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K R Jessen

Publications and source records attributed to K R Jessen.

At least 91 records · Page 5Linked to original sources
PubMed1987

Axonal signals regulate the differentiation of non-myelin-forming Schwann cells: an immunohistochemical study of galactocerebroside in transected and regenerating nerves.

Little is known about the factors involved in directing and maintaining the divergent differentiation of the 2 major Schwann cell variants, myelin and non-myelin-forming cells, in peripheral nerves. There is strong evidence that the differentiation of myelin-forming cells depends critically on cell-cell signaling through contact with appropriate axons. In this paper we ask whether this remarkable dependence of the Schwann cell on axonal contact for full differentiation is unique to those cells that form myelin or whether axonal signaling is also an important factor in the differentiation of non-myelin-forming Schwann cells. Sciatic nerves or cervical sympathetic trunks of adult rats were either transected or crushed and the axons allowed to degenerate and, in the case of crushed nerves, to regenerate into the distal stump for periods of time varying from 2 d to 9 weeks. The distal stump of the nerve was excised at specific times, the Schwann cells dissociated and immunolabeled with antibodies to galactocerebroside. In the sciatic nerve, which contains a mixture of non-myelin-forming and myelin-forming Schwann cells, transection resulted in a loss of galactocerebroside expression from the surface of all the Schwann cells in the distal stump over a 9 week period, irrespective of their original phenotype. In crushed sciatic nerves, where axons were allowed to regrow into the distal stumps, the number of Schwann cells expressing immunohistochemically detectable quantities of galactocerebroside in the stump declined over the first 3 weeks, but by 9 weeks after crush the total percentage of galactocerebroside-positive cells in the nerve had risen to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1986

Light microscopic immunolocalization of laminin, type IV collagen, nidogen, heparan sulphate proteoglycan and fibronectin in the enteric nervous system of rat and guinea pig.

The localization of the extracellular matrix components laminin, fibronectin and type IV collagen in the enteric nervous system and the surrounding smooth muscle was investigated by immunohistochemical methods, using tissue sections of rat and guinea pig large intestine. None of these molecules were detectable inside the enteric ganglia. In contrast, they were easily demonstrable in association with the basement membrane of satellite cells within sensory and sympathetic ganglia. All of these molecules were, however, present in or nearby the basement membrane that surrounds each enteric ganglion. This agrees with previous ultrastructural observations that, in small mammals, neither basement membranes nor large connective tissue spaces are found inside enteric ganglia. The matrix molecules under study were also detected in the basement membrane of the nearby smooth muscle cells that make up the muscle layer of the gut wall. Fibronectin was frequently observed as a broad staining pattern suggesting its localization in the lamina reticularis rather than in the lamina densa. In addition, nidogen and heparan sulphate proteoglycan were demonstrated in the basement membrane of both enteric ganglia and Schwann cells.

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PubMed1986

Distribution of the adhesion molecules N-CAM and L1 on peripheral neurons and glia in adult rats.

There is considerable evidence that the cell surface glycoproteins N-CAM and L1 are important mediators of cell-cell adhesion in the nervous system, at least during development. Numerous studies have been devoted to the molecular properties of these proteins and their adhesion role in embryonic and early postnatal development. Much less is known about their importance in mature tissues. A rigorous and comprehensive description of the cell distribution of these molecules in the adult nervous system would clearly form a useful baseline for functional and biochemical studies. In the present work we have addressed this issue and studied the distribution of N-CAM and L1 throughout adult, as opposed to developing, rat peripheral nervous tissue. Particular attention was paid to the ganglia of the enteric nervous system, since adhesion mechanisms within these ganglia are likely to be placed under unusual demands. We report, for the first time, the presence of N-CAM and L1 on mature sensory, sympathetic and enteric neurons in adult rats. Thus, immunostaining of cell suspensions or short-term cultures showed N-CAM and L1 surface labelling on sympathetic and both large and small dorsal root sensory neurons. Both antigens were also present on the surface of enteric neurons in cultures prepared from 10-day-old rats and neonatal guinea pigs. Immunostaining of sections of enteric ganglia from adults indicated that both molecules were also expressed by mature enteric neurons. In sections of mature sciatic nerve neither N-CAM nor L1 immunoreactivity were detected at the site where the plasma membrane of myelinated axons meets the ad-axonal plasma membrane of the myelin-forming Schwann cell. Thus, both N-CAM and L1 were detected on all major classes of peripheral neurons, while their levels in the plasma membrane of myelinated axons may be significantly down-regulated. Similarly, both N-CAM and L1 were present on all major classes of non-myelin-forming peripheral glia in adult rats. This includes the enteric glial cells of the myenteric ganglia, non-myelin-forming Schwann cells in the sciatic nerve, sympathetic trunk and fine autonomic nerves in the gut wall, and the satellite glial cells of sympathetic and dorsal root sensory ganglia. In contrast, myelin-forming Schwann cells did not express detectable levels of N-CAM and only very low levels of L1, which was mainly located near the nodes of Ranvier.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1986

Immunohistochemical demonstration of GABAergic neurons in the enteric nervous system.

Application of a highly specific antiserum against GABA to whole-mount preparations of the guinea pig and rat myenteric plexus resulted in discrete and unambiguous immunolabeling of a subpopulation of myenteric neuronal cell bodies and fibers. The anti-GABA antiserum, which was raised against GABA conjugated by glutaraldehyde to BSA, was applied to glutaraldehyde-fixed whole mounts and subsequently visualized using the peroxidase-antiperoxidase method. In the guinea pig ileum and colon, immunoreactive varicose nerve fibers and scattered nerve cell bodies were found within the myenteric plexus. Immunostained fibers were also seen in the tertiary plexus and in the circular muscle, running parallel to the muscle bundles. GABA immunoreactivity in these intramuscular nerves was most pronounced in the colon. In the rat, immunoreactive fibers were prominent throughout the myenteric plexus. They formed dense networks within the myenteric ganglia, which also contained immunopositive nerve cell bodies, and ran between them in the interconnecting nerves. Some immunoreactive nerve fibers were seen in the circular muscle. Control experiments using non-immune sera or adsorbed anti-GABA antiserum showed no staining. These results add a definitive support to our previous suggestion that GABA serves as an autonomic neurotransmitter in vertebrates. In addition to the present immunohistochemical evidence, this hypothesis is supported by biochemical, autoradiographic, transmitter release, electrophysiological, and pharmacological studies on the enteric nervous system of several species. It is now important to determine the functional role of GABAergic neurons within the complex neuronal circuitry that controls gut functions.

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PubMed1985

Characterization of a plasma membrane protein present in non-myelin-forming PNS and CNS glia, a subpopulation of PNS neurons, perineurial cells and smooth muscle in adult rats.

A plasma membrane protein common to non-myelin-forming peripheral glia, including non-myelin-forming Schwann cells, satellite cells and enteric glia, is recognized and defined by monoclonal antibody A5E3. It is not detectable immunohistochemically on myelin-forming Schwann cells. The antigen is also present in large amounts on smooth muscle cells and perineurial cells, on some PNS neurons, and at lower levels on astrocytes of adult rat. In neonatal but not adult animals, the antigen is present on skeletal muscle fibres and myoblasts. In immunoblots and immune precipitation experiments on smooth muscle and Schwann cell extracts the antigen is a polypeptide with an apparent molecular weight of 130 kd. In being present in some non-neural tissues, albeit very highly restricted in cell type, this antigen resembles several other cell surface glycoproteins found in large amounts in the nervous system.

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PubMed1985

Glial fibrillary acidic polypeptides in peripheral glia. Molecular weight, heterogeneity and distribution.

Glial fibrillary acidic (GFA) polypeptides are present in major categories of rat peripheral glia including non-myelin-forming Schwann cells, enteric glia and some satellite cells. They can be detected both immunochemically and immunohistochemically. The immunoreactivity is associated with a polypeptide which has an MW of 49 000, indistinguishable from that of glial fibrillary acidic protein (GFAP) from rat brain. In spite of this, the GFA polypeptides found in the peripheral nervous system and central nervous system are not identical since they can be distinguished both immunohistochemically and immunochemically by a monoclonal GFAP antibody which recognizes GFAP in astrocytes and some enteric glia, but not GFAP in non-myelin-forming Schwann cells, satellite cells and many enteric glia. GFA-related molecules can also be detected in human Schwann cells by immunofluorescence. The results suggest, however, that the glial filament polypeptides of peripheral glia and astrocytes are less closely related in the human than in the rat. The glial distribution of GFAP is closely paralleled by 2 cell surface proteins, Ran-2 and A5E3 antigen. Although GFAP, Ran-2 and A5E3 are individually expressed by diverse cell types, the phenotype GFAP+, Ran-2+, A5E3+ defines a narrow group including only non-myelin-forming Schwann cells, enteric glia and astrocytes. These observations suggest that the non-myelin-forming cells of the central and peripheral nervous system may share some common functions.

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PubMed1985

Galactocerebroside is expressed by non-myelin-forming Schwann cells in situ.

Interest in the glycosphingolipid galactocerebroside (GC) is based on the consensus that in the nervous system it is expressed only by myelin-forming Schwann cells and oligodendrocytes, and that it has a specific role in the elaboration of myelin sheaths. We have investigated GC distribution in two rat nerves--the sciatic, containing a mixture of myelinated and non-myelinated axons, and the cervical sympathetic trunk, in which greater than 99% of axons are non-myelinated. Immunohistochemical experiments using mono- and polyclonal GC antibodies were carried out on teased nerves and cultured Schwann cells, and GC synthesis was assayed biochemically. Unexpectedly, we found that mature non-myelin-forming Schwann cells in situ and in short-term cultures express unambiguous GC immunoreactivity, comparable in intensity to that of myelinated fibers or myelin-forming cells in short-term cultures. GC synthesis was also detected in both sympathetic trunks and sciatic nerves. In the developing sympathetic trunk, GC was first seen at day 19 in utero, the number of GC-positive cells rising to approximately 95% at postnatal day 10. In contrast, the time course of GC appearance in the sciatic nerve shows two separate phases of increase, between day 18 in utero and postnatal day 1, and between postnatal days 20 and 35, at which stage approximately 94% of the cells express GC. These time courses suggest that Schwann cells, irrespective of subsequent differentiation pathway, start expressing GC at about the same time as cell division stops. We suggest that GC is a ubiquitous component of mature Schwann cell membranes in situ. Therefore, the role of GC needs to be reevaluated, since its function is clearly not restricted to events involved in myelination.

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PubMed1984

Molecular identity, distribution and heterogeneity of glial fibrillary acidic protein: an immunoblotting and immunohistochemical study of Schwann cells, satellite cells, enteric glia and astrocytes.

Glial fibrillary acidic protein has been firmly established as the predominant component of astrocyte intermediate filaments. It has also been detected immunohistochemically in the glial cells of the enteric nervous system and some Schwann cells in the P.N.S. The molecular identity of this GFAP immunoreactivity in the P.N.S. has so far not been investigated. This study compares GFAP in the C.N.S. and P.N.S. of adult rats both immunochemically and immunohistochemically. Using SDS polyacrylamide gel electrophoresis combined with immunoblotting, and a polyclonal antiserum to brain GFAP, we show that the peripheral GFAP immunoreactivity resides in a polypeptide with a molecular weight of 49 kd, which is identical to that of rat brain GFAP. Furthermore, we find that this GFAP reactivity can be detected immunohistochemically in Schwann cells in a wide variety of nerves in the P.N.S. and in some satellite cells in both sensory and sympathetic ganglia, in addition to enteric glia. The pattern of distribution of GFAP filaments in Schwann cells suggests that, in the nerves surveyed, they may be expressed by most or all non-myelin forming Schwann cells but not by myelin-forming Schwann cells. We also show, using a monoclonal antibody to GFAP (anti-GFAP-3) in both immunohistochemical and immunoblotting studies, that the GFAP found in most peripheral glia is not identical to that of astrocytes since it lacks an antigenic determinant, defined by this monoclonal antibody, which is present in astrocytes. An exception to this finding is seen in the myenteric plexuses where immunohistochemically detectable GFAP is found in some, but not all, of the enteric glia, using the monoclonal antibody. Thus, the results suggest that GFA polypeptides may be a heterogeneous group, that share some common determinants and a common molecular weight, and show a widespread and complex distribution in the glia of both the C.N.S. and P.N.S.

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PubMed1984

Nonmyelin-forming Schwann cells coexpress surface proteins and intermediate filaments not found in myelin-forming cells: a study of Ran-2, A5E3 antigen and glial fibrillary acidic protein.

Little is known about the molecular properties of the nonmyelin-forming glia of the P.N.S. In addition, the relationship between these cells and C.N.S. glia is poorly understood, in contrast with the well-documented biochemical and functional similarities between myelin-forming Schwann cells and oligodendrocytes. We have shown elsewhere that two cell surface proteins found on astrocytes, Ran-2 and A5E3 antigen, and the intermediate filament protein, glial fibrillary acidic protein (GFAP), are all widely expressed in situ by nonmyelin-forming Schwann cells in various nerves from adult rats, but not by myelin-forming Schwann cells. Here we investigate whether these three proteins are exclusively coexpressed by the same population of Schwann cells in situ in adult nerves, or alternatively whether subpopulations of nonmyelin-forming Schwann cells can be defined that express one or two, but not all three of these antigens. The distribution of two surface proteins, Ran-2 and A5E3 antigen, both defined by monoclonal antibodies, is compared with the distribution of the intracellular intermediate filament protein GFAP in peripheral nerve trunks of adult rats using double label immunofluorescence. It is clear that the expression of all three proteins is confined to the same population of Schwann cells, namely, the Schwann cells surrounding the unmyelinated axons. The myelin-forming Schwann cells surrounding the larger axons do not express immunohistochemically detectable amounts of any of the proteins. In teased nerve preparations from the preganglionic sympathetic trunk, sciatic nerve, brachial plexus, dorsal and ventral roots, a complete correspondence is found between expression of Ran-2 and GFAP, and between A5E3 and GFAP in nonmyelin-forming Schwann cells. No Schwann cells positive for Ran-2 alone, A5E3 antigen alone, or GFAP alone were found. The same constellation of antigens is also expressed by astrocytes in the adult rat C.N.S. and enteric glia in the P.N.S. and not by other cell types. The phenotype A5E3+, Ran-2+, GFAP+ is thus characteristic of major categories of adult rat P.N.S. and C.N.S. glial cells, suggesting that this may reflect some common function for these three cell types.

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PubMed1983

The enteric nervous system in tissue culture. I. Cell types and their interactions in explants of the myenteric and submucous plexuses from guinea pig, rabbit and rat.

This paper describes methods for removing the ganglionated myenteric and submucous plexuses from the mammalian gut and maintaining them as explants in tissue culture. A detailed account is given of cell types, their interactions and the development of these cultures during 5 weeks in vitro. Three major cell types were identified in the cultures: neurons, glial cells and fibroblasts. The development of the plexuses in culture was studied in detail for the myenteric plexus from the guinea pig taenia coli. It followed a characteristic pattern, in which the merging of individual ganglia into a continuous monolayer of flattened neurons was accompanied and followed by the formation of an extensive outgrowth zone of flat glial cells covered by a dense mesh of outgrowing neurites. In older cultures, neuronal migration resulted in the reformation of discrete and compact aggregates, which consisted of neurons and glial cells, and were interconnected by thick neurite bundles. This arrangement resembles in many ways the original organization of enteric nervous tissue in vivo. This is the first time the enteric ganglia have been freed from the gut wall and grown in culture as explants of nervous tissue. These preparations open many new directions for investigations of the largest and most complex division of the peripheral nervous system, including studies of the molecular nature of neuronal and glial cell surfaces, analysis of cell-cell interactions, trophic factors and developmental signals.

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PubMed1983

The enteric nervous system in tissue culture. II. Ultrastructural studies of cell types and their relationships.

Tissue culture preparations of the myenteric plexus from the guinea pig taenia coli have been studied by electron microscopy. Three main cell types can be identified: neurons, enteric glial cells and fibroblasts. The ultrastructure of these cells resembles that of the same cells in situ. Neuronal processes form close associations with other neurons and glial cells, but not with fibroblasts. After extended periods in culture, neurons and glial cells form aggregates of cells which resemble ganglia of the myenteric plexus in situ, having a compact neuropil and synapses between neuronal elements. Aggregates are connected to each other by thick bundles of neurites. Vesicle-containing nerve profiles are common; the majority contain a predominance of small agranular vesicles, but some contain many large granular or large opaque vesicles; profiles may also contain variable mixtures of these kinds of vesicles.

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PubMed1983

The enteric nervous system in tissue culture. III. Studies on neuronal survival and the retention of biochemical and morphological differentiation.

The maintenance of differentiated properties and survival rates of enteric neurons, grown in explant cultures for periods of up to 3 weeks, was studied. Using catecholamine fluorescence, immunohistochemistry and autoradiography, it was found that adrenergic neurons, VIP-containing neurons and putative GABAergic neurons, which constitute small subpopulations of guinea pig myenteric neurons in vivo, were all represented in plexus explants after maintenance in culture for 2-3 weeks. The pattern of expression of the transmitter-related enzymes, acetylcholinesterase and monoamine oxidase, paralleled that found in in situ studies. Investigation of neuronal structure by intracellular injection of horseradish peroxidase revealed that the cultured neurons continue to express the wide diversity in gross morphology which characterizes these cells in vivo. Employing autoradiography following uptake of [3H]GABA to label putative GABAergic neurons, their survival rate from days 1 to 15 of culturing was determined. No neuronal death was detected between days 1 and 5, while the number of neurons decreased between days 5 and 15. These observations suggest that enteric neurons maintained in explant cultures survive well and maintain to a high degree their histochemical and morphological properties.

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PubMed1983

Distribution of neurons with high-affinity uptake sites for GABA in the myenteric plexus of the guniea-pig, rat and chicken.

The occurrence of neurons possessing high-affinity uptake sites for GABA was studied in the myenteric plexus of the guinea-pig ileum, caecum, and proximal and distal colon, the rat proximal colon, and the chicken gizzard with the use of 3H-GABA and autoradiography. Experiments were carried out on plexuses that had been freshly isolated from the gut wall or on isolated plexuses that had been maintained as explant cultures for 7 to 14 days. Scattered neurons selectively labelled with 3H-GABA were found in the myenteric plexuses from all the areas examined. The results suggest that GABAergic neurons are widely distributed in the enteric nervous system.

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PubMed1983

Gamma-aminobutyrate as an autonomic neurotransmitter: release and uptake of [3H]gamma-aminobutyrate in guinea pig large intestine and cultured enteric neurons using physiological methods and electron microscopic autoradiography.

To provide further evidence that some enteric neurons use gamma-aminobutyrate (GABA) as a neurotransmitter, we have demonstrated a depolarization-induced release of [3H]GABA from isolated myenteric ganglia in culture, and from segments of large intestine containing the myenteric plexus. In addition, light and electron microscopic autoradiography has been employed to visualize the putative GABAergic neurons and their projections, both in cultured ganglia and in sections from the gut wall. Explant cultures of the guinea-pig myenteric plexus, containing only neurons and glia intrinsic to the gut, were incubated with 0.14 microM [3H]GABA, washed and then repeatedly depolarized by 62 mM K+. The depolarizations always evoked release of [3H]GABA. The evoked release was reversibly blocked by 5 mM Co2+, suggesting a dependence on Ca2+ influx, a characteristic of neuronal transmitter release. Strips of the guinea-pig taenia coli, containing the myenteric plexus, were incubated with 0.14 or 0.7 microM [3H]GABA, washed and subjected to electrical field stimulation. This caused release of [3H]GABA, which could be evoked successively on repeated stimulation. The release was of neuronal origin and Ca2+ dependent, since it was abolished by 3 microM tetrodotoxin and reversibly blocked by 10 mM Co2+. By combined electrophoresis and chromatography the released tritium was identified as being attached to GABA. Autoradiography, following incubation with low concentrations of [3H]GABA, was used to identify specifically putative GABAergic neurons. Light microscopic autoradiography of cultured ganglia, and electron microscopic autoradiography of sections from the taenia coli including the myenteric plexus, were in good agreement, showing a selective and heavy labelling over a sub-population of neurons, and light labelling over glial cells. The majority of neurons and the non-neural cells were unlabelled. The electron microscopic autoradiographs also showed heavy labelling over some, but not all, axons in the fine axon bundles that innervate the longitudinal muscle of the taenia. These results strongly support our previous suggestion that a population of myenteric neurons are GABAergic, although more work is needed before this is fully established. Our data also suggest that some of the putative GABAergic neurons project out to the gut musculature, where their axons, together with axons from other neurons, run in bundles to form the intramuscular nerves. We therefore propose that one of the roles of these neurons in the gut is the presynaptic modulation of transmitter released from neighbouring axons in these nerves.

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PubMed1983

Astrocyte-like glia in the peripheral nervous system: an immunohistochemical study of enteric glia.

The similarities between the enteric nervous system of the gut and the central nervous system (CNS), both of which function as complex integrative nervous networks, include striking ultrastructural similarities between the glia of the enteric nervous system and the astrocytic glia of the CNS. In this paper we have determined whether this anatomical resemblance also extends to the molecular level by examining the enteric glial cells to see whether they express several surface and intracellular molecules which are highly restricted to glia and to astrocytes in particular. Indirect immunofluorescence was used to visualize the antigens in frozen sections of gut wall and in whole mount, tissue culture, and freshly dissected preparations of myenteric and submucous plexuses from rats of various ages. It was found that enteric glial cells expressed the intracellular proteins glial fibrillary acidic protein, glutamine synthetase, and vimentin both in situ and in culture. The surface antigen Ran-2 was expressed in situ but not in culture, and the surface antigen Ran-1 was expressed in culture but not in situ. Cultured enteric glial cells did not express fibronectin in significant quantity, nor did they make galactocerebroside. From these results we conclude that the adult phenotype of enteric glia in situ closely resembles that of astrocytes, while in culture some of their cell surface features change, reverting to those seen during development. Because these cells possess distinctive molecular features and numerically form one of the major populations of peripheral glia, it is appropriate to classify them as a third distinctive category of peripheral glial cells, in addition to satellite and Schwann cells. The molecular similarities between these cells and astrocytes, in addition to their anatomical resemblance, suggest that a further study of enteric glia will provide new insights into the role of glia in integrative nervous tissues.

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