Terminal Plexus Research Articles

Pathological changes of glial cells in the enteric nervous system of the colon with chronic slow-transit constipation

The origin, development and differentiation of enteric nervous system neuroglia and its involvement in the pathogenesis of gastrointestinal diseases and neurodegenerative diseases have been little studied.Aim of this work is a comparative morphological study of glial cells in the ganglionic plexuses of the enteric nervous system and analysis of neuroglial relationships in chronic slow-transit constipation using immunohistochemical methods.Material and methods. Resection material obtained at the Department of Faculty Surgery, S.P. Fedorov Faculty of Surgery of S.M. Kirov Military Medical Academy during planned surgical operations was used. The objects of the study were fragments of the sigmoid and colon obtained as a result of surgery for chronic slow-transit constipation (five cases, women aged 37–40 years). The study was carried out using immunohistochemical glial markers (GFAP, S100β protein, etc.).Results. Two types of glia were found in the myenteric ganglionic plexus of the large intestine: astrocyte-like and neurolemmocytic. The astrocyte-like type is similar to the neuroglia of the central nervous system, the neurolemmocytic type is similar to the glia of the autonomic nervous system. It has been established that astrocyte-like glia is found only in the Aauerbach ganglionic plexus, while neurolemmocytes are found in all innervated tissues of the intestinal wall. Reactive, dystrophic and degenerative changes in neurocytes, glial elements, agangliogenosis in the Auerbach plexus were found in all cases of chronic slow-transit constipation. Destructive changes in the neuromuscular terminal plexuses, interstitial edema and inflammatory monocytic reaction and leukocyte infiltration in the intestinal mucosa and intestinal submucosa, found in several cases.Conclusions. The results obtained allow classifying chronic slow-transit constipation as a neurodegenerative disease.

Morphological features of basal laminas of enteral nervous system structures in chronic slow transit constipation

BACKGROUND: Studies on basal laminas in the tissues of the enteric nervous system are few and are carried out on experimental models in vivo and in vitro, performed on animals. The morphological features of the structure and localization of BL, their cellular sources of origin in various tissues of the gastrointestinal tract in normal and pathological conditions remain poorly studied.
 AIM: Study of morphological features and distribution of basal laminas in human colon tissues and their changes in pathology.
 MATERIALS AND METHODS: Fragments of the large intestine, obtained as a result of surgery for chronic slow-transit constipation, performed in S. M. Kirov Military Medical Academy were studied. The selective marker of basal laminas, type IV collagen, as well as neuronal and glial immunohistochemical markers (PGP 9.5, GFAP, S100 proteins) were used in the work
 RESULTS: It has been shown that the greatest immunoreactivity within the intestinal wall is observed in the myenteric membrane, weak in the vessels of the submucosa, locally expressed in the subepithelial region of the mucous membrane (in the upper sections of the crypts). In smooth muscle, basal laminas were found around the smooth muscle cells of the longitudinal and concentric layers of the muscular membrane, mucous membrane, veins and arteries, as well as in the endothelium. It has been shown that the ganglionic Auerbachs plexus is delimited from closely adjacent muscle layers of a continuous basal lamina, similar to the basal plate (glia limitans) of the brain and spinal cord of the CNS. It is clearly defined by its appearance it has the form of a continuous hollow tubular structure. The sources of the formation of the basal plate around the ganglia of Auerbach and Meissners plexuses are various glial elements: in the first plexus, astrocyte-like and non-myelinated Schwann cells (both types located in the neuropil), and in the second plexus, glia of the autonomic nervous system (satellite cells of neurons and neurolemmocytes of postganglionic nerve fibers).
 CONCLUSIONS: For the first time, the transition of basal lamina from the Auerbachs plexus to numerous basal plates of neurolemmocytes of the Remakov fibers of the main terminal nerve plexus, which are involved in the innervation of the smooth muscle cells of the muscular membrane, is shown. Signs of dystrophic changes in the basal lamina structure associated with pathological changes in chronic slow transit constipation (tissue edema, inflammatory reactions, manifestations of agangliosis, gliosis, focal denervation of muscle cells, degeneration of nerve endings of neuromuscular and ganglionic plexuses) are shown in the work.

Morphological signs of neurogenic inflammation in rat epicardial adipose tissue during aging

The aim of this work is to study the neuroinflammatory process in the epicardial adipose tissue (EAT) of the aorticpulmonary region of the rat heart during aging. The work was performed on Wistar rats aged 18-23 months (n=18). The adipose tissue of the pericardial region of rats was the object of study. Neuroimmunohistochemical markers (9.5 protein, tyrosine hydroxylase, synaptophysin) were used to study EAT innervation. The method of staining with toluidine blue and azure-eosin was used to study inflammation processes. Using histological and immunohistochemical methods, involutive and neurodegenerative changes in parasympathetic and sympathetic postganglionic nerve fibers were revealed in the white and brown adipose tissue of the heart of old rats (18-23 months old). A number of pathological changes were revealed in EAT: fibrosis, dystrophic changes and lysis of white adipocytes, disintegration of varicose axons of the terminal nerve plexus, as well as the formation of focal monocyticlymphoid infiltrates. It has been shown that the axons of the terminal nervous network are in close relationship with immune and inflammatory cells (lymphocytes, plasmablasts, monocyte-macrophage elements, mast cells). The noted morphological features indicate a neurogenic type of immune inflammation in the EAT of the heart. The identified changes may be the cause of chronic disorders of lipid metabolism during aging, leading to the development of pathological processes in the tissues of the main vessels of the aortic-pulmonary region of the heart, and also serve as prognostic indicators for clinical practice.

Pathological changes in the nervous structures of the aortic wall tissue adjacent to an unstable atherosclerotic plaque

To study of nerve structures in the aortic wall in atherosclerosis using a complex of immunohistochemical markers. The objects of the study were excised fragments of the wall of the thoracic and abdominal aorta along with visually determined unstable atherosclerotic plaques. To study nerve structures on paraffin sections, immunohistochemical reactions were performed for the PGP 9.5 protein, tyrosine hydroxylase, and synaptophysin. It has been established that pronounced pathological changes are observed in the nervous structures of the aortic wall near unstable atherosclerotic plaques. Reactive, dystrophic, and severe degenerative changes in neurocytes, nerve fibers, and glial cells are described in the elements of the nervous apparatus of the adventitia (microganglia, nerve trunks, and nerve plexuses). It was found that only sympathetic neurons and their postganglionic fibers remain in the intramural ganglia, while the structures of the parasympathetic nervous apparatus undergo degeneration. Destruction of perivascular nerve plexuses and vasa vasorum in the adventitia, as well as degeneration of varicose axons of the main terminal synaptic plexus at the border of adventitia and superficial smooth muscle layer of the media were demonstrated. It is assumed that the presence of inflammatory infiltrates in the adventitia and intima, denervation and death of vasa vasorum can serve as factors determining the development of the atherosclerotic process.

MORPHOLOGY AND FUNCTION OF THE AUTONOMOUS NERVOUS SYSTEM

The autonomic nervous system consists of the sympathetic and parasympathetic divisions. The central part is represented by supra-segmental and segmental centres. Parasympathetic segmental centres in the brain are accessory nucleus of the oculomotor nerves, superior salivary nucleus of the facial nerve, inferior salivary nucleus of the glossopharyngeal nerve and dorsal nucleus of the vagus nerve. In the spinal cord, these are the intermediate lateral nuclei. Sympathetic segmental centres in the brain are absent, and in the spinal cord, intermediate-lateral nuclei are located in the lateral horns in the eighth cervical, all thoracic and 1-2 lumbar spinal segments. The peripheral part of the autonomic nervous system is represented by pre-nodal and post-nodal branches, paravertebral, prevertebral and terminal nodes and plexuses. The intramural part of the autonomic nervous system lies in the larger part of a wide and narrow-loop net and represented with a large number of nerve cells different by their shapes and sizes and clustered as intramural nodes, or individual nerve cells included along the net loops. The autonomic plexuses of the abdominal cavity are topographically divided into celiac, superior and inferior mesenteric, abdominal aortic, mesenteric, superior and inferior hypogastric region.

Comparison of lateral and medial rectus muscle in human: an anatomical study with particular emphasis on morphology, intramuscular innervation pattern variations and discussion on clinical significance

This paper aims to present various aspects of the anatomy of horizontal (i.e., lateral and medial) rectus muscles. It mainly compares morphology and detailed patterns of intramuscular innervation of those muscles. It is also one of the first reports that uses the Sihler's stain to examine human extraocular muscles. The study was conducted on 80 isolated cadaveric hemi-heads. Sihler technique of nerves staining served to expose the course of intramuscular branches of the oculomotor and abducens nerves. The lateral rectus was longer (48mm versus 46.5mm) and more distant from the limbus (6.8mm versus 5.7mm) than the medial rectus muscle. Three variants of the abducens nerve primary division were observed in the lateral rectus muscle. In the medial rectus muscle, the motor branch from the oculomotor nerve was more evenly divided into sub-branches. In both examined horizontal rectus muscles, primary muscular branches split into secondary sub-branches, which undergo numerous further divisions. The most numerous terminal sub-branches formed the terminal plexus. The distance between the insertion and the anterior-most end of the terminal plexus referenced to the total length of the muscle ranged from 35.4 to 48.5% for the lateral rectus muscle and from 36.3 to 50.5% for medial rectus muscle. Both horizontal rectus muscles share similar general pattern of distribution of intramuscular nerves, with characteristic root-like arborizations of sub-branches. The terminal nerve plexus was observed near half of both muscles' length. Knowledge of variations and innervation pattern of the extraocular muscles may be relevant during ophthalmology surgeries.

Иммуногистохимическое исследование иннервации надпочечника крысы

The aim of the study was to study the innervation of the cortical part and medulla of the rat adrenal gland using neuroimmunohistochemical markers. Original data on the innervation of the rat Wistar (n = 8) adrenal cortex and medulla were obtained using immunohistochemical detection of the PGP 9.5 protein, synaptophysin, tyrosine hydroxylase, peripherin and serotonin. It was established that all zones of the cortex (glomerular, bundle, and reticular) are innervated by nerve fibers of various neurotransmitter identity. In the cortex, the innervation of the glomerular zone is most pronounced. A thick terminal plexus of varicose axons around islets of endocrinocytes, arterioles and nerve cells was detected in this zone. Cholinergic nerve structures (plexus of preterminal nerve fibers and the terminal synaptic network, which consists of varicose parasympathetic axons located around groups of neuroendocrine cells and sinusoidal capillaries) prevail in the medulla. Parasympathetic and sympathetic intramural ganglia were found in the medulla. Chromaffin cells immunoreactive to various catecholamines and serotonin were found in the adrenal medulla. It was assumed that different sources of sympathetic innervation of the organ are present. These are the medulla's own neurons and sympathetic trunk neurons. Such innervation is important for the regulation of local blood circulation.The results obtained in this study can be used both in scientific research and in the diagnosis of adrenal diseases.

Intramuscular innervation of the lateral rectus muscle evaluated using sihler's staining technique: Potential application to strabismus surgery.

The latest research suggests that the abducens nerve may be divided into subbranches that reach functionally distinct zones of the lateral rectus muscle. The goal of the study was to examine this muscle's innervation, including the detailed distribution of the intramuscular subbranches of the abducens nerve. Twenty-five lateral rectus muscle specimens were harvested (with the orbital segment of the abducens nerve), fixed in 10% formalin solution, and stained with Sihler's whole mount nerve staining technique. Subbranches running to the lateral rectus divided into two main groups: superior and inferior. Both groups of subbranches are distributed in a fan-shaped manner, show a characteristic "tree-like" branching pattern and form terminal plexus near the proximal half of the lateral rectus muscle. However, some smaller subbranches run as far as the muscle's insertion, and recurrent subbranches also reach its origin. With respect to their course to the muscle's origin or insertion, the smallest subbranches running within the muscle may be associated with innervation of the tendon. In the majority of cases (88%), superior and inferior subbranches of the abducens nerve overlapped in the central one-third of the lateral rectus muscle's width so that any clearly distinct anatomical segments of the muscle could be observed based on Sihler's technique. In the remaining 12% of specimens, superior and inferior groups of subbranches innervated two distinct compartments of the lateral rectus muscle with no overlapping. Dense, fan-shaped distribution of abducens nerve intramuscular subbranches can be observed within the lateral rectus muscle. Clin. Anat. 33:585-591, 2020. © 2019 Wiley Periodicals, Inc.

Intramuscular Nerve Distribution in the Medial Rectus Muscle and Its Clinical Implications

ABSTRACTPurpose: The intramuscular nerve distribution in the extraocular muscles may be crucial for understanding their physiological and pathological responses. This study aimed to determine the oculomotor nerve distribution in the medial rectus muscle (MR) using Sihler’s staining.Method: Thirty-seven MRs from 23 cadavers were investigated. The MR including the oculomotor nerve was finely dissected from its origin to its insertion point into the sclera. The total length of the muscle-belly, tendon length and maximum width of the muscle were measured. We evaluated the pattern of distribution and the length of the intramuscular nerve distribution by gross observation after performing Sihler’s staining, which is a method for visualizing the distribution of nerve fibers without alteration of the nerve.Results: The total length of the muscle-belly, tendon length, and muscle width were 37.6 ± 4.6 mm, 4.4 ± 1.9 mm, and 10 ± 1.8 mm, respectively. The oculomotor nerve enters the MR at a mean of two-fifths along the muscle (24 ± 2.0 mm posterior to the insertion point) and then typically divides into a few branches (mean of 2.1). The intramuscular nerve distribution showed a Y-shaped ramification, forming the terminal nerve plexus, and its course typically finished at around 17 ± 1.5 mm posterior to the muscle insertion point by gross observation. The nerve plexus in the upper part generally coursed more distally than the lower part.Conclusion: This new information regarding the nerve distribution pattern of MR will be helpful for understanding MR function and the diverse pathophysiology of strabismus.

Neuronal connections of direct and indirect pathways for stable value memory in caudal basal ganglia.

Direct and indirect pathways in the basal ganglia work together for controlling behavior. However, it is still a controversial topic whether these pathways are segregated or merged with each other. To address this issue, we studied the connections of these two pathways in the caudal parts of the basal ganglia of rhesus monkeys using anatomical tracers. Our previous studies showed that the caudal basal ganglia control saccades by conveying long‐term values (stable values) of many visual objects toward the superior colliculus. In experiment 1, we injected a tracer in the caudate tail (CDt), and found local dense plexuses of axon terminals in the caudal‐dorsal‐lateral part of substantia nigra pars reticulata (cdlSNr) and the caudal‐ventral part of globus pallidus externus (cvGPe). These anterograde projections may correspond to the direct and indirect pathways, respectively. To verify this in experiment 2, we injected different tracers into cdlSNr and cvGPe, and found many retrogradely labeled neurons in CDt and, in addition, the caudal‐ventral part of the putamen (cvPut). These cdlSNr‐projecting and cvGPe‐projecting neurons were found intermingled in both CDt and cvPut (which we call “striatum tail”). A small but significant proportion of neurons (<15%) were double‐labeled, indicating that they projected to both cdlSNr and cvGPe. These anatomical results suggest that stable value signals (good vs. bad) are sent from the striatum tail to cdlSNr and cvGPe in a biased (but not exclusive) manner. These connections may play an important role in biasing saccades toward higher valued objects and away from lower valued objects.

Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome.

This study seeks to characterize lesion distribution in Parsonage-Turner Syndrome (PTS) using high-resolution MRI. MRIs of 27 patients with clinically confirmed PTS were reviewed. Two radiologists independently evaluated the brachial plexus proper, side and terminal plexus branches, and more distal, upper extremity nerves. All patients had at least 1 clinically involved nerve. MRI revealed that the plexus appeared normal in 24 of 27 patients; in 3 other patients, signal hyperintensity was seen immediately proximal to the take-off of abnormal side or terminal branch nerves. Focal intrinsic constrictions were detected in 32 of 38 nerves. MRI interobserver agreement was high (Cohen's κ = 0.839). MRI findings, corroborated by electrodiagnostic testing, localized abnormalities to plexus branches and peripheral nerves, suggesting that PTS is characterized by 1 or more mononeuropathies rather than changes involving a portion of or the complete plexus proper. These results may improve diagnosis, prognostication, and management. Muscle Nerve 58: 359-366, 2018.

Intramuscular Distribution of the Abducens Nerve in the Lateral Rectus Muscle for the Management of Strabismus

ABSTRACTAims: To elucidate the intramuscular distribution and branching patterns of the abducens nerve in the lateral rectus (LR) muscle so as to provide anatomical confirmation of the presence of compartmentalization, including for use in clinical applications such as botulinum toxin injections.Methods: Thirty whole-mount human cadaver specimens were dissected and then Sihler’s stain was applied. The basic dimensions of the LR and its intramuscular nerve distribution were investigated. The distances from the muscle insertion to the point at which the abducens nerve enters the LR and to the terminal nerve plexus were also measured.Results: The LR was 46.0 mm long. The abducens nerve enters the muscle on the posterior one-third of the LR and then typically divides into a few branches (average of 1.8). This supports a segregated abducens nerve selectively innervating compartments of the LR. The intramuscular nerve distribution showed a Y-shaped ramification with root-like arborization. The intramuscular nerve course finished around the middle of the LR (24.8 mm posterior to the insertion point) to form the terminal nerve plexus. This region should be considered the optimal target site for botulinum toxin injections. We have also identified the presence of an overlapping zone and communicating nerve branches between the neighboring LR compartments.Conclusion: Sihler’s staining is a useful technique for visualizing the entire nerve network of the LR. Improving the knowledge of the nerve distribution patterns is important not only for researchers but also clinicians to understand the functions of the LR and the diverse pathophysiology of strabismus.

A cadaveric study on anatomical variations of the superficial palmar arch

Background: The Superficial Palmar arch (SPA) is an anastomosis between the ulnar and radial artery in the palm. Maximum contribution in the arch is by an ulnar artery and it is completed by superficial palmar branch of radial artery or arteria princeps pollicis or arteria radialis indicis or median artery. The SPA develops as a terminal plexus of axis artery which is later joined by median, ulnar and radial arteries as these arteries develop. Materials & Methods: Present study conducted in the Department of Anatomy, Chettinad Hospital and Research Institute on 50 (28 right and 22 left) formalin fixed hands were used. The variations observed were classified as per Coleman and Anson, 1961, classification of the superficial palmar arch. Results: As per Coleman and Anson classification, complete arch of type A was seen in 43 hands (86%) and of type B in 3 hands (6%). In this study incomplete arch was seen in 4 hands (8%, 1 right and 3 left), persistent median artery type H supplying the radial side of the palm and digits was seen in only one hand (2%). Conclusion: The data regarding the study on variations of SPA is helpful in crushing injury of hand, arterial grafting, and vascular trauma of the upper extremity.

Nerwiakowłókniak krtani jako przyczyna duszności – opis przypadku i przegląd literatury

Neurofibromas of the larynx occur extremely rarely and present in 0.5% of laryngeal benign tumors. Schwannomas occur more frequently (1,5% of laryngeal benign tumors)and its extracranial prevalence in head and neck is between 25–45%.Laryngeal neurofibroma usually develops in places rich in terminal nerve plexuses. The nerve of origin is usually an internal branch of the superior laryngeal nerve. Hence, aryepiglottic folds and arytenoids are most commonly affected.Symptoms of neurofibroma are determined by the location. Hoarseness, dysarthria, dyspnea, globus sensation are most commonly associated with neurofibroma. The other symptoms include: cough, obstructive sleep apnea, dyspnea on exertion. Because of its benign character, neurofibroma can remain asymptomatic for years.In computed tomography scans neurofibroma shows as a hypodense heterogenic tumor, well-delineated, with smooth edges. Heterogenic and medium enhancement is observed after contrast administration. A “target” appearance is typical for the plexus subtype of neurofibroma, this consists of low signal intensity centrally, high signal peripherally and lobulated pattern.The choice of treatment for laryngeal neurofibroma depends on its location, size and associated symptoms. Currently there are no specific guidelines with regard to the management of laryngeal neurofibromas. Tumor resection is possible by both endoscopic or external approach. Endoscopic CO2 laser excision is recommended for patients who present small localized lesions, well visible in direct laryngoscopy.

Microscopic anatomy of the liver.

Microscopic anatomy of the liver.

Anatomy of the Anterior Vagus Nerve: An Anatomic Description and its Application in Surgery

Objective: Anatomic study of human corpses in order to obtain specific measurements of the anterior vagus nerve for its application in the surgical field. Methods: After analyzing the literature, dissections were performed on 15 human corpses, provided by the Universidad del Salvador. Descriptions were made of our observations. Results: The most frequently found structure in esophageal hiatus was a plexus. The cardial branch was present in 100% of the dissections. There were a constant number of gastric branches, between five and seven. The hepatic branch originated from the plexus in the majority of the cadavers. The distance between first and last branch points was variable. No relationship between the hepatic branch and left hepatic artery was observed. Conclusions: The structure most commonly found in the esophageal hiatus was the terminal plexus of the anterior vagus nerve. The hepatic branch most frequently originated directly from this plexus, although in a considerable number of cases its origin was found either proximal or distal to this structure. We could not confirm the literature stating the relationship between the hepatic branch and the left hepatic artery through our studies. The number of gastric branches was constant. The distance between the first and last gastric branch was extremely variable, which can be explained by the anthropometric differences between the cadavers. No relationship was found between the number of gastric branches and the length of the main gastric branch.

Distribution and Structural Organization of the Autonomic Nervous Apparatus in the Rat Pancreas (an immunohistochemical study)

Immunohistochemical reactions for neurofilaments (NF), peripherin (PRP), synaptophysin (SP), and tyrosine hydroxylase, combined with Nissl staining with toluidine blue, were used to study thick sections passing through all segments of the pancreas of adult white rats (n = 7). The topographies and distribution densities of processes were determined in different parts of the pancreas. The greatest density of processes was seen in the body of the gland. Abundant innervation of the organ by nerve plexuses was found: a large-looped plexus consisting of nerve trunks and bundles of myelinated and unmyelinated nerve fibers staining for NF, a second consisting of fine postganglionic bundles of axons and microganglia, staining for PRP, and a third, detected with reactions for SP, which was the main terminal plexus and consisted of axons with varicose thickenings with en passant synapses. The interactions between SP-positive terminals (distant en passant synapses) and blood vessels, endocrine (islet), and exocrine cells and the output ducts of pancreatic lobules are described in detail; the structural characteristics of the parasympathetic ganglia, their neurons, and the pericellular synaptic apparatus are presented; questions regarding the innervation and nature of the endocrine cells of islets are discussed. Attention is drawn to the fact that neurons were not detected in the islets of the rat pancreas in any case.

Development of Innervation to Maxillary Whiskers in Mice

The maxillary vibrissal pad is a unique, richly innervated sensory apparatus. It is highly evolved in the rodent that it constitutes a major source of sensory information to the somatosensory cortex. In this report, indocarbocyanine tracing and immunofluorescence were used to study the embryonic and early neonatal development of innervation to maxillary vibrissal follicles in mice. The first sign of vibrissal follicle innervation occurred at embryonic day 12 (E12), when the lateral nasal and maxillary processes were penetrated by nerve branches with small terminal plexuses assuming the positions of vibrissal follicle primordia. Between E13 and E15, the nerve plexuses at the presumptive follicles grew in size and became more numerous with no signs of specific receptor subtype formation. By E17, the nerve plexuses had grown further in size and the region-specific receptor subtype specification developed. At birth (P0), the superficial vibrissal nerves began to innervate the apical part of the inner conical body, whereas the deep vibrissal nerve gave off the recurrent cavernous branches. At P3, all of the different sets of receptor subtypes had regional distributions, densities and morphologies comparable to those described in adult mice. A 3-day old mouse had all complements of sensory receptors necessary for somatosensory transduction as revealed not only by neuroanatomic tracing but also with immunofluorescence for several markers of neurosensory differentiation. Our data reveal a hitherto unknown time table for the development of peripheral sensory receptors in the vibrissal follicles. This time table parallels that of their central targets in the somatosensory barrel cortex, which develops at P4.

Connections of the superior paraolivary nucleus of the rat: projections to the inferior colliculus

GABAergic neurotransmission contributes to shaping the response properties of inferior colliculus (IC) neurons. In rodents, the superior paraolivary nucleus (SPON) is a prominent and well-defined cell group of the superior olivary complex that sends significant but often neglected GABAergic projections to the IC. To investigate the trajectory, distribution and morphology of these projections, we injected the neuroanatomical tracer biotinylated dextran amine into the SPON of albino rats. Our results demonstrate that: (1) the SPON innervates densely all three subdivisions of the ipsilateral IC: central nucleus (CNIC), dorsal cortex (DCIC) and external cortex (ECIC). The SPON also sends a sparse projection to the contralateral DCIC via the commissure of the IC. (2) SPON axons are relatively thick (diameter >1.2 μm), ascend to the midbrain tectum in the medial aspect of the lateral lemniscus, and, for the most part, do not innervate the nuclei of the lateral lemniscus. (3) SPON fibers ramify profusely within the IC and bear abundant en passant and terminal boutons. (4) The axons of neurons in discrete regions of the SPON form two laminar terminal plexuses in the ipsilateral IC: a medial plexus that spans the CNIC and DCIC parallel to the known fibrodendritic laminae of the CNIC, and a lateral plexus located in the ECIC and oriented more or less parallel to the surface of the IC. (5) The projection from SPON to the ipsilateral IC is topographic: medial SPON neurons innervate the ventromedial region of the CNIC and DCIC and the ventrolateral region of the ECIC, whereas more laterally situated SPON neurons innervate more dorsolateral regions of the CNIC and DCIC and more dorsomedial regions of the ECIC. Thus, SPON fibers follow a pattern of distribution within the IC similar to that previously reported for intracollicular and corticocollicular projections.

Striatal Alterations of Secretogranin-1, Somatostatin, Prodynorphin, and Cholecystokinin Peptides in an Experimental Mouse Model of Parkinson Disease

The principal causative pathology of Parkinson disease is the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta projecting to the striatum in the brain. The information regarding the expression of neuropeptides in parkinsonism is very limited. Here we have elucidated striatal neuropeptide mechanisms in experimental parkinsonism using the unilateral 6-hydroxydopamine model to degenerate dopamine neurons. A thoroughly controlled sample preparation technique together with a peptidomics approach and targeted neuropeptide sequence collections enabled sensitive detection, identification, and relative quantitation of a great number of endogenous neuropeptides. Previously not recognized alterations in neuropeptide levels were identified in the unilateral lesioned mice with or without subchronic 3,4-dihydroxy-L-phenylalanine administration, the conventional treatment of Parkinson disease. Several of these peptides originated from the same precursor such as secretogranin-1, somatostatin, prodynorphin, and cholecystokinin. Disease-related biotransformation of precursors into individual peptides was observed in the experimental model of Parkinson disease. Several previously unreported potentially biologically active peptides were also identified from the striatal samples. This study provides further evidence that neuropeptides take part in mediating the central nervous system failure associated with Parkinson disease.