Keywords
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Neurological disease, zebrafish model |
Introduction
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Current world wide estimates of people with the two most common neurodegenerative disease is around 18 million for Alzhiemer’s disease (20) and 6.3 million for Parkinson’s disease (7); prevalence of autism is as low as 6% in USA and up to 20 % in India (8). Aggregation of misfolded proteins is a common pathology shared by all neurodegenerative diseases, although nature of aggregates, and symptoms vary(5). It is inevitable that all neurodegenerative disease could share a common link in the protein aggregation pathway and therefore in the progress of the disease. Mutations that compromise autophagy include presenilin 1 (Alzheimer Disease), huntingtin (Huntingtons Disease), F -synuclein, parkin, LRRK2, PINK1 (Parkinsons Disease), dyenin, ESCRT-III (Amyotrophic lateral sclerosis) and laforin (Lafora disease) (17). Furthermore reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important modulators of core cellular functions such as apoptosis, ion transport, and calcium mobilization leading to altered excitotoxicity and apoptosis the two key causes of neuronal death (6). It has been also shown, that induction of ubiquitin-proteasome machinery could alleviate the deposition of toxic aggregates (1). We therefore choose to induce alterations in these pathways to model neurodegenerative disorders and further to model neurodevelopmental disorders we used compounds that compromise brain development. Lead a proven neurotoxin in the developing brain of rats causes oxidative stress and apoptosis(15), cholesterol metabolism is associated with Alzheimers disease (11) and further membrane cholesterol has shown to upregulate glutamatergic receptors(18). Acetyl choline has also proven to cause glutamate – induced neurotoxicity in cultured hippocampus neurons(12). Zebrafish is a versatile model to understand developmental toxicity and becoming increasing popular(13,19,21). Creating a neuropathological state in zebrafish supported by compromised behaviour on exposure to proven chemical neurotoxins would establish a simple yet robust model. Although genetic models are outstanding as they are very specific, they are laborious and time consumptive. A toxic model validated at both cellular and behaviour levels would nevertheless suffice to screen for Hiits that could be translated to mammalian models. |
Materials and Method
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Zebra fish were procured from local aquarium specialist and acclimatized for a month. For egg collection male and female zebrafish were maintained in isolated tanks for a week prior to mating, and eggs were collected in the morning after the fish were put together. The eggs were immediately transferred to sterile aquarium water. To expose for induction of toxicity Groups of 6 fry, 48hpf, were transferred to 100ml of water each containing 0.1/ml Lead, 0.1ug/ml Acetylcholine and 1ug/ml of cholesterol reconstituted with 0.01% of DMSO. Fry were maintained at 28°C, and light and dark cycle of 14/10 hours. Screening was periodically done every 24 hours upto 7 dpf. |
Assay |
To count the number of pectoral fin movement fry were gently transferred to a cavity slide under 4X bright field microscope and the number of pectoral fin movement were counted for every minute Neuronal apoptosis was quantified by staining fry with 0.5 ug of acridine orange and corrected total cell fluorescent intensity was quantified by imageJ software available online. Distance travelled by the fry within 10 seconds after touching the tail was measured as a response to touch. Nature of swimming was observed such as normal, slow or haphazard |
Discussion
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The hallmarks of neurodegenerative diseases is degenerative neuronal cells leading to impaired cognitive and movement disorders. Lead treatment proves to affect cognition as in decreased swimming distance in response to touch, and impaired movement as in decreased pectoral fin movement although swimming behaviour was normal; apoptosis of brain cells is evident. In the case of acetylcholine and cholesterol treatment hyperactive or uncontrollable movement is evident as in faster pectoral fin movement and increased swimming distance in response to touch, moreover swimming motion of these fry were faster and haphazard compared to control fish. Further poor development of brain and skeletal architecture is evident in cholesterol treatment as observed in disintegration of the fry head on glass slide. Hence lead can be used to model both cognitive and movement disorders as observed in most neurodegenerative diseases, while cholesterol and acetylcholine can be used to model neurodevelopmental disease as in attentiondeficit/ hyperactivity disorder (ADHD). It has also been hypothesized that hyperactive glutamatergic system is connect to ADHD and Amyotrophic lateral sclerosis (10), therefore modelling with both cholesterol and lead without doubt offers more accurate replication of molecular pathogenesis in such cases. The hyperactivity is strongly pronounced enough unlike in doubtable mild compromise of cognitive functions (18). Chemical neurotoxicity is promising since it can be used very specifically to identify developmental toxicity (2,3). In the case of Parkinson’s disease 6-hydroxydopamine, MPTP, rotenone and paraquat have been employed based on the investigational view(9), similarly toxic modelling hold great promise in the case of neurodevlopmental modelling since neural development and patterning can strongly be linked with the human system (19). |
Figures at a glance
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References
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- Aaron Ciechanover and Patrik Brundin. The ubiquitin proteasome system in review neurodegenerative diseases: sometimes the chicken, sometimes the egg. Neuron 2003; 40:427–446.
- Adrian Hill, C. Vyvyan Howard, Uwe Strahle, and Andrew Cossins. Neurodevelopmental Defects in Zebrafish (Danio rerio) at Environmentally Relevant Dioxin (TCDD) Concentrations. Toxicol Sciences. 2003;76:392–399.
- Adrian J. Hill, Hiroki Teraoka, Warren Heideman, and Richard E. Peterson. Zebrafish as a Model Vertebrate for Investigating Chemical Toxicity. Toxicol Sciences.2005:86 6–19.
- Anna Fernández, Laura Llacuna, José C. Fernández- Checa, and Anna Colell. Mitochondrial Cholesterol Loading Exacerbates Amyloid Beta Peptide-Induced Inflammation and Neurotoxicity. J Neurosci. 2009; 29(20): 6394–6405.
- Daniel M. Skovronsky, Virginia M.-Y. Lee, and John Q Trojanowski. Neurodegenerative Diseases: New Concepts of Pathogenesis and Their Therapeutic Implications.. Annu. Rev. Pathol.2006;1:151–70
- Emerit J, Edeas M, Bricaire F. Neurodegenerative diseases and oxidative stress. Biomed Pharmacother. 2004; 58(1):39-46.
- European Parkinson’s disease association. https://www.epda.eu.com/.
- Jamal H Al Hamed, Attia Z Taha, Amr A Sabra, Hassan Bella. Attention Deficit Hyperactivity Disorder (ADHD): Is it a Health Problem among Male Primary School Children. Bahrain Medical Bulletin. 2008;30:(2).
- Jordi Bove´, Delphine Prou, Ce´line Perier, and Serge Przedborski. Toxin-Induced Models of Parkinson’s Disease. The American Society for Experimental Neuro Therapeutics.Inc. 2005;(2):484–494.
- Lule D, Ludolph AC, Ludolph AG. Neurodevelopmental and neurodegenerative diseases - is there a pathophysiological link? Attention-deficit/hyperactivity disorder and amyotrophic lateral sclerosis as examples. Med Hypotheses. 2008;70(6):1133-8.
- Marta Valenza and Elena Cattaneo. Cholesterol dysfunction in neurodegenerative diseases: is Huntington's disease in the list? Prog in Neurobiol. 2006;80(4):165-176.
- Mark P. Mattson. Acetylcholine potentiates glutamate-induced neurodegeneration in cultured hippocampal neurons. Brain Research. 1989;497(2):402-406.
- Morris JA. Zebrafish: A model system to examine the neurodevelopmental basis of schizophrenia. Prog Brain Res. 2009;179:97-106.
- N. Ivanchak, E. L. Abner, S. A. Carr, S. J. Freeman, A. Seybert, J. Ranseen, and G. A. Jicha1. Attention- Deficit/Hyperactivity Disorder in Childhood Is Associated with Cognitive Test Profiles in the Geriatric Population but Not with Mild Cognitive Impairment or Alzheimer's Disease. Journal of Aging Research. 2011; ID 729801.
- Pachauri V, Saxena G, Mehta A, Mishra D, Flora SJ. Combinational chelation therapy abrogates leadinduced neurodegeneration in rats. Toxicol Appl Pharmacol. 2009;240(2):255-64.
- Rob Willemsen, Wiebren Hasselaar, Herma van der Linde, Vincenzo Bonifati. Zebrafish as a new model organism for Parkinson’s disease. Proceedings of Measuring Behavior 2008.
- Sovan sarkar. Role of autophagy in neurodegenerative diseases. Current Science. 2011;101 (4): 464.
- Selina Wray and Wendy Noble. Linking Amyloid and Tau Pathology in Alzheimer’s Disease:The Role of Membrane Cholesterol in AL-Mediated Tau Toxicity. The Journal of Neuroscience. 2009; 29(31):9665–9667a.
- Tropepe V, Sive HL.Can zebrafish be used as a model to study the neurodevelopmental causes of autism? Genes Brain Behav. 2003;2(5):268-81.
- World Health Organization. https://www.searo.who.int/en/Section1174/Section1 199/Section1567/Section1823_8066.htm.
- Yanwei Xi, Sandra Noble and Marc Ekker. Modeling Neurodegeneration in Zebrafish. Curr Neurol Neurosci. 2011;11:274–282.
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