Fig 1.
Body weights of streptozotocin-induced diabetic rats (STZ) and sham control (CTRL) rats before, and at 3, 5, 7, 14, 21 and 28 days after experimental model induction via systemic drug injection.
Both groups increased their body weights over time (Repeated measures ANOVA, p<0.0001), whereas the STZ group consistently showed lower weight gain than the CTRL group after systemic drug administration (Post-hoc Sidak’s multiple comparisons correction tests, *p<0.0001).
Fig 2.
Blood glucose level at 1 month after streptozotocin (STZ) or sham control (CTRL) treatment.
(Two-tailed unpaired Student’s t-test between STZ and CTRL groups, *p<0.05.)
Fig 3.
Diffusion tensor MRI of white matter integrity in the prechiasmatic optic nerve (ON), optic tract (OT) and anterior commissure (AC) (arrows).
(Top row) Color-encoded fractional anisotropy (FA) directionality maps; (Middle row) FA value maps; (Bottom row) Illustrations of the regions of interest (ROI) in yellow at the corresponding Bregma locations for quantitative analyses. Note the relatively lower FA in the optic nerves of the streptozotocin (STZ) group compared to the sham control (CTRL) group. Color ball illustrates the corresponding principal diffusion directions in the color-encoded FA directionality map: blue: caudal-rostral; red: left-right; and green: dorsal-ventral.
Fig 4.
Quantitative comparisons of fractional anisotropy (FA), axial diffusivity (λ//) and radial diffusivity (λ┴) of the bilateral prechiasmatic optic nerve, optic tract and anterior commissure between streptozotocin (STZ) and sham control (CTRL) rats in diffusion tensor MRI.
(Post-hoc Sidak’s multiple comparisons correction tests, *p<0.05; **p<0.01.)
Fig 5.
Chromium (Cr)-enhanced MRI of the retina in the streptozotocin (STZ) and sham control (CTRL) groups.
(Top panel) Cr-enhanced MRI of the retina at 1 month after systemic STZ or CTRL administration, and 1 day after intravitreal Cr injection into the left eye. The regions of interest (ROI) for quantitative measurements were illustrated on both sides of the retina in yellow. Note the signal enhancements in the left retina of both groups (arrows); (Bottom panel) Quantitative comparisons of Cr signal enhancements in the retina. Significantly higher signal intensities were found in the left retina than the right retina of both STZ and CTRL groups (Post-hoc Sidak’s multiple comparisons correction tests, p<0.001). No apparent difference was found in Cr enhancement in the retina between the two groups. (Post-hoc Sidak’s multiple comparisons correction tests, p>0.05.)
Fig 6.
Manganese (Mn)-enhanced MRI of anterograde Mn transport along the visual pathway in streptozotocin (STZ) and sham control (CTRL) groups.
(Left panel) Mn-enhanced MRI of the visual brain nuclei at 1 month after systemic STZ or CTRL administration, and 1 day after intravitreal MnCl2 injection into the right eye. The regions of interest (ROI) for quantitative measurements were illustrated on both sides of the lateral geniculate nucleus (LGN), superior colliculus (SC) and visual cortex (VC) in yellow (arrows). Note the signal enhancements in the left lateral geniculate nucleus and left superior colliculus of both groups; (Right panel) Quantitative comparisons of Mn signal enhancements in the visual brain nuclei. Significantly higher signal intensities were found in the left LGN and SC than the right ones in both STZ and CTRL groups (Post-hoc Sidak’s multiple comparisons correction tests, p<0.01). No apparent difference in signal intensity was found between left and right VC in either group (Post-hoc Sidak’s multiple comparisons correction tests, p>0.05). No apparent difference in Mn enhancement was found in the lateral geniculate nucleus, the superior colliculus or the visual cortex between the two groups (Post-hoc Sidak’s multiple comparisons correction tests, p>0.05).