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Sodium iodate selectively injuries the posterior pole of the retina in a dose-dependent manner: morphological and electrophysiological study.

Machalińska A, Lubiński W, Kłos P, Kawa M, Baumert B, Penkala K, Grzegrzółka R, Karczewicz D, Wiszniewska B, Machaliński B - Neurochem. Res. (2010)

Bottom Line: Sequential morphological and functional features of retinal damage in mice exposed to different doses (40 vs. 20 mg/kg) of sodium iodate (NaIO(3)) were analyzed.The peak of photoreceptor apoptosis was found on the 3rd day, but the lower dose induced more intense reaction within the central retina than in its peripheral region.In conclusion, these results indicate that peripheral area of the retina reveals better resistance to NaIO(3) injury than its central part.

View Article: PubMed Central - PubMed

Affiliation: Department of Histology and Embryology, Pomeranian Medical University, Szczecin, Poland. annam@sci.pam.szczecin.pl

ABSTRACT
Sequential morphological and functional features of retinal damage in mice exposed to different doses (40 vs. 20 mg/kg) of sodium iodate (NaIO(3)) were analyzed. Retinal morphology, apoptosis (TUNEL assay), and function (electroretinography; ERG) were examined at several time points after NaIO(3) administration. The higher dose of NaIO(3) caused progressive degeneration of the whole retinal area and total suppression of scotopic and photopic ERG. In contrast, the lower dose induced much less severe degeneration in peripheral part of retina along with a moderate decline of b- and a-wave amplitudes in ERG, corroborating the presence of regions within retina that retain their function. The peak of photoreceptor apoptosis was found on the 3rd day, but the lower dose induced more intense reaction within the central retina than in its peripheral region. In conclusion, these results indicate that peripheral area of the retina reveals better resistance to NaIO(3) injury than its central part.

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Related in: MedlinePlus

Representative images visualizing histopathological changes within the central part of the retina recorded 1 (c), 7 (d, e), and 28 (f) days after NaIO3 injection in both the higher and lower doses; (a, b) saline-treated control mice. Retinal morphology was analyzed in the whole eye flat mounts (FMs) with RPE nuclei pseudocolored blue and green indicating RPE autofluorescence (a and d) as well as in H/E stained sections (b, c, e, and f). The blackarrow (f) indicates glial (Műller) cells phagocyting melanine remnants. GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer
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Fig1: Representative images visualizing histopathological changes within the central part of the retina recorded 1 (c), 7 (d, e), and 28 (f) days after NaIO3 injection in both the higher and lower doses; (a, b) saline-treated control mice. Retinal morphology was analyzed in the whole eye flat mounts (FMs) with RPE nuclei pseudocolored blue and green indicating RPE autofluorescence (a and d) as well as in H/E stained sections (b, c, e, and f). The blackarrow (f) indicates glial (Műller) cells phagocyting melanine remnants. GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer

Mentions: When using the higher dose of NaIO3 (40 mg/kg) we observed progressive degeneration of the neurosensory retina along with widespread loss of RPE cells. These changes spread through the posterior pole and the peripheral region, indicating significant damage within the whole retinal area. On the first day after NaIO3 administration we discerned marked RPE damage with slight changes in the neurosensory retina in the form of some disorganization of the outer and inner segments of the photoreceptors (Fig. 1c). Individual RPE cells were flattened and most were devoid of nuclei, although they maintained their orientation and boundaries. On the third day after NaIO3 injection we detected complete destruction of the RPE, which had been replaced by a thin layer of melanin released along Bruch’s membrane (Fig. 2c). At this time point, the retinal pigment epithelium FMs revealed a discontinuous melanin sheet displaying empty spaces with nuclei present, possibly belonging to inflowing cells (Fig. 2d). Discontinuity of the RPE layer, macrophage infiltration, and disrupted structure of the outer and inner photoreceptor segments were observed in the retinal H-E stained sections (Fig. 2c). Moreover, TUNEL staining revealed the presence of massive apoptosis in the outer nuclear layer, which corroborated immense degeneration of the photoreceptors (Fig. 2b). By the 7th day after NaIO3 delivery, the thickness of the outer nuclear layer decreased significantly and the outer and inner photoreceptor segments were markedly shortened (Fig. 1e). The RPE flat mount obtained at this time point revealed an irregular network of melanin remnants spread along Bruch’s membrane (Fig. 1d). On the 18th and 28th days after NaIO3 administration we observed bumpy melanin clumping scattered along Bruch’s membrane with no apparent RPE cover. There were also features suggesting that glial cells might contribute to the phagocytosis of melanin remnants (Fig. 1f). The retinal thickness was drastically reduced, predominantly due to the progressive photoreceptor loss.Fig. 1


Sodium iodate selectively injuries the posterior pole of the retina in a dose-dependent manner: morphological and electrophysiological study.

Machalińska A, Lubiński W, Kłos P, Kawa M, Baumert B, Penkala K, Grzegrzółka R, Karczewicz D, Wiszniewska B, Machaliński B - Neurochem. Res. (2010)

Representative images visualizing histopathological changes within the central part of the retina recorded 1 (c), 7 (d, e), and 28 (f) days after NaIO3 injection in both the higher and lower doses; (a, b) saline-treated control mice. Retinal morphology was analyzed in the whole eye flat mounts (FMs) with RPE nuclei pseudocolored blue and green indicating RPE autofluorescence (a and d) as well as in H/E stained sections (b, c, e, and f). The blackarrow (f) indicates glial (Műller) cells phagocyting melanine remnants. GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2957578&req=5

Fig1: Representative images visualizing histopathological changes within the central part of the retina recorded 1 (c), 7 (d, e), and 28 (f) days after NaIO3 injection in both the higher and lower doses; (a, b) saline-treated control mice. Retinal morphology was analyzed in the whole eye flat mounts (FMs) with RPE nuclei pseudocolored blue and green indicating RPE autofluorescence (a and d) as well as in H/E stained sections (b, c, e, and f). The blackarrow (f) indicates glial (Műller) cells phagocyting melanine remnants. GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer
Mentions: When using the higher dose of NaIO3 (40 mg/kg) we observed progressive degeneration of the neurosensory retina along with widespread loss of RPE cells. These changes spread through the posterior pole and the peripheral region, indicating significant damage within the whole retinal area. On the first day after NaIO3 administration we discerned marked RPE damage with slight changes in the neurosensory retina in the form of some disorganization of the outer and inner segments of the photoreceptors (Fig. 1c). Individual RPE cells were flattened and most were devoid of nuclei, although they maintained their orientation and boundaries. On the third day after NaIO3 injection we detected complete destruction of the RPE, which had been replaced by a thin layer of melanin released along Bruch’s membrane (Fig. 2c). At this time point, the retinal pigment epithelium FMs revealed a discontinuous melanin sheet displaying empty spaces with nuclei present, possibly belonging to inflowing cells (Fig. 2d). Discontinuity of the RPE layer, macrophage infiltration, and disrupted structure of the outer and inner photoreceptor segments were observed in the retinal H-E stained sections (Fig. 2c). Moreover, TUNEL staining revealed the presence of massive apoptosis in the outer nuclear layer, which corroborated immense degeneration of the photoreceptors (Fig. 2b). By the 7th day after NaIO3 delivery, the thickness of the outer nuclear layer decreased significantly and the outer and inner photoreceptor segments were markedly shortened (Fig. 1e). The RPE flat mount obtained at this time point revealed an irregular network of melanin remnants spread along Bruch’s membrane (Fig. 1d). On the 18th and 28th days after NaIO3 administration we observed bumpy melanin clumping scattered along Bruch’s membrane with no apparent RPE cover. There were also features suggesting that glial cells might contribute to the phagocytosis of melanin remnants (Fig. 1f). The retinal thickness was drastically reduced, predominantly due to the progressive photoreceptor loss.Fig. 1

Bottom Line: Sequential morphological and functional features of retinal damage in mice exposed to different doses (40 vs. 20 mg/kg) of sodium iodate (NaIO(3)) were analyzed.The peak of photoreceptor apoptosis was found on the 3rd day, but the lower dose induced more intense reaction within the central retina than in its peripheral region.In conclusion, these results indicate that peripheral area of the retina reveals better resistance to NaIO(3) injury than its central part.

View Article: PubMed Central - PubMed

Affiliation: Department of Histology and Embryology, Pomeranian Medical University, Szczecin, Poland. annam@sci.pam.szczecin.pl

ABSTRACT
Sequential morphological and functional features of retinal damage in mice exposed to different doses (40 vs. 20 mg/kg) of sodium iodate (NaIO(3)) were analyzed. Retinal morphology, apoptosis (TUNEL assay), and function (electroretinography; ERG) were examined at several time points after NaIO(3) administration. The higher dose of NaIO(3) caused progressive degeneration of the whole retinal area and total suppression of scotopic and photopic ERG. In contrast, the lower dose induced much less severe degeneration in peripheral part of retina along with a moderate decline of b- and a-wave amplitudes in ERG, corroborating the presence of regions within retina that retain their function. The peak of photoreceptor apoptosis was found on the 3rd day, but the lower dose induced more intense reaction within the central retina than in its peripheral region. In conclusion, these results indicate that peripheral area of the retina reveals better resistance to NaIO(3) injury than its central part.

Show MeSH
Related in: MedlinePlus