title: Lactucopicrin ameliorates oxidative stress mediated by scopolamine-induced neurotoxicity through activation of the NRF2 pathway.
abstract: Cholinergic activity plays a vital role in cognitive function, and is reduced in individuals with neurodegenerative diseases. Scopolamine, a muscarinic cholinergic antagonist, has been employed in many studies to understand, identify, and characterize therapeutic targets for Alzheimer's disease (AD). Scopolamine-induced dementia is associated with impairments in memory and cognitive function, as seen in patients with AD. The current study aimed to investigate the molecular mechanisms underlying scopolamine-induced cholinergic neuronal dysfunction and the neuroprotective effect of lactucopicrin, an inhibitor of acetylcholine esterase (AChE). We investigated apoptotic cell death, caspase activation, generation of reactive oxygen species (ROS), mitochondrial dysfunction, and the expression levels of anti- and pro-apoptotic proteins in scopolamine-treated C6 cells. We also analyzed the expression levels of antioxidant enzymes and nuclear factor (erythroid-derived 2)-like 2 (NRF2) in C6 cells and neurite outgrowth in N2a neuroblastoma cells. Our results revealed that 1 h scopolamine pre-treatment induced cytotoxicity by increasing apoptotic cell death via oxidative stress-mediated caspase 3 activation and mitochondrial dysfunction. Scopolamine also downregulated the expression the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase, and the transcription factor NRF2. Lactucopicrin treatment protected C6 cells from scopolamine-induced toxicity by reversing the effects of scopolamine on those markers of toxicity. In addition, scopolamine attenuated the secretion of neurotrophic nerve growth factor (NGF) in C6 cells and neurite outgrowth in N2a cells. As expected, lactucopicrin treatment enhanced NGF secretion and neurite outgrowth. Our study is the first to show that lactucopicrin, a potential neuroprotective agent, ameliorates scopolamine-induced cholinergic dysfunction via NRF2 activation and subsequent expression of antioxidant enzymes.
authors.affiliation: Lab of Pharmacognosy, College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea.
authors.forename: Ramu
authors.initials: R
authors.lastname: Venkatesan
authors.affiliation: Lab of Pharmacognosy, College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea.
authors.forename: Lalita
authors.initials: L
authors.lastname: Subedi
authors.affiliation: Department of Biochemistry, College of Medicine, Gachon University, #191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea.
authors.forename: Eui-Ju
authors.initials: EJ
authors.lastname: Yeo
authors.affiliation: Lab of Pharmacognosy, College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea; Gachon Medical Research Institute, Gil Medical Center, Inchon 21565, Republic of Korea; Gachon Institute of Pharmaceutical Science, Gachon University, #191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Republic of Korea. Electronic address: sunnykim@gachon.ac.kr.
authors.forename: Sun Yeou
authors.initials: SY
authors.lastname: Kim
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D007783:Lactones / Q000494:pharmacology*; D018727:Muscarinic Antagonists / Q000633:toxicity; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012601:Scopolamine / Q000633:toxicity*; D012717:Sesquiterpenes / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D007783:Lactones; D018727:Muscarinic Antagonists; D051267:NF-E2-Related Factor 2; C495637:Nfe2l2 protein, rat; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; C001458:intybin; D012601:Scopolamine
keywords: (-)-Scopolamine hydrobromide trihydrate (PubChem CID: 20055509); 2′,7′-Dichlorofluorescein diacetate (PubChem CID: 104913); AChE inhibitors; Antioxidant; Galantamine hydrobromide (PubChem CID: 121587); Lactucopicrin; Lactucopicrin (PubChem CID: 174880); NRF2; ROS; Retinoic acid (PubChem CID: 444795); Rhodamine 123 (PubChem CID: 65217); Scopolamine; Thiazolyl blue tetrazolium bromide (PubChem CID: 64965)