Citation:

Jasmine, B. Evaluating Flame Retardant-Induced Changes in Cortical Network Ontogeny using Microelectrode Arrays. Society of Toxicology 2017 annual meeting, Baltimore, MD, March 12 - 16, 2017.

Impact/Purpose:

This abstract describes screening flame retardant compounds for activity in developing neural networks to identify potential developmental neurotoxicants.

Description:

Flame retardants (FR) are used in a variety of consumer products and human exposure to these compounds is generally via inhalation of household dust. Historically, brominated FRs (BFRs) were widely used in consumer products; due to their ability to bioaccumulate and potential neurotoxicity, BFRs are being replaced by organophosphorous FRs (OPFRs). However, information on the developmental neurotoxicity (DNT) potential of OPFRs is limited and further research is needed. The current study examined FR-induced changes in neural network ontogeny in 48 well microelectrode array (MEA) plates containing 16 electrodes/well. Spontaneous activity was assessed in cortical networks developmentally exposed to 18 FR compounds (9 OPFRs, 7 BFRs, phenol, and the BFR mixture Firemaster 550; 0.03-30 µM) over 12 days in vitro (DIV). The primary cortical culture was prepared from the neocortex of Long Evans rat pups (0-24hrs old) and maintained in culture for 12 DIV. Treated media was added to the cells two hours after seeding (DIV 0) and network activity was assessed on DIV 2,5,7,9, and 12 for 15 minutes. Following the final recording on DIV 12, the LDH and CellTiter Blue cytotoxicity assays were employed to estimate cytotoxicity. The majority of FRs had no effect on general network activity including the number of active electrodes (#AE) and mean firing rate (MFR). On DIV 12, 3 brominated FR (2-Ethylhexyl-2,3,4,5-tetrabromobenzoate, 2,2’,4,4’-Tetrabromodiphenyl ether, and 2,2’,4,4’,5-Pentabromodiphenyl ether) decreased #AE and MFR at concentrations concomitant with cytotoxicity (20 uM), while 2 FRs (PBDE-47 and Bis (2-ethylhexyl) phthalate (DEHP)) decreased these parameters in the absence of cytotoxicity. Effects on 16 parameters of network ontogeny were further quantified using area under the curve analysis to collapse developmental rate and network maturity into a single measure for each concentration, and then generate EC50 values. For all parameters, both PBDE-47 and DEHP resulted in EC50 values below those that caused cytotoxicity. These results indicate that DEHP and some BFRs disrupt development of neural networks in vitro, while other classes of FRs do not. (This abstract does not represent EPA policy).

Record Details: