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PubMed1988

Morphology of ganglion cell dendrites in the albino rat retina: an analysis with fluorescent carbocyanine dyes.

The ganglion cell dendrites of the rat retina were investigated by means of the strongly fluorescent, non-polar carbocyanine dye 1,1-dioctadecyl-3,3,3',3'-tetramethyl-indocarbodyanine perchlorate (diI or diI-C18-3 or D282) which was taken up by retinofugal axons and transported in the retrograde direction. The dye completely outlined the somata, the axons and the dendritic trees of several retinal ganglion cells and allowed qualitative and quantitative investigations. By means of this labeling technique, the diameters were determined in 272 dendrites and somata of various ganglion cell sizes. A comparison of the measurements with those reported in the literature revealed that the diI could be taken up by all classes of retinal ganglion cells. The most frequently labeled cells were those of class II, which have small to middle-sized perikarya (16.7 +/- 2.5 microns in diameter) and small to middle-sized dendritic trees (187 +/- 70 microns in diameter) with a high branching frequency (88 +/- 19 branching points). Retinal ganglion cells of class I were less frequent and have large perikarya (21.9 +/- 3.4 microns in diameter) with large dendritic trees (318 +/- 55 microns in diameter) and medium branching frequency (60 +/- 19 branching points). Class III cells which were described incompletely in the literature, appeared to be small to middle-sized in their perikaryal diameter (15.9 +/- 2.5 microns) but have large dendritic trees (299 +/- 63 microns in diameter) and a low branching frequency (40 +/- 10 branching points). In about 10% of the retinal ganglion cells with completely filled dendritic fields, the somata were situated outside the dendritic extensions, as viewed on the whole mounted retina. These "asymmetric" retinal ganglion cells appeared to belong to class II cells and were evenly distributed throughout the entire retina and were not related to neighboring blood vessels. The orientation of the asymmetric dendrites was random in relation to the optic disc. The axons of asymmetric retinal ganglion cells were almost always oriented opposite to the direction of the dendritic trees. If the dendrites extended towards the optic disc, the proximal parts of the corresponding axons were oriented towards the periphery of the retina, turning then at 180 degrees to the optic disc. Less than 1.5% of the retrogradely filled cells were displaced ganglion cells and extended dendritic trees within the deep inner plexiform larger.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Extrinsic determinants of retinal ganglion cell structure in the cat.

The degree to which a retinal ganglion cell's environment can affect its morphological development was studied by manipulating the distribution of ganglion cells in the developing cat retina. In the newborn kitten there is an exuberant ganglion cell projection from temporal retina to the contralateral lateral geniculate nucleus (LGNd) (Leventhal et al., 1988) and from nasal retina to the ipsilateral LGNd. Neonatal, unilateral optic tract section results in the survival of many of these ganglion cells (Leventhal et al., 1988). The morphology of ganglion cells which survive in regions of massively reduced ganglion cell density was studied. As reported previously (Linden and Perry, 1982; Perry and Linden, 1982; Ault et al., 1985; Eysel et al., 1985), we found that the dendritic fields of all types of ganglion cells on the border of an area depleted of ganglion cells extended into the depleted area. The cell bodies and dendritic fields of alpha and beta cells within depopulated areas, as well as on the borders of the depopulated areas, were larger than normal. The dendritic fields of these cells also exhibited abnormal branching patterns. For alpha and beta cell types the relative increase in size tended to be greatest where the relative change in density was the greatest. In fact, isolated beta cells within the cell-poor area centralis region resembled normal central alpha cells in the cell-rich region of the area centralis in the same retina. Interestingly, in the same regions of reduced density where alpha and beta cells were dramatically larger than normal, the cell body and dendritic field sizes of other cell types (epsilon, g1 and g2 were unchanged. These results indicate that neuronal interactions during development contribute to the morphological differentiation of retinal ganglion cells and that different mechanisms mediate the morphological development of different classes of cells in cat retina.

Animals↗
PubMed1996

Hyperthermia and hypoxia increase tolerance of retinal ganglion cells to anoxia and excitotoxicity.

PURPOSE: Knowledge of the mechanisms by which retinal ganglion cells are damaged may provide information required to develop novel treatments for diseases that cause retinal ganglion cell death. The authors investigated whether the expression of the 72-kDa heat shock protein in cultured rat retinal ganglion cells increases tolerance to hypoxic and excitotoxic injury. METHODS: Hyperthermia (42 degrees C for 1 hour) and sublethal hypoxia (9% O2 for 6 hours) were used to induce synthesis of the 72-kDa heat shock protein in cultured rat retinal ganglion cells and cultured retinal Müller cells. Induction of the 72-kDa heat shock protein was detected with immunocytochemical and immunoblot techniques. Survival of cultured retinal ganglion cells after exposure to anoxia (< 1% O2 for 6 hours) and glutamate (200 microns for 6 hours) was measured and compared to control cultures stressed previously by hyperthermia or sublethal hypoxia. The effect of quercetin, a blocker of heat shock protein synthesis, was evaluated in parallel experiments. RESULTS: Heat shock protein immunoreactivity was expressed in cultured retinal ganglion cells and Müller cells after hyperthermia and sublethal hypoxia. The mean (+/- standard deviation) retinal ganglion cell survival rates after exposure to anoxia (expressed as a percentage of untreated control cultures) in cells pretreated with sublethal hypoxia (83% +/- 17%) and hyperthermia (82% +/- 19%) were significantly greater than for cells that had no pretreatment (50% +/- 18%, P < 0.001). The mean (+/-standard deviation) retinal ganglion cell survival rate after exposure to glutamate in cells pretreated with sublethal hypoxia (82% +/- 19%) and hyperthermia (86% +/- 17%) were significantly greater than for cells that had no pretreatment (56% +/- 17%, P < 0.001). Inhibition of heat shock protein synthesis with quercetin abolished the protective effects of sublethal hypoxia and hyperthermia on cell survival after anoxia and glutamate exposure. CONCLUSIONS: The neuroprotective effect of hyperthermia and sublethal hypoxia suggests that heat shock proteins confer protection against ischemic and excitotoxic retinal ganglion cell death.

Animals↗
PubMed1975

Monkey retinal ganglion cells: morphometric analysis and tracing of axonal projections, with a consideration of the peroxidase technique.

This paper presents evidence on the retinal distribution and central projections of retinal ganglion cells of various cell body sizes in the adult macaque monkey. The ganglion cell sizes have been determined by computer assisted measurement of camera lucida drawings at various eccentricities of both flat mounted and sectioned retinae. The pattern of projections of individual ganglion cells to the dorsal lateral geniculate nucleus and superior colliculus has been studied using retrograde axonal transport of horseradish peroxidase. Following peroxidase injections into the parvocellular laminae of the geniculate, virtually every ganglion cell was labeled within a circumscribed zone of the retina known to project to the region of the geniculate immediately surrounding the injection needle tip. After magnocellular injections, only the largest cells of the peripheral retina and approximately 26% of the ganglion cells of the parafovea were labeled. Peroxidase injections into the superior colliculus produced labeling of scattered ganglion cells of all sizes in the retina, although no labeled cells were found within the centralmost 10 degrees eccentricity. From these observations it is concluded that all ganglion cells of the macaque retina project to the parvocellular layers of the dorsal lateral geniculate, but that only the largest ganglion cells of the more peripheral retina and not all cells of the parafovea project to the magnocellular laminae. In contrast, only scattered ganglion cells, although these are of all sizes, appear to project to the superior colliculus. Two major problems with the peroxidase tracing technique are described: 1. The extent of stainable peroxidase activity around the injection site appears to be larger than the area of injected tracer actually available for uptake by axons to produce labeled cells. 2. Cut or damaged axons appear to incorporate peroxidase sufficiently to produce labeling of the cell body.

Animals↗
PubMed1978

Retinal ganglion cells in the crucian carp (Carassius carassius). II. Overlap, shape and tangential orientation of dendritic trees.

Ganglion cells were studied in methylene blue stained flat-mounted retinas. Three categories of cells are described: small (S) and large (L) ganglion cells in the main ganglion cell layer, and large ganglion cells (LD) with somata more or less displaced into the inner plexiform layer. These LD cells have two to four very thick primary dendrites and are identifiable as ganglion cells by their axons. An analysis of published data reveals that the large ganglion cells of the crucian carp (type L and LD) have several striking characteristics in common with the large ganglion cells of the dogfish, the frog and the cat: (1) they are selectively stained by methylene blue; (2) they comprise only 2-5% of all the ganglion cells; (3) the large cells can be divided into two or three subtypes, and within each subtype the dendritic trees usually cover the retinal surface with a two- or threefold overlap. New ganglion cells are formed from neuroblasts at the retinal margin and most dendrites first grow along this neuroblastic zone. Thus the main dendrites of the L and LD cells tend to be oriented parallel to the margin all around the periphery of a crucian carp retina. Independent of the size of the eye this parallel orientation disappears at the same relative distance from the margin (about one-third of the distance from the margin to the optic disc). If all L and LD cells are formed at the retinal margin and first develop oriented dendrites, we have to assume that the more randomly oriented dendritic trees in the central retina have undergone a reorganization.

Animals↗
PubMed1981

The distal limb motor neurons in the thoracic ganglion of the spiny lobster.

The 16 motor neurons which innervate the muscles in the limb distal to the autotomy plane have been found in the third thoracic ganglion of the southern rock lobster, Jasus novaehollandiae. They were traced from the autotomy plane to the ganglion by stripping them from the small and large leg nerves to the edge of the ganglion where they were filled with cobalt dye. Cell bodies of 11 of these neurons lie in an anterior cluster of somata, and the remainder lie in a ventral rind of somata. The neurites from these somata expand into enlarged central segments, 400 micrometers long and 10-30 micrometers in diameter. These segments run parallel and in apposition to each other as they course through the neuropile a few cell layers beneath the dorsal surface of the ganglion. Near their origin some central segments send branches both medially between fibers of the interganglionic connectives, and anteroventrally into the connective. Distally the segments give rise to side branches which project around the anterior and posterolateral borders of the neuropile. The central segments constrict near the lateral edge of the neuropile, rise to its surface, and form axons. Eight axons, including those which innervate the flexor muscle of the carpus, enter an anterior motor tract which exists the side of the ganglion in a first root, the source of the small leg nerve. The remaining eight axons, which include those that innervate the extensor muscle of the carpus, enter a posterior motor tract which exists the side of the ganglion in a second root, the source of the large leg nerve. All the motor fibers which innervate the muscles of the limb, with the exception of the retractor of the coxa, run in these two tracts within the ganglion. Fibers which innervate the retractor of the coxa and the muscles of the thorax leave the ganglion in a third root at the posterodorsal border of the ganglion. The central segment, as the common structure of confluence of neuropilar branches, is the likely candidate for the integrating region of each neuron.

Animals↗
PubMed1983

Postnatal changes in retinal ganglion cell and optic axon populations in the pigmented rat.

The number of ganglion cells in the retina of the postnatal rat has been examined. We estimated both the number of axons in the optic nerve and the number of cells which can be retrogradely labelled with horseradish peroxidase from injections into the brain. In the retina of the newborn rat there are at least twice as many ganglion cells as in the adult rat. By retrograde labelling of the ganglion cells and following transection of their axons 24-48 hrs later we can find no evidence that ganglion cells withdraw their axon without degeneration of the patent cell body. We have found that the excess ganglion cells are lost over the first ten postnatal days and during this period we observe pyknotic nuclei in the ganglion cell layer. From our estimates of the total number of neurones in the ganglion cell layer and the number of ganglion cells found at different ages we conclude that the migration of amacrine cells into the ganglion cell layer occurs in the first five postnatal days.

Age Factors↗
PubMed1989

Ganglion cell arrangement and axonal trajectories in the anterior lateral line nerve of the weakly electric fish Apteronotus leptorhynchus (Gymnotiformes).

To determine the organizational principles underlying the peripheral electrosensory nervous system of weakly electric gymnotiform teleosts we labelled each of the four anterior lateral line nerve branches with HRP. We determined the position of labelled cell bodies within the ganglion and followed anterogradely filled fibers to their termination sites in one of the four somatotopic maps in the electroreceptive lateral line lobe (ELL). Within the ganglion, cell bodies exhibit a loose somatotopy based on nerve branch position: trunk electroreceptors have their cell bodies located in the caudal ganglion; cell bodies to the head receptors are rostral. Cell bodies to the head exhibit a rough dorsoventral polarity, supraorbital cells tend to be located dorsally, infraorbital cells centrally, and mandibular cells ventrally. Despite this general somatotopy there is substantial overlap (up to 30%) of cell bodies among regions. There appears to be no rostrocaudal topography within nerve branch regions. Iontophoretic WGA-HRP injected into the medial segment of the ELL retrogradely labelled cell bodies that innervate ampullary organs. These cell bodies were dispersed throughout the ganglion, indicating that cell bodies do not cluster by receptor type. Peripherally directed axons from the ganglion appear to undergo an active reorganization in order to form the nerve branches. Within nerve branches, axons to a particular area of skin do not cluster together. Centrally from the ganglion, axons retain the position of their cell body until they reach the ELL border. Once in the ELL, fibers become sorted in the deep fiber layer according to receptor type and the map they terminate in. This reorganization involves rearrangement of fascicles and axons within fascicles. In toto, proceeding from peripheral to central, the electrosensory periphery loses at least a portion of its receptor topography in the distal nerve and ganglion and then acquires both a functional and somatotopic organization after reaching the ELL; conceptually it is torn down and rebuilt again. From an ontogenetic perspective, axonal growth occurs from the ganglion outward; the fact that ganglion cell bodies are not highly organized while the receptors they innervate and their central processes are suggests that active axonal guidance mechanisms are involved.

Animals↗
PubMed1983

Presynaptic modulation of activity and molecular forms of acetylcholinesterase in the rat superior cervical ganglion during early postnatal development.

Preganglionic nerve trunk of the rat superior cervical ganglion was transected shortly after birth in order to evaluate the influence of preganglionic nerves on the development of acetylcholinesterase and choline acetyltransferase in ganglionic neurons. In spite of an early decentralization, specific activity of acetylcholinesterase in the ganglion is increasing during the first 3 wk of life until it is about equal to the activity which remains in the superior cervical ganglion decentralized in an adult animal. Thus, the preganglionic nerves, which per se contribute the presynaptic fraction of total ganglionic AChE activity in normal innervated ganglia, apparently exert no significant regulatory effect on the specific activity of the fraction of acetylcholinesterase affiliated with the developing ganglionic cells. However, the absence of innervation during development is strongly reflected in the pattern of acetylcholinesterase molecular forms. The activity of the 16 S molecular form of AChE remains high in the developing superior cervical ganglion, decentralized at birth, in contrast to the substantial absolute and relative decrease of specific activity of this form during development of a normally innervated ganglion. A high proportion of 16 S AChE probably reflects a shift of decentralized immature ganglion nerve cells toward a cholinergic character. In accordance with this assumption, choline acetyltransferase activity in early decentralized ganglia is significantly higher than that in the ganglia decentralized in adult animals.

Acetylcholinesterase↗
PubMed1975

The major ganglion in the pelvic plexus of the male rat: a histochemical and ultrastructural study.

To further evaluate the role of autonomic ganglia in the regulation of pelvic visceral activity, the neural elements in the major pelvic ganglion of the male rat have been studied with histochemixal and electron microscopic techniques. The principal findings are that the ganglion is composed of cholinergic and adrenergic ganglion cells as well as small intensely fluorescent (SIF) cells. Polarity in the ganglion is indicated by clustering of small ganglion cells which stain intensely for acetylcholinesterase (AChE) along the pelvic nerve while larger cells, with weak to moderate AChE activity, collect near small branches of the hypogatrric nerve. Some cholinergic ganglion cells are enclosed by a plexus of adrenergic terminals. SIF cells appear to be in contact with both cholinergic and adrenergic cells, although many of the fluorescent beads around adrenergic neurons may be short dendrites of ganglion cells, rather than processes of SIF cells. Two types of SIF cells may be distingiosjed on the basis of size and morphology of their granulated vesicles. Afferent synapses of the cholinergic type were common on SIF cells of the large granule and small granule type. Portions of SIF cells with large granules occur within the capsule of ganglion cells. Contacts seen here were interpreted as efferent synapses from SIF cells to the dendrites of ganglion cells.

Acetylcholinesterase↗
PubMed1990

Identification of all GABA-immunoreactive neurons projecting to the lobster stomatogastric ganglion.

The stomatogastric ganglion of lobsters (Homarus or Jasus) contains a large number of gamma-aminobutyric acid-immunoreactive processes originating from ten fibres in the single input nerve, the stomatogastric nerve. The cell bodies and axonal pathways of these ten fibres have been identified using gamma-aminobutyric acid immunohistochemistry in combination with Lucifer Yellow staining (double labelling) and nickel chloride backfilling (selective gamma-aminobutyric acid immunoinhibition). It is shown that eight gamma-aminobutyric acid-immunoreactive neurons project to the stomatogastric ganglion: gamma-aminobutyric acid neurons 1 and 2, found posterior to the oesophageal ganglion, entering the stomatogastric nerve via the oesophageal nerve as well as sending an axonal branch into each superior oesophageal nerve; gamma-aminobutyric acid neurons 3 and 4, found anterior to the oesophageal ganglion, each sending an axonal branch into each inferior oesophageal nerve to reach the stomatogastric nerve via the commissural ganglion and the superior oesophageal nerve; and gamma-aminobutyric acid neurons 5 and 6, found in each commissural ganglion, projecting into the stomatogastric nerve via the inferior oesophageal nerve, the oesophageal ganglion and the oesophageal nerve. These gamma-aminobutyric acid-immunoreactive neurons were also characterized by electrophysiological methods coupled with Lucifer Yellow labelling, and their picrotoxin-sensitive effects on several stomatogastric ganglion neurons were demonstrated. The present results provide a firm basis for further studies concerning the physiological significance of one class of neurochemically-defined input neurons to stomatogastric ganglion networks.

Animals↗
PubMed1982

Inner plexiform circuits in the carp retina: effects of cholinergic agonists, GABA, and substance P on the ganglion cells.

Th effects on ganglion cell light responses and spontaneous activity of neurotransmitter candidates, applied by nebulizer spray and iontophoresis, were studied in the isolated carp retina. ACh, GABA, and substance P had strong effects on the ganglion cells; dopamine and the amino acids aspartate, glutamate, and glycine and only weak effects. ACh and substance P exerted their actions even when synaptic transmission was blocked by cobalt chloride, suggesting postsynaptic receptors for those agents on the ganglion cell membrane. The 3 amino acids and dopamine do not appear to act directly on the ganglion cells. The pharmacological sensitivity of ganglion cells was correlated with their physiological response type. About three-quarters of ON/OFF and half of other transiently responding ganglion cells were excited by micromolar concentrations of cholinergic agonists; most ON-center sustained ganglion cells were insensitive. The light response of some of the ACh-sensitive cells could be suppressed by cholinergic antagonists. Substance P generally excited ganglion cells with an ON-component in their light response. GABA inhibited cells of all response types, but affected least the OFF-center tonic cells. In view of these observations, and of corroborating histological evidence, we propose that ACh, GABA, and substance P are neurotransmitters that are released by amacrine cells and affect receptors located on ganglion cells.

Acetylcholine↗
PubMed1988

Enhancement of naturally occurring cell death in the sympathetic and parasympathetic ganglia of the chicken embryo following blockade of ganglionic transmission.

Both presynaptic and postsynaptic blockade of ganglionic transmission during the period of naturally occurring ganglion cell death reduced the number of surviving neurons in the sympathetic ganglia (SG) and ciliary ganglion (CG). The CG was chosen for analysis because there was a temporal separation between cell proliferation and death in the CG but not in the SG. Ganglion cell proliferation and migration were unaffected by ganglionic blockade. The increased ganglion cell loss that followed ganglionic blockade was accompanied by an increased number of degenerating cells. These results indicate that the decreased number of healthy ganglion cells that followed ganglionic blockade was the result of enhanced naturally occurring cell death.

Animals↗
PubMed1991

Effect of guanethidine on dopamine in small intensely fluorescent cells of the superior cervical ganglion of the rat.

To determine the portion of ganglionic dopamine stored in the small intensely fluorescent (SIF) cells of the superior cervical ganglion, rats were treated chronically with the neurotoxin guanethidine (50 mg/kg i.p. daily for 6, 13 or 18 days) which destroys noradrenergic neurons. The guanethidine effect was assessed in the ganglion using biochemistry of dopamine and norepinephrine and immunocytochemistry of tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH). After 18 days of treatment, the ganglionic norepinephrine content was reduced by 80%, but the dopamine content was reduced by only 20%. Morphologic analysis of ganglia stained to distinguish noradrenergic neurons (TH positive, DBH positive) and SIF cells (TH positive, DBH negative) indicated that guanethidine treatment reduced the number of noradrenergic neurons by 70%, dropping from 19413 +/- 1402 to 6515 +/- 1296 per ganglion, but increased the number of dopaminergic SIF cells by 80% from 578 +/- 150 to 1056 +/- 151 per ganglion. Based on these findings, it is concluded that a substantial portion of the dopamine in the rat superior cervical ganglion is located outside the noradrenergic neurons, i.e. in the SIF cells. Extrapolating the data obtained using guanethidine versus control rat leads to infer that although the proportion of SIF cells in the superior cervical ganglion is small (3 +/- 1% of the SIF and noradrenergic neurons combined), about 40% of the total ganglionic dopamine resides in SIF cells, with the remainder serving as precursor in noradrenergic neurons.

Animals↗
PubMed1993

Enkephalin-containing neurons in the inferior mesenteric ganglion projecting to the distal colon of cat: evidence from combined retrograde tracing by fluorescent microspheres and immunohistochemistry.

Retrograde tracing with rhodamine fluorescent microspheres combined with fluorescein immunolabelling of methionine-enkephalin showed the presence of enkephalin-like material in neurons of the inferior mesenteric ganglion (sympathetic prevertebral ganglion) projecting to the distal colon in cat. Two weeks after injecting the microspheres into the wall of the distal colon, the inferior mesenteric ganglion was dissected out and incubated for 24 hours in a colchicine-containing culture medium in order to facilitate the detection of enkephalins in the soma of ganglion neurons. It was observed that retrogradely labelled ganglion cells contained enkephalin-like immunoreactive material. These ganglion cells corresponded to enkephalin-like postganglionic neurons, the terminals of which were located inside the wall of the distal colon. These enkephalin-like neurons were numerous and scattered throughout the ganglion. Sometimes enkephalin-like immunoreactive fibers, probably originating from spinal preganglionic neurons, ran close to immunoreactive and non-immunoreactive retrogradely labelled ganglion cells. This suggests that enkephalin-like immunoreactive fibers may make synaptic connections with enkephalin-like and non-enkephalin-like postganglionic neurons projecting to the distal colon. The present study establishes for the first time the existence of an enkephalin-like postganglionic pathway to the digestive tract originating from a sympathetic prevertebral ganglion. This finding indicates that the enkephalinergic innervation of the cat digestive tract may have at least two possible sources: (i) the sympathetic prevertebral ganglia; and (ii) the enteric nervous ganglia.

Animals↗
PubMed1994

Distribution of extrinsic enkephalin-containing nerve fibers in the rat rectum and their origin in the major pelvic ganglion.

The distribution of nerve fibers containing enkephalin (ENK)-like immunoreactivity was examined in the rectum of aganglionosis rats (AGRs) which completely lack the intramural ganglion cells in the large intestine, and was compared with that of their normal littermates. Furthermore, Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL)-like immunoreactive neurons projecting to the rectum were examined using retrograde tracing combined with immunohistochemistry in the major pelvic ganglion of normal male rats. In the intermuscular space of the aganglionic rectum of AGRs, unlike the pattern of the normal intermuscular plexus, moderate numbers of ENK-like-immunoreactive fibers were arranged in an irregular, coarse network; greatly diminished numbers of immunoreactive fibers were found in the submucosa. No ENK-like-immunoreactive fibers were seen in the circular muscle layer and mucosa. In the normal rat rectum, ENK-like-immunoreactive fibers were seen throughout all layers, and immunoreactive nerve cells were found predominantly in the myenteric plexus of colchicine-treated animals. Fluoro-Gold injected into the upper rectum labelled numerous principal ganglion neurons in the major pelvic and inferior mesenteric ganglia. Less than 10% of tracer-labelled neurons were positive for fluorescein immunolabelling of MEAGL in the major pelvic ganglion; no immunoreactive neurons were found in the inferior mesenteric ganglion. In the major pelvic ganglion of the colchicine-treated normal rats, about 5% of principal ganglion neurons were immunoreactive for MEAGL. Comparison of serial paraffin sections of the major pelvic ganglion stained for tyrosine hydroxylase (TH), MEAGL and vasoactive intestinal polypeptide (VIP), respectively, revealed that more than half of MEAGL-like immunoreactive neurons were also positive for TH; there was no case showing co-existence of MEAGL with VIP in the principal neurons. These results indicate that a small number of enkephalin-containing neurons in the major pelvic ganglion project to the rectum, and that more than half of these neurons are postganglionic sympathetic. They may terminate mainly in the myenteric ganglia in the rectum.

Animals↗
PubMedDate not supplied

Electrophysiological analysis of the convergence of peripheral inputs onto neurons of the coeliac ganglion in the guinea pig.

The convergence of intestinofugal axons from different intestinal regions onto individual neurons in the coeliac ganglion of the guinea pig was investigated using intracellular recording methods in vitro. Peripheral nerve trunks from the distal ileum, the most proximal colon and the colon near the colonic flexure were electrically stimulated along with preganglionic fibres running in the splanchnic nerve. Fast cholinergic excitatory synaptic potentials (EPSPs) were seen in ganglion cells in response to stimulation of each nerve trunk. Roughly half of 78 neurons impaled received inputs from stimulation of peripheral nerves, and almost all of these received input from the proximal colon. Most cells responded to stimulation of more than one peripheral nerve indicating that coeliac neurons receive converging inputs from intestinofugal neurons located in more than one intestinal region. In a second series of experiments, segments of intestine were left attached to the ganglion and distended with saline to stimulate peripheral mechanosensory input to the coeliac ganglion. In each experiment, two segments were stimulated. A subgroup of ganglion cells exhibited spontaneous fast EPSPs and the frequency of these potentials was increased by distension of one or other of the attached intestinal segments. However, few neurons responded to distension of both of the attached intestinal segments suggesting that some of the intestinofugal inputs to the coeliac ganglion identified by electrical stimulation may be sensitive to sensory modalities other than distension. Hexamethonium (0.5 mM) applied to the intestine, and not to the coeliac ganglion, reduced the frequency of the spontaneous synaptic potentials seen in coeliac ganglion cells, but did not abolish the response to distension of the colon (n = 8). When the Ca2+ concentration of the solution bathing the proximal colon was reduced to block all synaptic transmission in the enteric plexuses the background synaptic input was further depressed, but again the response to distension was little changed (n = 4). This suggests that at least some of the neurons projecting from the colon to the coeliac ganglion are first order mechanosensory neurons.

Animals↗
PubMed1988

Neuropeptide Y and vasoactive intestinal peptide coexist in rat thyroid nerve fibers emanating from the thyroid ganglion.

Neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) occur in nerve fibers around blood vessels and between follicles in the thyroid gland of the mouse and rat. VIP-immunoreactive fibers are numerous, while NPY-immunoreactive fibers are fewer. Most of the latter fibers contain noradrenaline (NA) as well as NPY, while a subpopulation was found to contain VIP instead of NA. We have determined the origins of rat thyroid nerve fibers containing NPY, VIP or NPY/VIP by investigating 3 conceivable sources, i.e. the superior cervical ganglion, the nodose ganglion and the thyroid ganglion. Chemical sympathectomy or removal of the superior cervical ganglion did not affect the frequency of VIP-immunoreactive fibers but eliminated most of the NPY-immunoreactive fibers as well as all NA-containing nerve fibers (recognized by antibodies to dopamine-beta-hydroxylase). The NPY-immunoreactive fibers that remained after sympathectomy occurred around blood vessels and between follicles and contained VIP. Cervical vagotomy (removal of the nodose ganglion including the adjacent vagus) did not overtly affect the frequency of NPY/VIP-, VIP-, or NPY/NA-containing fibers in the thyroid. In contrast, extirpation of the thyroid ganglion, which is situated immediately outside the thyroid capsule, greatly reduced the number of VIP- and NPY/VIP-containing fibers in the rat thyroid. On the whole, the results of radioimmunoassay of NPY and VIP agreed well with the immunocytochemical findings. High performance liquid chromatography confirmed the identity of NPY and VIP. The present findings suggest the existence in the rat thyroid of one NPY-containing nerve fiber population that harbours NA and emanates from the superior cervical ganglion; one NPY-containing fiber population that is non-adrenergic, harbours VIP and originates in the thyroid ganglion; and a second VIP-containing fiber population that is devoid of NPY and appears to derive from the thyroid ganglion.

Animals↗