acid-phosphatase and Retinal-Degeneration

The eyes of normal Briard dogs, Briards affected with inherited retinal pigment epithelial dystrophy (RPED) and a range of normal crossbred and beagle dogs were examined and the histopathology of RPED in the Briard was compared with the histopathological features of ageing in the normal canine retina. RPED was characterised by the accumulation of auto-fluorescent lipofuscin-like inclusions in the retinal pigment epithelium (RPE), which initially involved only non-pigmented RPE cells overlying the tapetum but subsequently spread to all pigmented RPE cells. Secondary neuro-retinal degeneration was characterised by a gradual loss of the outer nuclear layer and the subsequent atrophy and degeneration of the inner retina. The loss of primary photoreceptors in the peripheral retina was accompanied by the migration of photoreceptor nuclei and appeared to resemble severe changes due to ageing. Intra-vitreal radiolabelled leucine was used to examine the rate of turnover of the outer segments of the rods in some Briards, but no significant variations were found. The activity of acid phosphatase in RPE was assayed in vitro and showed comparable regional variations in Briard and crossbred dogs. The results suggest that RPED in the Briard is unlikely to be due either to an increased rate of turnover of rod outer segments (and thus an increased phagocytic load) or to a primary insufficiency of lysosomal enzyme.

Topics: Acid Phosphatase; Aging; Animals; Dog Diseases; Dogs; Microscopy, Fluorescence; Pigment Epithelium of Eye; Retina; Retinal Degeneration; Rod Cell Outer Segment; Species Specificity

In this study acid phosphatase (ACPase) was localized in the retinal pigment epithelium (RPE) of normal and Royal College of Surgeons (RCS) rats pink-eyed and pigmented with inherited retinal dystrophy to determine differences in staining during the post-engulfment stages of phagocytosis using two substrates, Na-beta-glycerophosphate and cytidine-5'-monophosphate. Staining was similar using either substrate and in the normal RPE the Golgi system, lysosomes and phagosomes were ACPase-positive. In the dystrophic RPE, which has a diminished capacity to phagocytose photoreceptor rod outer segments, ACPase staining was localized on melanosomes in the pigmented dystrophic and on the apical microvillous membranes in the pink-eyed dystrophic, but was not localized on phagosomes in either the pink-eyed or pigmented dystrophic RPE. Since only a few phagosomes were seen at any given time in dystrophic RPE in vivo, a tissue explant system was used to examine the number of latex beads phagocytosed by normal and RCS RPE, as well as the number of phagosomes containing both beads and ACPase activity in the normal and mutant RPE. Our findings indicate that in the dystrophic, fewer phagosomes are ACPase-positive than in the normal, and that some enzyme may be inappropriately shunted to either the apical microvilli or to melanosomes instead of to phagolysosomes.

Topics: Acid Phosphatase; Animals; Cytidine Monophosphate; Glycerophosphates; Histocytochemistry; Microscopy, Electron; Organoids; Phagocytes; Pigment Epithelium of Eye; Rats; Retinal Degeneration; Substrate Specificity

In retinas of rats (RCS) with inherited retinal dystrophy, cells interpreted as macrophages infiltrate the outer nuclear layer and subsequently appear in the interphotoreceptor space, where they accummulate during the course of the disease. The morphology and distribution of these cells and their relations to the pigment epithelial cells were investigated. Macrophages, regardless of their location, possessed morphological features that distinguished them from the pigment epithelial cells. Premelanosomes and melanosomes, typical of pigment epithelial cells, were never observed in macrophages. There was no evidence to indicate that, during the period studied, the pigment epithelial cells had become dedifferentiated or had migrated from Bruch's membrane. Macrophages, like pigment epithelial cells, phagocytized little or no outer segment material. The findings indicate that, at least during the interval studied, the cells that infiltrate the retina and interphotoreceptor space are macrophages rather than pigment epithelial cells.

Topics: Acid Phosphatase; Animals; Esterases; Lysosomes; Macrophages; Phagocytosis; Pigment Epithelium of Eye; Rats; Rats, Inbred Strains; Retinal Degeneration

Ultrastructural changes in the retinal pigment epithelium (RPE) and adjacent photoreceptor cells have been followed in the Wistar rat during the course of long-term vitamin A deficiency. Of particular interest has been the discovery of unusual concentric aggregates within the photoreceptor outer segments and the inner cytoplasm of the RPE. The aggregates were present throughout the course of the retinal degeneration induced by vitamin A deficiency and could be identified in the RPE either by themselves in the apical cytoplasm or within phagolysosomes. It is postulated that the concentric aggregates result initially from abnormal formation or condensation of outer segment membranes and are then slowly degraded by lysosomal action in the RPE cytoplasm. In addition, acid phosphatase activity and typical phagosomes (shed outer segment packets) have been demonstrated in the cytoplasm of the RPE of the vitamin A deficient rats. The latter findings indicate that, at least to some extent, the normal phagocytic and lytic processes of the RPE are retained in this nutritional disorder.

Topics: Acid Phosphatase; Animals; Cytoplasm; Female; Lysosomes; Male; Phagocytosis; Photoreceptor Cells; Pigment Epithelium of Eye; Rats; Retinal Degeneration; Time Factors; Vitamin A Deficiency

Four acid hydrolase activities are demonstrable by light microscopy in pigment epithelial cell lysosomes of rats (Royal College of Surgeons--RCS) with inherited retinal dystrophy and in control (Fischer) rats. The enzymes include acid phosphatase, aryl sulfatase, N-acetyl-beta-glucosaminidase, and esterase activities. No marked differences are observed in distribution or staining intensity of lysosomes in the two strains of rat. Acid hydrolase activities are not localized in sites other than lysosomes. Acid phosphatase and aryl sulfatase activities are also demonstrable by electron microscopy. In both strains, acid phosphatase reaction product is localized to various forms of lysosomes in pigment epithelial cells. A diffuse precipitate, considered to be nonspecific in origin, is seen in the cytoplasm, apical processes, outer segments (control), and outer segment debris (RCS). The precipitate is probably due to adsorption of lead from the incubation medium or of lead phosphate that diffuses from heavy accumulations in nearby lysosomes. Aryl sulfatase reaction product, in contrast to acid phosphatase, is localized to far fewer lysosomes and there is virtually no nonspecific precipitate. The findings indicate that lysosomes of RCS pigment epithelial cells possess several cytochemically demonstrable acid hydrolase activities. There is no evidence for the localization of acid phosphatase (or aryl sulfatase) activities in sites other than lysosomes.

Topics: Acid Phosphatase; Animals; Arylsulfatases; Esterases; Histocytochemistry; Hydrolases; Lysosomes; Pigment Epithelium of Eye; Rats; Rats, Inbred Strains; Retinal Degeneration

Topics: Acid Phosphatase; Animals; Cathepsins; Choroid; Glucuronidase; Hypertension; Lysosomes; Pigment Epithelium of Eye; Rats; Retina; Retinal Degeneration

In rats with primary retinal degeneration, lens extraction combined with total retinal detachment provided a model for injection of a tracer of colloidal carbon into the subretinal space. Electron microscopy and acid phosphatase cytochemistry were subsequently used to analyze the ingestion of tracer by the retinal pigment epithelium. It was found that the attachment, ingestion, and digestion phases of the phagocytic process were apparently preserved. From this evidence it is suggested that there is no lack of phagocytic power in the retinal pigment epithelium of affected rat strains.

Topics: Acid Phosphatase; Animals; Carbon Radioisotopes; Cytoplasmic Granules; Phagocytosis; Pigment Epithelium of Eye; Rats; Retinal Degeneration; Retinal Detachment

Light deprivation retarded retinal degeneration in albino dystrophic rats. In pigmented dystrophic rats the presence of pigment in the eye retarded the degenerative process. Retinol labilized rat retinal lysosomes in vitro. Acetylsalicylic acid stabilized retinal lysosomes even in the presence of the concentration of retinol which produced the maximum labilization. The effect of acetylsalicyclic acid was concentration dependent, maximum stabilization being produced by 0.25-0.50 mM. The results provide further evidence for the hypothesis that hereditary retinal degeneration in rats is mediated by an increased amount of retinol (produced by the action of light on an unusually labile type of visual pigment) causing a premature release of lysosomal enzymes.

Topics: Acid Phosphatase; Animals; Aspirin; Darkness; DNA; Female; Galactosidases; Genes, Recessive; Glucuronidase; Hexosaminidases; In Vitro Techniques; Light; Lysosomes; Male; Rats; Retina; Retinal Degeneration; RNA; Sensory Deprivation; Vitamin A

Topics: Acid Phosphatase; Biopsy; Child; Child, Preschool; Electroencephalography; Electromyography; Female; Fundus Oculi; Humans; Infant; Lipidoses; Male; Microscopy, Electron; Myotonic Dystrophy; Neurologic Examination; Ophthalmoscopy; Pedigree; Retinal Degeneration; Schwann Cells; Sural Nerve; Syndrome; Visual Acuity

Topics: Acid Phosphatase; Animals; Cell Differentiation; Cell Movement; Glycoside Hydrolases; Hexosaminidases; Histocytochemistry; Histological Techniques; Hypertrophy; Macrophages; Mice; Mice, Inbred Strains; Phagocytosis; Photoreceptor Cells; Retina; Retinal Degeneration

Topics: Acid Phosphatase; Amidohydrolases; Animals; Female; Histocytochemistry; Lysosomes; Male; Naphthalenes; Peptide Hydrolases; Rats; Retina; Retinal Degeneration; Retinitis Pigmentosa

Topics: Acid Phosphatase; Animals; Azo Compounds; Dimethyl Sulfoxide; Enzyme Activation; Histocytochemistry; Lead; Lysosomes; Mice; Nitrates; Phosphates; Retinal Degeneration; Staining and Labeling