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Screening for the developmental toxicity of retinoids: use of the sea urchin model
T A Kahn1, J Blumer, R A Silverman
1Department of Dermatology, Case Western Reserve University, Cleveland, Ohio 44106.
Abstract:
Retinoids are being used increasingly in dermatologic practice. Fetal malformation is a major form of toxicity associated with certain retinoids. In this study, the developmental toxicity of isotretinoin, its metabolites, and a structurally related analog, tretinoin, were evaluated using the sea urchin model. The American sea urchin, Arbacia punctulata, completes its major developmental stages within 24 hr and has been previously utilized for screening human teratogens. The parent compound, isotretinoin, induced dose-dependent delayed rather than dysmorphic development of the sea urchin embryo. In contrast, its metabolites, 4-oxo-isotretinoin and 4-oxo-tretinoin, and the analog tretinoin induced strikingly dysmorphic development. This may indicate that the metabolites of isotretinoin, rather than the parent compound, may be responsible for the fetal abnormalities observed in the "isotretinoin teratogen syndrome." Therefore, the sea urchin model might serve as a discriminating and rapid screening test for identifying other potential developmentally toxic retinoids.
Insights
Retinoids like isotretinoin can cause fetal malformations. This study used sea urchins to find that isotretinoin metabolites, not the parent drug, may cause developmental toxicity, suggesting a novel screening method.
Area of Science:
- Developmental toxicology
- Pharmacology
- Marine biology
Background:
- Retinoids are increasingly used in dermatology.
- Fetal malformation is a significant toxicity associated with certain retinoids.
- Isotretinoin is a known teratogen, but the specific toxic agents are not fully understood.
Purpose of the Study:
- To evaluate the developmental toxicity of isotretinoin, its metabolites, and tretinoin.
- To investigate the utility of the sea urchin model for screening teratogenic retinoids.
- To determine if isotretinoin metabolites are responsible for observed fetal abnormalities.
Main Methods:
- Utilized the American sea urchin (Arbacia punctulata) model for developmental toxicity screening.
- Exposed sea urchin embryos to varying doses of isotretinoin, its metabolites (4-oxo-isotretinoin, 4-oxo-tretinoin), and tretinoin.
- Observed and analyzed embryonic development over 24 hours.
Main Results:
- Isotretinoin induced dose-dependent delayed development, not dysmorphic features.
- Metabolites (4-oxo-isotretinoin, 4-oxo-tretinoin) and tretinoin caused significant dysmorphic development.
- The sea urchin model showed differential responses to the parent compound versus its metabolites and analog.
Conclusions:
- Isotretinoin metabolites, rather than the parent compound, may be the primary cause of fetal abnormalities in the "isotretinoin teratogen syndrome."
- The sea urchin model is a promising tool for rapid screening of developmental toxicity in retinoids.
- Further research into retinoid metabolism and teratogenicity is warranted.