Histological and electrophysiological changes in the retinal pigment epithelium after injection of sodium iodate in the orbital venus plexus of pigmented rats
Hamid Aboutaleb Kadkhodaeian MS 1, Taki Tiraihi PhD 1, Narsis Daftarian MD 2, Hamid Ahmadieh MD 3, Hossein Ziaei MD 3, Taher Taheri MD 4
1 Deparment of Anatomical Sciences, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
2 Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
3 Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
4 Shefa Neuroscience Research Center, Khatam-Al-Anbia Hospital, Tehran, Iran
Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, No. 23, Paidarfard St., Boostan 9 St., Pasdaran Ave., Tehran 16666
Department of Anatomy, Tarbiat Modares University, Jalal Al Ahmad Highway, Tehran 14155
Source of Support: None, Conflict of Interest: None
Purpose: To characterize histopathologic and electroretinographic (ERG) changes in the retina of pigmented rats injected with sodium iodate in order to establish a model of retinal degeneration for future cell therapy studies.
Methods: In 50 male pigmented rats weighing 250-300 grams, NaIO3was injected into the left orbital venous plexus at 40 and 60 mg/kg doses (25 eyes in each group). Fourteen rats received phosphate buffered saline (PBS) injection in their left orbital plexus and were considered as the sham-control group. Histopathologic and ERG studies were performed at baseline and on days 1, 7, 14 and 28 after the injections.
Results: Progressive retinal pigment epithelial (RPE) changes were observed from the first day of injection in both the 40 and 60 mg/kg study groups in a dose dependent manner. These changes manifested as loss of melanin pigment and accumulation of lipofuscin in RPE cells with subsequent cell death and patchy loss of RPE cells (in flat mounts), as well as thinning of the outer nuclear layer and later the inner nuclear layer in the succeeding days. ERG showed a progressive and significant decrease in a- and b- wave amplitudes in both case groups relative to baseline values and the controls (P < 0.05).
Conclusion: NaIO3injection into the retrobulbar venous plexus of pigmented rats can result in significant and progressive damage to the RPE and subsequently to the neuroretina of the injected eye, and may serve as a model of retinal degeneration.