the involvement of apoptosis in acrolein-induced neurotoxicity. In addition, dose-dependent elevations in receptor interacting protein kinase (RIPK)1 and RIPK3 levels (biomarkers of necroptosis) were observed in the acrolein-infused SN, suggesting that acrolein induced programmed necrosis. The second part of my study, 14-day oral administration of acrolein was employed with similar neurotoxicity in the nigrostriatal dopaminergic system of rat brain. Systemic acrolein induced behavioral changes and dose-dependently elevated HO-1 and 4-HNE levels in the SN of acrolein-fed rat. In addition to the acrolein-induced α-synuclein aggregation, immunostaining study showed co-localization of acrolein and α-synuclein in the SN, suggesting that acrolein is capable of inducing protein conjugation. Systemic acrolein induced neuroinflammation by increasing glial fibrillary acidic protein and ED-1 levels and activating caspase 1 in the SN of acrolein-treated rats. The apoptotic mechanisms of acrolein were delineated by activation of caspase 9 and 12, suggesting that acrolein-induced apoptosis was mediated via mitochondrial pathway and endoplasmic reticulum stress. In addition to acrolein-induced α-spectrin cleavage, dose-dependent elevation in receptor interacting protein kinase (RIPK)1 and RIPK3 levels, biomarkers of necroptosis, was observed in the SN of acrolein-treated rats, suggesting that systemic acrolein induced programmed necrosis. Our in vitro study using cortical homogenates showed that incubation of acrolein at 37 °C for 4h increased the levels of lipid peroxides. Antioxidants including glutathione and melatonin inhibited acrolein-induced lipid peroxidation. Taken together, acrolein appears to be a neurotoxin to the nigrostriatal dopaminergic system via protein conjugation/aggregation, neuroinflammation, necrosis, apoptosis and necroptosis in the nigrostriatal dopaminergic system of rat brain. Furthermore, our data suggest that anti-oxidative treatment may be a possible therapeutic strategy of acrolein-induced neurodegeneration.