Chlorpyrifos- and chlorpyrifos oxon-induced neurite retraction in pre-differentiated N2a cells is associated with transient hyperphosphorylation of neurofilament heavy chain and ERK 1/2

Journal Article · Sat Oct 01 04:00:00 EDT 2016 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/J.TAAP.2016.08.008· OSTI ID:22690801

Harris, Wayne ^[1]; Arnott, Gordon ^[2]; Flaskos, John ^[3]; Lloyd Mills, Chris ^[2]

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1. Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS (United Kingdom)
2. School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS (United Kingdom)
3. Laboratory of Biochemistry and Toxicology, School of Veterinary Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

Chlorpyrifos (CPF) and CPF-oxon (CPO) are known to inhibit neurite outgrowth but little is known about their ability to induce neurite retraction in differentiating neuronal cells. The aims of this study were to determine the ability of these compounds to destabilize neurites and to identify the key molecular events involved. N2a cells were induced to differentiate for 20 h before exposure to CPF or CPO for 2–8 h. Fixed cell monolayers labeled with carboxyfluorescein succinimidyl ester or immunofluorescently stained with antibodies to tubulin (B512) or phosphorylated neurofilament heavy chain (Ta51) showed time- and concentration-dependent reductions in numbers and length of axon-like processes compared to the control, respectively, retraction of neurites being observed within 2 h of exposure by live cell imaging. Neurofilament disruption was also observed in treated cells stained by indirect immunofluorescence with anti-phosphorylated neurofilament heavy chain (NFH) monoclonal antibody SMI34, while the microtubule network was unaffected. Western blotting analysis revealed transiently increased levels of reactivity of Ta51 after 2 h exposure and reduced levels of reactivity of the same antibody following 8 h treatment with both compounds, whereas reactivity with antibodies to anti-total NFH or anti-tubulin was not affected. The alteration in NFH phosphorylation at 2 h exposure was associated with increased activation of extracellular signal-regulated protein kinase ERK 1/2. However, increased levels of phosphatase activity were observed following 8 h exposure. These findings suggest for the first time that organophosphorothionate pesticide-induced neurite retraction in N2a cells is associated with transient increases in NFH phosphorylation and ERK1/2 activation. - Highlights: • Chlorpyrifos and chlorpyrifos oxon induced rapid neurite retraction in N2a cells. • This occurred following transient hyperphosphorylation of ERK 1/2. • It was concomitant with hyperphosphorylation of neurofilament heavy chain (NFH). • Subsequent NFH dephosphorylation was associated with increased phosphatase activity. • Thus, the above changes reflect key events in chlorpyrifos induced neurodegeneration.

• OSTI ID: 22690801
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Vol. 308; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
60 APPLIED LIFE SCIENCES
CONCENTRATION RATIO
ESTERS
MICE
MICROTUBULES
MONOCLONAL ANTIBODIES
NERVE CELLS
PESTICIDES
PHOSPHATASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
REACTIVITY
TOXICITY
TRANSIENTS