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Macro and microstructural organization of the dog's caudal mesenteric ganglion complex (Canis familiaris-Linnaeus, 1758).

The caudal mesenteric ganglion (CMG) is located ventral to the abdominal aorta involving the initial portion of the caudal mesenteric artery. Its macro and microstructural organization was studied in 40 domestic dogs. From the CMG, there were three nerves: the main hypogastric, the left hypogastric and the right hypogastric. The main hypogastric nerve emits two branches: the left colonic nerve and the cranial rectal nerve. Afterwards they give rise to branches to the descending colon (colonic nerves) and rectum (rectal nerves). The cranial rectal nerve, and left and right hypogastric nerves were directed to the pelvic ganglia. The microscopic study permitted the observation of the histological organization of the CMG, which is a ganglionic complex composed of an agglomeration of ganglionic units. Each ganglionic unit is composed of three major cell types: principal ganglion neurones (PGNs), glial cells and small intensely fluorescent (SIF) cells, and they were separated by nerve fibres, septa of connective tissue (types 1 and 3 collagen fibres), fibroblasts and intraganglionic capillaries. Hence, the ganglionic unit is the morphological support for the microstructural organization of the CMG complex. Further, each ganglionic unit is constituted by a cellular triad (SIF cells, PGN and glial cells), which is the cytological basis for each ganglionic unit.

Age Factors↗

The microsurgical anatomy of the ciliary ganglion and its clinical importance in orbital traumas: an anatomic study.

The ciliary ganglion can easily be injured during surgery for the repair of orbital fractures and laterally situated intraorbital mass lesions. The aim of this study is to elucidate the microsurgical anatomy of the ciliary ganglion and to emphasize its clinical importance in orbital traumas and surgeries. The orbits of 10 adult cadavers were fixed with 10 % formalin and dissected under the microscope with special attention to the presence and location of the ciliary ganglion. The motor (parasympathetic), sympathetic, and sensory roots, and the short ciliary nerves were exposed. Its relationship with other intraorbital neural and vascular structures were investigated. Some anatomic landmarks were determined and the distances between these landmarks were measured. The ciliary ganglion is an intraorbital neural structure approximately 3 mm in size, situated near the orbital apex, posterolateral to the globe in loose areolar tissue between the optic nerve and lateral rectus muscle. The mean distance between the ganglion and the optic nerve was 2.9 mm (range: 2.70 - 3.10 mm) and the mean distance between the lateral rectus muscle and the ganglion was 10.4 mm (range: 9.20 - 11.20 mm). Six to 10 short ciliary nerves arise from the ganglion and run forward in a curving manner with the ciliary arteries above and below the optic nerve. The ciliary ganglion should be taken into the account especially during lateral approaches to the orbit and the patients should be warned before the surgery about possible mydriatic or tonic pupils as a complication.

Adult↗

The vascular pattern of the human dorsal root ganglion and its probable bearing on a compartment syndrome.

STUDY DESIGN: A descriptive anatomic investigation of the vasculature of the dorsal root ganglions. OBJECTIVES: To determine whether the blood supply of the various spinal ganglions is sufficiently consistent to derive a "generic" description and illustration that would be applicable to all spinal levels, and to ascertain whether this vascular pattern is inherently predisposed to the development of a closed compartment syndrome. SUMMARY OF BACKGROUND DATA: The few previous descriptions of spinal ganglionic vasculature do not include photographic evidence showing uniformity in the arterial distribution plan at all ganglionic levels. The venous drainage, although verbally reconstructed from microscopic sections, lacks any indication of its probable role in the etiology of a compartment syndrome. METHODS: Three perinatal cadavers received latex/India ink injections, and their removed radiculomedullary systems were cleared, transilluminated, and macroscopically photographed. Paravertebral sections were grossly removed from the spines of two adult anatomic cadavers and received retrograde venous injections of a fine suspension of barium sulfate. The intervertebral foraminal tissues were then dissected from the bone, and radiographs of them were made. For comparative reference, a nerve root/ganglion complex of a rabbit was arterially injected with a more dilute preparation of the latex/India ink suspension. RESULTS: Macroscopic photographs of perinatal dorsal root ganglions showed that the pattern of the intraganglionic arterial distribution was sufficiently consistent to allow a graphic rendering and labeling of a "generic" ganglion. The series of incomplete retrograde venous injections adequately indicated the pressure labile location of a periganglionic venous plexus. CONCLUSIONS: The common development, structure, and function of the human dorsal root ganglions have resulted in the evolution of a uniform nutritional vascular pattern that can be conceptualized in a single visual image. Its plan of a primarily internal arterialization with a superficial venous drainage renders it vulnerable to the ischemic conditions consequent on external pressures and/or internal edematous swelling. This vascular arrangement may contribute to a propensity for the ganglion to develop a compartment syndrome when subjected to compression by periforaminal degenerative or neoplastic space-occupying lesions.

Adult↗

Intracellular analysis and structural correlates of the organization of inputs to ganglion cells in the retina of the turtle.

Intracellular recording from the ganglion cells of the retina of the turtle Pseudemys scripta elegans shows that the photoresponses are characterized by either of two reversal potentials. These have been related to the bipolar and amacrine cell inputs to ganglion cells. Of the recorded ganglion cells, 33% (type A) are driven predominantly by one type of input, attributed to bipolar cells. Other ganglion cells (66%, type B) receive a mixed input from bipolar and amacrine cells. Type A ganglion cells show a higher conduction velocity (up to 3 m/s) and a higher firing frequency (up to 160 spikes per second) than type B cells. By injecting Procion yellow into bipolar, amacrine and ganglion cells it may be observed that type A ganglion cells ramify only in those regions of the inner plexiform layer that contain cell processes originating exclusively from the bipolar cell type predicted from the recordings. Type B ganglion cells ramify throughout the inner plexiform layer in either a multi-stratified or a diffuse fashion.

Action Potentials↗

Synaptic Contacts and the Transient Dendritic Spines of Developing Retinal Ganglion Cells.

The dendrites of ganglion cells in the mammalian retina become extensively remodelled during synapse formation in the inner plexiform layer. In particular, after birth in the cat, many short spiny protrusions are lost from the dendrites of ganglion cells during the time when ribbon, presumably bipolar, synapses appear in the inner plexiform layer and when conventional, presumed amacrine, synapses increase significantly in number. It has therefore been postulated that these transient spines may be the initial or preferred substrates for competitive interactions between amacrine or bipolar cell terminals that subsequently result in the formation of appropriate synapses onto the ganglion cells. If so, the majority of synapses made onto developing ganglion cells should be found on these dendritic spines. To test this hypothesis, we determined the synaptic connectivity of identified ganglion cells in the postnatal cat retina during the period of peak spine loss and synapse formation. The dendritic trees of ganglion cells were intracellularly filled with Lucifer yellow that was subsequently photo-oxidized into an electron-dense product suitable for electron microscopy. In serial reconstructions of the dendrites of a postnatal day 11 (P11) alpha ganglion cell and a P14 beta ganglion cell, conventional and ribbon synapses were found predominantly on dendritic shafts. Only three out of a total of 341 dendritic spines from the two cells received direct presynaptic input, all of which were conventional synapses. Thus, our observations suggest that the transient dendritic spines are not the preferred postsynaptic sites as previously suspected. However, it is possible that these structures play a different role in synaptogenesis, such as mediating interactions between retinal neurons that may lead to cell - cell recognition, a necessary step prior to synapse formation at the appropriate target sites (Cooper and Smith, Soc. Neurosci. Abstr., 14, 893, 1988).

Journal Article↗

Synaptic potentials recorded by the sucrose-gap method from the rabbit superior cervical ganglion.

1. Compound ganglionic potentials evoked by stimulation of the preganglionic nerves to the superior cervical ganglion of the rabbit were recorded by the sucrose-gap method.2. When the distal part of the ganglion was bathed in flowing isotonic sucrose solution or sodium-deficient solutions, ganglionic action potentials were no longer evoked, only large synaptic potentials.3. The compound synaptic potential, which remained unaltered for more than 1 h, originated in a population of cells at the interface between the Krebs and sucrose solutions. Hexamethonium reduced the size but did not alter the time course of the synaptic potential.4. It is suggested that a higher concentration of sodium ions is required for the generation of ganglionic action potentials than for either conduction in the postganglionic axons or production of synaptic potentials.5. When lithium replaced sodium in the solution bathing the distal part of the ganglion, the synaptic potential was greatly reduced in amplitude. Impulse propagation in the postganglionic axons was only slightly impaired when lithium replaced sodium in the solution bathing the axons.6. A quantitative assessment of the potency of the ganglion-blocking drugs nicotine, pentolinium, hexamethonium and pempidine was made by measuring the depression of the synaptic potentials produced by bathing the distal part of the ganglion in flowing isotonic sucrose solution. The concentrations which produced a 50% depression were 8.1 muM nicotine, 26.5 muM pentolinium, 111 muM hexamethonium and 22.2 muM pempidine.

Animals↗

Effects of divalent cations on responses of a sympathetic ganglion to 5-hydroxytryptamine and 1,1-dimethyl-4-phenyl piperazinium.

1 The effects of raising or lowering [Ca(2+)](o) or [Mg(2+)](o) on potential changes evoked by 5-hydroxytryptamine (5-HT) and by the nicotinic agonist, 1,1-dimethyl-4-phenyl piperazinium (DMPP) have been investigated.2 Changes in membrane potential were measured at the ganglion or in postganglionic axons by the sucrose-gap technique. The ganglionic response to both 5-HT and DMPP was a depolarization followed by an after-hyperpolarization (AH). AH decayed exponentially over most of its time course; the time constant of decay for 5-HT responses was 4.4 +/- 0.3 min (mean +/- s.e.mean, rate constant 0.23 min(-1)) and that for DMPP responses was not significantly different, being 3.9 +/- 0.3 min (rate constant 0.26 min(-1)).3 Increasing [Ca(2+)](o) to 5.1 or 7.6 mM caused some hyperpolarization of the ganglion, reduced the amplitude of depolarizations evoked by 5-HT by 29% and usually potentiated responses to DMPP (average 12%). Ca-free solutions caused a depolarization of the ganglion, increased the amplitude of depolarizations evoked by 5-HT by 23% and reduced that of depolarizations to DMPP by 32%. [Mg(2+)](o) 12.7 and 25.4 mM caused depolarizations of the ganglion and reduced the amplitude of depolarizations evoked by 5-HT by 34 and 84%, respectively, and those to DMPP by 10 and 75%, respectively. Mg-free solutions or low [Mg(2+)](o) caused a slow depolarization of the ganglion and reduced the amplitude of depolarizations to both 5-HT and DMPP by approx. 20%. Ca/Mg-free solutions produced a slow depolarization of the ganglion, increased the amplitude of depolarizations evoked by 5-HT by 78% and reduced those to DMPP by 58%.4 Increasing [Ca(2+)](o) reduced the amplitude of AH evoked by 5-HT by 50% and increased that to DMPP by 73%, while prolonging AH duration and increasing the time constant of decay. Ca-free solutions had complex effects on AH evoked by 5-HT, which were increased on average by 116%, and depressed AH evoked by DMPP; in both cases there was a decrease in the time constant of decay. [Mg(2+)](o) 12.7 mM reduced the amplitude of AH evoked by 5-HT more than that evoked by DMPP, and increased the rate of decline of the exponential phase. Low Mg solutions reduced in amplitude the AH evoked by 5-HT by 56% and the AH evoked by DMPP by 38%. The time constant of decay was increased. Ca/Mg-free solutions reduced AH amplitude in both 5-HT and DMPP responses. The effects on time constant are consistent with the generation of AH by an electrogenic sodium pump, the ATP-ase of which is Mg(2+)-dependent and inhibited by Ca(2+).5 Responses to 5-HT could be recorded from postganglionic axons and consisted of a rapid depolarization, sometimes followed by an AH whose time constant of decay was smaller than that of ganglionic responses. Full dose-response curves in control and test media could be obtained. In Ca/Mg-free solutions, 5-HT depolarizations were potentiated but no significant shift in the curve was observed.6 It is suggested that divalent cations modulate the coupling between 5-HT receptor and ion channel, an increase in [Ca(2+)](o) reducing the coupling or stabilizing the ion channel in the closed conformation. Ca(2+) and Mg(2+) may compete for the same binding site. This mechanism does not appear to be involved at nicotinic receptors and their related ion channels.

Animals↗

Reinnervation of the amphibian cardiac ganglion after complete or partial denervation.

The interactions between regenerating and sprouted nerve terminals during reinnervation of neurones were tested in the parasympathetic cardiac ganglion in frogs. 1. After partial (unilateral) vagotomy, remaining intact preganglionic vagal axons rapidly sprouted and innervated the entire ganglion. At later intervals after nerve damage, regenerating vagal axons were able to reinnervate ganglion cells despite the presence of synapses from sprouted nerve terminals. 2. When vagal reinnervation took place after unilateral vagotomy, synaptic input from the sprouted vagus nerve declined. 3. The presence of synapses from intact and sprouted nerve terminals in the ganglion after partial denervation measurably delayed the rate of vagal reinnervation. 4. After complete denervation (bilateral vagotomy), ganglionic reinnervation was rapid and complete. However, cells initially received an excessive number of preganglionic inputs and an abnormal distribution of left/right vagal innervation in the ganglion. 5. At long intervals (up to 85 weeks) after ganglionic reinnervation, some reduction of excess vagal inputs took place, indicating there was a slow re-organization of ganglionic synapses. 6. The number of boutons per cell body as revealed by zinc iodide-osmium staining remained constant after vagal reinnervation, despite an initial excessive synaptic reinnervation and subsequent synaptic remodelling.

Action Potentials↗

Apportionment of the terminals from single preganglionic axons to target neurones in the rabbit ciliary ganglion.

We have studied the apportionment of terminals from single preganglionic axons to target neurones in the ciliary ganglion of adult rabbits. Both electrical recording and intra-axonal injection of horseradish peroxidase (HRP) showed that each preganglionic axon innervates only a small fraction of the ganglion cell population (about 10-20 of the approximately 400 ganglion cells). Examination of ganglia in whole mounts showed that neurones whose cell bodies were enveloped by HRP-labelled boutons from a single axon were often surrounded by other neurones which received no contacts from the labelled fibre. Electron microscopical examination of labelled presynaptic terminals on individual ganglion cells confirmed that the boutons of single axons were sharply confined to particular target cells. This suggests that individual target neurones (or portions of them) are the unit of innervation during the development of these synaptic connexions. Comparison of the amplitudes of synaptic responses in singly and multiply innervated ganglion cells indicated that, on average, an individual axon made a weaker synaptic connexion with a multiply innervated neurone than with neurone that received only one input. Moreover, neurones innervated by several different axons tended to have fewer synapses on their somata than neurones innervated by only one or two preganglionic axons. Individual post-synaptic profiles were often contacted exclusively by labelled terminals when examined in the electron microscope. Since many of these neurones are multiply innervated, this observation suggests some regional separation of the several inputs contacting the same cell. For several reasons, however, this inference must be regarded as tentative. Taken together, these findings provide a possible explanation of the correlation between the dendritic geometry of ganglion cells and the number of different axons that innervate them (Purves & Hume, 1981). The several axons that initially innervate ganglion cells without dendrites evidently compete during early life until only a single input remains. On ganglion cells with dendrites, however, the number of inputs that persists is proportional to dendritic complexity. The present results suggest that the diminished competition between axons innervating neurones with dendrites may result from some degree of terminal segregation on dendritic arborizations.

Action Potentials↗

Rearrangement of synapses on guinea-pig sympathetic ganglion cells after partial interruption of the preganglionic nerve.

The rearrangement of synaptic connexions maintained by the intact preganglionic axons was examined with intracellular recording after partial denervation of the guinea-pig superior cervical ganglion. After sprouting, the number of superior cervical ganglion cells innervated by each residual preganglionic axon was increased by a factor of about three. These new synaptic connexions were stable in the absence of reinnervation of the ganglion by the injured axons. The intact preganglionic axons that sprouted in the superior cervical ganglion abandoned most of the synaptic connexions they normally maintain with neurones in the stellate ganglion. Several months after the partial denervation some of the injured preganglionic axons had usually re-established synaptic connexions with neurones in the superior cervical ganglion. However, both the rate and final degree of reinnervation were poor compared to reinnervation after complete denervation. During reinnervation of the superior cervical ganglion by the injured axons, there was a reduction in the degree of innervation of this ganglion by the sprouting axons. These results support the idea of an ongoing competition between preganglionic axons, and indicate some of the factors that probably determine the synaptic balance under normal and experimental conditions.

Action Potentials↗

In situ and in vitro identification and characterization of cardiac ganglion neurons in the crab, Carcinus maenas.

The aim of this study was to investigate the intrinsic membrane properties and hormonal responses of individual central pattern generating neurons in the cardiac ganglion of the shore crab Carcinus maenas. Because the cardiac ganglion in this crustacean species is buried within the heart musculature and is therefore inaccessible for direct morphological and electrophysiological analysis, we developed two novel in vitro preparations. First, to make the ganglion accessible, we established a brief enzymatic treatment procedure that enabled us to isolate the entire cardiac ganglion, in the absence of muscle tissue. Second, a cell culture procedure was developed to isolate individual neurons in vitro. With the use of both isolated ganglionic and neuronal cell culture techniques, this study provides the first direct account of the neuroanatomy of the cardiac ganglion in shore crabs. We demonstrate that cultured neurons not only survived the isolation procedures, but that they also maintained their intrinsic membrane and transmitter response properties, similar to those seen in the intact ganglion. Specifically, we tested the peptides proctolin, crustacean cardioactive peptide, the FLRFamide-related peptide F2, and an amine (serotonin) on both isolated ganglion and in vitro culture neurons. We measured changes in neuronal burst rate, burst amplitude, pacemaker slope, and membrane potential oscillation amplitude in response to the above four hormones. Each hormone either increased neuronal activity in spontaneously bursting neurons, or induced a bursting pattern in quiescent cells. The in vitro cell culture system developed here now provides us with an excellent opportunity to elucidate cellular, synaptic and hormonal mechanisms by which cardiac activity is generated in shore crabs.

Animals↗

Quantitative study on the fetal cervical dorsal root ganglion and observations on its relationship with the spinal nerve complex in the albino mouse.

In mouse fetuses aged 12, 14, 16, 18 and 20 days, the cervical dorsal root ganglion was studied quantitatively. The main growth in volume of the interneuroblastic spaces was between the 12th and 16th day of pre-natal life while the main increase in volume of its neuroblasts occurred in the subsequent 4 days. Thus, it was postulated that the growth and branching of the neuroblastic dendrites, growth of the neuroglial elements and the vascular ramifications inside the ganglion occurred mainly between the 12th and 16th day of pre-natal life. Different modalities in the spatial relationship between the dorsal root ganglion and the different components of the spinal nerve were met with. At times, the trunk of the spinal nerve was located inside the ganglion. At that site, the posterior primary ramus emerged from it and appeared as a branch of the ganglion. The ventral root sometimes passed close to the fibrous capsule of the ganglion. In other cases, it passed inside the ganglion, dividing the ganglionic neuroblasts into dorsal and ventral groups. These either remained ensheathed by one fibrous capsule or became divided into two separate masses that remained connected to each other by the fibrous dural sheath.

Animals↗

Comparing the somal size and nuclear positions of the monkey stellate and coeliac ganglion cells.

The stellate and coeliac ganglia of 2 Macaque monkeys were cut serially at 1 micron thickness and analysed. Results from the analysis of 82 stellate and 60 coeliac ganglion cells in 1 monkey show that in cross-sections, the neuronal nuclei may be eccentric, centric or nearly centric and remain so throughout the longitudinal extent of the neuron. In both ganglia, the majority of neurons possess eccentric nuclei, but in the coeliac ganglion, the percentage of neurons with centric and/or nearly centric nuclei is higher (41.7%) than that in the stellate ganglion (26.3%). While 5% of neurons in the coeliac ganglion are binucleated, no binucleated neurons were found in the stellate ganglion. The somal size ranges of the stellate (10-39 microns) and the coeliac (14.5-45 microns) ganglion neurons as obtained from both monkeys are quite close. The percentage frequency distribution of the stellate ganglion neurons in monkey 1 was also quite similar to that of the coeliac ganglion neurons. It is concluded that different neuronal size is not likely to be associated with different target organs.

Animals↗

Involvement of cyclic AMP in multiple, excitatory actions of biogenic amines on the cardiac ganglion of the horseshoe crab Limulus polyphemus.

Cyclic AMP appears to be involved in several excitatory actions of amines on neurones of the Limulus cardiac ganglion. Amines selectively increase levels of cardiac ganglion cyclic AMP with a magnitude and time course similar to that observed for amine-induced excitation of cardiac ganglion burst rate. With respect to either the physiological or biochemical effect, the apparent order of potency is octopamine greater than epinephrine approximately dopamine greater than norepinephrine. Elevation of cardiac ganglion cyclic AMP levels by octopamine or dopamine is dose-dependent and is potentiated by the phosphodiesterase inhibitor 3-isobutyl 1-methylxanthine (IBMX). Several pharmacological agents which influence cyclic nucleotide metabolism, including forskolin, IBMX and 8-substituted cyclic AMP analogues, have amine-like effects on the Limulus cardiac ganglion. These effects include increased burst rate of the isolated cardiac ganglion and decreased burst duration, interburst interval and number of spikes per burst in follower neurones. Forskolin and IBMX increase levels of cardiac ganglion cyclic AMP, and IBMX also increases cyclic GMP levels in this tissue. Amines, forskolin and IBMX have direct effects on follower neurones pharmacologically isolated from pacemaker cell input. Octopamine, forskolin and IBMX depolarize follower neurones, while dopamine hyperpolarizes these cells. Amines, forskolin and IBMX elicit burst-like potentials in follower neurones, and increase the size of evoked, unitary junction potentials recorded in cardiac muscle fibres. These pharmacological and biochemical data suggest that multiple, excitatory effects of biogenic amines on the Limulus cardiac ganglion are mediated by simultaneous increases in cyclic AMP at several loci within this neural network.

1-Methyl-3-isobutylxanthine↗

Ganglionic adrenergic action modulates ovarian steroids and nitric oxide in prepubertal rat.

Both peripheral innervation and nitric oxide (NO) participate in ovarian steroidogenesis. The purpose of this work was to analyse the ganglionic adrenergic influence on the ovarian release of steroids and NO and the possible steroids/NO relationship. The experiments were carried out in the ex vivo coeliac ganglion-superior ovarian nerve (SON)-ovary system of prepubertal rats. The coeliac ganglion-SON-ovary system was incubated in Krebs Ringer-bicarbonate buffer in presence of adrenergic agents in the ganglionic compartment. The accumulation of progesterone, androstenedione, oestradiol and NO in the ovarian incubation liquid was measured. Norepinephrine in coeliac ganglion inhibited the liberation of progesterone and increased androstenedione, oestradiol and NO in ovary. The addition of alpha and beta adrenergic antagonists also showed different responses in the liberation of the substances mentioned before, which, from a physiological point of view, reveals the presence of adrenergic receptors in coeliac ganglion. In relation to propranolol, it does not revert the effect of noradrenaline on the liberation of progesterone, which leads us to think that it might also have a "per se" effect on the ganglion, responsible for the ovarian response observed for progesterone. Finally, we can conclude that the ganglionic adrenergic action via SON participates on the regulation of the prepubertal ovary in one of two ways: either increasing the NO, a gaseous neurotransmitter with cytostatic characteristics, to favour the immature follicles to remain dormant or increasing the liberation of androstenedione and oestradiol, the steroids necessary for the beginning of the near first estral cycle.

Adrenergic alpha-Antagonists↗

Pregnancy in rats is modulated by ganglionic cholinergic action.

The control of ovarian steroidogenesis during pregnancy is mainly of endocrine origin. At present, there is little information about the influence of neural factors on the gestation physiology. The purpose of this work was to study the action of cholinergic agents in celiac ganglion upon the liberation of progesterone and ovarian androstenedione in the second half of pregnancy in rats. We used the ex vivo celiac ganglion-superior ovarian nerve-ovary integrated system (celiac ganglion-SON-ovary) that was incubated in buffer solution for 180 min, with the celiac ganglion and the ovary located in different compartments and linked by the SON. The results obtained indicate that the control values of ovarian androstenedione vary according to the pregnancy day analyzed. The addition of acetylcholine in ganglion decreased the liberation of both steroids on Day 15 whereas at the end of pregnancy it decreased the liberation of androstenedione without modifying progesterone. Due to the effect observed with atropine and hexametonium, acetylcholine action might occur through unspecific ganglionic pathways (Days 15 and 21) or through muscarinic ganglionic receptors (Days 19 and 20). Thus, we conclude that the cholinergic sympathetic system from the celiac ganglion might be a fine modulator of the pregnancy physiology.

Acetylcholine↗

The cholinergic influence on the mesenteric ganglion affects the liberation of ovarian steroids and nitric oxide in oestrus day rats: characterization of an ex vivo system.

The axons that constitute the ovarian nervous plexus originate mostly in the principal neurons of the superior mesenteric ganglion (SMG) that is part of the sympathetic ganglionic chain and exhibits cholinergic receptors. In order to observe the effect of acetylcholine, the main neurotransmitter in the ganglionic transmission, the purpose of the present work was: first, to standardize an integrated ex vivo superior mesenteric ganglion-ovarian nervous plexus-ovary (SMG-ONP-O) system in oestrus day rats; secondly, to determine if the ganglionic cholinergic stimulus modifies the release of nitric oxide and steroids in the ovary compartment in the absence of humoral factors; and thirdly, to investigate if there are differences in the responses between the left and right ovaries caused by the neural stimulus. The ex vivo experimental left and right systems were developed and standardized. The systems were incubated in Krebs-Ringer phosphate buffer in a Dubnoff metabolic shaker. The progesterone release was determined to standardize the incubation times, obtaining different responses between the left and right systems, which shows that both systems have their own autonomic tone. Non-specific stimulation with KCl in the ganglion compartment provoked different responses in terms of release of progesterone and oestradiol. Progesterone decreased in the left and right systems. However, oestradiol diminished at short times and increased at 60 and 120 min in the left ovary, whereas it increases at 30 and 60 min in the right ovary. These different responses show the sensitivity and viability of both systems. When acetylcholine was used in the ganglion compartment, the release of nitric oxide, progesterone, androstenedione and oestradiol was evaluated. The liberation of nitrite increased at 15, 30 and 60 min in the left system and decreased in the right system at 120 min. Progesterone showed a decrease in its release at 15, 30 and 120 min and androstenedione at 15 min in the left ovary compartment. In the right ovary, only progesterone decreased in relation to the control at 120 min while androstenedione did not show significant changes. Oestradiol showed an increase in the left ovary compartment at all the studied times, while in the right ovary it did not show any changes. These results indicate that the neural stimulus from the superior mesenteric ganglion through the ovarian nervous plexus is one of the factors modulating the secretory activity of the ovarian steroids and nitric oxide. The system is viable and also shows a different sensitivity of the left ovary in relation to the right one at least in this cycle stage, characterized by marked irrigation and profound structural changes in the ovary.

Acetylcholine↗

Distribution of neuropeptides in rat pterygopalatine ganglion: light and electron microscopic immunohistochemical studies.

The distribution and quantity of neuropeptides in the rat pterygopalatine ganglion were studied by using complete serial paraffin sections of the ganglion immunostained with antiserum against several neuropeptides. The pterygopalatine ganglion, composed of 4932 +/- 291 (mean +/- SD) neurons, was triangular in shape with a tapering caudal tail. The most commonly found peptide in neurons was vasoactive intestinal polypeptide (VIP) (99.0%), followed by neuropeptide Y (NPY) (54.1%) and enkephalin (10.5%). The rostro-ventromedial and caudal parts of the ganglion where intensely VIP-immunoreactive neurons predominate project to the nasal mucosa, while the rostro-dorsolateral part of the ganglion where NPY-immunoreactive neurons predominate projects to the Harderian gland. The coexistence of VIP/NPY (47.4%), VIP/NPY/enkephalin (6.6%) or VIP/enkephalin (3.9%) in the ganglionic neurons was recognized. Calcitonin gene-related peptide (CGRP)- and substance P-immunoreactive varicosities formed synaptic contacts with the somatic spine or soma, which confirmed that the reflex arch, composed of axon collaterals of trigeminal ganglionic neurons and parasympathetic ganglionic neurons, operates through direct synapses. Enkephalin-immunoreactive varicosities, which were probably derived from parasympathetic preganglionic neurons, also made synaptic contact with the somatic spine.

Animals↗