The environmental pollutant BDE-209 regulates NO/cGMP signaling through activation of NMDA receptors in neurons

The common flame retardant decabrominated diphenyl ether (BDE-209) is a persistent organic pollutant. Epidemiological studies have revealed that prenatal or postnatal exposure to BDE-209 can result in delayed cognitive development, and BDE-209 has been shown to be toxic to cultured neurons with maturation interference effects. However, its neurotoxic mechanism remains unclear. Nitric oxide/cyclic guanosine monophosphate (NO/cGMP) signaling plays an important role in regulating neuronal maturation. We examined the influence of BDE-209 (100, 200, and 400 nM) on NO production and cGMP levels signaling in rodent neurons in vitro, with or without pretreatment N-methyl-D-aspartate (NMDA) receptor antagonism. We found that nanomolar concentrations of BDE-209 affected levels of the second messengers NO and cGMP, and that these effects could be blocked by NMDA receptor antagonism. Moreover, BDE-209 activation of NMDA receptors inhibited the expression of phosphodiesterases (PDEs), which modulate intracellular cGMP levels, and increased the Bcl-2/Bax ratio, favoring apoptosis induction. Our studies implicate the NMDA-NO/cGMP pathway in the pathogenic mechanism through which BDE-209 induces neurotoxicity.