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PubMedDate not supplied

Substance P-immunoreactive retinal ganglion cells and their central axon terminals in the rabbit.

Retinal ganglion cells are the projection neurons that link the retina to the brain. Peptide immunoreactive cells in the ganglion cell layer (GCL) of the mammalian retina have been noted but their identity has not been determined. We now report that, in the rabbit, 25-35% of all retinal ganglion cells contain substance P-like (SP) immunoreactivity. They were identified by either retrograde transport of fluorescent tracers injected into the superior colliculus, or by retrograde degeneration after optic nerve section. SP immunoreactive cells are present in all parts of the retina and have medium to large cell bodies with dendrites that ramify extensively in the proximal inner plexiform layer. Their axons terminate in the dorsal lateral geniculate nucleus, superior colliculus and accessory optic nuclei, and these terminals disappear completely after contralateral optic nerve section and/or eye enucleation. In the dorsal lateral geniculate nucleus large, beaded, immunoreactive axons and varicosities make up a narrow plexus just below the optic tract, where they define a new geniculate lamina. The varicosities make multiple synaptic contacts with dendrites of dorsal lateral geniculate nucleus projection neurons and presumptive interneurons in complex glomerular neuropil. This is direct evidence that some mammalian retinal ganglion cells contain substance P-like peptides and strongly suggests that, in the rabbit, substance P (or related tachykinins) may be a transmitter or modulator in a specific population or populations of retinal ganglion cells.

Animals↗
PubMed2004

Recording spikes from a large fraction of the ganglion cells in a retinal patch.

To understand a neural circuit completely requires simultaneous recording from most of the neurons in that circuit. Here we report recording and spike sorting techniques that enable us to record from all or nearly all of the ganglion cells in a patch of the retina. With a dense multi-electrode array, each ganglion cell produces a unique pattern of activity on many electrodes when it fires an action potential. Signals from all of the electrodes are combined with an iterative spike sorting algorithm to resolve ambiguities arising from overlapping spike waveforms. We verify that we are recording from a large fraction of ganglion cells over the array by labeling the ganglion cells with a retrogradely transported dye and by comparing the number of labeled and recorded cells. Using these methods, we show that about 60 receptive fields of ganglion cells cover each point in visual space in the salamander, consistent with anatomical findings.

Action Potentials↗
PubMed2003

Generation of retinal ganglion cells is modulated by caspase-dependent programmed cell death.

Programmed cell death occurs during both early and late neural development. The mechanisms for the regulation and execution of the early cell death as well as its developmental role are still not fully understood. In this work we have studied the early programmed cell death in the retinal neuroepithelium. Apoptotic cells were selectively located around the optic nerve head in the retinal neuroepithelium of 2- to 6-day-old chick embryos. TUNEL-positive cells and cells which were immunostained for activated caspase-3 showed overlapping distributions suggesting that caspase-3 is involved in the early retinal cell death. Caspase-3 involvement in early retinal cell death was also demonstrated by in vivo treatment with caspase inhibitors z-DEVD-fmk and Boc-D-fmk. After 6 h of treatment, the number of TUNEL-positive cells was reduced by 50%. Sustained treatments (20 h) resulted in a slight widening in the central part of the neural retina but the retinal ganglion cell axons maintained their organization and navigation towards the optic fissure. The most prominent result after inhibition of cell death was an increase in the number of retinal ganglion cells which also produced an enlargement of the ganglion cell layer and an increased number of ganglion cell axons. In conclusion, our results show that caspase-dependent programmed cell death occurs in the embryonic chick retina and that it plays a role to modulate the generation of retinal ganglion cells.

Aging↗
PubMed1999

Compartmentalisation of the developing trigeminal ganglion into maxillary and mandibular divisions does not depend on target contact.

During development axons contact their target tissues with phenomenal accuracy but the mechanisms that control this homing behaviour remain largely elusive. A prerequisite to the study of the factors involved in hard-wiring the nervous system during neurogenesis is an accurate calendar of developmental events. We have studied the maxillary and mandibular components of the trigeminal system to determine the stages during embryogenesis when a gross somatotopic order is first established within the trigeminal ganglion and the axons projecting to the brainstem. The retrograde transganglionic fluorescent tracers DiO and DiI were injected into the maxillary and mandibular arches or their derivatives in fixed mouse embryos staged between 13 and 40 somites (E9-E11). After 1-4 wk, the distribution of the 2 tracers was determined using confocal laser scanning microscopy. The first maxillary nerve cell bodies and their developing axons were labelled at the 30 somite stage (E10). This was 2 somite stages earlier than the mesencephalic nucleus and the ganglion cell bodies of the mandibular nerve. The gross somatotopic division of cells within the trigeminal ganglion projecting to the maxillary and mandibular targets was established by the 32 somite stage (E10). This arrangement was evident as 2 groups of cell bodies occupying adjacent but separate regions of the trigeminal ganglion. The central branches of the maxillary and mandibular cell bodies entered the metencephalon as 2 distinct bundles at the same stage. The trigeminal motor nucleus was first detected at the 38 somite stage (E10.5). Gross somatotopy in the major divisions of the trigeminal ganglion is established before outgrowing axons have contacted their peripheral target tissue at E10.5. This suggests that target tissues do not induce somatotopy.

Animals↗
PubMedDate not supplied

Spread of injectate during C6 stellate ganglion block and fascial arrangement in the prevertebral region: an experimental study using donated cadavers.

BACKGROUND AND OBJECTIVES: The precise fascial space through which the injectate spreads during stellate ganglion block (SGB) remains unclear. Recent studies using magnetic resonance imaging or computed tomography have suggested that the injectate is deposited around and/or within the longus colli muscle during SGB. However, a fascial space, close to the longus colli, is the most likely route of spread. We identified the prevertebral interlaminal space (PVILS), situated between the anterior and posterior laminae of the prevertebral layer of the fascia, as an important route for the spread of the injectate and as a potential pathway to the ganglion. The danger of downward spread of deep infections through this space has previously been recognized. METHODS AND RESULTS: Using the 6th cervical vertebra paratracheal approach technique, we performed experimental SGB with 10 mL latex on donated cadavers. Spreading of latex into the PVILS was observed in 45 of 52 (86.5%) cadavers that had been fixed with formaldehyde after death, and 5 of 8 (62.5%) fresh cadavers. In these experiments, the latex usually reached the ganglion via the PVILS (39 of 45 and 5 of 5, respectively). Moreover, after direct injection into the PVILS, latex reached the ganglion in 13 of a further 19 (68.4%) postmortem-fixed donated cadavers. CONCLUSION: These results suggest that the PVILS plays a critical role in the spread of injectate as well as being a potential pathway to the stellate ganglion during SGB.

Autonomic Nerve Block↗
PubMed2002

[Histomorphometric assessment of spiral ganglion neurite outgrowth in vitro].

BACKGROUND: During the last years, various groups of growth factors have been identified to influence spiral ganglion cell survival and neurite extension in the mammalian cochlea. To evaluate and compare the effects of different growth factors, a precise histomorphometrical analysis of neurite outgrowth patterns has to be applied. The here presented technique is compared to already published methods, that only approximately estimate the neurite length. METHOD: A software has been developed to analyse digitalised scans of spiral ganglion cells and to measure the length of the neurites. Therefore, the neurites are being separated in any given number of straight lines. The totals of these lines can then be added like a polygon. This polygon method was compared to a semi-quantitative procedure in which the neurite length was determined by concentric circles that were crossed by the neurites in a certain distance. The accuracy of both methods was analysed. Both methods were performed in 20 specimen of neonatal rat spiral ganglion cells after in vitro stimulation with neurotrophic factors. RESULTS: The semi-quantitative method has shown to involve a systematic error between +/- 10 to 15 %. The polygon method, on the contrary, has a systematic error of around +/- 1 %, which admits much more accurate measurement of spiral ganglion neurite outgrowth. CONCLUSION: With the described polygon method, spiral ganglion neurite growth patterns in cell culture studies can be characterised more precisely and, thus, helps to better differentiate the action domain of neurotrophic factors.

Animals↗
PubMed1989

Retinal ganglion beta cells project transiently to the superior colliculus during development.

In adult cats, retinal ganglion cells of the beta class project almost exclusively to the lateral geniculate nucleus rather than to the superior colliculus (SC). We have examined whether this target specificity is present during early development. To identify ganglion cells that send axons to the SC in development, rhodamine-labeled microspheres were deposited in the SC at embryonic day (E) 38, E43, or postnatal day (P) 4. Retinae were then removed between E56 and P32 and kept alive in a tissue-slice chamber so that ganglion cells that had been retrogradely labeled with microspheres could be injected intracellularly with Lucifer yellow to reveal their morphological class. Many beta cells could be retrogradely labeled by microspheres injected into the SC at E38 or E43. They were indistinguishable from beta cells projecting to the lateral geniculate nucleus and were found even when a single injection was restricted to the caudal portion of the SC. In contrast, beta cells could not be retrogradely labeled by microspheres injected into the SC at P4. The disappearance of a beta-cell projection to the SC cannot be explained entirely by cell death since as late as P32, well after the major period of ganglion cell death, many beta ganglion cells labeled with microspheres at E38 were still present. These observations suggest that many beta cells initially extend an axon collateral to the SC that is subsequently lost some time after E43. Thus, to achieve the remarkable specificity present in the adult visual system, beta cells must withdraw axon collaterals from an entire target nucleus. Similar collateral elimination may give rise to the specificity of afferent connections in other sensory systems.

Animals↗
PubMed1991

(-)-baclofen and gamma-aminobutyric acid inhibit calcium currents in isolated retinal ganglion cells.

Of the various synaptic inputs known to converge upon retinal ganglion cells, the major inhibitory inputs are thought to be GABAergic. Although gamma-aminobutyric acid (GABA) is known to activate anion-selective ion channels in retinal ganglion cells, we have tested the possibility that GABA can also modulate cationic conductances in these cells, as seen in other central and peripheral neurons. Specifically, we have made whole-cell patch-clamp recordings to test whether voltage-gated calcium currents in isolated goldfish retinal ganglion cells are sensitive to GABAB receptor ligands. (-)-Baclofen and GABA inhibited calcium currents activated by moderately long depolarizations and, during large depolarizations (e.g., to 0 mV), also appeared to accelerate the rate of current decay. The calcium current inhibition induced by (-)-baclofen and GABA was not prevented by 2-hydroxysaclofen, phaclofen, or bicuculline, even though bicuculline suppressed a GABA-activated conductance in these cells. These results demonstrate the presence of baclofen- and GABA-sensitive calcium currents in vertebrate retinal ganglion cells as well as the coexistence of GABAA and GABAB receptors in individual retinal ganglion cells.

Animals↗
PubMed1994

Amino acid receptors of midget and parasol ganglion cells in primate retina.

Primate retinas contain two major ganglion cell types. Midget (or P type) cells have relatively sustained responses to light; the amplitude and polarity of these responses vary with stimulus wavelength. Parasol (or M type) cells are more sensitive to stimulus contrast and respond more transiently but are not selective for color. Both types can be further subdivided into a and b subtypes, according to the level of their dendritic stratification in the inner plexiform layer. To determine whether differences in receptors for amino acid transmitters are the basis for any differences in ganglion cell light responses, we made whole-cell, patch-clamp recordings from identified ganglion cells in slice preparations of macaque and baboon retinas. We found that midget and parasol cells of both a and b types had similar responses to excitatory amino acids, including kainate, alpha-amino-3-hydroxy-5-methylisoxalzole-4-propionic acid, and N-methyl-D-aspartate, with reversal potentials near the equilibrium potential for cations. Kainate responses were blocked by 6,7-dinitroquinoxaline, and N-methyl-D-aspartate responses were blocked by D-(-)-2-amino-7-phosphonoheptanoic acid. The four types of ganglion cells also had similar responses to bath-applied inhibitory amino acids. All cells had both gamma-aminobutyric acid and glycine receptors with reversal potentials near the equilibrium potential for Cl-, and the relative amplitudes of the responses to excitatory and inhibitory amino acids were similar among the various cell types. These results suggest that the differences in response properties of the different classes of ganglion cells in primate retina may be determined, to a significant degree, by the properties of the amacrine and bipolar cells that provide their input rather than by the nature of their postsynaptic receptors.

Animals↗
PubMed1996

POU domain factor Brn-3b is required for the development of a large set of retinal ganglion cells.

The three members of the Brn-3 family of POU domain transcription factors are found in highly restricted sets of central nervous system neurons. Within the retina, these factors are present only within subsets of ganglion cells. We show here that in the developing mouse retina, Brn-3b protein is first observed in presumptive ganglion cell precursors as they begin to migrate from the zone of dividing neuroblasts to the future ganglion cell layer, and that targeted disruption of the Brn-3b gene leads in the homozygous state to a selective loss of 70% of retinal ganglion cells. In Brn-3b (-/-) mice other neurons within the retina and brain are minimally or not at all affected. These experiments indicate that Brn-3b plays an essential role in the development of specific ganglion cell types.

Animals↗
PubMed2000

Flow cytometry for quantification of retrogradely labeled retinal ganglion cells by Fluoro-Gold.

PURPOSE: To count retrogradely labeled retinal ganglion cells by Fluoro-Gold. METHODS: Retinal ganglion cells were retrogradely labeled using bilateral injections of Fluoro-Gold into the superior colliculus. One week after injections, retinas were dissociated and immunolabeled using specific antibody against Fluoro-Gold. The Fluoro-Gold labeled cells were then counted using flow cytometry. RESULTS: Flow cytometry revealed that approximately 7% of the dissociated retinal cells were ganglion cells retrogradely labeled by Fluoro-Gold (Fig. 1B). Based on the total count of retinal cells per eye, the total number of retinal ganglion cells was estimated at approximately 131,250 +/- 2,542 per rat eye. The coefficient of variation of counts was calculated as 1.98%. CONCLUSIONS: The use of flow cytometry facilitates simple, reproducible and rapid quantification of virtually all of the retinal ganglion cells labeled by Fluoro-Gold in a single rat eye.

Animals↗
PubMed2002

Expression of activating transcription factor 3 and growth-associated protein 43 in the rat geniculate ganglion neurons after chorda tympani injury.

The purpose of this study was to evaluate the degree of damage in the geniculate ganglion and its target organ as a result of chorda tympani (CT) injury. We performed unilateral transection of the rat CT and examined expression of the activating transcription factor 3 (ATF3), a neuronal injury marker, and the growth-associated protein 43 (GAP-43), a regeneration-associated molecule. The mean proportion of ATF3-immunoreactive (ir) neurons in the geniculate ganglion was approximately 32% at 3 days after CT injury, but these neurons were never detected in the naive ganglion. Using in situ hybridization, the mean percentage of GAP-43 mRNA-labeled neurons (signal : noise ratio > or = 10) was observed to have increased significantly to approximately 60% for 1-7 days after CT injury, while that in the naive ganglion was < 15%. The results of morphological studies using scanning electron microscopy and immunohistochemistry indicated that atrophic change and reduction of protein gene-product 9.5-ir fibers in the denervated papillae, mainly in the intragemmal region, were observed after CT injury. Increase in GAP-43 mRNA, suggesting CT axonal regeneration, may have a role in recovery from taste disorders. However, this regenerative process may be involved in abnormal activity in the axotomized neurons or the adjacent intact neurons and so one must not disregard the existence of injured geniculate ganglions when considering the treatment of diseases that cause CT injury.

Activating Transcription Factor 3↗
PubMed1999

4-methylcatechol, a potent inducer of nerve growth factor synthesis, protects spiral ganglion neurons from aminoglycoside ototoxicity--preliminary report.

The degeneration of spiral ganglion neurons after hair cell destruction following aminoglycoside ototoxicity is associated not only with the direct effect on the neurons, but also with a loss of neurotrophic factors provided by auditory hair cells. The neurotrophic factors, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), have been reported to be effective in enhancing neuronal survival against aminoglycoside ototoxicity in vivo. To determine whether 4-methylcatechol (4-MC), a potent inducer of nerve growth factor synthesis, can protect spiral ganglion neurons after aminoglycoside treatment in vivo, we studied the spiral ganglion neurons of gentamicin (GM)-treated mice with or without 4-MC administration. We found that the number of surviving spiral ganglion neurons of 4-MC-treated animals was significantly greater than for those treated with GM alone. Our results suggest that 4-MC promotes synthesis of NGF (and/or other neurotrophins), which enhances spiral ganglion neuron survival after gentamicin treatment.

Animals↗
PubMed2005

"Disc cysts" and "posterior longitudinal ligament ganglion cysts": synonymous entities? Report of three cases and literature review.

OBJECTIVE AND IMPORTANCE: Extradural cysts intimately associated with relatively normal lumbar discs have rarely been reported. Histologically nonspecific, most have been designated posterior longitudinal ligament (PLL) or annulus fibrosus (AF) "ganglion cysts." Recently, "disc cysts" have been distinguished as a separate entity, mostly on the grounds of cyst-disc communication. CLINICAL PRESENTATION: Three young male patients presented with unilateral sciatica. In all cases, magnetic resonance imaging demonstrated rounded, cystic lesions (i.e., hypointense on T1- but hyperintense on T2-weighted scans) adjacent to minimally dehydrated, nonherniated disc spaces. INTERVENTION: At surgery, each cyst was found intimately related to either the AF (Case 3) or the PLL (Cases 1 and 2) of the adjacent disc; and direct disc-space communication was evident in Case 3. After cystectomy, with or without discectomy, all patients achieved complete and long-lasting resolution of their sciatic symptoms. Histological appearances were typical of ganglion cysts in all three cases, with evidence of prior hemorrhage in Cases 1 and 3. CONCLUSION: Our results and those of others suggest that all such cysts are ganglion cysts that derive from either the AF or the PLL at the disc level. Although disc cysts might be AF ganglion cysts exhibiting disc communication, their separate distinction is probably unnecessary. Cystectomy alone affords complete symptomatic remission; discectomy is usually unnecessary. Although anticipated with ganglia in general, neither spontaneous resolution nor postoperative recurrences have been witnessed. Unlike ganglia in general or juxtafacet ganglion cysts, such cysts seem to be unusually restricted to young men.

Adult↗
PubMed1995

Cellular localization of dopamine D2 receptor messenger RNA in the rat trigeminal ganglion.

The actions of dopamine are mediated by specific, high-affinity, G protein-coupled receptors. Multiple subtypes of dopamine receptors have been characterized, including the D2 subtype (D2R). Cells within the dorsal root and petrosal ganglia of the rat express D2R messenger RNA (mRNA) consistent with D2R expression by primary sensory neurons. We hypothesized that neurons of the trigeminal ganglion express D2R mRNA. Total cellular RNA from rat trigeminal ganglia was analyzed on Northern blots under high stringency conditions. Hybridization of trigeminal ganglion RNA resulted in a signal which comigrated with striatal, pituitary, and hypothalamic D2R mRNA. To determine the distribution of D2R expressing cells in the trigeminal ganglion, cryostat sections were analyzed by in situ hybridization followed by emulsion autoradiography. We identified a population of clustered cells labeled with dense grain concentrations over their cytoplasms. These findings demonstrate the expression of D2 dopamine receptor mRNA in discrete subpopulations of neurons in the rat trigeminal ganglion. Our observations suggest that drugs active at dopamine receptors of the D2 subtype are potential modulators of sensory activity of neurons whose cell bodies reside in the trigeminal ganglion. D2 dopamine receptors may thus have a role in clinical pain syndromes involving the head and neck.

Animals↗
PubMed1990

Ganglionic blockade improves neurologic outcome from incomplete ischemia in rats: partial reversal by exogenous catecholamines.

The authors investigated the effects of nitrous oxide (N2O), ganglionic blockade, and combined infusion of epinephrine and norepinephrine (0.1 microgram.kg-1.min-1 each) on neurologic outcome and brain histopathology in a model of incomplete cerebral ischemia in the rat. Thirty-eight Sprague-Dawley rats were assigned to one of four groups: group 1 (n = 10) received 70% N2O in O2; group 2 (n = 12) received 70% N2O in O2, plus ganglionic blockade; and group 3 (n = 10) received 70% N2O in O2, plus ganglionic blockade and catecholamine infusion. In groups 1-3, ischemia was produced by right carotid occlusion combined with hemorrhagic hypotension (35 mmHg) for 30 min. Group 4 (n = 6) received 70% N2O in O2 and hemorrhagic hypotension without carotid occlusion for 30 min. At the end of ischemic and nonischemic hypotension, the carotid artery was unclamped and the blood slowly reinfused. Neurologic outcome was evaluated for a 5-day period with a graded deficit score (0 = normal to 39 = stroke-related death). Brain histopathology was evaluated in coronal section at the level of the caudate nucleus according to a 6-point scale, from 0 = normal to 5 = total hemispheric infarction. Arterial blood gases, pH, and body temperature were kept constant in all groups. Compared to N2O alone (group 1), treatment with ganglionic blockade (group 2) decreased plasma catecholamines by 75% and significantly improved neurologic outcome from incomplete cerebral ischemia (P less than 0.05). Administration of exogenous epinephrine and norepinephrine in the presence of N2O and ganglionic blockade (group 3) worsened neurologic outcome compared to group 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

The metabotropic glutamate agonist 2-amino-4-phosphonobutyric acid (APB) does not activate currents in postnatal retinal ganglion cells.

Whereas in the mature retina the glutamate agonist 2-amino-4-phosphonobutyric acid (APB) selectively activates currents in rod bipolar and ON-cone bipolar cells, recent molecular studies have suggested the possibility of a transient appearance of the APB-sensitive receptor in developing retinal ganglion cells. In the present study the whole-cell and perforated variations of the patch-clamp method were employed to assess the responsivity of postnatal cat retinal ganglion cells to APB. Recently, APB treatment has been shown in our laboratory to block the normal stratification of retinal ganglion cell dendrites into ON and OFF sublaminae of the inner plexiform layer. Although application of this glutamate agonist elicited inward sustained currents, amino acid analysis revealed that the APB product (RBI) was contaminated by 8% glycine. In subsequent experiments applications of uncontaminated APB (Cal Biochem) never yielded responses in postnatal retinal ganglion cells which displayed normal currents to other glutamate agonists. The findings do not support the notion of transient expression of APB receptors in retinal ganglion cells during the development period studied.

Aminobutyrates↗
PubMed2002

Inhibition of the c-Jun N-terminal kinase signaling pathway influences neurite outgrowth of spiral ganglion neurons in vitro.

OBJECTIVES: Inhibitors of the c-Jun N-terminal kinase (JNK) signaling pathway have been demonstrated to protect hair cells of the auditory system and different types of neurons from various insults, and their use for future therapeutic applications has been proposed. In the study, we evaluated the effects of inhibition of the JNK pathway on process outgrowth from spiral ganglion neurons. METHODS: Spiral ganglion explants from rats (postnatal days 3-5) that were cultured on laminin were treated with neurotrophin-3 and/or the JNK signaling pathway inhibitor CEP-11004. Both neurite length and number of the explants were evaluated and statistically analyzed by analysis of variance. RESULTS: Inhibition of the JNK signaling pathway reduced process outgrowth from spiral ganglion explants. The reduction, both in length and number of neurites, was reversed by the application of neurotrophin-3. CONCLUSIONS: The results indicate that an intact JNK signaling pathway is important for process outgrowth of spiral ganglion neurons. However, neurotrophin-3 stimulates process extension by a JNK independent pathway. Our results demonstrate that inhibition of the JNK pathway can have adverse effects on the extension of spiral ganglion neurons, but that the negative effects can be ameliorated by appropriate treatment.

Analysis of Variance↗