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Jessl L, Lenz R, Massing FG, Scheider J, Oehlmann J. Effects of estrogens and antiestrogens on gonadal sex differentiation and embryonic development in the domestic fowl ( Gallus gallus domesticus). PeerJ 2018; 6:e5094. [PMID: 30002959 PMCID: PMC6034593 DOI: 10.7717/peerj.5094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/05/2018] [Indexed: 01/11/2023] Open
Abstract
Since it is known that environmental contaminants have the potential to cause endocrine disorders in humans and animals, there is an urgent need for in vivo tests to assess possible effects of these endocrine disrupting chemicals (EDCs). Although there is no standardized guideline, the avian embryo has proven to be particularly promising as it responds sensitively to a number of EDCs preferentially impacting the reproductive axis. In the present study we examined the effects of in ovo exposure to fulvestrant and tamoxifen as antiestrogenic model compounds and co-exposure to both substances and the potent estrogen 17α-ethinylestradiol (EE2) regarding sex differentiation and embryonic development of the domestic fowl (Gallus gallus domesticus). The substances were injected into the yolk of fertilized eggs on embryonic day 1. On embryonic day 19 sex genotype and phenotype were determined, followed by gross morphological and histological examination of the gonads. Sole EE2-treatment (20 ng/g egg) particularly affected male gonads and resulted in an increased formation of female-like gonadal cortex tissue and a reduction of seminiferous tubules. In ovo exposure to tamoxifen (0.1/1/10 µg/g egg) strongly impaired the differentiation of female gonads, led to a significant size reduction of the left ovary and induced malformations of the ovarian cortex, while fulvestrant (0.1/1/10 µg/g egg) did not affect sexual differentiation. However, both antiestrogens were able to antagonize the feminizing effects of EE2in genetic males when administered simultaneously. Since both estrogens and antiestrogens induce concentration-dependent morphological alterations of the sex organs, the chick embryo can be regarded as a promising model for the identification of chemicals with estrogenic and antiestrogenic activity.
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Affiliation(s)
- Luzie Jessl
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Hesse, Germany.,R-Biopharm AG, Darmstadt, Hesse, Germany
| | - Rebecca Lenz
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Hesse, Germany.,Dr. Drexler + Dr. Fecher GmbH, Groß-Umstadt, Hesse, Germany
| | - Fabian G Massing
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Hesse, Germany.,ERM GmbH, Neu-Isenburg, Hesse, Germany
| | - Jessica Scheider
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Hesse, Germany
| | - Jörg Oehlmann
- Department Aquatic Ecotoxicology, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Hesse, Germany
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Jessl L, Scheider J, Oehlmann J. The domestic fowl (Gallus gallus domesticus) embryo as an alternative for mammalian experiments - Validation of a test method for the detection of endocrine disrupting chemicals. CHEMOSPHERE 2018; 196:502-513. [PMID: 29329082 DOI: 10.1016/j.chemosphere.2017.12.131] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/20/2017] [Accepted: 12/21/2017] [Indexed: 06/07/2023]
Abstract
In recent decades the embryo of Gallus g. domesticus has been widely used as a model for the study of early sexual development and the potential impact of substances affecting development, including endocrine disrupting chemicals (EDCs). Since there is no standardized procedure available for experiments with the chicken embryo, the objective of our project is to expedite the protocol to assess the potential effects of EDCs on early sexual differentiation. The main aim of the present study was to systematically investigate the natural variability of individual developmental and histological key parameters in untreated and solvent-treated control groups, since this has been insufficiently addressed so far. A further aim was to provide robust values for all parameters investigated in control and substance experiments, using two known estrogenic compounds, bisphenol A (75/150/300 μg/g egg) and 17α-ethinylestradiol (20 ng/g egg). On embryonic day 1 eggs were injected with the estrogenic compounds. On embryonic day 19 histological gonadal data as well as morphological parameters were noted. In baseline experiments with control groups the selected endpoints showed reproducible results with low variabilities. Furthermore, gonadal endpoints responded sensitively to the treatment with the two model EDCs. Thus, these endpoints are recommended for the assessment of suspected EDCs in which the values provided for all parameters can serve as validity criteria in future experiments. The embryo of G. domesticus has shown to be a suitable alternative to currently accepted mammalian bioassays for the impact assessment of EDCs on reproductive tissues.
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Affiliation(s)
- Luzie Jessl
- Goethe University Frankfurt am Main, Institute for Ecology, Evolution and Diversity, Department Aquatic Ecotoxicology, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
| | - Jessica Scheider
- Goethe University Frankfurt am Main, Institute for Ecology, Evolution and Diversity, Department Aquatic Ecotoxicology, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
| | - Jörg Oehlmann
- Goethe University Frankfurt am Main, Institute for Ecology, Evolution and Diversity, Department Aquatic Ecotoxicology, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
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Dubansky B, Verbeck G, Mach P, Burggren W. Methodology for exposing avian embryos to quantified levels of airborne aromatic compounds associated with crude oil spills. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2018; 58:163-169. [PMID: 29408758 DOI: 10.1016/j.etap.2018.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 01/09/2018] [Indexed: 06/07/2023]
Abstract
Oil spills on birds and other organisms have focused primarily on direct effects of oil exposure through ingestion or direct body fouling. Little is known of indirect effects of airborne volatiles from spilled oil, especially on vulnerable developing embryos within the bird egg. Here a technique is described for exposing bird embryos in the egg to quantifiable amounts of airborne volatile toxicants from Deepwater Horizon crude oil. A novel membrane inlet mass spectrometry system was used to measure major classes of airborne oil-derived toxicants and correlate these exposures with biological endpoints. Exposure induced a reduction in platelet number and increase in osmolality of the blood of embryos of the chicken (Gallus gallus). Additionally, expression of cytochrome P4501A, a protein biomarker of oil exposure, occurred in renal, pulmonary, hepatic and vascular tissues. These data confirm that this system for generating and measuring airborne volatiles can be used for future in-depth analysis of the toxicity of volatile organic compounds in birds and potentially other terrestrial organisms.
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Affiliation(s)
- Benjamin Dubansky
- University of North Texas, Department of Biological Sciences, Developmental Integrative Biology Cluster, 1155 Union Circle, Denton, TX, 76203, United States.
| | - Guido Verbeck
- University of North Texas, Department of Chemistry and Biochemistry, Laboratory for Imaging Mass Spectrometry, 1417 Hickory Street, Denton, TX, 76203, United States
| | - Phillip Mach
- University of North Texas, Department of Chemistry and Biochemistry, Laboratory for Imaging Mass Spectrometry, 1417 Hickory Street, Denton, TX, 76203, United States; Aberdeen Proving Ground, 5183 Balckhawk Rd, E3150, Gunpowder, MD, 21010, United States
| | - Warren Burggren
- University of North Texas, Department of Biological Sciences, Developmental Integrative Biology Cluster, 1155 Union Circle, Denton, TX, 76203, United States
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Dean KM, Baltos LD, Carro T, Iwaniuk AN, Bohannon MEB, Ottinger MA. Comparison of vehicle mortality followingin ovoexposure of Japanese quail (Coturnix japonica) eggs to corn oil, triolein and a fatty acid mix. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/23273747.2016.1224022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Gad SC, Spainhour CB, Shoemake C, Pallman DRS, Stricker-Krongrad A, Downing PA, Seals RE, Eagle LA, Polhamus K, Daly J. Tolerable Levels of Nonclinical Vehicles and Formulations Used in Studies by Multiple Routes in Multiple Species With Notes on Methods to Improve Utility. Int J Toxicol 2016; 35:95-178. [PMID: 26755718 DOI: 10.1177/1091581815622442] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Formulation of nonclinical evaluations is a challenge, with the fundamental need to achieve multiples of the clinical exposure complicated by differences in species and routes of administration-specific tolerances, depending on concentrations, volumes, dosing regimen, duration of each administration, and study duration. Current practice to approach these differences is based on individual experience and scattered literature with no comprehensive data source (the most notable exception being our 2006 publication on this same subject). Lack of formulation tolerance data results in excessive animal use, unplanned delays in the evaluation and development of drugs, and vehicle-dependent results. A consulting firm, a chemical company, and 4 contract research organizations conducted a rigorous data mining operation of vehicle data from studies dating from 1991 to 2015, enhancing the data from this author's 2006 publication (3 of the six 2015 contributors were also 2006 contributors). Additional data were found in the published literature. The results identified 108 single-component vehicles (and 305 combination formulations) used in more than 1,040 studies across multiple species (dog, primate, rat, mouse, rabbit, guinea pig, minipig, pig, chick embryo, and cat) by multiple routes for a wide range of study durations. The tabulated data include maximum tolerated use levels by species, route, duration of study, dose-limiting toxicity where reported, review of the available literature on each vehicle, guidance on syringe selection, volume and pH limits by route with basic guidance on nonclinical formulation development, and guidance on factors to be considered in nonclinical route selection.
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Kenow KP, Meyer MW, Rossmann R, Gendron-Fitzpatrick A, Gray BR. Effects of injected methylmercury on the hatching of common loon (Gavia immer) eggs. ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:1684-1693. [PMID: 21789674 DOI: 10.1007/s10646-011-0743-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/09/2011] [Indexed: 05/31/2023]
Abstract
To determine the level of in ovo methylmercury (MeHg) exposure that results in detrimental effects on fitness and survival of loon embryos and hatched chicks, we conducted a field study in which we injected eggs with various doses of MeHg on day 4 of incubation. Eggs were collected following about 23 days of natural incubation and artificially incubated to observe hatching. Reduced embryo survival was evident in eggs injected at a rate of ≥1.3 μg Hg/g wet-mass. When maternally deposited Hg and injected Hg were considered together, the median lethal concentration of Hg (LC(50)) was estimated to be 1.78 μg Hg/g wet-mass. Organ mass patterns from eggs of chicks injected at a rate of 2.9 μg Hg/g differed from that of controls and chicks from the 0.5 μg Hg/g treatment, largely related to a negative relation between yolk sac mass and egg mercury concentration. Chicks from eggs in the 2.9 μg Hg/g treatment were also less responsive to a frightening stimulus than controls and chicks from the 0.5 μg Hg/g treatment. We also found that the length of incubation period increased with increasing egg mercury concentration. Tissue Hg concentrations were strongly associated (r(2) ≥ 0.80) with egg Hg concentration.
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Affiliation(s)
- Kevin P Kenow
- Upper Midwest Environmental Sciences Center, US Geological Survey, La Crosse, WI 54603, USA.
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7
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Heinz GH, Hoffman DJ, Klimstra JD, Stebbins KR, Kondrad SL. Toxicity of methylmercury injected into eggs when dissolved in water versus corn oil. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2011; 30:2103-2106. [PMID: 21702059 DOI: 10.1002/etc.601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/25/2011] [Accepted: 05/24/2011] [Indexed: 05/31/2023]
Abstract
In a previous study, the embryotoxicity of methylmercury dissolved in corn oil was compared among 26 species of birds. Corn oil is not soluble in the water-based matrix that constitutes the albumen of an egg. To determine whether the use of corn oil limited the usefulness of this earlier study, a comparison was made of the embryotoxicity of methylmercury dissolved in corn oil versus water. Mallard (Anas platyrhynchos) and chicken (Gallus gallus) eggs were injected with methylmercury chloride dissolved in corn oil or water to achieve concentrations of 0, 0.2, 0.4, 0.8, and 1.6 µg/g mercury in the egg on a wet weight basis. Hatching success at each dose of mercury was compared between the two solvents. For mallards, 16.4% of the eggs injected with 1.6 µg/g mercury dissolved in water hatched, which was statistically lower than the 37.6% hatch rate of eggs injected with 1.6 µg/g mercury dissolved in corn oil, but no differences in hatching success were observed between corn oil and water at any of the other doses. With chicken eggs, no significant differences occurred in percentage hatch of eggs between corn oil and water at any of the mercury doses. Methylmercury dissolved in corn oil seems to have a toxicity to avian embryos similar to that of does methylmercury dissolved in water. Consequently, the results from the earlier study that described the toxicity of methylmercury dissolved in corn oil to avian embryos were probably not compromised by the use of corn oil as a solvent.
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Affiliation(s)
- Gary H Heinz
- US Geological Survey, Patuxent Wildlife Research Center, Beltsville, Maryland, USA.
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8
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Schnars JL, Voss MA, Stauffer JR. An egg injection technique to evaluate the effect of polychlorinated biphenyls on the hatching success of the snapping turtle (Chelydra serpentina serpentina). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2011; 30:915-919. [PMID: 21191884 DOI: 10.1002/etc.455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/20/2010] [Accepted: 11/01/2010] [Indexed: 05/30/2023]
Abstract
Embryos of oviparous organisms are exposed to contaminants by two pathways: contaminant uptake from the surrounding environment, and the transfer from female to offspring (maternal transfer). The initial source of contaminant exposure for most embryos is likely to be maternal transfer; therefore, maternal transfer studies are critical in determining the effects of contaminants on future populations. Injection of contaminants directly into eggs is one route of experimental contaminant exposure that permits controlled doses and potential reliable replication. This technique, however, has been used in the past with little success in reptiles. The objective of the present study was to evaluate egg injection as a means of mimicking maternal transfer of polychlorinated biphenyls (PCBs) to snapping turtle eggs. Eggs from several clutches were injected with a PCB solution and incubated at several temperatures and moisture levels to measure interactive effects of injection, environmental condition, and contaminant load on hatching success. The injection technique allowed for application of consistent and specific doses among replicates. Overall hatching success in this study was 61% and was as high as 71% within specific treatments. Hatching success was much higher in this study than in other studies using egg injections to mimic maternal transfer in chelonians and crocodilians.
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Affiliation(s)
- Jeanette L Schnars
- The Regional Science Consortium, Tom Ridge Environmental Center, Erie, Pennsylvania, USA.
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Evaluation of Steviol Injection on Chicken Embryos: Effects on Post-hatch Development, Proportional Organ Weights, Plasma Thyroid Hormones and Metabolites. J Poult Sci 2010. [DOI: 10.2141/jpsa.009059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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10
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Developmental toxicity in white leghorn chickens following in ovo exposure to perfluorooctane sulfonate (PFOS). Reprod Toxicol 2009; 27:307-318. [DOI: 10.1016/j.reprotox.2008.10.009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/23/2008] [Accepted: 10/31/2008] [Indexed: 11/22/2022]
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Augspurger TP, Tillitt DE, Bursian SJ, Fitzgerald SD, Hinton DE, Di Giulio RT. Embryo toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to the wood duck (Aix sponsa). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2008; 55:659-669. [PMID: 18704254 DOI: 10.1007/s00244-008-9198-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 07/05/2008] [Indexed: 05/26/2023]
Abstract
We examined the sensitivity of the wood duck (Aix sponsa) embryo to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by injecting the toxicant into their eggs. Six groups of wood duck eggs (n = 35 to 211 per trial) were injected with 0 to 4600 pg TCDD/g egg between 2003 and 2005. Injections were made into yolk prior to incubation, and eggs were subsequently incubated and assessed weekly for mortality. Significant TCDD-induced mortality was not observed through day 25 (90% of incubation). Liver, heart, eye, and brain histology were generally unremarkable. Hepatic ethoxyresorufin-O-deethylase activity, a biomarker of dioxin-like compound exposure, was induced by 12-fold in the 4600 pg/g treatment relative to controls. The median lethal dose for chicken (Gallus domesticus) eggs we dosed identically to wood duck eggs was about 100 pg/g, similar to other assessments of chickens. Among dioxin-like compound embryo lethality data for 15 avian genera, the wood duck 4600 pg/g no-observed-effect level ranks near the middle. Because no higher doses were tested, wood ducks may be like other waterfowl (order Anseriformes), which are comparatively tolerant to embryo mortality from polychlorinated dibenzo-p-dioxins and dibenzofurans when exposed by egg injection.
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Affiliation(s)
- T P Augspurger
- U.S. Fish and Wildlife Service, 551-F Pylon Drive, Raleigh, NC 27606, USA.
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Ottinger MA, Lavoie E, Thompson N, Barton A, Whitehouse K, Barton M, Abdelnabi M, Quinn M, Panzica G, Viglietti-Panzica C. Neuroendocrine and behavioral effects of embryonic exposure to endocrine disrupting chemicals in birds. ACTA ACUST UNITED AC 2007; 57:376-85. [PMID: 18006066 DOI: 10.1016/j.brainresrev.2007.08.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/26/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022]
Abstract
Endocrine disrupting chemicals (EDCs) exert hormone-like activity in vertebrates and exposure to these compounds may induce both short- and long-term deleterious effects including functional alterations that contribute to decreased reproduction and fitness. An overview of the effects of a number of EDCs, including androgenic and estrogenic compounds, will be considered. Many studies have been conducted in the precocial Japanese quail, which provides an excellent avian model for testing these compounds. Long-term impacts have also been studied by raising a subset of animals through maturation. The EDCs examined included estradiol, androgen active compounds, soy phytoestrogens, and atrazine. Effects on behavior and hypothalamic neuroendocrine systems were examined. All EDCs impaired reproduction, regardless of potential mechanism of action. Male sexual behavior proved to be a sensitive index of EDC exposure and embryonic exposure to a variety of EDCs consistently resulted in impaired male sexual behavior. Several hypothalamic neural systems proved to be EDC responsive, including arginine vasotocin (VT), catecholamines, and gonadotropin releasing hormone system (GnRH-I). Finally, EDCs are known to impact both the immune and thyroid systems; these effects are significant for assessing the overall impact of EDCs on the fitness of avian populations. Therefore, exposure to EDCs during embryonic development has consequences beyond impaired function of the reproductive axis. In conclusion, behavioral alterations have the advantage of revealing both direct and indirect effects of exposure to an EDC and in some cases can provide a valuable clue into functional deficits at different physiological levels.
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Affiliation(s)
- Mary Ann Ottinger
- Department of Animal and Avian Sciences, University of Maryland College Park, MD 20742, USA.
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Gad SC, Cassidy CD, Aubert N, Spainhour B, Robbe H. Nonclinical vehicle use in studies by multiple routes in multiple species. Int J Toxicol 2007; 25:499-521. [PMID: 17132609 DOI: 10.1080/10915810600961531] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The laboratory toxicologist is frequently faced with the challenge of selecting appropriate vehicles or developing utilitarian formulations for use in in vivo nonclinical safety assessment studies. Although there are many vehicles available that may meet physical and chemical requirements for chemical or pharmaceutical formulation, there are wide differences in species and route of administration specific to tolerances to these vehicles. In current practice, these differences are largely approached on a basis of individual experience as there is only scattered literature on individual vehicles and no comprehensive treatment or information source. This approach leads to excessive animal use and unplanned delays in testing and development. To address this need, a consulting firm and three contract research organizations conducted a rigorous data mining operation of control (vehicle) data from studies dating from 1991 to present. The results identified 65 single component vehicles used in 368 studies across multiple species (dog, primate, rat, mouse, rabbit, guinea pig, minipig, chick embryo, and cat) by multiple routes. Reported here are the results of this effort, including maximum tolerated use levels by species, route, and duration of study, with accompanying dose limiting toxicity. Also included are basic chemical information and a review of available literature on each vehicle, as well as guidance on volume limits and pH by route and some basic guidance on nonclinical formulation development.
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Affiliation(s)
- Shayne C Gad
- Gad Consulting Services, Cary, North Carolina 27518, USA.
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DeWitt JC, Meyer EB, Henshel DS. Environmental toxicity studies using chickens as surrogates for wildlife: effects of injection day. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2005; 48:270-277. [PMID: 15750775 DOI: 10.1007/s00244-004-2006-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2003] [Accepted: 06/23/2004] [Indexed: 05/24/2023]
Abstract
Domestic chicken embryos are frequently used for avian developmental toxicity studies of polyhalogenated aromatic hydrocarbons, which are often injected into eggs with oil-based vehicles. Injection times range from immediately prior to incubation (embryonic day zero, E0) to after 4 days of incubation (E4) and beyond. Because the majority of organogenesis in chicken embryos occurs during the first 4 days of development, injection after E0 may miss critical, sensitive, developmental periods. We evaluated whether differences in the day of vehicle administration would lead to differences in standard measures of embryotoxicity. We assessed embryotoxicity using mortality, organ somatic indices, teratogenesis, and behavior in hatchling chickens developmentally exposed to a high volume (1.0 microl/g egg) of corn oil vehicle, which was injected into the airsac at E0 or E4. The E0 vehicle group had 76.5% higher overall embryo mortality, embryos died earlier in development, and hatchlings took more than two times longer to right in a righting reflex test compared to the E4 vehicle group. Other behavioral results demonstrated that hatchling chickens from the E0 vehicle group performed differently from their respective no-inject controls, whereas hatchling chickens from the E4 vehicle group did not. The bursal somatic index differed statistically by injection day and weighed 23.7% more in the E0 vehicle group than the E4 vehicle group. These results suggest that the embryonic day of contaminant injection is an important consideration, particularly when using a high volume of vehicle to evaluate developmental toxicity of a contaminant on embryo mortality or behavior.
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Affiliation(s)
- Jamie C DeWitt
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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