Terminal Plexus Research Articles

Effects of 6-hydroxydopa

After a single i.v. injection, 6-OHDOPA is capable of causing destruction and/or functional impairment of noradrenergic nerve terminals in both the central and the peripheral nervous system. By analogy with the effects of 6-hydroxydopamine and histochemical observations of preterminal accumulation of neurotransmitters, the conclusion that 6-OHDOPA causes degenerative changes in the terminal plexus is derived. There is no question that the final determination of neuronal degeneration should come from electron microscopic studies. The accumulation of histochemically observable catecholamine fluorescence in nonterminal axons, the time course of depletion and recovery of NE within various peripheral organs and impairment of uptake of exogenously administered NE support the conclusion that 6-OHDOPA has the potential to cause selective destruction of noradrenergic terminals. 6-OHDOPA is a valuable tool for the investigation of central pathways and functional organization of the noradrenergic neurons in the brain. Injection of 6-OHDOPA into the cerebral ventricles can produce a highly specific reduction in the NE content of the central nervous system while leaving dopaminergic neurons unaffected. This factor will be useful for the exploration of the behavioral contributions of central noradrenergic neurons.

Localization of biogenic amines and monoamine oxidase in the rabbit hippocampus

Comparison of the localization of monoamines and monoamine oxidase in the rabbit hippocampus shows that most pyramidal and all granular neurons contain no monoamines. Up to 1% of pyramidal and about 3% of polymorphic neurons are noradrenergic, and some of the latter are basket cells. Their terminals, containing both noradrenalin and monoamine oxidase, are in contact with the bodies and processes of the pyramidal and granular neurons. Single serotoninergic polymorphic neurons are found in sectors H1 and H2 of the cornu ammonis and in sector H5 of the fascia dentata of the hippocampus; they have few terminals. Noradrenergic afferents enter the cornu ammonis in the external bundle of the alveus and in the septal tract, which runs along the inner surface of the fimbria. Noradrenergic terminal plexuses surround the bodies of the pyramidal cells and are concentrated at the level of the apical dendrites of the pyramids and at the base of the granular neurons of the fascia dentata. Convergence of noradrenergic and serotoninergic terminals is found on some pyramidal, granular, and polymorphic neurons. The high concentration of serotonin in the hippocampus despite the minimal number of serotoninergic neurons can be explained by the large number of serotonin-containing stellate cells of nonneural nature. They are localized on groups of pyramidal neurons in sectors H1 and H2 and also on blood vessels. Individual variations are found in the number of serotonin-containing neurons in the hippocampus and in the number and distribution of serotonin-containing stellate cells.

The effect of lesions of catecholamine-containing neurons upon monoamine content of the brain and EEG and behavioral waking in the cat

Summary In order to determine the specific catecholamine content of catecholamine-containing neurons of the pons and mesencephalon and to investigate their role in mechanisms of waking, electroylitic lesions of these neurons were performed in 19 cats which were subsequently continously recorded and simultaneously observed for 8–13 days after surgery. Following sacrifice, monoamine levels of dopamine, noradrenaline, and serotonin were assayed in the diencephalon and telencephalon by spectrofluorimetric technique, and the extent of the lesions was determined by histological preparation and examination of the pons and mesencephalon. A quantitative analysis of the relationships among the percentage of area destroyed, the percentage of monoamine in the rostral brain and percentage of electrocortical waking (of total recording time) was performed by multiple correlations. The behavioral state of the animal was classified into 3 categories which were compared according to the variables mentioned above. Lesions of the catecholamine-containing neurons of groups A9 and A10 located in the substantia nigra and the ventral tegmental area were correlated with a decrease of dopamine in the rostral brain. Lesions of the nebula complex (ensemble of sparse cell bodies and a rich plexus of green fluorescent axon collaterals and terminals located in the central reticular formation of the mesencephalon) were correlated with noradrenaline as was the total volume of the mesencephalic lesions. Destruction of the catecholamine-containing cell bodies of part of group A6 produced a decrease in noradrenaline. A behavioral state characterized by akinesia, hypertonus and a total lack of behavioral arousal was associated with significantly large decreases in dopamine and extensive destruction of the dopamine-containing neurons of the ventral tegmentum (A9 and A10). Electrocortical waking was significantly correlated with noradrenaline and destruction of nebula complex and total volume of the lesion. Destruction of catecholamine-containing cells of the dorsolateral pontine tegmentum (anterior portion of A6) produced a decrease in electrocortical waking with no behavioral deficit. A dissociation between behavioral arousal and electrocortical waking was exhibited in animals with predominant lesions of either the ventral tegmentum or mesenceophalic reticular formation. In conclusion two mechanisms were hypothesized to be involved in the maintenance of waking: (1) dopaminergic neurons of the ventral tegmentum which may be essential for the maintenance of behavioral arousal, and (2) noradrenergic neurons of the pons and possibly the medulla which may mediate tonic cortical activation.

Afferent axons and their relations with neurons in the nucleus lateralis of the cerebellum: a light microscopic study.

The axons of Purkinje cells are the sole corticonuclear afferents to the lateral nucleus. The terminal arborizations of these axons consist of many (30–50) varicose branchlets, which issue from a thick, myelinated parent axon. Each terminal plexus fills a conical field which penetrates the lateral nucleus radially encompassing the cell bodies and parts of the dendritic trees of approximately 40 neurons. The fields of neighboring Purkinje axons overlap considerably. The non-cortical axons are simple, usally unbranched varicose fibers of three sizes: (1) thick, with large varicosities, (2) medium sized with smaller varicosities, or (3) fine, delicate threads with beadlike varicosities. These axons cross the dendritic trees of successive neurons as they penetrate into the nucleus in a radial fashion.

Cholinergic mechanisms in pial vessels. Histochemistry, electron microscopy and pharmacology.

Plexuses of cholinergic nerve terminals were demonstrated (acetylcholinesterase staining) in pial arteries (down to a diameter of about 15μ) at the base of the brain and on the brain convexities of mice, rats, rabbits, hamsters, guinea-pigs, and cats. The pial veins were less well supplied than the arteries. Consecutive formaldehyde gas treatment (to visualize adrenergic nerves) and acetylcholinesterase staining revealed that the adrenergic and cholinergic plexuses followed each other closely, the axon terminals running together in the same Schwann cell strands. This was confirmed by electron microscopy after KMnO4 fixation or 5-hydroxydopamine treatment. The varicosities of cholinergic and adrenergic axons were sometimes seen as close as 250 A. In the neuro-effector area, the terminals of both nerve types (naked or surrounded by an incomplete Schwann cell covering) approached the smooth muscle cells as close as 800–1100 A, and they were separated from the latter only by the fused neuronal and muscular basement membranes. In this area axo-axonal contacts were observed. The adrenergic, but not the cholinergic, nerves disappeared after bilateral removal of the superior cervical sympathetic ganglia. Isolated cat middle cerebral artery contracted strongly with acetylcholine, and the effect was inhibited by atropine.

The effects of DMPP on adrenergic nerves in perfused hearts

Correlation of changes in the norepinephrine content with histochemically observed changes in adrenergic nerves within the perfused guinea-pig heart was made after intermittent injections of 1,1-dimethyl-4-phenylpiperazinium (DMPP). Heart rates and amplitude of contractions were also recorded for 2 hr. DMPP was administered to untreated hearts and to hearts of animals pretreated with α-methyl-p-tyrosine (α-MPT), H 22/54 [(3,4-dihydroxyphenyl) β-propylacetamide], or reserpine. Multiple injections of DMPP (2 hr) did not change the NE content of the ventricle. DMPP caused a significant decrease in ventricular NE in hearts of animals pretreated with α-MPT, H 22/54, or reserpine. Visualization of adrenergic nerves of the ventricles after DMPP administration showed a reduction in intensity of fluorescence only in hearts of animals pretreated with H 22/54 or reserpine. The explanation for the lack of visual discrimination of changes in fluorescence of the α-MPT-pretreated hearts is unknown. No change in intensity of fluorescence was noted in the chromaffin cells of the atria in any of the groups of animals studied. These experiments support the concept that certain ganglion stimulants, such as DMPP, serve to release the sympathetic neurohumor from the terminal ground plexus of nerve fibers within the heart. It also appears that release of NE is accompanied by a very efficient resynthesis within the nerve terminals.

Intra- and extraganglionic peripheral cholinergic neurons in the urogenital organs of the cat.

The distribution of cholinergic neurons in the urinary tract and male genital organs of the cat was studied by a histochemical method for acetylcholinesterase. In addition to cell clusters in autonomic ganglia (intraganglionic cells), isolated extraganglionic cholinergic cells were found within the innervated tissues, usually in association with nerve trunks and blood vessels. Smaller neural cells with multiple axonal processes, identical to Cajal's “interstitial cells”, were found in the meshes of the terminal nerve plexus in smooth muscle, lamina propria and vascular wall.

Cerebellar monoamine nerve terminals, a new type of afferent fibers to the cortex cerebelli.

The monoamine innervation of the cerebellum of the rat has been studied by both in vivo and in vitro techniques using the histochernical fluorescence method for the demonstration of catecholamines (CA) and certain tryptamines. By way of a pharmacological approach using inter alia protriptyline, which acts mainly by blocking the membrane pump of the noradrenaline (NA) neurons, evidence was obtained that CA nerve terminals in the cerebellum mainly represent NA nerve terminals. These were found to innervate practically all parts of the cerebellar cortex with a patchy innervation pattern and with an innervation of especially the anterior and posterior lobes. The terminals mainly seem to make axodendritic contacts in the molecular and granular layers without any strict localization of the terminal plexus to any special plane of the cerebellar folia. The fibers enter the cerebellum via the inferior cerebellar peduncle and run in the white matter of the cortex cerebelli. Incubation studies with 6-hydroxytryptamine indicate that there exists also a 5-hydroxytryptamine (5-HT) innervation of the cortex cerebelli, although not as pronounced as the NA innervation. The 5-HT nerve terminals are very fine, varicose fibers and innervate mainly the molecular layer, especially of the anterior lobe. The terminals run mainly in the transverse plane of the folium parallel to the surface. Thus, the pattern of innervation of these 5-HT afferents is different from that of the NA nerve terminals. In the uvula, structures which may represent the “rosettes” of the mossy fibers or golgi axon terminals in the granular layer take up and accumulate monoamines after incubation with amine in vitro. The exact nature of these structures remains to be elucidated.The cerebellar nuclei receive a very low to low degree of innervation of NA and 5-HT nerve terminals.

Release of adrenergic transmitter from terminal nerve plexus in artery

Studies of the release of the adrenergic transmitter in the rabbit pulmonary artery have been carried out in vitro. At a stimulation frequency of 10 per second, the release was 52.9 pg per gram wet weight per pulse. The mean number of nodes or varicosities per gram wet weight of artery was 9.3×107. If 80% of the released transmitter is taken up by tissues in the artery wall, these values correspond to the average release of approximately 400 molecules ofl-norepinephrine per node per pulse. The transmitter concentrations in the region of the muscle in the outermost lamina of the vessel during sympathetic activity are discussed in relation to the spatial dimensions of the neuroeffector cleft. The release of the total contents of a vesicle on the average every 7 or 8 pulses from each node is consistent with these requirements.

Transmitter release in skin and muscle blood vessels during sympathetic stimulation.

ARTICLESTransmitter release in skin and muscle blood vessels during sympathetic stimulationBG Zimmerman, and L WhitmoreBG Zimmerman, and L WhitmorePublished Online:01 May 1967https://doi.org/10.1152/ajplegacy.1967.212.5.1043MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByPsychological Stress as a Determinant of Skin Barrier Function: Immunological Pathways and Therapeutic Opportunities23 August 2016Psychological Stress and the Cutaneous Immune Response: Roles of the HPA Axis and the Sympathetic Nervous System in Atopic Dermatitis and PsoriasisDermatology Research and Practice, Vol. 2012Effect of blood flow and muscle contraction on noradrenaline spillover in the canine gracilis muscleCanadian Journal of Physiology and Pharmacology, Vol. 78, No. 1Mathematical modelling of the enteric nervous network. 4. Analysis of adrenergic transmissionMedical Engineering & Physics, Vol. 17, No. 1Noradrenaline spillover during exercise in active versus resting skeletal muscle in manActa Physiologica Scandinavica, Vol. 131, No. 4The Role of Alpha Receptors in the Facilitation of the Chemoreflex and Inhibition of the Carotid Occlusion Reflex by Clonidine3 July 2009 | Clinical and Experimental Hypertension, Vol. 2, No. 6Factors influencing transmission at adrenergic synapsesProgress in Neurobiology, Vol. 4Comparison of Adrenergic Mechanisms in an Elastic and a Muscular Artery of the RabbitCirculation Research, Vol. 30, No. 5Activity and Thermosensitivity of Canine Cutaneous Veins after Inhibition of Monoamine Oxidase and Catechol-O-Methyl TransferaseCirculation Research, Vol. 25, No. 5Release of adrenergic transmitter from terminal nerve plexus in arteryAgents and Actions, Vol. 1, No. 1 More from this issue > Volume 212Issue 5May 1967Pages 1043-1054 Copyright & PermissionsCopyright © 1967 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1967.212.5.1043PubMed4381569History Published online 1 May 1967 Published in print 1 May 1967 Metrics

The sympathetic nerve supply to the inner ear.

Two different systems of sympathetic nerve supply to the inner ear are demonstrated by the histochemical method of Falex and Hillarp: 1. The perivascular adrenergic innervation, which is a continuous plexus around the vertebral, basilar, inferior anterior cerebellar and labyrinthine arteries reaching as far as the modiolar branches. 2. A blood-vessel independant innervation-system which forms a rich terminal plexus in the area of the habenula perforata. On the basis of a larger serie of degeneration studies on cats it appears that the postganglionic fibres of this bloodvessel independent system originate in the superior cervical ganglion and reach the inner ear either via tympanic plexus — facial nerve — internal acoustic meatus or via auricular branch of X — facial nerve and internal acoustic meatus. Clinical implications of these findings are discussed.

The Adrenergic Innervation of the Labyrinth

Using the method of Falck and Hillarp for the histocliemical demonstration of catecholamines, an adrenergic innervation is selectively shown in fresh tissue preparations of various parts of the labyrinth. Two different groups of adrenergic fibres are found: (1) A rich perivascular plexus continuous with the plexus of the basilar artery. It is only found around the labyrinthine artery and its greater brandies. (2) An extensive adrenergic network in the lamina spiralis ossea and underneath the vestibular sensory epithelia independent of blood vessels. It forms a dense terminal plexus in the area of the habenula perforata. With selective transection of the vestibular, cochlear or entire VIII nerve it could be demonstrated that these adrenergic fibres originate in the central nervous system and reach the periphery with the cochlear nerve. A possible interpretation of their functional significance is presented.

On the presence of adrenergic nerves in the pars intermedia of the frog, Rana temporaria

By means of a highly specific and sensitive fluorescence method, a plexus of catecholamine-containing nerve terminals has been demonstrated in the pars intermedia of the frog, Rana temporaria L. This plexus, which synaptically encloses the intermedia cells, possesses the basic characteristics of an adrenergic ground-plexus. There is support for the hypothesis that these adrenergic fibers mediate the inhibitory control by the brain of the pars intermedia.

Age changes in the blood supply to molar teeth of rats.

Abstract1. Rats, varying in age from one month to over one year, were used to study the changes in the vascular supply to the molar teeth and periodontium as a result of aging. The blood vessels were demonstrated by the saline‐India‐gelatin perfusion method. The jaws and teeth were fixed in a formol‐acetic acid‐alcohol solution, decalcified, dehydrated, and embedded in nitro‐cellulose in the usual manner. The embedded specimens were sectioned at 100–250 μ, cleared by the Spalteholz method and mounted unstained.2. In immature animals (younger than four months) the pulpal terminal vascular capillary networks were located at the predentin border. As the animals became progressively older, there was a gradual “withdrawal” of the terminal capillary plexuses from the odontoblastic zone so that at eight months of age, all the vascular terminals were restricted in location to the pulpal‐odontoblastic border.3. In the young animal the vessels supplying the periodontal ligament passed gingivally paralleling the bony surface of the membrane with the cemental side being devoid of vessels. During the process of aging, the above basic pattern was altered in the following manner: (a) The apposition of cellular cementum on the apical third of the root was accompanied by the presence of capillary terminals in or adjacent to the layer of cellular cementum. (b) There was a progressive decrease and eventually a loss of the interseptal vessels and their perforating branches. (c) Vascular twigs originating from the main periodontal vascular trunk were found in areas of cemental resorption indicating their need in the process of repair.

Environmental temperature and the reptilian nervous system.

IT has been found that the terminal plexus of the reptilian brain undergoes marked changes with the environmental temperature.

Die Innervation der Drüsenzellen der Pars distalis der Hypophyse bei der Ente

Es wird bei der Ente an Hand von Bielschowsky-Gros-Praparaten die Innervation der Drusenzellen der Pars distalis der Hypophyse beschrieben. Beinahe in allen Teilen der Pars distalis wird ein dichter nervoser Endplexus in den Drusenzellstrangen gefunden. Jede einzelne Drusenzelle steht in unmittelbarem Kontakt mit feineren und groberen Nervenfasern des Plexus. Diese nervose Formation wird als eine morphologische Basis fur die aus bisherigen experimentellen Arbeiten gefolgerte Wirkung des Nervensystems auf die Bildung und Abgabe der Hormone in der Pars distalis interpretiert und ihr die Ubertragung von Nervenimpulsen auf die einzelnen Drusenzellen zugeschrieben.