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Biomedical subjects

B Ehinger

Publications and source records attributed to B Ehinger.

At least 109 records · Page 6Linked to original sources
PubMed1988

Peptide immunoreactive neurons in the human retina.

The distribution of peptide-immunoreactive neurons in the human retina was investigated. Neurons displaying immunoreactivity towards substance P, vasoactive intestinal polypeptide (VIP), somatostatin, neuropeptide Y (NPY) and peptide histidine-isoleucine (PHI) were found in amacrine cells with cell bodies situated in the innermost part of the inner nuclear layer and nerve fibers ramifying in the inner plexiform layer in a manner differing according to the peptide investigated. Two other cell types were found. In the middle of the inner plexiform layer cell bodies showing immunoreactivity towards substance P, VIP and PHI were found. In the ganglion cell layer there were cell bodies showing immunoreactivity towards substance P, somatostatin, VIP and NPY. Substance P immunoreactive, somatostatin and NPY immunoreactive fibers situated at the border between the inner nuclear and outer plexiform layers and traversing the inner nuclear layer were also found.

Humans↗
PubMed1987

Gamma-aminobutyric acid- and glutamic acid decarboxylase-immunoreactive neurons in the retina of different vertebrates.

The localization of gamma-aminobutyric acid (GABA)- and L-glutamate 1 carboxy-lyase (GAD)-immunoreactive neurons was compared in the skate, frog, pigeon, chicken, rabbit, and man. Horizontal cells show both GABA and GAD immunoreactivity in the skate, frog, and bird. Certain amacrine cells show GABA and GAD immunoreactivity in all species. The distribution of GABA- and GAD-immunoreactive cell bodies and cell processes was very similar, if not identical, in the skate and man. In the other species, cell populations with GAD immunoreactivity also showed GABA immunoreactivity. However, in the bird, frog, and rabbit, the GABA-immunoreactive amacrine cells were at least twice as numerous as the GAD-immunoreactive cells. In birds, the distributions of the GAD and GABA immunoreactivities were different in the sublayers of the inner plexiform layer. The reason for the difference is currently unknown. GABA-immunoreactive bipolar-like cells were seen in the frog.

Animals↗
PubMed1987

GABA-immunoreactive neurons in the photosensory pineal organ of the rainbow trout: two distinct neuronal populations.

The distribution of putative GABA-ergic neurons in the photosensory pineal organ of the rainbow trout was investigated by use of a specific antiserum against gamma-aminobutyric acid (GABA). GABA-immunoreactive (GABA-IR) neurons were located in the rostral portion of the pineal end-vesicle, presumably constituting a population of interneurons. GABA-IR neurons were also found in the pineal stalk. The axons of these neurons were traced along the pineal stalk toward the brain. The terminal areas of these axons could not be established. GABA-IR glial cells were observed in the pineal end-vesicle, but not in the pineal stalk.

Animals↗
PubMed1987

GABA and GAD-like immunoreactivity in the primate retina.

GABA immunoreactivity was studied and compared with GAD immunoreactivity in the retinae of baboon, cynomolgus monkey and man. The central and peripheral parts of the retinae were investigated separately in cynomolgus monkey and in man. The same kinds of structures were stained with both antisera. Cells with a position corresponding to amacrine cells were stained, as well as processes in the inner plexiform layer and some cells in the ganglion cell layer. The outer plexiform layer and some cells with the position and configuration of horizontal cells also appeared immunoreactive. Staining was also observed in bipolar-like cells, in man most clearly when using the GABA antiserum in sections from the central parts of the retina. It is possible that horizontal cells, as well as bipolar-like cells, may play a previously unsuspected role in GABAergic transmission in the primate retina.

Animals↗
PubMed1987

Histamine in the retina.

Retina and choroid were rapidly and gently extracted from chickens, guinea-pigs, rats, rabbits and cows. They were frozen, weighted and pooled in 3% trichloroacetic acid in a refrigerator. Using a radioenzymic assay, histamine was found to be present in the retina of guinea-pig (4.26 +/- 0.677 nmol g-1), rabbit (1.08 +/- 0.422 nmol g-1) and cow (0.189 +/- 0.036 nmol g-1), but not detected in chicken and rat. In the choroid, histamine was found in all species except rat (chicken: 4.92 +/- 0.542 nmol g-1; guinea-pig: 121.5 +/- 4.46 nmol g-1; rabbit: 18.7 +/- 3.93 nmol g-1; cow; 0.36 +/- 0.095 nmol g-1). The study verifies the presence of histamine in the retina of some species, and thereby supports previous fluorometry assays.

Animals↗
PubMed1986

Neuropeptide Y (NPY) immunoreactive neurons in the retina of different species.

Neurons displaying Neuropeptide Y (NPY) immunoreactivity were found among amacrine cells in the retina of baboon, pig, cat, pigeon, chicken, frog, trout, carp and goldfish. The immunoreactive cell bodies were located in the middle and the innermost cell rows of the inner nuclear layer with processes forming one, two or three more or less well-defined sublayers in the inner plexiform layer. The location and the density of the sublayers varied with the species investigated. In the frog retina, bipolar-like cell bodies were found in the middle of the inner nuclear layer as well as sparsely occurring ovoid cell bodies in the ganglion cell layer. Like the amacrine cells, these cells emitted processes ramifying in three sublayers in the inner plexiform layer.

Animals↗
PubMed1986

Calcium-independent release of gamma-aminobutyrate from nerve processes in the developing rabbit retina.

Retinas from 3- and 10-day-old rabbits, and from young (29 days), or adult animals were used to study in parallel the development of synaptic vesicles in amacrine cells and the Ca2+ dependence of the K+-stimulated [3H]gamma-aminobutyrate release from them. Few synaptic vesicles were observed in the amacrine cell processes in retinas from the 3-day-old rabbits. The number of vesicles significantly increased between 3 and 10 days and increased further between day 10 and the adult animal. The Ca2+ dependence of the K+-stimulated release decreased with increasing age. There is thus a poor correlation between the Ca2+ dependent transmitter release and the number of synaptic vesicles in the nerve terminal, favouring the existence of a Ca2+ dependent nonvesicular process for the [3H]gamma-aminobutyrate release in the rabbit retina.

Aging↗
PubMed1986

GABA immunoreactivity in the retina.

Presumed GABA neurons were studied in chick, guinea pig, and rabbit retinae with an immunohistochemical procedure aimed at direct demonstration of the endogenous GABA. In all species, a subset of amacrine cells was immunoreactive, as well as numerous fibers in the inner plexiform layer. In the chick, immunoreactivity was also demonstrated in horizontal cells, and single cell processes could be distinguished in both plexiform layers. The study indicates that the endogenous stores of GABA in GABAergic neurons can be visualized with immunohistochemical techniques. This direct approach thus gives additional information and probably is less subject to nonspecific staining than the demonstration of enzymes linked to GABA synthesis and metabolism. It also gives superior resolution in comparison with the autoradiographic techniques currently used for demonstrating GABA neurons. Invest Ophthalmol Vis Sci 27:674-678, 1986.

Animals↗
PubMed1985

Retinal neuropeptides in the skates, Raja clavata, R. radiata, R. oscellata (Elasmobranchii).

The distribution of immunoreactive neuropeptides was investigated in the retina of three species of skates (Raja clavata, R. radiata, R. oscellata), elasmobranch fish often used in electrophysiological work on the retina. Enkephalins, neuropeptide Y (NPY), substance P and glucagon were found in different types of amacrine cells. All four peptides appeared in cell bodies in the innermost part of the inner nuclear layer. Processes from the cells containing enkephalins were numerous and ramified throughout the inner plexiform layer. Processes from the cells containing glucagon were thick and rare, and were found throughout the inner plexiform layer, at times with a predominance in sublaminae 1 and 4. NPY-immunoreactive fibres appeared mainly in sublamina 1 but also in 2 or 3, and substance-P-immunoreactive fibres in sublaminae 1, 4 and 5. Antisera against somatostatin, VIP or neurotensin did not show any immunoreactivity in the skate retina.

Animals↗
PubMed1985

Quantitation and immunohistochemistry of catecholamines in the posterior segment of the eye.

Dopamine, noradrenaline, and adrenaline were assayed with HPLC in the light adapted retinae of carp, frog, chicken, pigeon, rat, guinea-pig, rabbit, cat, pig and cow. Dopamine varied from 0.6 to 2.6 nmol/g wet weight and was not influenced by sympathectomy. The dopamine figures agree with previously published results. Noradrenaline concentrations varied from not detectable to 0.06 nmol/g wet weight in different species. Homolateral sympathectomy significantly decreased the noradrenaline figure in rabbits. There are no previous figures for noradrenaline for most of the species. Adrenaline was not detected in any species. Immunohistochemical analysis showed noradrenaline to be present in choroidal nerves, but noradrenaline immuno-reactivity was not seen in the retina (chicken, rat, guinea-pig, rabbit, cat, cow). It is concluded that dopamine is the major catecholamine in the retina. Noradrenaline was found present only in minute amounts in the assays, and much of its was likely to stem from sympathetic nerve fibres. The study did not demonstrate any noradrenergic neurons in the retina.

Animals↗
PubMed1985

Neurotransmitter release by certain neuropeptides in the chicken retina.

The ability of certain neuropeptides (glucagon, somatostatin, leu-enkephalin and neurotensin) to release known neurotransmitters (glycine, GABA, dopamine and 5-hydroxytryptamine) was tested in the chicken retina. Tritiated neurotransmitters were injected intravitreally in chicken eyes. After excision, the retina was stimulated in vitro with the neuropeptide in micromolar concentrations while monitoring the efflux of radioactivity from the retina. A rise of the efflux represents a stimulus dependent release. Neurotensin release [3H] glycine, [3H]dopamine and [3H]5-hydroxytryptamine. Leu-enkephalin released [3H]dopamine and somatostatin released [3H]5-hydroxytryptamine. Glucagon was without effect. [3H]GABA was not released by any of the neuropeptides.

Animals↗
PubMed1984

Neurotransmitter localization in the skate retina.

The retina of the skate (Raja clavata, R. radiata and R. oscellata) was studied by autoradiography following intraocular injections or incubations with [3H]GABA, [3H]isoguvacine, [3H]glycine, [3H]dopamine or [3H]5-hydroxytryptamine. Fluorescence immunohistochemistry was also used to demonstrate the endogenous content, accumulation, and retention of 5-hydroxytryptamine. The [3H]GABA was taken up by glia, and [3H]isoguvacine failed to appreciably label any neurons. [3H]Glycine was accumulated by amacrine cells, possibly of two subtypes. The [3H]dopamine was taken up by a few rare cells in the inner nuclear layer, which sent processes into the inner plexiform layer. Both autoradiography and immunohistochemistry showed 5-hydroxytryptamine to be efficiently accumulated by two types of cells in the inner nuclear layer: a bipolar cell type and an amacrine cell type. The morphology of the bipolar cells suggests they are of the ON depolarizing type. Immunohistochemistry also demonstrated the retention of accumulated 5-hydroxytryptamine by these two cell types, and that the bipolar cells contained far less endogenous 5-hydroxytryptamine than the amacrine cells did. The latter cell type can be presumed to use 5-hydroxytryptamine as its neurotransmitter. The results show the distribution of presumed glycinergic, dopaminergic and indoleaminergic neurons. They also show that there are two fundamentally distinct types of indoleamine neurons, a bipolar cell type with a low and an amacrine cell type with a high content of 5-hydroxytryptamine.

Animals↗
PubMed1984

Neuropeptide Y immunoreactive neurons in the guinea-pig uvea and retina.

Neuropeptide Y (NPY) is a recently discovered, amidated 36 amino acid residue neuropeptide present in many but not all sympathetic noradrenergic neurons. In the guinea-pig eye, NPY immunoreactive fibers were found to have the same distribution as noradrenergic fibers except that there were fewer at the iris dilator, in the cornea, and in the chamber angle. In the anterior uvea, the NPY immunoreactive fibers disappeared after excision of the homolateral superior cervical sympathetic ganglion, whereas in the choroid, many NPY immunoreactive fibers remained, indicating that they originate elsewhere. NPY immunoreactivity thus is not found in all sympathetic adrenergic neurons nor is it found only in such nerve fibers. In the retina, NPY immunoreactive fibers formed a single layer of processes in sublamina 1 of the inner plexiform layer. NPY immunoreactive cell bodies were found in the innermost cell row of the inner nuclear layer. The immunoreactivity was concentrated to the hillock region of these cells.

Adrenergic Fibers↗
PubMed1983

Glucagon immunoreactive neurons in the retina of different species.

Neurons displaying glucagon immunoreactivity were detected among the amacrine cells in the retina of goldfish, frog and pigeon. Nerve cell bodies were located in the inner nuclear layer with their processes ramifying in 2-3 more or less well-defined sublayers in the inner plexiform layer. The distribution of cell bodies and processes varied with the species. In pigeon retina two separate populations of glucagon immunoreactive neurons were found among the amacrine cells. In frog retina glucagon immunoreactivity was also discerned in cell bodies in the ganglion cell layer. These cell bodies sent processes outwards to the inner plexiform layer. No glucagon immunoreactive neurons were detected in the retina of the rat, rabbit, cat, pig or cow.

Animals↗
PubMed1983

Retinal GABA neuron labelling with [3H]isoguvacine in different species.

Retinas from goldfish, chicken, rate, guinea-pig, rabbit and humans were exposed to [3H]isoguvacine either by intravitreal injection in vivo or by incubation in a balanced salt solution. The distribution of radioactivity was then studied by autoradiography. The substance labelled a set of presumed amacrine cells in all types of animals. The inner plexiform layer was well demarcated and a variable number of ganglion cells was marked. In goldfish and chicken, radioactivity could also be seen in horizontal cells, particularly when the retina had detached from the pigment epithelium. Even 24 hr after an intraocular injection there was a significant amount of radioactivity left in nerve cells. Only a little glial labelling could be seen at any time. Since the distribution of labelled neurones was similar to that of GABA neurones and since isoguvacine is a potent GABA agonist, it seems reasonable to presume that [3H]isoguvacine labels GABA neurones. The uptake is predominantly neuronal with strong binding to presumed GABA storage sites.

Animals↗
PubMed1983

Connexions between retinal neurons with identified neurotransmitters.

Dopaminergic and indoleamine accumulating neurons can be demonstrated both in the light and the electron microscopes. Considerable differences have been found between different animal species. There are two types of dopaminergic neurons, the interamacrine cells and the interplexiform cells. The interamacrine cells contact only other amacrine cells. They receive synapses from other amacrine cells which are likely to operate with, e.g. GABA or glycine as neurotransmitter. The dopamine turnover in the dopaminergic interamacrine cells is very rapidly activated by light. Dopaminergic interplexiform neurons are known only in teleost fish and New World monkeys. They have approximately the same contacts in the inner plexiform layer as the interamacrine cells, but, in addition, send processes to the outer plexiform layer and there contact both horizontal cells and bipolar cells. The function of the dopaminergic neurons has not been determined. The indoleamine accumulating amacrine neurons are in Cebus monkeys, cats and rabbits contacted by bipolar cells in dyads and form reciprocal synapses with them. They are also contacted by amacrine cells and make synapses on other with them. They are also contacted by amacrine cells and make synapses on other amacrine cells and on ganglion cells. The contacts are different in teleost fish, where the indoleamine accumulating cells mainly contact other amacrine cells only. The transmitter of the indoleamine accumulating neurons is debated in mammals but is most likely 5-hydroxytryptamine in other vertebrates.

Animals↗
PubMed1983

Substance P fibres in the anterior segment of the rabbit eye.

Some laboratories have obtained diverging results regarding the presence of substance P fibres in the cornea possibly because different antibodies were used. This has been further investigated by comparing results with several antibodies on identically treated sections from the anterior segment of rabbit eyes. In the uvea all antisera gave identical results showing substance P fibres in the iris and ciliary processes. In the cornea, on the other hand, polyclonal rabbit or guinea-pig antibodies gave high background fluorescence and no immunofluorescence fibres were detected. In contrast, the background staining was low with the monoclonal antibody so that substance p immunoreactive fibres could be demonstrated subepithelially, intraepithelially and in the corneal stroma.

Animals↗