Morphology and Topography of the Celiac Plexus in Degu (Octodon Degus).

Here, we investigate the morphology and topography of the celiac plexus components in degu (Octodon degus). The study was performed using six adult individuals of both sexes. Macromorphological observations were performed using a derivative of the thiocholine method specially adapted for this study type (Gienc, 1977). The classical H&E technique was used for analysis of the cytoarchitectonic of the ganglion, and the AChE (Karnovsky and Roots, 1964) and SPG (De la Torre, 1980) techniques to observe cholinergic and adrenergic activity. The celiac plexus of degu is located on the ventral and lateral surface of the abdominal aorta, at the level where the celiac artery separates from the aorta. This structure consists of two large and two smaller aggregations of neurocytes connected with postganglionic fibers. Histochemical investigations have demonstrated the mainly cholinergic characteristic of the intraganglionic and postganglionic fibers of the celiac plexus, while the adrenergic fibers accompanied only the blood vessels and neurocytes revealed differentiation of adrenergic activity. Histological analysis revealed that neurocytes occupied about half of the cross-section area, with the nerve fibers, connective tissue, and blood vessels forming the remaining part. Ganglionic cells were oval, and usually contained a single nucleus, although two nuclei were sometimes observed.

Neurochemical differentiation of functionally distinct populations of autonomic neurons.

The coeliac ganglion of guinea pigs displays a unique topographical arrangement of neurochemically and functionally distinct populations of sympathetic neurons. The authors used multiple-labeling immunohistochemistry to investigate the neurochemical differentiation of these neurons during embryonic and fetal development. Sympathoadrenal precursors, located on either side of the abdominal aorta, were intensely immunoreactive for tyrosine hydroxylase (TH-IR), neurofilament, and the human natural killer 1 antibody at midembryonic stages (Carnegie stages 16-19). During late embryonic stages (stages 20-23), a single bilobed ganglion had formed. At this time, neuropeptide Y immunoreactivity (NPY-IR) was widely expressed in sympathetic neurons (with moderate TH-IR) and chromaffin cells (with intense TH-IR). The onset of somatostatin (Som-IR) expression followed that of NPY-IR and was restricted to sympathetic neurons. However, at late embryonic stages, most TH-IR neurons with Som-IR also expressed NPY-IR (a combination of peptides not found in the mature coeliac ganglion). Between late embryonic stages and the end of the early fetal period, there was a significant increase in the proportion of neurons in lateral regions that had both NPY-IR and TH-IR. At the same time, there was an increase in the proportion of neurons in medial regions that had both Som-IR and TH-IR. Neurons expressing both Som-IR and TH-IR were rarely observed in lateral regions of the coeliac ganglion. Thus, a clear topography within the coeliac ganglion is established during late embryonic and early fetal stages of development and reflects that found in the mature animal by the end of the early fetal period.

Nitric oxide released by gastric mechanoreceptors modulates nicotinic activation of coeliac plexus neurons in the rabbit.

The effects on the nicotinic activation of the coeliac plexus neurons of nitric oxide (NO) released within the coeliac plexus by gastric mechanoreceptors, in particular during gastroduodenal inhibitory reflex, were assessed. This study was performed in the rabbit on an in vitro preparation of the coeliac plexus connected to the stomach and the duodenum. The electrical activity of ganglionic neurons was recorded with intracellular recording techniques. Water-filled balloons were used for gastric distensions and recording of duodenal motility. When a 10-s train of pulses (20-40Hz) of supramaximal intensity was applied to the splanchnic nerves, gradual depression of nicotinic activation occurred. Gastric distension (50 mL, 7.5 min) modulated this depression phenomenon by inhibiting or facilitating the nicotinic activation. In the neurons impaled during the recording of duodenal motility, gastric distension triggered an inhibition of nicotinic activation concomitantly with a gastroduodenal inhibitory reflex organized by the coeliac plexus. If the gastric distensions were performed while the coeliac plexus was superfused by a NO scavenger, the nicotinic activation was unaffected and the gastroduodenal inhibitory reflex was abolished. Moreover, when the coeliac plexus was superfused with an inhibitor of nitric oxide synthase, gastric distensions were without effect on the nicotinic activation. These results demonstrate that NO released within the coeliac plexus by gastric mechanoreceptors, in particular during the gastroduodenal inhibitory reflex, modulates the central nicotinic activation of coeliac plexus neurons, so NO released within a prevertebral ganglion by gastric afferent fibres, in particular during the organization by this ganglion of a reflex regulating the gastrointestinal tract motility, also exerts a gating of the central inputs to the ganglionic neurons.

Responses of celiac and cervical vagal afferents to infusions of lipids in the jejunum or ileum of the rat.

Multiunit celiac and single-unit cervical recordings of vagal afferents were performed before and during infusions of fatty acids, triglycerides, or saline into either the ileum or jejunum of the rat. In multiunit recordings, lipids increased activity of vagal afferents to a greater extent than saline. The greatest increases in vagal afferent activity resulted from infusions of linoleic acid, conjugated linoleic acid, or oleic acid. The triglycerides, corn oil or Intralipid, were less effective than the fatty acids in affecting vagal afferent activity. Ileal pretreatment with the hydrophobic surfactant Pluronic L-81 significantly attenuated the response of celiac vagal afferents to ileal infusion of linoleic acid. Single-unit recordings of cervical vagal afferents supported the multiunit data in showing lipid-induced increased vagal afferent activity in approximately 50% of ileal units sampled and 100% of a limited number of jejunal units sampled. These data demonstrate that free fatty acids can activate ileal and jejunal vagal afferents in the rat, and this effect can be attenuated by pretreatment with a chylomicron inhibitor. These data are consistent with the view that lipid-induced activation of vagal afferents could be a potential substrate for the inhibitory effects of intestinal lipids on gastrointestinal function, food intake, and body weight gain.

[The relationship of late slow excitatory potential with 5-hydroxytryptamine and substance P in the guinea-pig celiac ganglion].

The work was carried out to investigate the relationship of non-cholinergic late slow excitatory potential (LS-EPSP) with 5-hydroxytryptamine (5-HT) and substance P (SP) in the neurons of the guinea pig celiac ganglion (CG) using intracellular electrodes in vitro. During repetitive stimulation of the splanchnic nerve (SN), LS-EPSP following a series of action potentials could be recorded in 161 out of 206 neurons (78.2%); Application of 5-HT and SP by superfusion or pressure ejection induced 5-HT depolarization in 102 out of 149 neurons (68.5%) and SP depolarization in 98 out of 188 neurons (52.1%), respectively; Most neurons, from which LS-EPSP could be recorded during stimulation of SN, were sensitive to 5-HT (73/88, 83.0%) and SP (68/114, 59.7%). However, only a small number of neurons not showing LS-EPSP during stimulation of SN were sensitive to 5-HT (10/26, 38.5%, P < 0.0001) and SP (11/36, 30.6%, P < 0.01). The results support the viewpoint that both 5-HT and SP are involved in the formation of LS-EPSP as transmitters; In addition, both effects of 5-HT and SP were examined in 133 neurons. There were 66 of these neurons (49.6%) to be sensitive to both 5-HT and SP, suggesting that there may be some functional relations between 5-HT and SP in the neurons of guinea pig CG.

The cellular network of interstitial cells associated with the deep muscular plexus of the guinea pig small intestine.

Systematic examination using electron microscopic montages and serial sections has demonstrated that three types of interstitial cell, namely gap junction-rich cells, glycogen-rich cells and fibroblast-like cells, are densely located along the whole extent of the deep muscular plexus of the guinea pig small intestine. They tend to be distributed in an alternating fashion in the cellular network, connected with muscle cells of the outer, circular layer by means of gap junctions. These three types of interstitial cell show close relations to two types of nerve varicosity: one type is characterized by clear round vesicles with diameters of about 50 nm, and the other by flattened vesicles measuring about 35 nm by 70 nm. Electron-dense patches have been observed at the cytoplasmic side of the axonal membranes. Muscle cells of both inner and outer circular layers also show close relations to these two types of nerve varicosity. These morphological features are discussed with the implication that they may have some regulatory role in intestinal movement.

Distribution of enteric nerve cells that project to the coeliac ganglion of the guinea-pig.

The digestive tract of the guinea-pig, from the esophagus to the rectum, was examined in detail to determine the distribution and relative abundances of neurons in these organs that project to the coeliac ganglion and the routes by which their axons reach the ganglion. A retrogradely transported neuronal marker, Fast Blue, was injected into the coeliac ganglion. The esophagus, stomach, gallbladder, pancreas, duodenum, small intestine, caecum, proximal colon, distal colon and rectum were analysed for labelled neurons. Retrogradely labelled neurons were found only in the myenteric plexus of these organs, and in the pancreas. No labelled neurons were found in the gallbladder or the fundus of the stomach, or in the submucous plexus of any region. A small number of labelled neurons was found in the gastric antrum. An increasing density of labelled neurons was found along the duodenum. Similarly, an increasing density of labelled neurons was found from proximal to distal along the jejuno-ileum. However, the greatest densities of labelled neurons were in the large intestine. Many labelled neurons were found in the caecum, including a high density underneath its taeniae. An increasing density of labelled neurons was found along the length of the proximal colon, and labelled neurons were found in the distal colon and rectum. In total, more labelled cell bodies occurred in the large intestine than in the small intestine. The routes taken by the axons of viscerofugal neurons were ascertained by lesioning the nerve bundles which accompany vessels supplying regions of the digestive tract. Viscerofugal neurons of the caecum project to the coeliac ganglion via the ileocaeco-colic nerves; neurons in the proximal colon project to the ganglion via the right colic nerves, and neurons in the distal colon project to the ganglion via the mid colic and intermesenteric nerves. Neurons in the rectum project to the coeliac ganglion via the intermesenteric nerves. These nerves (except for the intermesenterics) all join nerve bundles from the small intestine that follow the superior mesenteric artery. All viscerofugal neurons of the caecum were calbindin-immunoreactive (calb-IR) and 94% were immunoreactive for vasoactive intestinal peptide (VIP-IR). In the proximal colon, 49% of labelled neurons were calb-IR and 85% were VIP-IR. In the distal colon, 80% of labelled neurons were calb-IR and 71% were VIP-IR.

[The sources of the innervation of the sphincter of the esophagogastric junction in rats]. / Istochniki innervatsii sfinktera pishchevodno-zheludochnogo perekhoda u krys.

The investigation has been performed by means of the luminescent microscopical method. The retrograde axonal transport of the fluorescent marker primuline has demonstrated that a definite amount of labelled cells are observed in the celiac plexus, in nodes of the thoracic part of the sympathetic trunk (predominantly in Th6-Th8). Innervation of the EGP sphincter is mainly performed from the sympathetic trunk nodes (Th6-Th8) and from the celiac plexus.

[Extra-organic sources of innervation of the sigmoid]. / Ekstraorgannye istochniki innervatsii sigmovidnoi kishki.

By means of horseradish peroxidase administration into the wall of the sigmoid colon central part, localization, relative amount, body forms and size of the neurons, dealing with innervation of the given part of the colon have been determined. Labelled neurons are present in the colon wall, in ganglia of the caudal mesenteric artery nervous plexus, in the caudal and cranial mesenteric ganglia in the celiac plexus ganglia, in nodes and internodal branches of the lumbar part of the sympathetic trunk (the left one predominantly) and in the spinal ganglia from TXIII up to LVII. In the grey substance of the spinal cord labelled neurons are not revealed. The main part of the postganglionar sympathetic neurons, projecting their axons to the sigmoid colon, are situated in the caudal mesenteric ganglion. In the spinal ganglia the most part of the labelled neurons are to the left at the level of LII-LVI, to the right--at the level of LII-LV. The optimal time for revealing the greatest number of the labelled neurons are the 1st-3d days after administration of the enzyme. Capture of the lable takes place later in the neurons of those ganglia, which are situated more further from the place of peroxidase administration.

[Age and features of the content of myelinated fibers in nerves of the splenic plexus of man]. / Vozrastnye osobennosti soderzhaniia mielinovykh volokon v nervakh selezenochnogo spleteniia cheloveka.

The amount of the myelin fibers (MF) has been calculated in transversal serial sections of the nervous-vascular complexes of the splenic artery in newborns, in persons of mature (the 1st and 2d periods), elderly and old ages. In each age group 20 complexes have been studied. The total amount of the MF in persons of mature age (the 1st period) in 4.2-6 times greater (initial--terminal parts of the plexus) than in newborns, in the persons of old age it is 4-2.1 times less than in persons of mature age (in both cases P less than 0.001). Thin MF predominate, their relative contents in the aggregate of all classes of the MF in newborns are 92%, in mature persons--87%, in old persons--65%. Decreasing part of the thin MF together with increase of their absolute amount in the mature persons, comparing to the newborns, depends on higher rates in differentiation of middle and thick MF. Phenotyping peculiarities and stages of productive development, stabilization (the 1st-2d periods of the mature age), involutions of the nerve connections are defined in the splenic artery. The amount of the MF predominates in the nerves of the initial part of the plexus comparing to its terminal part. There is a direct correlative dependence between the amount of the MF in the plexus nerves and the size of the lumen in the splenic artery. Changes in the amount of the MF of different classes reflects qualitative differences of the splenic innervation relations at certain stages of the human postnatal development.

[Electrophysiologic and histochemical characteristics of the fiber composition of the subdiaphragmatic portion of the vagus nerves]. / Elektrofiziologicheskaia i gistokhimicheskaia kharakteristika sostava volokon poddiafragmal'noi chasti bluzhdaiushchikh nervov.

The fibre composition of subphrenic branches of the vagus nerves was studied electrophysiologically and histochemically. In anaesthetized cats, the presence of multicomponent electrical responses was found during stimulation of preganglionic fibres of splanchnic nerves in the splanchnic branch of the dorsal vagus trunk; the presence of synaptically interrupted fibres was shown. Histochemically, adrenergic fibres were found both in the central and in the peripheral stumps of subphrenic branches of the vagus nerves. Most strongly fluorescent fibres were regularly found in the peripheral stump of the splanchnic branch of the dorsal vagus trunk. The data obtained suggest that processes of ganglionic neurons of the celiac plexus ascend within splanchnic and other branches of the vagus nerves.

[Innervation of the heart from an abdominal plexus in man]. / Inervação do coração a partir de um plexo abdominal no homem.

The authors studied 43 necropsy specimens from adult individual by dissection under a stereomicroscope and by staining methods (Cajal-De Castro and Palmgren silver impregnations, Kluver Barrera and Pal-Weigert for myelinated fibers, and van Gieson and Azan trichromic methods). They suggest the presence of a direct nervous connection between the hepatic plexus (celiac plexus) and the high atrium via the left branches of the hepatic artery and portal vein, venous ligament, left hepatic vein, and v. cava inferior, passing through the foramen for the v. cava. This connection is made by very fine nerves from the upper part of the venous ligament until the left atrium, which generally are only visible on the microscopic level.

[Morphological changes in nodes of the celiac plexus as affected by extensive abdominal surgery]. / Morfologicheskie izmeneniia v uzlakh chrevnogo spleteniia pod vliianiem krupnykh abdominal'nykh operatsii.

Experiments on 163 dogs were made to study the time course of histological and ultrastructural changes in celiac plexus nodes after resection of the two-thirds of the stomach as well as after some other large operations on the abdominal organs (economic gastric resection, cholecystectomy, resection of the small intestine). It has been demonstrated that since the first days after operation the gangliocytes and neuroglial cells of celiac plexus nodes manifested histological changes detectable at light and electron microscopy levels. These changes were largely reversible in nature despite destructive processes eventuating in the death of some gangliocytes, pericapsular gliocytes and neurolemmocytes. The most overt changes were observed towards the first week after operation, the number of neurons with reversible changes amounting to 42% and that having the signs of destruction to 9.9%. At the later stages the intensity of the histological changes was noticeably reduced. Analogous data were obtained during studies of the time course of the histological changes after other above-indicated operations. However, the intensity of the changes was substantially less than that seen after resection of the two-thirds of the stomach. The evidence obtained allows the conclusion that the pathological structural changes that develop in the celiac plexus after resection of the two-thirds of the stomach play one of the leading parts in the pathogenesis of the post-gastroresection syndrome.

[Age and morphofunctional characteristics of celiac ganglia chromaffin tissue in normal and hypokinetic animals]. / Vozrastnaia morfofunktsional'naia kharakteristika khromaffinnoi tkani chrevnykh uzlov v norme i pri gipokinezii.

Accumulation of chromaffin cells (ChC) in the celiac nodes have been studied in young (6-month-old) and old (28-30-month-old) rats; 50 intact and 32 rats kept at hypokinesia for 6 weeks have been used. In the young intact rats accumulation of the ChC have been found in 51% and in the old ones-in 82% of cases. In the young rats 85% of the accumulations are localized inside the nodes, 4%-in their trunks and 12%-near the nodes, and in the old rats-69%, 8% and 23%, respectively. In the young and in the old rats the ChC section area is 133+/-4, 147+/-13 mkm2, nuclei-33.7+/-0.7 and 36.9+/=1.3 mkm2 and nuclear-plasmic relations-0.34 and 0.33, respectively. In the young rats the ChC with a high perikaryon density make 40%, with middle-32%, with low-28%, in the old rats-40%, 36% and 24%, respectively. The greater the ChC, the smaller the nuclear-plasmic ratio and perikaryon density. Low indices on the density and nuclear-plasmic ratio correspond to the excretion phase, and the high indices-to prevalence of synthesis and accumulation. These correlations reflect the morpho-functional profile of the chromaffin component in the nodes. Thus, with aging the chromaffin tissue of the celiac nodes is represented by a greater number of accumulations, while the morpho-functional indices of the ChC accumulations remain unchanged. Under hypokinesia, in the young and old rats mass of the chromaffin tissue decreases. The body and the nuclear area of the ChC decreases and by the end of the experiment it makes: in the young rats 104+/-5 and 30.6+/-1.1 mkm2, and in the old rats-100+/-3 and 29.7+/-2 mkm2. Rearrangement of the morpho-functional profile, manifested in increasing content of the ChC with high density and in decreasing congulatory role in the celiac nodes decrease. By the end of the experiment, in young rats normal function is approaching, in the old rats-the rearrangement is of stable character.

A cytochemical and ultrastructural study of the "S.I.F." cells in cat sympathetic ganglia.

According to the hypothesis of Eccles and Libet, the small intensely fluorescent cells (S.I.F. cells) in the sympathetic ganglion would represent an essential element in the inhibition of the principal neuron. As a contribution to the study of this important problem, we have investigated serial sections in superior cervical (S.C.G.) and celiac (C.G.) ganglia of the cat, a species that has not been extensively studied up to now, both by fluorescence and electron microscopy. We have shown that the "S.I.F." cells are three times fewer in the cat S.C.G. than in the rat S.C.G. There are five times more "S.I.F." cells in the C.G. of the cat than in the S.C.G. of the same species. Moreover we have described two types of "S.I.F." cells. Type I is composed of cells characterized by highly polymorphous large dense-cored vesicles. These cells lack processes and are grouped in clusters centered on fenestrated capillaries. They could be endocrine function cells. Type II is formed of isolated cells which exibit long processes and establish synaptic junctions with the dendrites of the principal neurons. In this case, the dense-cored vesicles are very regular and much smaller. These cells could be equivalent to interneurons. Type I very strongly predominates in the S.C.G. and C.G. of the cat where it represents more than 90% of the "S.I.F." cell total observed by fluorescence microscopy. A priori such a quantitative and qualitative heterogeneity hardly consistent with Eccles and Libet's hypothesis based on the existence of dopaminergic interneurons only, allows the question to be raised as to the functional significance of the "S.I.F." cells in ganglion physiology. The notion of modulation of ganglionic transmission does not seem to be quiered by these new data but could be founded on different forms of action embodied in the broader conception of the neuromodulation phenomenon.