Docosahexaenoic acid utilization during rod photoreceptor cell renewal

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Journal of Neuroscience; (USA)

OSTI ID:6530107

Gordon, W C; Bazan, N G ^[1]

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1. Louisiana State Univ., New Orleans (USA)

The supply of docosahexaenoic acid (22:6) to the frog retina, and its subsequent use by retinal cells, was studied by autoradiography and biochemical methods. Different delivery routes of 3H-22:6 were evaluated. Predominant uptake by the neural retina, mainly in ganglion cell axons, outer synaptic layer, and Mueller cells, was observed when the radiolabeled fatty acid was given intravitreally or by short-term incubations of eyecups. In short-term eyecup incubations, Mueller cells preferentially labeled, suggesting their involvement as a transient storage site. After intravenous or dorsal lymph sac injections of 3H-22:6, most of the retinal label was seen in rod photoreceptor cells. Two different labeling patterns were found in rod outer segments (ROS) as a function of postinjection time: an overall diffuse labeling pattern, as well as a dense-label region at the ROS base. This dense-label region expanded until it reached the apex of the ROS after about 30 d. HPLC analysis of fatty acid methyl esters from retinal lipid extracts showed that 3H-22:6 comprised essentially all of the label until after day 46, indicating lack of metabolic recycling of this molecule. Lipid-extracted retinal residue was devoid of radioactivity, demonstrating that protein did not contain significant covalently bound label. 3H-22:6 acylated to phospholipids in photoreceptor membranes moved apically, as evidenced by the expanding labeled region from the base of the ROS. Oil droplets in both the pigment epithelium and the cone photoreceptors labeled heavily, suggesting that 22:6 may be transiently stored. ROS tips that were phagocytosed by the pigment epithelium contained label similar in density to that of the outer segments, demonstrating that 22:6-phospholipids, at least in part, cycle through the pigment epithelial cells during visual cell renewal.

• OSTI ID: 6530107
• Journal Information: Journal of Neuroscience; (USA), Journal Name: Journal of Neuroscience; (USA) Vol. 10:7; ISSN JNRSD; ISSN 0270-6474
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMPHIBIANS
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
AQUATIC ORGANISMS
AUTORADIOGRAPHY
BODY
BODY AREAS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHROMATOGRAPHY
EPITHELIUM
ESTERS
EYES
FACE
FROGS
HEAD
HEXADECANOIC ACID
HYDROGEN COMPOUNDS
LABELLING
LIPIDS
LIQUID COLUMN CHROMATOGRAPHY
MEMBRANES
METABOLISM
MONOCARBOXYLIC ACIDS
NERVE CELLS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
PHOSPHOLIPIDS
RETINA
SENSE ORGANS
SEPARATION PROCESSES
SOMATIC CELLS
TISSUES
TRITIUM COMPOUNDS
VERTEBRATES