Polybrominated diphenyl ethers (PBDEs) are persistent environmental pollutants considered as neurotoxicants and endocrine disruptors with important biological effects ranging from alterations in growth, reproduction, and effects on the hypothalamus-pituitary-adrenal axis. The vasopressinergic (AVPergic) system is a known target for pentaBDEs mixture (DE-71) and the structurally similar chemicals, polychlorinated biphenyls. However, the potential adverse effects of mixtures containing octaBDE compounds, like DE-79, on the AVPergic system are still unknown. The present study aims to examine the effects of perinatal DE-79 exposure on the AVPergic system. Dams were dosed from gestational day 6 to postnatal day 21 at doses of 0 (control), 1.7 (low) or 10.2 (high) mg/kg/day, and male offspring from all doses at 3-months-old were subjected to normosmotic and hyperosmotic challenge. Male offspring where later assessed for alterations in osmoregulation (i.e. serum osmolality and systemic vasopressin release), and both vasopressin immunoreactivity (AVP-IR) and gene expression in the hypothalamic paraventricular and supraoptic nuclei. Additionally, to elucidate a possible mechanism for the effects of DE-79 on the AVPergic system, both neuronal nitric oxide synthase immunoreactivity (nNOS-IR) and mRNA expression were investigated in the same hypothalamic nuclei. The results showed that perinatal DE-79 exposure AVP-IR, mRNA expression and systemic release in adulthood under normosmotic conditions and more evidently under hyperosmotic stimulation. nNOS-IR and mRNA expression were also affected in the same nuclei. Since NO is an AVP regulator, we propose that disturbances in NO could be a mechanism underlying the AVPergic system disruption following perinatal DE-79 exposure leading to osmoregulation deficits.
Keywords: DE-79; Neuroendocrine disruptors; Nitric oxide; Osmoregulation; PBDEs; Vasopressin.
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