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Antagonism by propranolol of the ganglion stimulant action of 5-hydroxytryptamine.

The effects of racemic propranolol and its constituent isomers were studied on ganglionic stimulation produced in situ by close arterial injection of 5-HT and DMPP to the superior cervical ganglion. Ganglion stimulation was recorded in terms of the resultant contraction of the nictitating membrane. d,l-Propranolol caused a biphasic antagonism of the ganglion stimulant effect of 5-HT. At low doses, 0.5-10 mug, the antagonism was surmountable by increasing the amount of 5-HT. The l-isomer (0.2-4 mug) but not d-propranolol also caused antagonism. At higher doses, 0.1-5 mg, both d,l- and d-propranolol caused a second type of blockade of 5-HT which was not surmountable and resembled that seen with procaine. The ganglion stimulant effects of DMPP and acetylcholine were only antagonised by the higher doses of d- and d,l-propranolol. d,l-Propranolol did not reduce the direct stimulation by 5-HT on the muscle of the nictitating membrane.

Acetylcholine↗
PubMed1989

Dopamine receptors in the stellate ganglion of the dog.

Effects of fenoldopam, a selective DA1 dopamine receptor agonist, and dipropyl dopamine and propylphenethyl dopamine, preferential DA2 dopamine receptor agonists, on ganglion transmission were studied in pentobarbital-anesthetized, open-chest dogs. Tachycardia induced by electrical stimulation (supramaximal voltage, 0.5 ms duration, 1-2 Hz) of the preganglionic cardio-accelerator nerves was monitored as a measure of ganglionic transmission. Drugs were injected into the costocervical artery (i.a.) close to the arterial supply of the ganglion. Doses required to produce 30-40% inhibition of ganglionic transmission by the i.a. route were 2-8 micrograms for dipropyl dopamine, 4-16 micrograms for propylphenethyl dopamine, and 100 micrograms for fenoldopam. At these doses none of the agonists affected tachycardia induced by electrical stimulation of the postganglionic nerve. Domperidone (5 micrograms/kg i.v.), a selective DA2 dopamine receptor antagonist, markedly antagonized the effects of dipropyl dopamine and propylphenethyl dopamine, but had only minor (and statistically insignificant) effects on the inhibitory effect of fenoldopam. SCH 23390 (5 micrograms/kg i.v.), a selective and potent DA1 antagonist, failed to modify the effects of any of the agonists. In a separate series, infusion of fenoldopam, 20 micrograms/kg per min i.v. for 5-7 min, facilitated postganglionic nerve stimulation and blocked the inhibitory effect of UK 14,304, an alpha 2-adrenoceptor agonist, on the postganglionic nerve. These results confirm and support the presence of DA2 but do not support the presence of the prototypal DA1 dopamine receptor in the mammalian ganglia. Furthermore, the alpha 2-adrenoceptor blocking property of fenoldopam points to the complication of using i.v. administration for studying its ganglionic actions while monitoring the target tissue effects in response to preganglionic nerve stimulation.

Animals↗
PubMed1990

Temperature dependence of angiotensin II-mediated depolarisation of the rat isolated nodose ganglion.

The ability of angiotensin II (A II) and 5-hydroxytryptamine (5-HT) to depolarise the rat isolated nodose ganglion preparation was examined. 5-HT depolarised the nodose ganglion, both at room temperature (20-24 degrees C) and at 35-37 degrees C. However, A II depolarised the nodose ganglion only under the latter condition, and these responses were blocked by the A II receptor antagonist saralasin. This study extends previous findings which have demonstrated A II binding sites on the nodose ganglion and axon, and identifies the rat nodose ganglion as a sensitive preparation in which to study the interactions between neuronal A II receptor activation and its blockade by A II receptor antagonists.

Angiotensin II↗
PubMed1988

Desheathing the nodose ganglion is not a reliable method of de-efferentation in the ferret.

The present study reports the results of physiological and anatomical experiments in which the purpose was to determine whether desheathing the nodose ganglion is a reliable method of vagal de-efferentation in the ferret. In physiological studies, the effects of electrically stimulating the treated and untreated vagal nerves on cardiovascular and intestinal responses were examined and compared with previously obtained data after left supranodose vagotomy. The anatomical studies illustrated the effects of desheathing the left nodose ganglion on the transport of horseradish peroxidase (HRP) within a thoracic vagal communicating branch. These data were compared to data from control animals and animals that had undergone left supranodose vagotomy. The results demonstrated that severing the fascicles overlying the left nodose ganglion and allowing the nerve fibers to degenerate, caused no reduction in labeled efferent cell bodies in the left dorsal motor nucleus of the vagus as compared to controls. However, after left supranodose vagotomy there were no efferent cell bodies labeled in the left dorsal motor nucleus of the vagus. Following degeneration of the fascicles, electrical stimulation of the peripheral cut end of this nerve did not abolish the efferent responses in 7 out of 9 animals studied, whereas supranodose vagotomy abolished the responses in all animals. These findings demonstrate that desheathing the nodose ganglion and thereby removing the nerve bundles overlying the nodose ganglion is not a guaranteed method of destroying the efferent fibers in the vagus nerve of the ferret. Supranodose vagotomy, therefore, is a more reliable method of de-efferentation in this species.

Animals↗
PubMed1983

The organization of inputs establishes two functional and morphologically identifiable classes of ganglion cells in the retina of the turtle.

Analyses of the photoresponses and morphologies of ganglion cells in the turtle retina suggests that these cells are of two types: type A ganglion cells receive predominantly bipolar inputs, while type B ganglion cells receive a mixture of inputs from bipolar and amacrine cells. According to these classification criteria, ganglion cells may reflect either activities of the outer or of the inner plexiform layer, respectively. To corroborate the validity of this classification a number of basic properties of ganglion cells were analysed. It was found that double colour opponency was characteristic of type A cells and directional selectivity was performed only by type B cells. In addition, the absolute sensitivity and the firing rate of type A cells were significantly higher than those of type B cells.

Animals↗
PubMed1989

The effect of dark adaptation on the responses of cat retinal ganglion cells to eyeball deformation.

Eyeball deformation in total darkness leads to an activation of on-center ganglion cells and an inhibition of off-center ganglion cells. After "deformation off" most on-center ganglion cell activity decreased slowly to the normal spontaneous dark level, while in off-center ganglion cells some returned according to an exponential function to normal dark activity, while others had a transient postinhibitory activation period. In general, the response type of latency class I and latency class II neurons was the same. Dark adaptation of 30-45 min duration only changed this neuronal response pattern slightly, if at all. A detailed statistical analysis is provided for the four classes of retinal ganglion cells recorded: latency class I on-center and off-center neurons and latency class II on-center and off-center neurons. The missing effects of dark adaptation on neuronal responses evoked by eyeball deformation are explained by three possible models. The more plausible one assumes that horizontal cells are depolarized by retinal stretch. Their interaction with cone on-bipolars or cone off-bipolars is fairly independent of photoreceptor adaptation or transmitter release at the cone pedicles and is still effective when all molecular receptor sites at cone/bipolar cell synapses are occupied during scotopic states of dark adaptation. In psychophysical experiments (two subjects), as in the neuronal responses, we also could not find any indication that the "pressure phosphenes" evoked by lateral eyeball indentation are altered during dark adaptation.

Action Potentials↗
PubMed1989

Responses of retinal ganglion cells to eyeball deformation: a neurophysiological basis for "pressure phosphenes".

By means of microelectrodes, the activity of single neurons (on-center, off-center ganglion cells, latency class I and class II neurons) was recorded from the optic tract of anesthetized cats. Eyeball deformation in total darkness led fairly consistently to an activation of the on-center ganglion cells, while off-center ganglion cells were inhibited. The latency and strength of this activation or inhibition seemed to be mainly dependent on the strength of eyeball indentation and the location of the neurons relative to the point of eyeball indentation. Some on-center neurons (mostly latency class I) also exhibited a short activation at "deformation off". For comparison, the responses of retinal ganglion cells to eyeball deformation in a hydrostatically open system and to a sudden increase in the intraocular pressure (closed system) are described. The neurophysiological data are explained by the assumption that eyeball indentation leads to a nonuniform tangential stretch of the retina, which exerts a locally variable depolarization of horizontal cells. This horizontal cell depolarization leads either directly or via a feedback loop through cone pedicles to a depolarization of on-bipolars and a hyperpolarization of off-bipolars. These effects determine in turn the responses seen at the ganglion cell level. It is emphasized that eyeball deformation can be used as an independent tool in transmitter studies of the retina.

Action Potentials↗
PubMed1989

Retinal ganglion cell distribution in the cebus monkey: a comparison with the cortical magnification factors.

The distribution of ganglion cells was determined in whole-mounted Cebus monkey retinae. Ganglion cell density along the horizontal meridian was asymmetric, being 1.2-4.3 higher in the nasal retinal region when compared to temporal retina at the same eccentricities. The total number of ganglion cells varied from 1.34 to 1.4 million. Ganglion cell density peaked at 49,000/mm2 about 0.5 mm nasal to the fovea. Comparison between ganglion cell density and areal cortical magnification factors for V1 and V2 reveals that the relative representation of the fovea increases in the visual cortex. This effect seems to be a general feature of the visual system of primates.

Animals↗
PubMed1994

Centrifugal inputs enhance responses of retinal ganglion cells in the Japanese quail without changing their spatial coding properties.

Centrifugal fibers originating in the midbrain innervate the avian retina. Stimulation of the centrifugal fibers enhances the responses of ganglion cells in the retinas of both chick and pigeon. The enhanced responses have been attributed to disinhibition, a reduction of the inhibitory surround component of the receptive fields of retinal ganglion cells. We found that stimulation of the centrifugal fibers in Japanese quail enhances the responses of retinal ganglion cells to drifting sine-wave gratings over a wide range of spatial frequencies. Our results do not support the idea that centrifugal inputs selectively influence receptive field surrounds. We also found that centrifugal inputs changed the temporal response properties of retinal ganglion cells by enhancing their responses to sine-wave gratings drifting across the retina at higher temporal frequencies (> 5 Hz). The result shows that centrifugal inputs from the midbrain can enhance responses of retinal ganglion cells without affecting the center-surround organization of their receptive fields. The centrifugal modulation of retinal responses may have a role in shifting visual attention.

Animals↗
PubMed1992

Effects of aging and food restriction on the trigeminal ganglion: a morphometric study.

A quantitative morphometric study of the rat trigeminal ganglion was conducted to determine the changes that occur with aging. All measurements were tracked from young to old age in two rat groups simultaneously. One group was fed ad libitum, the other was maintained on restricted food intake from 6 weeks on. Immunocytochemical and radioimmunoassay techniques were used to study the neuron group that produces the peptide, CGRP and to compare it with the CGRP-negative neuron group. We observed that in the trigeminal ganglion, soma diameters and nucleus diameters of all neurons, whether CGRP positive or negative, increased modestly with age; so did total ganglion weight. Food restriction delayed, but did not prevent the increases in neuron diameters. No significant changes occurred as a function of age in the total number of neurons per ganglion, the ratio of CGRP positive to CGRP negative neurons and ganglion content of CGRP. Food restriction did not affect the parameters that remained constant with age. These findings are in contrast to the marked inhibitory effect of food restriction on age-related increase in thyroid calcitonin, a hormone that is encoded by the same gene as CGRP.

Aging↗
PubMed1980

Autoradiographic study of the right stellate ganglionic fibers to the cat heart.

Autoradiographic techniques have been employed to demonstrate the distribution of the postganglionic sympathetic cardiac fibers originating from the right stellate ganglion in 3 cats. After exposing the ganglion through a right thoracotomy, a total of 500 muCi of tritiated leucine was injected into the right stellate ganglion of each cat. After 3 days the animals were sacrificed by vascular perfusion. The injected ganglia, the heart and great vessels were processed for autoradiography. The majority of the right stellate ganglionic fibers travelled between the trachea and aortic arch, and entered the cardiac fibers travelled between the trachea and aortic arch, and entered the cardiac plexus. Continuing through the plexus, these fibers coursed between the ascending aorta and the pulmonary arterial trunk to form a periarterial plexus around the left coronary artery and its branches. Most of the fibers followed the distribution of the ventral descending branch of the left coronary artery; a few followed the circumflex artery. A conspicuous subepicardial plexus was derived from the periarterial plexus and was most prominent in the cranial half of the left ventricle. Other fibers arising from the right stellate ganglion descended between the cranial vena cava and the right branch of the pulmonary artery. These ramified on the dorsolateral surface of the right atrium, and also formed a large bundle which passed caudally through the interatrial septum.

Adrenergic Fibers↗
PubMed1994

Properties of putative cardiac and non-cardiac neurones in the rat stellate ganglion.

Intracellular recordings were made from isolated left or right stellate ganglia of Wistar rats and the morphology of neurones studied after intracellular injection of hexammine cobaltic chloride or back-filling from the post-ganglionic nerve with cobalt lysine complex. The experiments attempted to identify the location, electrophysiological properties, morphology and chemosensitivity of putative cardiac neurones in the ganglion. These were identified by antidromic activation of the axon in a cardiac nerve and compared with neurones projecting towards the brachial plexus (non-cardiac neurones). Putative cardiac neurones were localized in the ganglion around the postganglionic nerve entry zone and showed considerable morphological diversity. They had complex dendritic trees with, on average, seven dendrites. They included both phasic and tonic neurones and were depolarized by muscarinic agonists, angiotensin and substance P; they invariably had a synaptic input from the sympathetic trunk and from a T1 or T2 ramus and, in 16% of cells, from a cardiac nerve. Non-cardiac neurones were more widely scattered through the stellate ganglion but were not clearly different in morphology, resting membrane potential or the proportion of phasic and tonic cells from putative cardiac neurones. They also showed depolarizing responses to muscarinic agonists, angiotensin and substance P. Angiotensin responses of stellate ganglion cells were blocked by the peptide antagonist, saralasin (1 microM).

Action Potentials↗
PubMed1994

Lack of long-term potentiation, non-cholinergic transmission and muscarinic inhibition in cat superior cervical ganglia innervated by nodose ganglion cells.

In anesthetized cats, in which a nodose-superior cervical ganglion (SCG) anastomosis had been performed 6-9 months earlier, the nictitating membrane contraction evoked by electrical stimulation of the cervical vagus nerve ipsilateral to the anastomosis was recorded. The competence of nodose neurons in regulation the multiple synaptic mechanisms of the sympathetic ganglion was tested by comparing this response with the responses to stimulation of (self-reinnervated SCG). The response of the nictitating membrane ipsilateral to the anastomosis was smaller and had a lower EC50 for hexamethonium (C6) than the responses of the nictitating membrane ipsilateral to the intact or sutured CST. A 40 Hz 10s stimulus train to the intact or sutured CST produced potentiation of ganglionic transmission lasting 1 hour or longer, while a similar stimulus train to the anastomosed cervical vagus nerve produced no potentiation. During block of ganglionic nicotinic transmission with C6, CST or vagus nerve stimulation evoked responses which increased in amplitude with increasing stimulus frequency and were blocked by the selective muscarinic receptor antagonist pirenzepine. When the anticholinesterase eserine was added, the responses evoked by preganglionic stimulation decreased in amplitude in the intact SCG, as previously shown [7], and in the self-reinnervated SCG. This effect, which is due to inhibition mediated by muscarinic receptors selectively blocked by AF-DX116, was absent in the anastomosed SCG. During block of ganglionic transmission with C6 and atropine, a 40 Hz stimulus train to the intact or to the sutured CST evoked a slow, small amplitude contraction that was enhanced by naloxone. This response, most likely mediated by peptides [6], was absent in the anastomosed SCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Loss of [125I]-pindolol binding to beta-adrenoceptors on rat nodose ganglion after chronic isoprenaline treatment.

The nodose ganglion contains the cell bodies of afferent nerves which convey predominantly sensory information from the viscera to the central nervous system (CNS). Autoradiographic studies show binding sites for beta-adrenoceptor ligands are present on sections of the rat nodose ganglion and also on the corresponding inferior vagal ganglion in humans, indicating the presence of beta-adrenoceptors in these ganglia. Since prolonged stimulation of beta-adrenoceptors in rats with the nonselective beta-adrenoceptor agonist isoprenaline (400 micrograms kg-1 day-1 s.c.) for 14 days results in desensitisation and/or down-regulation of receptors in peripheral tissues, such as heart, kidney and blood vessels, the effects of this treatment on the beta-adrenoceptor population on the nodose ganglion have been examined. Using [125I]-pindolol as a radioligand, autoradiographic studies revealed that specific binding was reduced by 74% in ganglia from isoprenaline-pretreated rats compared to that in ganglia from vehicle-pretreated rats, demonstrating down-regulation of receptors by isoprenaline. [125I]-Pindolol binding was sensitive to inhibition by ICI 118.551 (selective beta 2-adrenoceptor antagonist) but not to atenolol (selective beta 1-adrenoceptor antagonist), indicating receptors are predominantly of the beta 2-adrenoceptor subtype. No change in binding was apparent over the vagus nerve. The nodose ganglion appears to be an additional site at which beta 2-adrenoceptors may be down-regulated in vivo, possibly interfering with normal baro-, chemo- and sensory reflexes.

Animals↗
PubMed1988

The axon initial segment as a possible determinant of retinal ganglion cell dendritic geometry.

In wholemounted retinae of cat, rat and monkey, in which ganglion cells were retrogradely labelled with horseradish peroxidase, a quantitative analysis of the direction of the axon initial segment with respect to the optic disc and of the relationship between the axon initial segment and the direction and distribution of primary dendrites was performed on the class of largest ganglion cells. The results show the following. (1) In all 3 species, the majority of primary dendrites of ganglion cells are directed away from the axon initial segment. (2) Primary dendrites arise with a greater frequency from the region of the cell body opposite to the axon initial segment than close to it. (3) In cat the direction of the axon initial segments show less variance in their initial direction with respect to the optic disc than in rat or monkey. In adult cats the nucleus of alpha-ganglion cells occupies a central position. In the kitten the position of the nucleus is eccentric and lies in a part of the cell body opposite to the axon initial segment. The nucleus moves to a central position over the next 3 weeks. The position of the axon initial segment is discussed as a possible determinant of ganglion cell dendritic geometry.

Animals↗
PubMed1991

Thy-1 antigen is specific to ganglion cells in chicks.

The cellular localization of Thy-1 in the chick retina was investigated by selectively destroying certain populations of neurons with toxins. In control retinae four weeks after intravitreal injection of vehicle, there was strong immunoreactivity for Thy-1 in the nerve fibre layer, ganglion cell layer and inner plexiform layer. By contrast, 4 weeks after intraocular injection with 1.25 nmol of colchicine, virtually all ganglion cells had been destroyed, but most amacrine cells remained. Very little Thy-1 immunoreactivity was evident in these retinae. Four weeks after intraocular injection of 2 mumol of N-methyl-D-aspartic acid (NMDA), a large proportion of amacrine cells had been destroyed, but most ganglion cells remained. In these retinae Thy-1 immunoreactivity was present in the nerve fibre, ganglion cell and inner plexiform layers, in the latter with greater intensity than in controls. We conclude that in chicks the Thy-1 antigen is principally, if not exclusively restricted to ganglion cells.

Animals↗
PubMed1992

Push-pull modulation of ganglion cell responses of carp retina by amacrine cells.

The responses of a ganglion and an amacrine cell were recorded simultaneously in the carp retina. Sinusoidal current injected into amacrine cells modulated ganglion cell discharges either in phase (excitation) or in opposite phase (inhibition). ON-center ganglion cells received excitatory inputs and OFF-center ganglion cells received inhibitory inputs from ON-center amacrine cells. They received inputs of opposite polarity from OFF-center amacrine cells. Namely, inputs from ON-center and OFF-center amacrine cells augment the responses of ON-center and OFF-center ganglion cells in a push-pull manner.

Animals↗
PubMed1993

Human retinal ganglion cell development in early prenatal period using carbocyanine dye DiI.

Early development of retinal ganglion cell morphology has been studied in human fetuses of gestational age ranging from 7-8 weeks to 19-20 weeks by retrograde labelling with a lipophilic fluorescent dye, DiI. The retinal ganglion cells with simple and relatively uniform appearance having few dendritic processes between 7 to 11 weeks of gestation show progressive growth and elaboration of dendrites at 17-18 weeks revealing some morphological variation in shapes. It is by 19-20 weeks of gestation that the three major ganglion cell types resembling the alpha, beta and gamma classes of cat ganglion cells are identifiable in the developing human retina. The dendrites of some ganglion cells exhibit varicosities, filiform processes and spines even as early as 10-11 weeks indicating a possibility of involvement in synaptic connectivity.

Animals↗