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PubMed1999

Antibodies against neurofilament subunits label retinal ganglion cells but not displaced amacrine cells of hamsters.

Although neurofilament (NF) antibodies have been used to visualize ganglion cells and their axons in the retina, it is not known, however, how many ganglion cells contain NF, and how the various NF subunits are distributed in the ganglion cells. Moreover, it is not known whether displaced amacrine cells in the ganglion cell layer are also labelled. In order to see whether NF antibodies can be used as a specific marker for ganglion cells, antibodies raised against the low (NF-L), middle (NF-M) and high (NF-H) molecular weight subunits of NF were employed to stain retinal whole-mounts of adult hamsters after pre-labelling the ganglion cells with Granular Blue. It was found that NF-L and NF-H antibodies labelled 38,777 and 17,750 cells in the ganglion cell layer respectively. By co-localization with GB-labelled cells, 88% of NF-L positive cells and 91% of NF-H positive cells were found to be ganglion cells. In contrast, the NF-M antibody labelled only very few ganglion cells (418 per retina) although robust staining of axonal bundles was observed. Thus, NF antibodies may prove useful in studying this population of ganglion cells.

Animals↗
PubMed2003

Administration of brain-derived neurotrophic factor suppresses the expression of heat shock protein 27 in rat retinal ganglion cells following axotomy.

Optic nerve transection results in the apoptotic cell death of the majority of retinal ganglion cells by 14 days. The neurotrophin brain-derived neurotrophic factor (BDNF) enhances survival of retinal ganglion cells. In addition, the small heat shock protein Hsp27, with its anti-apoptotic effects, may be important for neuron survival following axotomy or trophic factor withdrawal. We recently reported the induction and expression of Hsp27 in a subset of retinal ganglion cells following axotomy. Here we have examined the effect of BDNF administration on the expression of Hsp27 in axotomized adult rodent retinal ganglion cells. Retinal ganglion cells were pre-labeled with Fluorogold prior to optic nerve transection and concomitant intraocular injection of BDNF or vehicle. Hsp27 immunofluorescence was examined in retinal sections from 4 to 28 days following injury. Consistent with previous survival studies, the number of Fluorogold-labeled retinal ganglion cells declined from 100% at 4 days to approximately 15% by 14 days following axotomy and vehicle injection. In contrast, with BDNF administration, retinal ganglion cell survival was maintained at 100% to 7 days following axotomy. We report that the number of Hsp27-positive injured retinal ganglion cells, as detected by immunohistochemical staining, was decreased by 50% in BDNF-treated retinas, when compared with vehicle-treated controls. This decreased expression of Hsp27 in response to BDNF treatment was seen both at early (4 days) and delayed (14 days) times. BDNF following optic nerve transection significantly reduced the expression of Hsp27 in retinal ganglion cells. These results indicate that BDNF may down-regulate alternate cell survival pathways, including the stress-induced expression of Hsp27, and may help to explain the failure of chronic neurotrophin treatment to maintain long-term retinal ganglion cell survival.

Animals↗
PubMed2002

Hypoplasia of spiral and Scarpa's ganglion cells in GABA(A) receptor beta(3) subunit knockout mice.

This study documents morphologic alterations in the spiral ganglion and Scarpa's ganglion from gamma-aminobutyric acid A (GABA(A)) receptor beta(3) subunit null mutant mice. The ganglion cells of the mutant mice were hypoplastic in hematoylin&eosin-stained sections. Hypoplasia was observed at every location of the spiral ganglion and Scarpa's ganglion except the apical cochlear turn. Calretinin immunostaining demonstrated a selective hypoplasia of calretinin-negative cells at every location of spiral and Scarpa's ganglion cells, while the soma area of calretinin-positive cells was not affected by the gene deletion. Meanwhile, in the spiral ganglion of both wild type and knockout mice, there were apical to basal gradients in the soma size and the proportion of calretinin-positive cells. The absence of statistically significant hypoplasia in hematoylin&eosin sections through the apical turn of the cochlea can be explained by the relatively higher proportion of calretinin-positive ganglion cells, which were unaffected by the gene deletion. These findings suggest that GABA(A) receptor isoforms containing the beta(3) subunit may play an important role in the development and differentiation of non-calyceal terminals of Scarpa's ganglion cells and type II and smaller type I spiral ganglion cells.

Animals↗
PubMed1989

Distribution and size of ganglion cells in the retinae of large Amazon rodents.

The topographical distribution of density and soma size of the retinal ganglion cells were studied in three species of hystricomorph rodents. Flat-mounted retinae were stained by the Nissl method and the ganglion cells counted on a matrix covering the whole retinae. Soma size was determined for samples at different retinal regions. The agouti, a diurnal rodent, shows a well-developed visual streak, reaching a peak density of 6250 ganglion cells/mm2. The total number of ganglion cells ranged from 477,427-548,205 in eight retinae. The ganglion-cell-size histogram of the visual streak region exhibits a marked shift towards smaller values when compared to retinal periphery. Upper and lower regions differ in both cell density and cell size. The crepuscular capybara shows a less-developed visual streak with a peak ganglion cell density of 2250/mm2. The shift towards small-sized cells in the visual streak is less marked. Total ganglion cell population is 368,840. In the nocturnal paca, the upper half of the fundus oculi includes a tapetum lucidum. The retina of this species shows the least-developed visual streak of this group, with the lowest peak ganglion cell density reaching 925/mm2. The total ganglion cell number (230,804) is also smaller than in the two other species. Soma-size spectra of this species are characterized by the presence, in the lower hemi-retina, of very large perikarya comparable in size to the cat's alpha ganglion cells.

Animals↗
PubMed1989

Parameters affecting the loss of ganglion cells of the retina following ablations of striate cortex in primates.

Partial lesions of striate cortex were made in newborn and adolescent or young adult macaque monkeys, one newborn squirrel monkey, and adult squirrel and owl monkeys. After survival times ranging from 3 1/2 weeks to 8 years, the retinas were examined for transneuronal retrograde ganglion cell loss and retinal projections to the dorsal lateral geniculate nucleus, and other targets were examined for changes. After lesions in infant macaque monkeys and long postoperative survivals, nearly 80% of the ganglion cells were lost in the altered portions of the retinas. The degeneration appeared to be exclusively of ganglion cells projecting to the parvocellular layers of the lateral geniculate nucleus, and the loss of this class of cell appeared to be complete or nearly complete for the affected portions of the retina. Cases with shorter survivals showed that nine-tenths of the potential loss occurred within 6 months, and about half of the potential loss took place within one month. In cases where lesions were placed in adolescent and young adult macaque monkeys, the loss also was of ganglion cells projecting to the parvocellular layers. However, the rate of cell loss was slower so that little or no cell loss was apparent after six months, and only one-third to three-fourths of the potential loss occurred within 12-14 months. A cell loss of 22% was measured in the altered portions of the retina of a squirrel monkey lesioned as an infant and surviving for 6 months, but no regions of ganglion cell loss were apparent in the retinas of owl and squirrel monkeys lesioned as adults and surviving as long as two or more years. We conclude that nearly 80% of the ganglion cells project to the parvocellular layers in macaque monkeys, and that the ultimate survival of these ganglion cells depends on the presence of target neurons in the parvocellular layers. Age is important in that the loss of ganglion cells proceeds rapidly in infant macaque monkeys, but slowly in older animals. Infant New World monkeys, judging from one squirrel monkey, are also susceptible to ganglion cell loss, although apparently at a rate comparable to older macaque monkeys. Finally, adult New World monkeys do not appear to be susceptible to ganglion cell loss. These age and species differences in rates of loss and susceptibility to loss challenge a "sustaining collateral" hypothesis proposed earlier (Weller et al., 1979), and suggest alternatives and modifications.

Aging↗
PubMedDate not supplied

Synaptic inputs to retrogradely labeled ganglion cells in the retina of the cane toad, Bufo marinus.

The entire population of ganglion cells in the retina of the toad Bufo marinus was labeled by retrograde transport of a lysine-fixable biotinylated dextran amine of 3000 molecular weight. Synaptic connections between bipolar, amacrine, and ganglion cells in the inner plexiform layer were quantitatively analyzed, with emphasis on synaptic inputs to labeled ganglion cell dendrites. Synapses onto ganglion cell dendrites comprised 47% of a total of 1234 identified synapses in the inner plexiform layer. Approximately half of the bipolar or amacrine cell synapses were directed onto ganglion cell dendrites, while the rest were made mainly onto amacrine cell dendrites. Most of the synaptic inputs to ganglion cell dendrites derived from amacrine cell dendrites (84%), with the rest from bipolar cell terminals. Synaptic inputs to ganglion cell dendrites were distributed relatively uniformly throughout all sublaminae of the inner plexiform layer. The present study provides unambiguous identification of ganglion cell dendrites including very fine processes, enabling a detailed analysis of the types and distribution of synaptic inputs from the bipolar and amacrine cell to the ganglion cells. The retrograde tracing technique used in the present study will prove to be a useful tool for identifying synaptic inputs to ganglion cell dendrites from neurochemically identified bipolar and amacrine cell types in the retina.

Animals↗
PubMedDate not supplied

Responses of directionally selective retinal ganglion cells to activation of AMPA glutamate receptors.

Previous studies in the rabbit retina have shown that drugs which block AMPA glutamate receptors abolish directional selectivity in ON-OFF directionally selective (DS) ganglion cells. The effects of activation of AMPA receptors on the directionally selective responses of these ganglion cells had not been studied. In the present study, extracellular recordings of the responses of ON-OFF DS ganglion cells to a moving bar of light were made in an in vitro rabbit retinal preparation. In control solution, bath application of AMPA (7-10 microM) abolished the light responses of most ON-OFF DS ganglion cells. On washout of AMPA, the light responses rapidly returned; however, the cells temporarily lost the ability to discriminate the direction of the moving bar of light. That is, the cells responded equally to movement in the preferred and null directions. Pretreatment of retinas with the glycine receptor antagonist strychnine (1-2 microM) did not alter the effects of AMPA. On the other hand, in retinas pretreated with the GABA(A) receptor antagonist SR95531 (0.2-0.25 microM), AMPA did not abolish the light responses of ON-OFF DS ganglion cells but instead abolished directional selectivity in these cells by bringing out a response to movement in the null direction. This finding suggests that an AMPA-induced GABA efflux from cells in the retina was responsible for the suppression of the light responses by AMPA. In control solution, application of the selective AMPA receptor agonist (S)-5-fluorowillardiine (2-3 microM) only temporarily abolished the light responses of ON-OFF DS ganglion cells. As the light responses returned, it was clear that directional selectivity had been abolished by (S)-5-fluorowillardiine. In control solution, blocking AMPA receptor desensitization with cyclothiazide (80-100 microM) greatly reduced the light responses of ON-OFF DS ganglion cells. As the light responses slowly returned on washout of cyclothiazide, directional selectivity was clearly reduced although not abolished. In retinas pretreated with SR95531, application of cyclothiazide abolished directional selectivity. Diazoxide (700-1000 microM), another blocker of AMPA receptor desensitization, abolished directional selectivity in ON-OFF DS ganglion cells without the need of adding SR95531 to the bathing solution. It is concluded that, in the rabbit retina, AMPA receptors play an important role in generating directional selectivity in ON-OFF DS ganglion cells. Moreover, excessive activation of AMPA receptors greatly compromises the mechanism for directional selectivity in ON-OFF DS ganglion cells.

Acetylcholine↗
PubMed1995

[Stellate ganglion block with transcutaneous electric nerve stimulation (TENS): a double-blind study with healthy probands].

OBJECTIVE: Blockade of the stellate ganglion is an established and highly effective diagnostic and therapeutic procedure for management of certain acute and chronic pain syndromes or other disorders. The paratracheal injection of a local anaesthetic is the simplest and most frequently used approach for blocking the cervicothoracic sympathetic nerves (ganglion stellate). However, since serious complications can occur during or following the anterior paratracheal technique including accidental intravenous or intraarterial injection, non-invasive methods for blockade of the stellate ganglion have been suggested. In 1980 Jenkner (15) reported the successful interruption of the sympathetic outflow from the stellate ganglion together with the relief of pain by transcutaneous electrical nerve stimulation (TENS), followed by the development of an "optimal wave form" in 1981 (14). Since we were unable to reproduce Jenkner's results of sympathetic blockade in our patients, this study was designed to investigate the effects of TENS on the sympathetic activity of the stellate ganglion in healthy volunteers. METHODS: 50 healthy volunteers were randomised into two groups (n = 25). In group I the left stellate ganglion was stimulated for 20 min by the mode described by Jenkner (monophasic pulse, small anode, large cathode, frequency 20 Hz), while group II was stimulated by conventional TENS (biphasic pulse, electrodes of identical size, frequency 100 Hz). The method of stimulation was blinded to both the investigator and the subjects investigated. Measurements included cutaneous blood flow of the volar forearm (laser Doppler), skin temperature on two sites of the cheeks (thermistor), pupil diameter and size of the palpebral fissures, sweat production (ninhydrine test) and global sensitivity and pain perception thresholds on both sides (electrical stimulation). Measurements were performed before TENS of the stellate ganglion, after 5, 10, 15 and 20 min of stimulation and 10 min after termination of TENS. Statistical analysis of the obtained data was performed by Friedman-Test and by Mann-Whitney-U-Test. p < 0.05 was assigned statistical significance. MAIN RESULTS: Skin temperature increased in both groups and on both sides by 1.2 degrees C, while skin perfusion rate, pupil size, size of the palpebral fissure and sweat production remained unchanged. Global sensitivity and pain perception thresholds of forehead decreased in both groups and on both sides, while there was no change of both parameters on the hands. CONCLUSION: No signs and symptoms of sympathetic blockade could be demonstrated in any of the groups, neither by TENS of the stellate ganglion as described by Jenkner nor by unspecific TENS. Thus, pain relief by TENS of the stellate ganglion as reported in the literature must involve other mechanisms than sympathetic blockade. In addition, TENS may not replace traditional blockade of the stellate ganglion by local anesthetics, if sympathetic blockade is required for diagnostic and therapeutic purposes.

Adult↗
PubMed2006

The effect of organ of corti loss on ganglion cell survival in humans.

HYPOTHESIS: Severe spiral ganglion cell loss does not necessarily follow loss of hair cells or supporting cells in humans. BACKGROUND: Despite some publications to the contrary, statements that loss of hair cells and/or supporting cells of the organ of Corti results in a severe loss of spiral ganglion cells in humans still appear in the literature, especially in respect to cochlear implants. This assumption is apparently based on studies in animals or cell culture and not from studies of human temporal bones. METHODS: Morphological analysis of archival temporal bones with microscopic and statistical analysis of ganglion cell, hair cell, and supporting cell populations was performed in 33 ears with total hearing losses of varying causes and durations of deafness. None of the ears had remaining hair cells. Six ears had had cochlear implants. RESULTS: Ganglion cell counts ranging from 2,889 to 34,299 and the corresponding percentage of remaining ganglion cells based on age-normative data were not significantly related to the duration of hearing loss (r = -0.13 and 0.02, respectively, p > 0.05) or to remaining supporting cell populations (r's from 0.15 to 0.27, p > 0.05). More than half of ears (51.5%) had ganglion cell counts within two standard deviations of age-normative means. Mean ganglion cell counts and percentage of remaining ganglion cells of ears with surviving peripheral processes (dendrites) did not differ significantly from those of ears with no peripheral processes. CONCLUSION: The loss of hair and supporting cells in the organ of Corti in humans does not necessarily result in as significant a loss of spiral ganglion cells as has been reported animals. In fact, our results suggest that ganglion cell loss may be a primary concomitant loss due to the disease process.

Adult↗
PubMed2005

Network of the sympathetic nervous system: focus on the input and output of the cervical sympathetic ganglion.

Unlike the thoracic and lumbar sympathetic nervous systems with paravertebral ganglions in individual spinal segments, the cervical sympathetic nervous system lacks segmental structures corresponding to the spinal segments and only three ganglions, namely the upper and middle cervical ganglions and the stellate ganglion, are present. Single axons have been observed in the ganglions using an anterograde-labeling method to analyze their expansion in order to investigate the relationship between the cervical sympathetic ganglions and the spinal cord in rats. Although segmental structures were not confirmed in the upper cervical ganglion, segmental structures were demonstrated in the stellate ganglion. Next, it was determined that some sympathetic preganglionic neurons, nitric oxide synthetase-positive preganglionic neurons, form dense nerve endings on the upper cervical ganglion neurons that project onto organs closely related to glandular secretion in the head and neck region. Finally, the relationship between the cell body size of upper cervical ganglion neurons and the size of the target was investigated for the three major salivary glands in rats and it was determined that no direct relationship was present.

Animals↗
PubMed1995

The extracellular matrix molecule tenascin: expression in the developing chick retinotectal system and substrate properties for retinal ganglion cell neurites in vitro.

To investigate the molecular mechanisms involved in the outgrowth of retinal ganglion cell axons in the tectum, the expression of the extracellular matrix molecule tenascin was analysed in the tectum and retina of chickens by immunocytochemistry and in situ hybridization. Tissue was analysed between embryonic days 4 and 12, just before and during the period when retinal ganglion cell axons innervate their target region, the optic tectum. In the tectum, tenascin immunoreactivity becomes detectable at the anterior pole at embryonic day 4, 2 days before retinal ganglion cell axons arrive, and spreads caudally with increasing age. At early stages, tenascin is predominantly accumulated in the stratum opticum, the zone of ingrowing retinal ganglion cell axons, and along their prospective pathway. In the stratum opticum, the molecule is associated with radial glial fibres, glial endfeet and retinal ganglion cell axons located in the immediate neighbourhood of radial glial fibres. At all ages investigated, tenascin mRNA is mainly restricted to cells located in the periventricular region, suggesting that the molecule is synthesized by radial glial cells. In the retina, tenascin is expressed by amacrine, displaced amacrine and horizontal cells but not by retinal ganglion cells. To investigate whether the accumulation of tenascin in the developing and prospective pathway of retinal ganglion cell axons may affect their rate of growth we assayed the substrate properties of tenascin for retinal ganglion cell neurites in vitro. When retinal ganglion cell suspensions from 6-day-old chick embryos were maintained on homogeneous mouse or chick tenascin/polyornithine substrates, neurite length was significantly increased when compared to polyornithine substrates at coating concentrations of 10 or 20 micrograms/ml. Higher coating concentrations (35 or 70 micrograms/ml) resulted in neurite lengths comparable to control values. Together, these observations suggest that tenascin in the developing and prospective stratum opticum might serve as a performed pathway to support growth of retinal ganglion cell axons in the tectum.

Animals↗
PubMed1987

Signal transmission in the catfish retina. IV. Transmission to ganglion cells.

1. To characterize the temporal dynamic responses of ganglion cells and to define the possible inputs giving rise to their responses in catfish retina, we recorded the ganglion cell responses evoked by 1) a step of light presented in the dark, 2) an incremental and decremental step from a background illumination, and 3) a white-noise modulated light. 2. For comparison, we recorded the responses of preganglionic cells evoked by the same set of stimuli as used for the ganglion cells. Type-C cells produced on-off transient depolarizations to step stimuli, whether presented in the dark or an illuminated background. Type-N amacrine cells produced complex transient responses to incremental and decremental steps, whereas their step-evoked responses in the dark were sustained polarizations. Bipolar cells produced sustained responses to all step stimuli. 3. Ganglion cells were classified into three types, based on their responses evoked by incremental and decremental steps of light. One class of ganglion cells produced responses similar to those of type-C cells, the second class produced responses similar to those of type-N cells, and the third class resembled bipolar cell responses, although spike discharges accompanied the ganglion cell responses. 4. The analysis of the first-order kernels indicates that the temporal properties of linear dynamic responses are established at the level of bipolar cells and encoded into spike trains of ganglion cells without a major transformation. 5. The second-order nonlinearity appeared at the amacrine cell level. Type-C and type-N cells produced a second-order kernel characteristic of each cell type. The second-order kernels produced in ganglion cells were similar to those produced either by type-C or type-N cells. 6. We conclude that bipolar cells are the major source of linear components of ganglion cell responses and that type-C and type-N amacrine cells are the major source of the nonlinear responses. These linear and second-order nonlinear signals were encoded into spike trains by ganglion cells without a major transformation of the temporal response properties.

Animals↗
PubMed1990

N-methyl-D-aspartate receptors of ganglion cells in rabbit retina.

1. Intracellular and extracellular recordings were obtained from ganglion cells in the rabbit retina. The effect of N-methyl-DL-aspartate (NMDLA) and N-methyl-D-aspartate (NMDA) antagonists were studied with the use of a perfusion method for drug application. 2. NMDLA excited all ganglion cell types and caused a characteristic burst firing pattern, which is not typical of physiological responses in the retina. When synaptic transmission was blocked with cobalt, NMDLA still excited ganglion cells, indicating a direct action. 3. A comparison of DL-2-amino-5-phosphonopentanoate (DL-AP-5) and DL-2-amino-7-phosphonoheptanoate (DL-AP-7) revealed that DL-AP-7 was a more specific NMDA antagonist. DL-AP-5 partially blocked the b-wave of the electroretinogram (ERG), an action typical of L-2-amino-4-phosphonobutyrate (L-APB), which specifically blocks on channels in the retina. 4. DL-AP-7 reversibly blocked the action of NMDLA on all ganglion cell types, but the effects of kainate (KA) and carbachol were unchanged. AP-7 was stereospecific and pharmacologically specific, with action typical of a competitive NMDA antagonist in the rabbit retina. 5. DL-AP-7 did not block light responses driven by center or surround stimulation for ON or OFF ganglion cells. Directional selectively was unchanged by DL-AP-7. However, most ganglion cells showed a reduction, typically 20-30%, in the number of action potentials produced by light stimulation. 6. In contrast to a previous report, we found no evidence that DL-AP-7 specifically inhibited sustained ON ganglion cells. The inhibition of sustained ON responses by DL-AP-5, previously attributed to NMDA antagonism, is probably because of the weak APB activity of L-AP-5. 7. We conclude that NMDA receptors do not mediate the major light-driven input to ganglion cells in the rabbit retina. By exclusion, transmission from bipolar cells to ganglion cells appears to be carried mostly by KA or quisqualate (QQ) receptors. However, because NMDA antagonists reduced the number of action potentials produced by light stimulation, it is likely that NMDA receptors carry a portion of the signal transmission to ganglion cells. The presence of NMDA receptors on third-order neurons is consistent with the release of glutamate from presynaptic neurons such as bipolar cells.

2-Amino-5-phosphonovalerate↗
PubMed1998

Interactions of inhibition and excitation in the light-evoked currents of X type retinal ganglion cells.

The excitatory and inhibitory conductances driving the light-evoked currents (LECs) of cat and ferret ON- and OFF-center X ganglion cells were examined in sliced and isolated retina preparations using center spot stimulation in tetrodotoxin (TTX)-containing Ringer. ON-center X ganglion cells showed an increase in an excitatory conductance reversed positive to +20 mV during the spot stimulus. At spot offset, a transient inhibitory conductance was activated on many cells that reversed near ECl. OFF-center X ganglion cells showed increases in a sustained inhibitory conductance that reversed near ECl during spot stimulation. At spot offset, an excitatory conductance was activated that reversed positive to +20 mV. The light-evoked current kinetics of ON- and OFF-center X cells to spot stimulation did not significantly differ in form from their Y cell counterparts in TTX Ringer. When inhibition was blocked, current-voltage relations of the light-evoked excitatory postsynaptic currents (EPSCs) of both ON- and OFF-X cells were L-shaped and reversed near 0 mV. The EPSCs averaged between 300 and 500 pA at -80 mV. The metabotropic glutamate receptor agonist 2-amino-4-phosphonobutyric acid (APB), was used to block ON-center bipolar cell function. The LECs of ON-X ganglion cells were totally blocked in APB at all holding potentials. APB caused prominent reductions in the dark holding current and synaptic noise of ON-X cells. In contrast, the LECs of OFF-X ganglion cells remained in APB. An increase in the dark holding current was observed. The excitatory amino acid receptor antagonist combination of D-amino-5-phosphono-pentanoic acid (D-AP5) and 2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo-(F)-quinoxalinedione (NBQX) was used to block ionotropic glutamate receptor retinal neurotransmission. The LECs of all ON-X ganglion cells were totally blocked, and their holding currents were reduced similar to the actions of APB. For OFF-X ganglion cells, the antagonist combination always blocked the excitatory current at light-OFF; however, in many cells, the inhibitory current at light-ON remained. ON-center X ganglion cells receive active excitation during center illumination, and a transient inhibition at light-OFF. In contrast OFF-center X ganglion cells experience a sustained active inhibition during center illumination, and a shorter increase in excitation at light-offset. Cone bipolar cells provide a resting level of glutamate release on X ganglion cells on which their light-evoked currents are superimposed [corrected].

Animals↗
PubMed2001

Light-dependent induction of cFos during subjective day and night in PACAP-containing ganglion cells of the retinohypothalamic tract.

Environmental light stimulation via the retinohypothalamic tract (RHT) is necessary for stable entrainment of circadian rhythms generated in the suprachiasmatic nucleus (SCN). In the current report, the authors characterized the functional activity and phenotype of retinal ganglion cells that give rise to the RHT of the rat. Retinal ganglion cells that give rise to the RHT were identified by transsynaptic passage of an attenuated alpha herpesvirus known to have selective affinity for this pathway. Dual labeling immunocytochemistry demonstrated co-localization of viral antigen and pituitary adenylate cyclase activating polypeptide (PACAP) in retinal ganglion cells. This was confirmed using the anterograde tracer cholera toxin subunit B (ChB). In normal and retinally degenerated monosodium glutamate (MSG)-treated rats, ChB co-localized with PACAP in axons of the retinorecipient zone of the SCN. Light-induced Fos-immunoreactivity (Fos-IR) was apparent in all PACAP-containing retinal ganglion cells and a population of non-PACAP-containing retinal ganglion cells at dawn of normal and MSG-treated animals. Within the next 3 h, Fos disappeared in all non-PACAP-immunoreactive cells but persisted in all PACAP-containing retinal ganglion cells until dusk. When animals were exposed to constant light, Fos-IR was sustained only in the PACAP-immunoreactive (PACAP-IR) retinal ganglion cells. Darkness eliminated Fos-IR in all PACAP-IR retinal ganglion cells, demonstrating that the induction of Fos gene expression was light dependent. When animals were maintained in constant darkness and exposed to light pulses at ZT 14, ZT 19, or ZT 6, Fos-IR was induced in PACAP-IR retinal ganglion cells in a pattern similar to that seen at dawn. Collectively, these data indicate that PACAP is present in ganglion cells that give rise to the RHT and suggest a role for this peptide in the light entrainment of the clock.

Animals↗
PubMed1999

Ganglion cell losses underlying visual field defects from experimental glaucoma.

PURPOSE: To investigate the relationship between ganglion cell losses and visual field defects caused by glaucoma. METHODS: Behavioral perimetry and histology data were obtained from 10 rhesus monkeys with unilateral experimental glaucoma that was induced by argon laser treatments to their trabecular meshwork. After significant visual field defects had developed, the retinas were collected for histologic analysis. The ganglion cells were counted by light microscopy in cresyl violet-stained retina sections, and the percentage of ganglion cell loss (treated to control eye counts) was compared with the depth of visual field defect (treated to control eye thresholds) at corresponding retinal and perimetry test locations. Sensitivity losses as a function of ganglion cell losses were analyzed for Goldmann III, white and Goldmann V, and short- and long-wavelength perimetry test stimuli. RESULTS: The relationship between the proportional losses of ganglion cells and visual sensitivity, measured with either white or colored stimuli, was nonlinear. With white stimuli, the visual sensitivity losses were relatively constant (approximately 6 dB) for ganglion cell losses of less than 30% to 50%, and then with greater amounts of cell loss the visual defects were more systematically related to ganglion cell loss (approximately 0.42 dB/percent cell loss). The forms of the neural-sensitivity relationships for visual defects measured with short- or long-wavelength perimetry stimuli were similar when the visual thresholds were normalized to compensate for differences in expected normal thresholds for white and colored perimetry stimuli. CONCLUSIONS: Current perimetry regimens with either white or monochromatic stimuli do not provide a useful estimate of ganglion cell loss until a substantial proportion have died. The variance in ganglion cell loss is large for mild defects that would be diagnostic of early glaucoma and for visual field locations near the fovea where sensitivity losses occur relatively late in the disease process. The neural-sensitivity relationships were essentially identical for both white and monochromatic test stimuli, and it therefore seems unlikely that the higher sensitivity for detecting glaucoma with monochromatic stimuli is based on the size-dependent susceptibility of ganglion cells to injury from glaucoma.

Animals↗
PubMed2002

Molecular phenotyping of retinal ganglion cells.

Classifying all of the ganglion cells in the mammalian retina has long been a goal of anatomists, physiologists, and cell biologists. The rabbit retinal ganglion cell layer was phenotyped using intrinsic small molecule signals (aspartate, glutamate, glycine, glutamine, GABA, and taurine) and glutamate receptor-gated 1-amino-4-guanidobutane excitation signals as the clustering dimensions for formal classification. Intrinsic signals alone yielded 7 ganglion cell superclasses and 1 amacrine cell superclass; the addition of excitation signals ultimately resolved 14 natural ganglion cell classes and 3 amacrine cell classes. Ganglion cells comprise two-thirds to three-quarters of the cells in the ganglion cell layer and exhibited distinct metabolic, coupling, and excitation phenotypes, as well as characteristic sizes, population fractions, and patterns. Metabolic signatures (mixtures of glutamate, aspartate, glutamine, and GABA) chemically discriminated ganglion from amacrine cells. Coupling signatures reflected heterologous coupling states across ganglion cells: (1) uncoupled, (2) coupled to GABAergic amacrine cells, and (3) coupled to glycinergic amacrine cells. Excitation signatures reflected differential channel permeation rates across classes after AMPA activation. Extraction of unique size and patterning features from the data sets further validated the robustness of the classification. Because the classifications were explicitly blinded to structure, this is strong evidence that molecular phenotype classes are natural classes. Correspondences of molecular phenotype classes to functional classes were inferred from size, coupling, encounter, and physiological attributes. Ganglion cell classes display markedly different ionotropic drives, which may partly explain the physiological brisk-sluggish spectrum of ganglion cell spiking patterns.

Agmatine↗
PubMed1991

[Purification and survival of retinal ganglion cell].

We had used a specific anti-Thy 1.1 antibody binding method and a nylonmembrane sieve method to isolate and purify retinal ganglion cells from neonatal rats in order to compare the effect of tectal extract on these purified cells retinal ganglion cells. Isolated retinal cell suspension with retinal ganglion cells retrograde-prelabelled with Fast Blue were seeded on culture dishes coated with the specific anti-Thy 1.1 antibody for 30 minutes before nonadherent cells were removed. The percentage purity of the adherent retinal ganglion cells determined microscopically to be 95%. However, the percentage purity of the Fast Blue-labelled retinal ganglion cells recovered using the nylon membrane of pore size 15 microns was only 60 +/- 5%. Retinal ganglion cells purified by both methods could survive and grow into large, active neurons with neurite outgrowths in the presence of tectal extract. A MTT colorimetric microassay was used to quantify the survival growth activity of these purified retinal ganglion cells after culture for 24 hours. The result showed that the optical density ratio (+Te/-Te) of the retinal ganglion cells purified by anti-Thy 1.1 antibody binding method was 12.3 (0.111/0.009) and by the nylon membrane method was 6.4 (0.102/0.016), and the optical density ratio of the non-purified retinal cells was 3.8 (0.095/0.025), p less than 0.01 for all 3 sets of results. It was concluded that in the absence of other cells, the purified retinal ganglion cells responded specifically to the trophic activity in tectal extract, the purer the retinal ganglion cells and the clearer the effect.

Animals↗