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YOSHIAKI TANAKA, Rina Takagi, Machiko Shimmura-Tomita, Fuminari Yamaguchi, Yuko Katayama, Tomohisa Suzuki, Masami Shinohara, Takeshi Ohta, Tomohiko Sasase, Akihiro Kakehashi; Pathological features of diabetic retinopathy in unilaterally nephrectomized Spontaneously Diabetic Torii fatty rats given 0.3% salt water. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2714.
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© ARVO (1962-2015); The Authors (2016-present)
Unilateral nephrectomy and salt supplementation in Spontaneously Diabetic Torii (SDT) fatty rats expedite kidney disorders. However, because few studies have studied diabetic retinopathy (DR) in SDT rats, we did so in this rat model.
Male SDT fatty rats underwent unilateral nephrectomy at age 9 weeks. One week later, rats had free access to 0.3% salt water for 13 weeks (Nx+0.3% salt SDT fatty). SDT fatty rats (controls) and Sprague Dawley (SD) rats (normal controls) were given water without salt (n=6 for each rat type). Serum chemistry parameters were measured when rats were sacrificed at age 23 weeks. The eyes were enucleated for histopathology. The mean retinal thickness was measured 500 μm from the optic nerve disc. The retinal folds, defined as deformation from the outer nuclear layer to the photoreceptor layer, were counted within 1,500 μm of the optic nerve disc. Immunostaining for GFAP and VEGF was performed. Quantitative analyses of the immunopositive regions were performed using the Hybrid Cell Count Module (Keyence, Tokyo, Japan).
The glomerular filtration rate in the Nx+0.3% salt SDT fatty rats (4.8±1.3 mL/min/1.73 m2) was worse (P<0.01) than in SDT fatty rats (22.3±4.9 mL/min/1.73 m2). However, the HbA1c in the Nx+0.3% salt SDT fatty rats (9.2±1.6%) improved (P<0.01) compared with the SDT fatty rats (12.5±0.6%). The mean retinal thicknesses in Nx+0.3% salt SDT fatty, SDT fatty, and SD rats, respectively, were 205.7±35.9, 201.1±18.4, and 155.6±27.5 μm (Nx+0.3% salt SDT fatty vs. SDT fatty rats, P=0.41). Retinal folds were seen in Nx+0.3% salt SDT fatty rats (1.50±0.84) and SDT fatty rats (1.16±0.52) (Nx+0.3% salt SDT fatty vs. SDT fatty rats, P=0.38) but infrequently in SD rats (0.08±0.20) (Fig). The respective mean area ratios of GFAP positivity in the specimens were 8.2±2.2%, 7.2±2.4%, and 2.4±0.8% (Nx+0.3% salt SDT fatty vs. SDT fatty rats, P=0.57) and those of VEGF positivity were 6.3±2.3%, 4.5±1.8%, and 3.7±1.7% (Nx+0.3% salt SDT fatty vs. SDT fatty rats, P=0.15).
DR progression in unilaterally nephrectomized SDT fatty rats given 0.3% salt water was not prominent compared with SDT fatty rats. DR progression may have been suppressed by the improved blood glucose level despite development of kidney dysfunction due to unilateral nephrectomy and salt supplementation. Further analysis and examination are needed.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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