Acute exposure: a more in-depth analysis of DWH oil impacts on vertebrate stress axis endpoints

The Deepwater Horizon (DWH) oil spill was the largest in U.S. history – the toxicity of DWH polycyclic aromatic hydrocarbons (PAHs) is well-established, but a knowledge gap exists regarding how they affect the vertebrate stress axis. We hypothesized that 1) marine vertebrates exposed to DWH PAHs experience stress axis impairment, and that co-exposure to an additional stressor may exacerbate these effects, 2) 5-HT may act as a secondary cortisol secretagogue in DWH PAH-exposed fish to compensate for impairment, and 3) the mechanism of stress axis impairment would be either a decrease in MC2R functionality or total kidney cholesterol concentration. In vivo plasma cortisol, plasma ACTH, plasma 5-HT concentrations in Gulf toadfish exposed to environmentally relevant DWH PAH concentrations for 7 days with or without exposure to chronic simulated predator stress was measured. In vitro cumulative kidney cortisol secretion in response to ACTH or 5-HT in kidneys from control or PAH exposed fish were tested. Furthermore, kidney cAMP and cholesterol concentrations and kidney mRNA expression of CYP1A and steroidogenic proteins (StAR, 11-beta-hydroxylase, P450scc) in control and PAH-exposed fish were analyzed.

Experiments were completed at RSMAS, University of Miami, MTLSS building rm. 211. Experiments were started in November 2019 and completed in March 2020.