+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on LinkedInFollow on LinkedIn

+ Translate

Iron, ferritin, transferrin, and transferrin receptor in the adult rat retina

Iron, ferritin, transferrin, and transferrin receptor in the adult rat retina

Investigative Ophthalmology & Visual Science 41(8): 2343-2351

PURPOSE: The retina and other, tissues need iron to survive. However, the normal iron metabolism in rodent retinas had not been characterized. This study was intended to investigate iron and iron homeostasis protein (ferritin, transferrin (Tf) and transferrin receptor (Tf-R)) distribution in 20- to 55-day-old rat retinas. METHODS: Iron was revealed on retinal sections directly by proton-induced x-ray emission (PIXE) and indirectly by electron microscopy (EM). Ferritin, Tf, and Tf-R proteins were localized by immunohistochemistry. Transferrin expression was localized by in situ hybridization (ISH). Transferrin and ferritin proteins and mRNA were analyzed by Western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR), respectively. RESULTS: Iron is widely and unevenly distributed throughout the adult rat retina. The highest concentration was observed by PIXE in the choroid and the retinal pigmented epithelial cell (RPE) layer, and in inner segments of photoreceptors (IS). Outer segments of photoreceptors (OS) also contain iron. EM studies suggested the presence of iron inclusions inside the photoreceptor discs. Choroid, RPE, and IS showed a strong immunoreactivity for ferritin. Transferrin accumulated mainly in the IS and OS areas and in RPE cells but can also be detected slightly in retinal capillaries. Western blot analysis for Tf and ferritin confirmed their presence in the adult neural retina. By RT-PCR, H- and L-chains of ferritin and Tf mRNAs were expressed in neural retina, but the main sites of Tf synthesis observed by ISH were the RPE and choroid cell layers. Tf-R immunoreactivity was detected in the ganglion cell layer, inner nuclear layer, outer plexiform layer, IS, RPE, and choroid. These results were similar for all stages studied. CONCLUSIONS: For the first time, the present study characterized both iron and iron homeostasis proteins in rodent retinas. In the outer retina, iron and ferritin shared the same distribution patterns. In contrast, Tf, mainly synthesized by RPE cells and detected in OS and IS areas, probably helps to transport iron to photoreceptors through their Tf-R. This is a likely pathway for filling iron needs in the outer retina.

(PDF emailed within 1 workday: $29.90)

Accession: 010885470

Download citation: RISBibTeXText

PMID: 10892882

Related references

Evidence for a sequential transfer of iron amongst ferritin, transferrin and transferrin receptor during duodenal absorption of iron in rat and human. World Journal of Gastroenterology 13(7): 1042-1052, 2007

Transferrin, Transferrin Receptor and Ferritin in Human Retina. ARVO Annual Meeting Abstract Search & Program Planner : Abstract No 3744, 2002

Localisation of ferritin, transferrin receptor and transferrin in the normal, iron loaded and iron deficient rat liver. Hepatology 22(4 PART 2): 392A, 1995

Iron, transferrin, ferritin and transferrin receptor in hypotransferrinemic mouse brain. FASEB Journal 9(3): A249, 1995

Serum transferrin receptor and transferrin receptor-ferritin index identify healthy subjects with subclinical iron deficits. Blood 92(8): 2934-2939, 1998

A comparison between the soluble transferrin receptor, transferrin saturation and serum ferritin as markers of iron state in hemodialysis patients. Nephron 92(1): 32-35, 2002

Tissue transferrin receptor, transferrin, and ferritin ELISA assays to assess levels in iron deficient anemic rats. FASEB Journal 12(5): A844, March 20, 1998

Single values of serum transferrin receptor and transferrin receptor ferritin index can be used to detect true and functional iron deficiency in rheumatoid arthritis patients with anemia. Arthritis and Rheumatism 43(5): 1016-1020, 2000

Regulation of transferrin receptor expression and ferritin content in human mononuclear phagocytes. Coordinate upregulation by iron transferrin and downregulation by interferon gamma. Journal of Clinical Investigation 91(3): 969-976, 1993

Increased levels of serum transferrin receptor and serum transferrin receptor/log ferritin ratios in men with prostate cancer and the implications for body-iron stores. Journal of Laboratory and Clinical Medicine 144(4): 176-182, 2004

Serum transferrin receptor, serum ferritin and serum transferrin receptor-ferritin index in adults with iron deficiency anaemia. Journal of Ayub Medical College, Abbottabad 23(3): 44-46, 2013

Soluble transferrin receptor and transferrin receptor-ferritin index in iron deficiency anemia and anemia in rheumatoid arthritis. Clinical Chemistry and Laboratory Medicine 43(3): 326-331, 2005

Soluble transferrin receptor and soluble transferrin receptor-ferritin index for evaluation of the iron status in elderly patients. Tohoku Journal of Experimental Medicine 202(2): 135-142, 2004

Components of biological variation in serum soluble transferrin receptor: relationships to serum iron, transferrin and ferritin concentrations, and immune and haematological variables. Scandinavian Journal of Clinical and Laboratory Investigation 57(1): 31-41, 1997

Effect of alpha-lipoic acid preparations on bilirubin and transferrin levels and ferritin iron and transferrin iron content. Ukrains'kyi Biokhimichnyi Zhurnal 73(2): 102-105, 2001