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M Manier

Publications and source records attributed to M Manier.

At least 19 recordsLinked to original sources
PubMed1997

Striatal target-induced axonal branching of dopaminergic mesencephalic neurons in culture via diffusible factors.

The effects of striatal target cells on the morphological development of dopaminergic neurons were studied in dissociated cultures of embryonic rat mesencephalon. Mesencephalic neurons were cultured for four days in presence of target striatal cells or non target cerebellar ones. The outgrowth of dopaminergic neurons, visualized after tyrosine hydroxylase immunohistochemistry, was examined by quantitative morphometry. In cocultures, the increased complexity of dopaminergic neurites (branching) was the most striking pattern. It was dependent on the presence of target striatal cells as compared to non target ones. Cultures raised in presence or absence of serum lead to suggest the implication of striatal neurons rather than glia. Using MAP2 and phosphorylated neurofilaments immunohistochemistry in combination with tyrosine hydroxylase immunolabelling, it could be shown that the target-induced branching effect concerned only axonal and not dendritic processes. To further define whether diffusible factors from the striatal target would participate in the axonal branching effect, mesencephalic cells were cultured in conditioned medium from striatal neurons. Striatal conditioned medium enhanced dopamine uptake and dopamine neuron branching to the same extent as that observed in striatal cocultures. These findings demonstrate that soluble factors secreted by striatal neurons themselves selectively influence the branching of dopaminergic axons in vitro.

Animals↗
PubMed1995

GDNF: existence of a second transcript in the brain.

The detection of the glial cell-line derived neurotrophic factor (GDNF) mRNA by RT-PCR in dissociated cell culture of rat embryonic or post-natal brain allowed the amplification of a doublet. The major band corresponded to the expected size and the minor one to a shorter product. We cloned and sequenced the latter product, and thus identified a mRNA potentially encoding for an isoform of the initially described precursor protein involved in GDNF synthesis.

Animals↗
PubMed1994

Evidence for dopamine D2 receptor mRNA expression by striatal astrocytes in culture: in situ hybridization and polymerase chain reaction studies.

The expression of dopamine D2 receptor mRNA in cultured rat striatal and cerebellar astrocytes was examined by in situ hybridization (ISH) and polymerase chain reaction (PCR). Cells double-labelled for glial fibrillary acidic protein (GFAP) immuno-histochemistry and dopamine D2 receptor mRNA (ISH) provide evidence that striatal but not cerebellar astrocytes express the dopamine D2 gene in vitro. These results were confirmed by polymerase chain reaction studies. As judged by GFAP immunostaining and morphology of the cells, this gene is almost exclusively expressed by astrocytes type 1. The expression of dopamine D2 receptor mRNA by striatal astrocytes in vitro, as found in this study, brings thus evidences for the existence of dopamine D2 receptors in such glial cells. This had been previously suggested from ligand binding studies but the typical dopaminergic nature of the binding to striatal astrocytes was left questionable. Our results with molecular biological techniques thus suggest that striatal dopamine might modulate the functions of striatal astrocytes.

Animals↗
PubMed1994

Accumulation of delta 2-tubulin, a major tubulin variant that cannot be tyrosinated, in neuronal tissues and in stable microtubule assemblies.

Tubulin is the major protein component of brain tissue. It normally undergoes a cycle of tyrosination-detyrosination on the carboxy terminus of its alpha-subunit and this results in subpopulations of tyrosinated tubulin and detyrosinated tubulin. Brain tubulin preparations also contain a third major tubulin subpopulation, composed of a non-tyrosinatable variant of tubulin that lacks a carboxy-terminal glutamyl-tyrosine group on its alpha-subunit (delta 2-tubulin). Here, the abundance of delta 2-tubulin in brain tissues, its distribution in developing rat cerebellum and in a variety of cell types have been examined and compared with that of total alpha-tubulin and of tyrosinated and detyrosinated tubulin. Delta 2-tubulin accounts for approximately 35% of brain tubulin. In rat cerebellum, delta 2-tubulin appears early during neuronal differentiation and is detected only in neuronal cells. This apparent neuronal specificity of delta 2-tubulin is confirmed by examination of its distribution in cerebellar cells in primary cultures. In such cultures, neuronal cells are brightly stained with anti-delta 2-tubulin antibody while glial cells are not. Delta 2-tubulin is apparently present in neuronal growth cones. As delta 2-tubulin, detyrosinated tubulin is enriched in neuronal cells, but in contrast with delta 2-tubulin, detyrosinated tubulin is not detectable in Purkinje cells and is apparently excluded from neuronal growth cones. In a variety of cell types such as cultured fibroblasts of primary culture of bovine adrenal cortical cells, delta 2-tubulin is confined to very stable structures such as centrosomes and primary cilia. Treatment of such cells with high doses of taxol leads to the appearance of delta 2-tubulin in microtubule bundles. Delta 2-tubulin also occurs in the paracrystalline bundles of protofilamentous tubulin formed after vinblastine treatment. Delta 2-tubulin is present in sea urchin sperm flagella and it appears in sea urchin embryo cilia during development. Thus, delta 2-tubulin is apparently a marker of very long-lived microtubules. It might represent the final stage of alpha-tubulin maturation in long-lived polymers.

3T3 Cells↗
PubMed1993

Intrastriatal transplants of embryonic dopaminergic neurons counteract the increase of striatal enkephalin immunostaining but not serotoninergic sprouting elicited by a neonatal lesion of the nigrostriatal dopaminergic pathway.

The aim of the our experiment was to compare the ability of intrastriatal implants of embryonic dopaminergic neurons to reverse two kinds of postlesion modification in the host brain: the change in the activity level of neurons in the denervated area and morphological modifications, e.g. collateral sprouting. The ascending dopaminergic system of 3-day-old rat pups was unilaterally lesioned by an intrahypothalamic injection of the neurotoxin 6-hydroxydopamine. This lesion has been described previously to induce an increase in the level of activity of striatal enkephalinergic neurons. The same lesion leads also to sprouting of the serotoninergic afferents in the striatum, leading to hyperinnervation of this structure. The existence of these modifications thus offers the possibility of testing the influence of grafts in one structure of the same animal on two lesion-induced reactions of different nature. A cell suspension obtained from mesencephali of embryonic day 14 rats and containing dopaminergic neurons was implanted into the denervated striatum of lesioned animals 5 days after the lesion. Nine months later the animals were killed and immunohistochemistry was performed on striatal sections using antibodies directed against tyrosine hydroxylase, methionine enkephalin and serotonin. Intensity of immunostaining (methionine enkephalin and serotonin) as well as innervation density (serotonin) was quantified through the use of a computer-assisted image analyser. The lesion led to the disappearance of striatal dopaminergic innervation. Implanted dopaminergic neurons were found scattered in the striatum and restored a dopaminergic innervation in a large portion of this structure. There was a marked increase in striatal methionine enkephalin immunostaining in lesioned animals, which was most pronounced in the dorsolateral part of the striatum (+ 150% compared to control values), while in the ventral part it was slight or non-existent. The density of striatal serotoninergic innervation was also increased by approximately 250% relative to control values. In grafted animals striatal enkephalin immunostaining was similar to that observed in control animals. On the other hand, the serotoninergic hyperinnervation was still present in the graft-bearing striata. These results suggest that while intrastriatal implants of embryonic dopaminergic neurons are able to counteract modifications in the functioning of local striatal neuronal systems such as the increase in enkephalinergic activity or receptor hypersensitivity occurring as a result of the lesion, they might be unable to reverse postlesion morphological modifications.

Animals↗
PubMed1992

Locus ceruleus modulates migrating myoelectric complex in rats.

The role of the locus ceruleus (LC) in the control of migrating myoelectric complex (MMC) was investigated in rats with lesions induced by injections of 6-hydroxydopamine (6-OHDA). Control animals received the vehicle alone. MMC was recorded in conscious rats chronically fitted with electrodes. After 6-OHDA was injected into the LC, lesions of the LC were total, partial (mostly rostral), or ineffective. The MMC period was significantly longer in animals with a total or partial lesion but was unchanged in animals with an ineffective lesion. No lesion of other brain noradrenergic nuclei was observed. The longer MMC period is comparable to that obtained after intracerebroventricular injection of 6-OHDA, which is responsible for a more diffuse destruction of brain noradrenergic systems, including LC itself. Bilateral lesions of the central tegmental tract, which carries ascending noradrenergic axons from the medullary and pontine cell groups outside the LC, do not alter the MMC cycle. Consequently, the LC is most likely the major brain noradrenergic candidate for modulating the MMC pattern in rats.

Animals↗
PubMed1991

Quantitative image analysis with densitometry for immunohistochemistry and autoradiography of receptor binding sites--methodological considerations.

Major technical progress in the development of computer-based image analysis has made possible the entry of autoradiography and immunohistochemistry into a new era where quantification by densitometry has become easily accessible. Autoradiography could become quantitative and displayed adequate reproducibility with the help of emulsion-coated films and the use of scales of standards of known radioactivity exposed and analyzed in parallel to the tissue sections. Immunohistochemistry after revelation by a color-based enzymatic technique can also become quantitative, providing that standardization of the crucial steps of the procedure and calibration through a parallel treatment of a scale of antigen standards can be ensured. Such an approach is described here in the rat with reference to tyrosine hydroxylase (TH), the main synthesizing enzyme for catecholamines, and with dopamine (DA) itself, a catecholaminergic neurotransmitter. The different parts of the procedure, which can influence the results, such as the fixation of the animals by perfusion and the evaluation of the fluctuations via the calibration curve, are discussed in detail. Biological validation of the proposed procedure is described by reference to experiments already well documented biochemically, such as the induction effect of reserpine on TH in the rat locus coeruleus and the depleting effect of alpha-methyltyrosine (AMPT), a well-known blocker of TH activity, on rat striatal DA content. Finally the importance of restricting the measurements to the (pseudo)linear portion of the calibration curve is illustrated by the autoradiographic identification of the differential intrastriatal repartition of the dopaminergic D1 and D2 receptor sites, particularly the dual patch-matrix compartments.

Animals↗
PubMed1991

Increase of striatal methionin enkephalin content following lesion of the nigrostriatal dopaminergic pathway in adult rats and reversal following the implantation of embryonic dopaminergic neurons: a quantitative immunohistochemical analysis.

The aim of the present study was to test whether intrastriatal implants of embryonic dopaminergic neurons are able to normalize the lesion-induced dysfunction of striatal enkephalinergic neurons, one of the major output systems of the striatum. The ascending dopaminergic pathway of adult rats was unilaterally lesioned. Three weeks later a cell suspension obtained from the mesencephali of ED14 rat embryos was implanted into the denervated striatum and striatal methionin enkephalin immunostaining was quantified six months later by the use of an image analyser. Methionin enkephalin immunostaining was unevenly distributed in the striatum of control animals. Besides the classical patch/matrix pattern, a mediolateral gradient was also present and, moreover, immunostaining decreased towards caudal levels. Seven months after the lesion of the nigrostriatal dopaminergic pathway, methionin enkephalin immunostaining was found to be increased in the denervated striatum by about 50%. However, relative increases were more sustained in the areas where basal methionin enkephalin immunostaining were lowest, i.e. the lateral striatum and posterior striatal areas. This resulted in an attenuation of the global gradients seen in the normal striatum. Increased immunostaining was also found in the ipsilateral globus pallidus. The implantation, into the denervated striatum, of embryonic dopaminergic neurons led to a reversal of the lesion-induced increase of striatal and pallidal methionin enkephalin immunostaining six months later. Moreover, this reversal resulted in an overshoot, as the level of immunostaining in the graft-bearing striatum was found to be lower than the levels found in the normal striatum. It is concluded that grafts of embryonic dopaminergic neurons can normalize the function of one of the major output systems of the striatum and, through it, influence more distant targets of this structure. This suggests a physiological basis for the behavioral effects observed previously with such grafts.

Animals↗
PubMed1991

Modulation of the migrating myoelectric complex by brain noradrenergic systems in rats.

The respective role of central and peripheral noradrenergic systems in the control of migrating myoelectric complex (MMC) was investigated in rats following lesions with 6-hydroxydopamine (6-OHDA). 6-OHDA was injected via intraperitoneal (ip), intracisternal (icis), and intracerebroventricular (icv) routes in rats. Control animals received the vehicle alone. One month later, MMC was recorded in conscious rats chronically fitted with electrodes. The MMC period was significantly lengthened after 6-OHDA ip or icv injection, and slightly shortened after 6-OHDA icis injection. No disruption of central noradrenergic systems was detected after ip lesions. Norepinephrine content was reduced in the digestive tract after ip lesions, in the spinal cord after icis lesions, and in the cortex, the hypothalamus, pons-medulla, and the spinal cord after icv lesions. After icis lesions, noradrenergic perikarya were spared in pons-medulla, whereas only pons noradrenergic perikarya were lesioned after icv lesions. We conclude that lesions of brain noradrenergic systems modify MMC periodicity in rats. The rostral noradrenergic systems may play the major modulatory role.

Animals↗
PubMed1989

Critical review on quantitative autoradiography of D1 and D2 dopaminergic receptors in the striatum of the mammalian brain: differential localization and plastic changes after pharmacological manipulation and dopaminergic input disruption.

Major technical progress in the development of computer-based image analysis systems has made possible the entry of autoradiographic and immunohistochemical techniques into a new era where quantification via densitometry and morphometry has become easily accessible. In this context, quantitative biochemical data can be adapted to anatomical and histological resolution. This adaptation is most efficient in the neuroscience fields because of the huge importance of cellular communication via neuronal networks in the nervous system. Therefore, any experimental approach to the brain which considers the brain as a 'black box' appears now as very crude. In fact, subtle heterogeneity in the distribution of biochemical markers can now be demonstrated, as illustrated here by the use of quantitative autoradiography of D1 and D2 dopaminergic receptors in the striatum of the mammalian brain. Also, local adaptive changes resulting from chronic blockade of the dopaminergic input can be detected after repeated treatments with dopaminergic antagonists selective for D1 or D2 receptors or with surgical lesioning of the dopaminergic nigrostriatal pathway. The resulting plastic changes are unevenly distributed throughout the striatal target organ and vary according to the mode of suppressing the dopaminergic flow: direct destruction of the dopaminergic pathway or selective pharmacological manipulation without physical elimination of the dopaminergic cells themselves. All these results are discussed and reviewed in light of the most recent reports in this field.

Animals↗
PubMed1987

Immunohistochemical evidence for the coexistence of cholinergic and catecholaminergic phenotypes in neurones of the vagal motor nucleus in the adult rat.

Catecholaminergic nerve cell bodies have been recently identified in the rat spinal cord. They lie in the rostral cervical segments and at the lumbosacral junction. Among them, many are located in parasympathetic areas. This finding led us to investigate the interactions between these catecholaminergic neurones and the cholinergic ones. To address this question, we performed sequential immunocytochemical detection of choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH) in the same sections. We could then identify the co-expression of both TH and ChAT-like immunoreactivities (LI) in some perikarya of the cervical spinal cord and medulla oblongata. Such cells are located in the caudal extension of the dorsal motor nucleus of the vagus nerve (DMNX) as well as in the caudal part of the medullary DMNX itself. Such a co-expression of TH-LI and ChAT-LI could not be found in the lumbosacral region, another parasympathetic territory where cell bodies displaying TH-LI were intermingled with those containing ChAT-LI. This is one of the first demonstrations of the co-existence of catecholaminergic and cholinergic phenotypes in some neurones of the adult mammalian nervous system. These observations also support the presence of catecholaminergic efferents within the vagus nerve.

Animals↗
PubMed1987

Denervation supersensitivity of striatal D2 dopamine receptors is restricted to the ventro- and dorsolateral regions of the striatum.

The precise topographical changes in striatal D2 dopamine receptors that occur after neurotoxic lesion of the mesostriatal dopaminergic pathway have been studied autoradiographically in the rat through the use of [3H]spiperone as a ligand. 6-Hydroxydopamine-induced lesion of the dopaminergic afferents to the striatum caused an increase in [3H]spiperone binding in the ventro- and dorsolateral but not in the ventro- and dorsomedian aspects of the striatum. This lesion caused a loss of tyrosine hydroxylase-like immunoreactivity in all striatal subregions. These results demonstrate that not all striatal D2 dopamine receptors are able to proliferate after dopaminergic denervation.

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↗
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↗
PubMed1984

Cardiovascular effects in the rat of intrathecal injections of apomorphine at the thoracic spinal cord level.

Intrathecal (i.t.) administration of apomorphine at the upper thoracic level lowered blood pressure and heart rate in awake rats. This decrease was dose-dependent and competitively antagonized by haloperidol (i.v. and i.t.) or domperidone (i.t.) but not by domperidone (i.v.). Furthermore, these effects of apomorphine were not affected by alpha- and beta-blocking drugs (i.t.). The results suggest a spinal site, at least in part, for the cardiovascular effect of apomorphine.

Animals↗
PubMedDate not supplied

Immunohistochemical study of the catecholaminergic innervation of the spinal cord of the rat using specific antibodies against dopamine and noradrenaline.

We have assessed the relative contributions of dopaminergic and noradrenergic descending systems to the catecholaminergic innervation of the rat spinal cord. Fibres and terminals were labelled with their own neurotransmitter by using specific antibodies raised against dopamine (DA) and noradrenaline (NA) respectively. For this purpose, immunohistochemistry according to the peroxidase anti-peroxidase technique was performed in different experimental conditions. Two group of rats received intracisternal 6-hydroxy-dopamine (6-OHDA) injections either with or without benzatropine pretreatment. Animals of a third group were not pretreated at all. While 6-OHDA induced a complete disappearance of spinal NA-like immunoreactivity (NA-LI), except for scarce residual fibres in the thoracic intermedio-lateral cell column, DA-like immunoreactivity (DA-LI) was unaffected by the lesion. This strongly suggests that the antisera used specifically labelled NA-containing and DA-containing fibres respectively. Spinal DA-LI and NA-LI innervations differed markedly in their topographical distributions and in the morphology of the corresponding fibres. DA-LI innervation was restricted to laminae I, III and IV and to the intermediate zone, especially the autonomic areas. In the ventral horn, it was sparse and more visible after acidification of the fixation solution. NA-LI innervation was much more widely spread. In addition, the organization of NA-LI fibres suggests that the innervation of the whole dorsal horn comes from a group of fibres travelling, at least partially, in the superficial dorsal horn.

Adrenergic Fibers↗
PubMedDate not supplied

Evidence for the existence of L-dopa- and dopamine-immunoreactive nerve cell bodies in the caudal part of the dorsal motor nucleus of the vagus nerve.

The precise neurochemical nature of tyrosine hydroxylase-immunoreactive neurons lying in the caudal part of the dorsal motor nucleus of the vagus nerve of the rat has been identified by immunohistochemistry of the catecholamines themselves. This region corresponds precisely to the area where tyrosine hydroxylase has been previously shown to be colocalized with choline acetyltransferase. Adjacent serial cryostat sections from the medulla oblongata and from the cervical spinal cord were treated either for choline acetyltransferase immunohistochemistry, aromatic L-amino acid decarboxylase and tyrosine hydroxylase immunolabelling or for tyrosine hydroxylase, dopamine, noradrenaline and L-dihydroxyphenylalanine (DOPA) immunostaining. The procedure involved the peroxidase-antiperoxidase method and an intensified diaminobenzidine reaction with imidazole. While no noradrenaline-positive cells were detectable in the dorsal motor vagal nucleus, tyrosine hydroxylase-, dopamine- and DOPA-immunoreactive perikarya were seen in the medial half of this nucleus, caudally the obex level. These results led us to conclude that these tyrosine hydroxylase-positive cells were effectively of dopaminergic nature and therefore that dopamine is a neurotransmitter contained in some neurons of the dorsal motor vagal nucleus. In the light of previous data showing colocalization of tyrosine hydroxylase and choline acetyltransferase in neurons of this portion of the nucleus, colocalization of dopamine with acetylcholine appears most likely. This might shed some light on the physiological consequences of dopamine action at target parasympathetic organs, such as the gastrointestinal tract.

Animals↗