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Biomedical subjects

J Thibault

Publications and source records attributed to J Thibault.

At least 109 records · Page 6Linked to original sources
PubMed1987

Anti-CNS antibodies in neurological and psychiatric disorders.

To investigate the possibility that anti-CNS antibodies may play a pathogenic role in a number of neurological and psychiatric disorders, a population study was undertaken. Serum samples were obtained from a total of 257 adults and were screened against sodium dodecyl sulphate polyacrylamide gel electrophoretic blots of various normal, necropsy-derived adult human brain regions. The incidence of IgG immunoreactive banding in the total sample was 30%. Within the diagnostic groups the incidence of banding was: controls 32%, schizophrenia 28%, mental retardation 27%, cerebellar ataxia 33%, Parkinson's disease 22%, myasthenia gravis 45% and epilepsy 31%. The differences are not statistically significant. There was no significant difference in the numbers and locations of bands between the various diagnostic groups and the controls. The overall incidence of immunoreactivity corresponding to the high molecular weight subunit of neurofilaments was only 6%, thus not confirming a previously reported incidence of 95%. The similarity between the diagnostic and the control sera suggests that caution should be exerted in interpreting the pathogenic significance of anti-CNS immunoreactive banding on Western blots.

Adult↗
PubMed1987

Neuroanatomical substrate for the inhibition of gonadotrophin secretion in goldfish: existence of a dopaminergic preoptico-hypophyseal pathway.

To investigate the existence of a dopaminergic preoptico-hypophyseal pathway in the goldfish, electrolytic lesions were placed in the rostral preoptic area and their effects on gonadotrophin levels and pituitary innervation examined. In a first experiment, the fish were sacrificed 2 days after surgery and the pituitary studied by electron microscopy. Numerous exocytosis profiles were observed in the gonadotrophs, confirming the large increase in serum gonadotrophin levels measured in the animals. In addition, type A and B degenerating fibers were detected in the neurohypophysis and the pars distalis, in particular at the level of the gonadotrophs. In the second experiment, the distribution of tyrosine hydroxylase-immunopositive fibers was studied in the pituitary of controls and lesioned animals. It was found that lesioning the anterior ventral preoptic region resulted in the disappearance of all positive fibers in the pars distalis, while those in the neurointermediate lobe appeared unaffected. The presence of a large group of catecholaminergic perikarya in the destroyed area was confirmed in control animals. These results and other data strongly support the existence of a dopaminergic preoptico-hypophyseal pathway, providing a morphological support for the inhibitory effect of dopamine on the release of anterior pituitary hormones in teleosts, in particular gonadotrophin.

Animals↗
PubMed1987

Catecholaminergic properties of cholinergic neurons and synapses in adult rat ciliary ganglion.

Parasympathetic neurons of the ciliary ganglion are innervated by preganglionic cholinergic neurons whose cell bodies lie in the brain stem; the ganglion cells in turn provide cholinergic innervation to the intrinsic muscles of the eye. Noradrenergic innervation of the iris is supplied by sympathetic neurons of the superior cervical ganglion. Using immunocytochemical and histochemical techniques, we have examined the ciliary ganglion of adult rats for the expression of cholinergic and noradrenergic properties. As expected, the postganglionic ciliary neurons possessed detectable levels of choline acetyltransferase immunoreactivity (ChAT-IR). Unexpectedly, many ciliary neurons also exhibited immunoreactivity for tyrosine hydroxylase (TH-IR). Some had dopamine beta-hydroxylase-like (DBH-IR) immunoreactivity, but none contained detectable catecholamines, even after treatment with nialamide and L-DOPA. A sparse plexus of fibers exhibiting faint TH-IR was present in the irises of acutely sympathectomized rats. The terminals of preganglionic axons in the ciliary ganglion exhibited not only immunoreactivity for ChAT, but also for TH and contained stores of endogenous catecholamine. Neither ciliary neurons nor their preganglionic innervation accumulated detectable stores of exogenous catecholamines. Rats sympathectomized as neonates by treatment with 6-hydroxydopamine subsequently had a greater proportion of neurons possessing detectable TH-IR in the ciliary ganglion; both the TH-IR perikarya and their axons in the iris were more intensely immunofluorescent. TH-IR was present in the ciliary neuron cell bodies of mouse, guinea pig, and ferret. These species, however, lacked detectable TH-IR or catecholamine stores in preganglionic terminals. These observations indicate that mature, functionally cholinergic neurons from 2 different embryonic origins, postganglionic ciliary neurons derived from the neural crest and preganglionic neurons derived from the neural tube, display several catecholaminergic properties.

Animals↗
PubMed1987

The neostriatal mosaic: II. Patch- and matrix-directed mesostriatal dopaminergic and non-dopaminergic systems.

Mesostriatal projections, which arise from dopaminergic and non-dopaminergic neurons in the ventral tegmental area, substantia nigra, and retrorubral area, are compartmentally organized in the striatum. Anterograde axonal tract tracing with Phaseolus vulgaris-leucoagglutinin (PHA-L), combined with immunohistochemical localization of tyrosine hydroxylase (TH) and autoradiographic localization of mu-opiate receptor binding sites, shows that midbrain projections to the striatum are distributed to either the mu-opiate receptor-rich "patch" or the receptor-poor "matrix" striatal compartments. Three morphologically distinct mesostriatal afferent fiber types are labeled. The first type, type A, forms a plexus of relatively thin (0.1-0.4 micron), smooth fibers with small varicosities (0.3-0.6 micron). A second type, type B, is similar to the first in forming a plexus of fibers, but is slightly thicker (0.2-0.6 micron), with more frequent varicosities (0.4-1.0 micron) that give this fiber type a crinkled appearance. The third type, type C, constitutes a minority of striatal afferents and is characterized by its large caliber (0.4-0.7 micron) with large bulbous varicosities (1.2-2.0 micron). Projections of the ventral tegmental area (A10 cell group) are primarily dopaminergic type A fibers directed to the matrix of the ventromedial striatum, including the nucleus accumbens. The retrorubral area (A8 cell group) also provides predominantly dopaminergic type A fibers to the striatal matrix, but these are distributed dorsally. The substantia nigra contains a mixed population of neurons that project to the striatum. Some, located in the dorsal tier of the pars compacta (dorsal A9 cell group), provide dopaminergic type A fibers to the striatal matrix. Others, in the ventral tier of the pars compacta (ventral A9 cell group) and in the ventral tier of the pars reticulata (displaced A9 cells), provide dopaminergic type B fibers to the striatal patches. An additional set of substantia nigra neurons that are non-dopaminergic is the source of type C fibers to the striatal matrix. Thus, distinct dorsal and ventral sets of midbrain dopaminergic neurons project, respectively, to striatal matrix and patches, and there is a non-dopaminergic mesostriatal projection to the matrix.

Afferent Pathways↗
PubMed1987

The neostriatal mosaic: III. Biochemical and developmental dissociation of patch-matrix mesostriatal systems.

In the previous paper (Gerfen et al., 1987) mesostriatal dopaminergic neurons were shown to be subdivided into dorsal and ventral tiers that project to the striatal matrix and patch compartments, respectively. The present study provides experimental evidence that these patch-matrix mesostriatal dopaminergic systems are biochemically and developmentally distinct. A 28 kDa calcium-binding protein (CaBP, or calbindin-D28 kDa) is expressed in dorsal tier mesostriatal dopaminergic neurons. The distribution of such neurons, located in the ventral tegmental area, dorsal tier of the substantia nigra pars compacta, and retrorubral area, matches that of dopaminergic neurons that project to the striatal matrix. Dopaminergic neurons that do not express CaBP--those in the ventral tier of the pars compacta and in the pars reticulata--are distributed in a pattern that matches the origin of the dopaminergic projection to the striatal patches. During development, dopaminergic afferents to the striatal patch compartment are in place prior to the development of those to the matrix. Injections of the neurotoxin 6-hydroxydopamine (6-OHDA) into the striatum of newborn rats result in a selective and long-lasting depletion of dopaminergic afferents in the striatal patches. The later-developing matrix projection is relatively spared by such lesions. The distribution of surviving dopaminergic neurons, labeled with tyrosine hydroxylase (TH) immunoreactivity, matches the pattern of dorsal tier neurons previously shown to provide inputs to the matrix. Surviving neurons also express CaBP immunoreactivity and have dendrites that spread mediolaterally, in the plane of the pars compacta. On the other hand, those neurons that project to the patches are selectively lesioned by the neonatal 6-OHDA striatal injections, do not express CaBP, and have dendrites that are directed ventrally into the pars reticulata.

Animals↗
PubMed1986

Organization of tyrosine-hydroxylase immunopositive neurons in the brain of the crested newt, Triturus cristatus carnifex.

The localization of neurons, fibers, and terminals containing tyrosine hydroxylase (TH)-like immunoreactivity was studied in the brain of the crested newt by using an antiserum to rat phaeochromocytoma tyrosine hydroxylase. Immunoreactive cells and fibers were found in the spinal cord, the medulla oblongata (lateral periventricular areas), and the acousticolateral area. In the tegmentum mesencephali, two bilateral clusters of labelled cells were localized in the ventrolateral periventricular gray extending toward the caudal hypothalamus. In the hypothalamic tuberal lobes, the TH-like reactive neurons, frequently of CSF-contacting type, lined the dorsal wall of the lateral infundibular recesses. A thick network of TH-like reactive nerve fibers and terminals was observed in the perivascular zone of the median eminence and in the adenohypophysial pars intermedia. A number of labelled cell bodies were also found in the dorsal thalamus (pars intercalaris diencephali), the paraventricular organ, and the ventral wall of the preoptic recess. In the telencephalon, immunoreactive innervation was identified in the striatum, together with immunopositive cell bodies in the olfactory bulbs. The pattern of organization of TH-immunoreactive systems in the newt showed, except for some peculiarities (e.g., the labelled cell bodies in dorsal thalamus), close similarities to the arrangement typical of mammals.

Animals↗
PubMed1986

Immunohistochemical study of catecholaminergic cell bodies in the rat spinal cord.

Immunohistochemistry of three specific synthesizing catecholamine enzymes was used in the rat spinal cord to determine precisely the distribution of catecholaminergic perikarya and the nature of the neurotransmitter they contain. Single and double labeling experiments were performed on cryostat sections from perfused rats. The peroxidase anti-peroxidase (PAP) and the indirect fluorescence techniques were used for labeling spinal catecholaminergic somata and separated into two completely different populations. The first is located in the upper cervical cord and includes three apparently distinct groups: a lateral cluster, of probably a noradrenergic nature, and two central subgroups where noradrenergic and dopaminergic neurons are intermingled. It is likely that these cervical cells represent caudal extensions of the medullary catecholaminergic cell groups. In the remaining cord, only tyrosine hydroxylase immunoreactive cell bodies have been found. Accordingly, this second population is probably dopaminergic. It is present almost exclusively in the first sacral segments, where it is located in the commissural (mostly lateral) grey matter and in the marginal dorsal horn.

Animals↗
PubMed1986

Serotonin initiates and autoamplifies its own synthesis during mouse central nervous system development.

Some cells from cultured embryonic mouse hypothalamus were found to express aromatic-L-amino acid decarboxylase (EC 4.1.1.28) activity and serotonin uptake and storage. These neuron-like cells differed from serotoninergic neurons in cultured embryonic mouse brain stem since they did not contain tryptophan hydroxylase. We studied the effect of the serotonin agonist 8-hydroxy-2-[di-(n-propyl)amino]tetralin on neuronal differentiation of hypothalamic cells from 12- to 15-day embryos. Repeated treatment of cultures with the serotonin agonist for 10 days resulted in an increased number of serotonin cells containing high levels of decarboxylase activity. Both the increase in cell numbers and the elevated decarboxylase activity could be suppressed by the addition of the serotonin antagonist metergoline to the culture medium. These data show that serotonin (or an agonist), acting on specific receptors, can initiate and amplify its own synthesis in embryonic hypothalamic neurons, as observed in the primitive hypothalamic nerve cell line F7 [De Vitry, F., Catelon, J., Dubois, M., Thibault, J., Barritault, D., Courty, J., Bourgoin, S. & Hamon, M. (1986) Neurochem. Int. 9, 43-53]. Such an autocrine-like mechanism may be active during nervous system development and may represent an example of learning at the cellular level.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1986

The influence of chemically-induced modifications of root surfaces on cell migration, attachment, and orientation.

Surface demineralization of tooth root surfaces has been shown to improve re-attachment of cells and to promote tissue reconstruction following periodontal surgery. Exposure of collagen fibers has been thought to facilitate migration, attachment, and orientation of fibroblasts on the root surface. However, using an in vitro assay, we have found that both attachment and orientation of human gingival fibroblasts on demineralized dentin surfaces are further improved following digestion of the exposed collagen with bacterial collagenase. In contrast, pronase and trypsin digestion of the surface collagen had no significant effect, whereas heat denaturation had an inhibitory effect. Dissociative extraction of the demineralized dentin slices with 4 mol/L guanidine hydrochloride (GuHCl) also improved attachment and orientation, and when undemineralized dentin was subjected to dissociative extraction, cell attachment was comparable and orientation superior to that on demineralized surfaces. These studies indicate that demineralization is not a prerequisite for facilitating attachment, and that enhanced attachment and orientation of cells are not dependent upon a collagenous substratum.

Animals↗
PubMed1986

[Catecholaminergic nuclei of sheep encephalon. Immunocytochemical study. I. Myelencephalon and metencephalon].

Using an anti-tyrosine hydroxylase antiserum, the whole of catecholaminergic perikarya of the myelencephalon and metencephalon of the sheep were visualized immunocytochemically. Compared with those of the rat, these neuronal groups in the sheep were featured, firstly, by a greater dispersion relative to their perikarya and, secondly, by the absence of A3 and A4 nuclei described by Dahlstrom and Fuxe.

Animals↗
PubMed1986

[Catecholaminergic centers of the sheep encephalon. Immunocytochemistry. II. Mesencephalon and diencephalon].

In the sheep, the structures exhibiting the whole of catecholaminergic containing perikarya of the sheep myelencephalon and metencephalon were studied in a previous work using tyrosine hydroxylase immunocytochemistry. Mesencephalon and diencephalon were investigated in the same way here. As seen in the precedent paper, catecholaminergic perikarya were more scattered in homologue structures of the sheep, as compared with the rat. Immunocytochemistry revealed more labeled structures than did the histochemical fluorescence method, suggesting a possible lack of dopadecarboxylase in these structures, that are not marked by the Falck technique.

Animals↗
PubMed1986

[Copurification of tyrosine hydroxylase from rat pheochromocytoma by protein kinase].

Rat pheochromocytoma contains a protein kinase activity which remains associated with tyrosine hydroxylase (TH) during its purification. The incorporation of phosphate in TH is observed after incubation of TH with labelled ATP and magnesium without the need for an exogenous protein kinase. This Ca2+ and cAMP-independent kinase activity is different from previously described TH phosphorylating kinases from rat pheochromocytoma and other tissues.

Adrenal Gland Neoplasms↗
PubMed1986

Developmental potential of quail dorsal root ganglion cells analyzed in vitro and in vivo.

The cell types present in quail dorsal root ganglia during early development were identified using markers for neurons, glial cells, and fibroblasts (Rohrer et al., 1985). Using the quail-chick transplantation technique, the potential of quail dorsal root ganglion cells to differentiate to adrenergic chromaffin cells, as identified by tyrosine hydroxylase immunostaining, was analyzed. A population of undifferentiated cells, which is present in quail dorsal root ganglia at embryonic day 5, was separated from neurons and glial cells. We show that this population contains cells that differentiate to adrenergic chromaffin cells after back-transplantation into 2-d-old chick embryos. A large proportion of these undifferentiated cells also differentiates to neurons in vitro. Precursors for adrenal chromaffin cells and for neurons are present in dorsal root ganglia in significant numbers only during early development.

Adrenal Glands↗
PubMed1985

Immunohistochemical demonstration of catecholaminergic cell bodies in the spinal cord of the rat. Preliminary note.

In order to elucidate the anatomy of the spinal dopaminergic system, an immunohistochemical study using a tyrosine-hydroxylase (TH) antibody was undertaken in the rat. Intracisternal 6-hydroxydopamine (6-OHDA) injections were administered to destroy most of the noradrenergic fibres that descend to the spinal cord while preserving the dopaminergic fibres. The density of the remaining TH-like immunoreactive fibres was relatively low at all levels of the spinal cord; the highest density was observed in layers III, IV and X. In addition, we report the first evidence for the existence of TH-like immunoreactive cell bodies at definite levels (especially sacral) of the spinal cord.

Animals↗
PubMed1985

Selective staining of a subset of Purkinje cells in the human cerebellum with monoclonal antibody mabQ113.

MabQ113 is a monoclonal antibody raised against rat cerebellum which selectively strains Purkinje cells. Likewise, in mabQ113-immunoperoxidase stained sections of human cerebellum, deposits of reaction product are found only in the Purkinje cells. The dendritic arborizations, cell body, and axonal processes are immunoreactive. In rat, mabQ113 reveals a series of parasagittal antigenic bands which run throughout the cerebellar cortex. The staining distribution in human cerebellar cortex likewise reveals heterogenous staining but the pattern is a complex one and seems to be unlike the parasagittal banding found in the rat. In a number of human diseases Purkinje cell degeneration is not uniform throughout the vermis and cerebellar hemispheres. It is possible that mabQ113+ and mabQ113- subsets of Purkinje cells may respond differentially to various pathological conditions.

Animals↗
PubMed1985

In vitro translation of human pheochromocytoma messenger RNAs: characterization of tyrosine-hydroxylase and dopamine-beta-hydroxylase.

mRNAs extracted from human pheochromocytoma were translated in vitro in a lysate of a rabbit reticulocytes. Two enzymes of the biosynthetic pathway of the catecholamines, tyrosine-hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), were characterized as translation products after immunoprecipitation by specific antisera and electrophoretic analysis. The precursor of TH is a polypeptide having a molecular mass of 62,000 identical to that found for the mature protein. The molecular mass of the precursor of DBH 73,000 while that of the mature form is 79,000. TH and DBH have been translated from mRNAs having sedimentation coefficients of 22S and 25S, respectively.

Adrenal Gland Neoplasms↗
PubMed1985

Factors controlling brown adipose tissue development.

Brown adipose tissue (BAT) is a site of non-shivering thermogenesis in mammals. Thermogenesis in brown adipocytes is related to the presence of a specific mitochondrial component called "uncoupling protein". When animals are chronically exposed to cold, their BAT is enlarged and exhibits several changes such as cellular differentiation, hyperplasia, mitochondriogenesis and marked synthesis of uncoupling protein. The hormonal and neural factors controlling this adaptive response have been studied. It is concluded that sympathetic innervation of BAT and released noradrenaline play an essential role in the development of BAT.

Adaptation, Physiological↗