PFOS-induced excitotoxicity is dependent on Ca2+ influx via NMDA receptors in rat cerebellar granule neurons

Hanne Friis Berntsen; Cesilie Granum Bjørklund; Rønnaug Strandabø; Trude Marie Haug; Angel Moldes-Anaya; Judit Fuentes-Lazaro; Steven Verhaegen; Ragnhild Elisabeth Paulsen; R Andrew Tasker; Erik Ropstad

doi:10.1016/j.taap.2018.08.015

PFOS-induced excitotoxicity is dependent on Ca²⁺ influx via NMDA receptors in rat cerebellar granule neurons

Toxicol Appl Pharmacol. 2018 Oct 15:357:19-32. doi: 10.1016/j.taap.2018.08.015. Epub 2018 Aug 23.

Affiliations

¹ Department of Production Animal Clinical Sciences, NMBU-School of Veterinary Science, P.O. Box 8146 Dep, N-0033 Oslo, Norway; Department of Administration, Lab Animal Unit, National Institute of Occupational Health, P.O. Box 8149 Dep, N-0033 Oslo, Norway. Electronic address: hanne.friis.berntsen@nmbu.no.
² Department of Production Animal Clinical Sciences, NMBU-School of Veterinary Science, P.O. Box 8146 Dep, N-0033 Oslo, Norway.
³ Department of Biosciences, University of Oslo, Oslo, Norway.
⁴ Department of Oral Biology, University of Oslo, Oslo, Norway.
⁵ R&D section, PET-center, University Hospital of North Norway (UNN), Tromsø, Norway; Neurobiology Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.
⁶ Department of Pharmaceutical Biosciences, University of Oslo, Oslo, Norway.
⁷ Department of Biomedical Sciences, University of Prince Edward Island, 550 University Avenue, Charlottetown PEI, C1A4P3, Canada.

PMID: 30144469
DOI: 10.1016/j.taap.2018.08.015

Abstract

Perfluoroalkyl acids (PFAAs) are persistent compounds used in many industrial as well as consumer products. Despite restrictions, these compounds are found at measurable concentrations in samples of human and animal origin. In the present study we examined whether the effects on cell viability of two sulfonated and four carboxylated PFAAs in cultures of cerebellar granule neurons (CGNs), could be associated with deleterious activation of the N-methyl-d-aspartate receptor (NMDA-R). PFAA-induced effects on viability in rat CGNs and unstimulated PC12 cells were examined using the MTT assay. Cells from the PC12 rat pheochromocytoma cell line lack the expression of functional NMDA-Rs and were used to verify lower toxicity of perfluorooctanesulfonic acid (PFOS) in cells not expressing NMDA-Rs. Protective effects of NMDA-R antagonists, and extracellular as well as intracellular Ca²⁺ chelators were investigated. Cytosolic Ca²⁺ ([Ca²⁺]_i) was measured using Fura-2. In rat CGNs the effects of the NMDA-R antagonists MK-801, memantine and CPP indicated involvement of the NMDA-R in the decreased viability induced by PFOS and perfluorohexanesulfonic acid (PFHxS). No effects were associated with the four carboxylated PFAAs studied. Further, EGTA and CPP protected against PFOS-induced decreases in cell viability, whereas no protection was afforded by BAPTA-AM. [Ca²⁺]_i significantly increased after exposure to PFOS, and this increase was completely blocked by MK-801. In PC12 cells a higher concentration of PFOS was required to induce equivalent levels of toxicity as compared to in rat CGNs. PFOS-induced toxicity in PC12 cells was not affected by CPP. In conclusion, PFOS at the tested concentrations induces excitotoxicity in rat CGNs, which likely involves influx of extracellular Ca²⁺ via the NMDA-R. This effect can be blocked by specific NMDA-R antagonists.

Keywords: Cerebellar granule neurons; Cytosolic Ca(2+); Excitotoxicity; Fura-2; N-methyl-d-aspartate receptor; Perfluorooctanesulfonic acid.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Alkanesulfonic Acids / toxicity*
Animals
Calcium / metabolism*
Caprylates / toxicity
Cell Survival / drug effects
Cerebellum / cytology*
Fluorocarbons / toxicity*
Gene Expression Regulation / drug effects
Neurons / drug effects*
PC12 Cells
Rats
Receptors, Ionotropic Glutamate
Receptors, N-Methyl-D-Aspartate / metabolism*

Substances

Alkanesulfonic Acids
Caprylates
Fluorocarbons
Receptors, Ionotropic Glutamate
Receptors, N-Methyl-D-Aspartate
perfluorooctanoic acid
perfluorooctane sulfonic acid
Calcium