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Kelly E, Petersen LH, Huggett D, Hala D. Reaction thermodynamics as a constraint on piscine steroidogenesis flux distributions. Comp Biochem Physiol A Mol Integr Physiol 2024; 287:111533. [PMID: 37844836 DOI: 10.1016/j.cbpa.2023.111533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/18/2023]
Abstract
While a considerable amount is known of the dynamics of piscine steroidogenesis during reproduction, the influence of thermodynamics constraints on its control has not been studied. In this manuscript, Gibbs free energy change of reactions was calculated for piscine steroidogenesis using the in silico eQuilibrator thermodynamics calculator. The analysis identified cytochrome P450 (cyp450) oxidoreductase reactions to have more negative Gibbs free energy changes relative to hydroxysteroid (HSD) and transferase reactions. In addition, a more favorable Gibbs free energy change was predicted for the Δ5 (cyp450 catalyzed) vs. Δ4 (HSD catalyzed) steroidogenesis branch-point, which converts pregnenolone to 17α-hydroxypregnenolone or progesterone respectively. Comparison of in silico predictions with in vivo experimentally measured flux across the Δ5 vs. Δ4 branch-point showed higher flux through the thermodynamically more favorable Δ5 pathway in reproducing or spawning vs. non-spawning fathead minnows (Pimephales promelas). However, the exposure of fish to endocrine stressors such as hypoxia or the synthetic estrogen 17α-ethinylestradiol (EE2), resulted in increased flux through both Δ5 and Δ4 pathways, indicating an adaptive response to increase steroidogenic redundancy. The correspondence of elevated flux through the Δ5 branch-point in spawning fish indicated the use of a thermodynamically favorable pathway to optimize steroid hormone productions during reproduction. We hypothesize that such selective use of a thermodynamically favorable steroidogenesis pathway may conserve reduced equivalents or transcriptional costs for investment to other biosynthetic or catabolic reactions to support reproduction. If generalizable, such an approach can provide novel insights into the structural principles and regulation of steroidogenesis or other metabolic pathways.
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Affiliation(s)
- E Kelly
- Binghamton University, 4400 Vestal Parkway E, Binghamton, NY, USA; Department of Marine Biology, Texas A&M University at Galveston, TX, USA
| | - L H Petersen
- Department of Marine Biology, Texas A&M University at Galveston, TX, USA
| | - D Huggett
- University of North Texas, Denton, TX, USA
| | - D Hala
- Department of Marine Biology, Texas A&M University at Galveston, TX, USA.
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Martin OV, Adams J, Beasley A, Belanger S, Breton RL, Brock TCM, Buonsante VA, Galay Burgos M, Green J, Guiney PD, Hall T, Hanson M, Harris MJ, Henry TR, Huggett D, Junghans M, Laskowski R, Maack G, Moermond CTA, Panter G, Pease A, Poulsen V, Roberts M, Rudén C, Schlekat CE, Schoeters I, Solomon KR, Staveley J, Stubblefield B, Sumpter JP, Warne MSJ, Wentsel R, Wheeler JR, Wolff BA, Yamazaki K, Zahner H, Ågerstrand M. Improving environmental risk assessments of chemicals: Steps towards evidence-based ecotoxicology. Environ Int 2019; 128:210-217. [PMID: 31059916 DOI: 10.1016/j.envint.2019.04.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/16/2019] [Accepted: 04/22/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Olwenn V Martin
- Dept of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Julie Adams
- School of Environmental Studies, Queen's University, Kingston, Ontario, Canada
| | | | - Scott Belanger
- Global Product Stewardship, Procter & Gamble, Cincinnati, OH, USA
| | | | - Theo C M Brock
- Wageningen Environmental Research, Wageningen University and Research, the Netherlands
| | | | - Malyka Galay Burgos
- European Centre for Ecotoxicology and Toxicology of Chemicals, Brussels, Belgium
| | | | | | | | - Mark Hanson
- Department of Environment and Geography, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Tala R Henry
- Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency, Washington, DC, USA
| | | | - Marion Junghans
- Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Dübendorf, Switzerland
| | - Ryszard Laskowski
- Institute of Environmental Sciences, Jagiellonian University in Kraków, Poland
| | - Gerd Maack
- German Environment Agency (UBA), Dessau-Roßlau, Germany
| | - Caroline T A Moermond
- National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Grace Panter
- wca (previously affiliated with Syngenta Ltd., Berkshire, UK), Faringdon, UK
| | | | | | | | - Christina Rudén
- Department of Environmental Science and Analytical Chemistry (ACES), Stockholm University, Sweden
| | | | | | - Keith R Solomon
- Centre for Toxicology, University of Guelph, Guelph, ON, Canada
| | | | - Bill Stubblefield
- Dept of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - John P Sumpter
- Dept of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Michael St J Warne
- School of Earth and Environmental Sciences, University of Queensland, Australia; Queensland Department of Environment and Science, Australia; Centre for Agroecology, Water and Resilience, Coventry University, UK
| | | | - James R Wheeler
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Abingdon, Oxfordshire, UK
| | - Brian A Wolff
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Holly Zahner
- United States Food and Drug Administration, Center for Veterinary Medicine, Rockville, MD, USA
| | - Marlene Ågerstrand
- Department of Environmental Science and Analytical Chemistry (ACES), Stockholm University, Sweden.
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Borghoff SJ, Fitch S, Rager JE, Huggett D. A hypothesis-driven weight-of-evidence analysis to evaluate potential endocrine activity of perfluorohexanoic acid. Regul Toxicol Pharmacol 2018; 99:168-181. [PMID: 30240830 DOI: 10.1016/j.yrtph.2018.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/31/2018] [Accepted: 09/01/2018] [Indexed: 12/11/2022]
Abstract
Perfluorohexanoic acid (PFHxA) is a potential impurity and environmental degradation product of C6-based fluorotelomer products. Considering the potential endocrine activity of perfluoroalkyl acids, a hypothesis-driven weight-of-evidence (WoE) analysis was conducted to evaluate the potential endocrine disruptor activity of PFHxA, as defined by World Health Organization (WHO), across estrogen (E), androgen (A), thyroid (T), and steroidogenesis (S) pathways. A comprehensive literature search identified primary and secondary studies across species for review. The ToxCast/Tox21 database provided in vitro data. Studies identified were reviewed for reliability, and relevance, with endocrine endpoints ranked, and lines of evidence evaluated across pathways. Overall, PFHxA showed no endocrine effects in Japanese medaka, juvenile rainbow trout, chickens or reproductive parameters in northern bobwhite with no significant activity in rodent repeated-dose toxicity, lifetime cancer, or reproductive and developmental studies. In vitro, there was weak or negative activity for T transport protein or activation of E, A or T receptors. PFHxA was also negative in vitro and in vivo for disrupting steroidogenesis. Based on this WoE endocrine analysis, PFHxA exposure did not cause adverse effects associated with alterations in endocrine activity in these models, as such would not be characterized as an endocrine disruptor according to the WHO definition.
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Affiliation(s)
| | - S Fitch
- ToxStrategies, Katy, TX, USA
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Nallani G, Venables B, Constantine L, Huggett D. Comparison of Measured and Predicted Bioconcentration Estimates of Pharmaceuticals in Fish Plasma and Prediction of Chronic Risk. Bull Environ Contam Toxicol 2016; 96:580-4. [PMID: 27003806 DOI: 10.1007/s00128-016-1782-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/15/2016] [Indexed: 05/13/2023]
Abstract
Evaluation of the environmental risk of human pharmaceuticals is now a mandatory component in all new drug applications submitted for approval in EU. With >3000 drugs currently in use, it is not feasible to test each active ingredient, so prioritization is key. A recent review has listed nine prioritization approaches including the fish plasma model (FPM). The present paper focuses on comparison of measured and predicted fish plasma bioconcentration factors (BCFs) of four common over-the-counter/prescribed pharmaceuticals: norethindrone (NET), ibuprofen (IBU), verapamil (VER) and clozapine (CLZ). The measured data were obtained from the earlier published fish BCF studies. The measured BCF estimates of NET, IBU, VER and CLZ were 13.4, 1.4, 0.7 and 31.2, while the corresponding predicted BCFs (based log Kow at pH 7) were 19, 1.0, 7.6 and 30, respectively. These results indicate that the predicted BCFs matched well the measured values. The BCF estimates were used to calculate the human: fish plasma concentration ratios of each drug to predict potential risk to fish. The plasma ratio results show the following order of risk potential for fish: NET > CLZ > VER > IBU. The FPM has value in prioritizing pharmaceutical products for ecotoxicological assessments.
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Affiliation(s)
| | - Barney Venables
- Department of Biological Sciences, University of North Texas, Denton, TX, 76203, USA
| | - Lisa Constantine
- Pfizer Global Research and Development, Eastern Point Rd, Groton, CT, 06340, USA
| | - Duane Huggett
- Environmental Risk Assessment, Waterborne Environmental Inc., Lessburg, VA, USA
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Hoke R, Huggett D, Brasfield S, Brown B, Embry M, Fairbrother A, Kivi M, Paumen ML, Prosser R, Salvito D, Scroggins R. Review of laboratory-based terrestrial bioaccumulation assessment approaches for organic chemicals: Current status and future possibilities. Integr Environ Assess Manag 2016; 12:109-122. [PMID: 26272585 DOI: 10.1002/ieam.1692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/09/2015] [Accepted: 07/13/2015] [Indexed: 06/04/2023]
Abstract
In the last decade, interest has been renewed in approaches for the assessment of the bioaccumulation potential of chemicals, principally driven by the need to evaluate large numbers of chemicals as part of new chemical legislation, while reducing vertebrate test organism use called for in animal welfare legislation. This renewed interest has inspired research activities and advances in bioaccumulation science for neutral organic chemicals in aquatic environments. In January 2013, ILSI Health and Environmental Sciences Institute convened experts to identify the state of the science and existing shortcomings in terrestrial bioaccumulation assessment of neutral organic chemicals. Potential modifications to existing laboratory methods were identified, including areas in which new laboratory approaches or test methods could be developed to address terrestrial bioaccumulation. The utility of "non-ecotoxicity" data (e.g., mammalian laboratory data) was also discussed. The highlights of the workshop discussions are presented along with potential modifications in laboratory approaches and new test guidelines that could be used for assessing the bioaccumulation of chemicals in terrestrial organisms.
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Affiliation(s)
- Robert Hoke
- DuPont, Haskell Global Centers for Health and Environmental Sciences, Newark, Delaware, USA
| | | | - Sandra Brasfield
- US Army Engineer Research and Development Center, Vicksburg, Mississippi
| | - Becky Brown
- AstraZeneca, Global Environment, Cheshire, United Kingdom; Present address: WCA, Brunel House, Volunteer Way, Faringdon, Oxfordshire, United Kingdom
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Wood DM, Panayi P, Davies S, Huggett D, Collignon U, Ramsey J, Button J, Holt DW, Dargan PI. Analysis of recreational drug samples obtained from patients presenting to a busy inner-city emergency department: a pilot study adding to knowledge on local recreational drug use. Emerg Med J 2010; 28:11-3. [DOI: 10.1136/emj.2009.085142] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Flippin JL, Huggett D, Foran CM. Changes in the timing of reproduction following chronic exposure to ibuprofen in Japanese medaka, Oryzias latipes. Aquat Toxicol 2007; 81:73-8. [PMID: 17166604 DOI: 10.1016/j.aquatox.2006.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 11/03/2006] [Accepted: 11/04/2006] [Indexed: 05/13/2023]
Abstract
Effluents from wastewater treatment plants and untreated sewage constitute a low concentration but continuous source of pharmaceutical products to the aquatic environment. One such drug, ibuprofen, is a non-steroidal anti-inflammatory agent that primarily acts through inhibition of cyclooxygenase (COX) activity. Oryzias latipes (Japanese medaka) were exposed for 6 weeks via water to three concentrations of ibuprofen (1-100 microg/L nominal concentrations) and a water control. Reproductive parameters, including frequency of spawning, fecundity, egg size, and rate of fertilization, were measured for each pair of adult medaka following 6 weeks of exposure. Livers homogenates from exposed individuals were assayed for COX activity and whole individuals were histologically examined for tissue damage. Increasing exposure to ibuprofen significantly increased the number of eggs per reproductive event, but decreased the number of spawning events per week. Liver tissue collected from females had less variability in COX activity with increasing concentration of ibuprofen exposure, and tended to have elevated hepatosomatic indices. No pathological damage was evident the in the gills, livers and head kidneys of animals from the highest exposure group. The results of this experiment begin to show that exposure to chronic low levels of ibuprofen alter the pattern of reproduction and may produce sex-specific responses in teleosts.
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Affiliation(s)
- Jennifer L Flippin
- Department of Biology, West Virginia University, Morgantown, WV 26506-6057, United States
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Hutchinson TH, Barrett S, Buzby M, Constable D, Hartmann A, Hayes E, Huggett D, Laenge R, Lillicrap AD, Straub JO, Thompson RS. A strategy to reduce the numbers of fish used in acute ecotoxicity testing of pharmaceuticals. Environ Toxicol Chem 2003; 22:3031-3036. [PMID: 14713046 DOI: 10.1897/02-558] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The pharmaceutical industry gives high priority to animal welfare in the process of drug discovery and safety assessment. In the context of environmental assessments of active pharmaceutical ingredients (APIs), existing U.S. Food and Drug Administration and draft European regulations may require testing of APIs for acute ecotoxicity to algae, daphnids, and fish (base-set ecotoxicity data used to derive the predicted no-effect concentration [PNECwater] from the most sensitive of three species). Subject to regulatory approval, it is proposed that testing can be moved from fish median lethal concentration (LC50) testing (typically using > or = 42 fish/API) to acute threshold tests using fewer fish (typically 10 fish/API). To support this strategy, we have collated base-set ecotoxicity data from regulatory studies of 91 APIs (names coded for commercial reasons). For 73 of the 91 APIs, the algal median effect concentration (EC50) and daphnid EC50 values were lower than or equal to the fish LC50 data. Thus, for approximately 80% of these APIs, algal and daphnid acute EC50 data could have been used in the absence of fish LC50 data to derive PNECwater values. For the other 18 APIs, use of an acute threshold test with a step-down factor of 3.2 is predicted to give comparable PNECwater outcomes. Based on this preliminary scenario of 91 APIs, this approach is predicted to reduce the total number of fish used from 3,822 to 1,025 (approximately 73%). The present study, although preliminary, suggests that the current regulatory requirement for fish LC50 data regarding APIs should be succeeded by fish acute threshold (step-down) test data, thereby achieving significant animal welfare benefits with no loss of data for PNECwater estimates.
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Affiliation(s)
- Thomas H Hutchinson
- AstraZeneca Global Safety Health and Environment, Brixham Environmental Laboratory, TQ5 8BA, United Kingdom.
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