PUBLICATION

Effects of Low-Dose Embryonic Thyroid Disruption and Rearing Temperature on the Development of the Eye and Retina in Zebrafish

Authors
Reider, M., Connaughton, V.P.
ID
ZDB-PUB-140925-2
Date
2014
Source
Birth defects research. Part B, Developmental and reproductive toxicology   101(5): 347-54 (Journal)
Registered Authors
Connaughton, Victoria P.
Keywords
development, methimazole, retina, thyroid, zebrafish
MeSH Terms
  • Animals
  • Antithyroid Agents/pharmacology*
  • Embryo, Nonmammalian/drug effects
  • Hypothyroidism/chemically induced
  • Methimazole/pharmacology*
  • Retina/embryology*
  • Retina/physiology*
  • Temperature
  • Thyroid Gland/physiology
  • Thyroid Hormones
  • Zebrafish/embryology*
PubMed
25250784 Full text @ Birth Defects Res. B Dev. Reprod. Toxicol.
Abstract
Thyroid hormones are required for vertebrate development, and disruption of the thyroid system in developing embryos can result in a large range of morphologic and physiologic changes, including in the eye and retina. In this study, our anatomic analyses following low-dose, chronic thyroid inhibition reveal that both methimazole (MMI) exposure and rearing temperature affect eye development in a time- and temperature-dependent fashion. Maximal sensitivity to MMI for external eye development occurred at 65 hr postfertilization (hpf) for zebrafish reared at 28°C, and at 69 hpf for those reared at 31°C. Changes in eye diameter corresponded to changes in thickness of two inner retinal layers: the ganglion cell layer and the inner plexiform layer, with irreversible MMI-induced decreases in layer thickness observed in larvae treated with MMI until 66 hpf at 28°C. We infer that maximal sensitivity to MMI between 65 and 66 hpf at 28°C indicates a critical period of thyroid-dependent eye and retinal development. Furthermore, our results support previous work that shows spontaneous escape from MMI-induced effects potentially due to embryonic compensatory actions, as our data show that embryos treated beyond the critical period generally resemble controls.
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