Abstract
Purpose: :
To determine the concentration and distribution of various metals in the rat neuroretina.
Methods: :
Retinas from adult male Sprague-Dawley rats (n=6) were immediately frozen in liquid nitrogen. Inductively coupled plasma mass spectrometry (ICPMS) (Agilent 7700 Series, Agilent Technologies, UK) was then used to quantify the level of different metals in dried neuroretina from one eye. Dried frozen sections (10 microns thick) of the fellow eye were used to determine the concentration of metals within individual retinal layers. Here, the 3 proton microbeam facility on the 2MV Tandetron accelerator at the Surrey Ion Beam Centre was used. Trace and minor element mapping of retinal sections was obtained with a beam of 3MeV protons focused to 1 micrometer in diameter using particle-induced X-ray emission (PIXE) combined with Rutherford backscattering spectrometry (RBS).
Results: :
The most abundant metal in the neuroretina was iron, followed by aluminium, zinc and vanadium. Copper, nickel, manganese, chromium, cobalt, selenium and cadmium were present in trace amounts. PIXE analysis yielded a non-homogenous pattern distribution of metals in the retina. The highest amounts (microg/g of dry retina) of iron were found in the RPE (121+32.9) and photoreceptor inner segments (107+39). Zinc was most concentrated in the inner nuclear layer (97+29.6) and the plexiform layers (OPL, 75+30.3; and IPL, 64+20.1). Copper was localised primarily in the photoreceptor inner segments (16+5.4) and also in the plexiform layers (OPL, 17+1; and IPL, 13.25+3.4).
Conclusions: :
The present studies provide new information related to the distribution and content of various metals in the mammalian retina.
Keywords: retina • retinal pigment epithelium