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Kayla Fogasina Titialii, Hannah Henson, Kristine Shady, Ann C Morris; Elucidating the effects of hyperglycemia on retinal development in Danio rerio. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3114.
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© ARVO (1962-2015); The Authors (2016-present)
Poor blood glucose regulation in Type I and II diabetes has been linked to various long term metabolic disruptions in adults, such as tissue damage in the eye. Yet, little is known about the effects of embryonic hyperglycemia on retinal development. To address this question, our lab has established a protocol for inducing hyperglycemia in zebrafish embryos which we have used to assess the effects of embryonic hyperglycemia.
All animal procedures were performed in accordance with guidelines established by the ARVO statement for the Use of Animals in Opthalmic and Vision Research. Wild-type and XOPS:GFP zebrafish embryos were submerged in fish water containing 50mM or 200mM glucose, fructose, or mannitol and/or 10 µM dexamethasone. Treatment began at either 10 or 24 hours post fertilization (hpf) until 72 or 96 hpf. At the end of the treatment, larval heads were fixed in paraformaldehyde, the rest of the body was homogenized and used to quantify glucose concentration using a glucose assay from Biovision. The fixed heads were processed for sectioning and immunohistochemistry to label and quantify various cell types in the retina including rod and cone photoreceptors, proliferating cells, ganglion, amacrine, bipolar, and horizontal cells. Each treatment was performed a minimum of three times, and 15-25 animals were included in each group.
Our results show that treatment with 50 or 200 mM glucose + 10 µM dexamethasone, 50 mM fructose, or 200 mM fructose +/- 10 µM dexamethasone starting at 10 or 24 hpf until 72 or 96 hpf increased glucose concentration of the embryos by more than 2.5-fold compared to untreated and mannitol-treated embryos. Hyperglycemia by glucose and dexamethasone treatment was associated with reduced eye size, a significant reduction in rod photoreceptor cells, and an increase in retinal cell apoptosis, in comparison to untreated embryos at 96 hpf. Hyperglycemia by fructose treatment was associated with an increase in rod and cone photoreceptors at 72 hpf.
Our results suggest that embryonic hyperglycemia results in abnormal retinal development in the zebrafish. Given the significant similarities in metabolic regulation and visual system development between zebrafish and humans, these findings should advance our understanding of how hyperglycemia during pregnancy or in neonates induces ocular complications, and may reveal useful therapeutic targets.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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