Search PubMed⌕ Search

Biomedical subjects

A Prochiantz

Publications and source records attributed to A Prochiantz.

At least 109 records · Page 6Linked to original sources
PubMed1984

Biogenic amine-sensitive adenylate cyclases in primary culture of neuronal or glial cells from mesencephalon.

Primary cultures of virtually pure mesencephalic neurons (5 days) or glials (4 weeks) from 14-day-old mouse embryo were obtained using appropriate medium. Membranes prepared from neuronal cells contained mainly serotonin and beta 1-adrenergic-sensitive adenylate cyclases. However, a low but significant classical dopamine-sensitive adenylate cyclase activity (D1 receptor) was detected. Contrasting with the data obtained from a previous study on striatal neurons no adenosine-sensitive adenylate cyclase was found on mesencephalic neurons. Study on the additive effects of the 3 biogenic amines-sensitive adenylate cyclases indicated that: all neuronal cells having dopamine receptors possess beta 1-adrenergic receptors (no additivity); beta 1-adrenergic and serotonin receptors on the one hand, and dopamine and serotonin receptors on the other hand, were coupled with independent adenylate cyclase systems localized either on two different domains of the same cell or on different cells (complete additivity). Membranes prepared from primary mesencephalic cultures of glial cells contained a mixture of beta 1- and beta 2-adrenergic receptor subtypes coupled with an adenylate cyclase (70% and 30%, respectively). No dopamine- or serotonin-sensitive adenylate cyclase was detected on mesencephalic glial cells.

Adenylyl Cyclases↗
PubMed1984

A combined light and electron microscopic method for the visualization of the same in vitro neuron by radioautography and serial sections.

We report here on a technical improvement which makes it possible to study, at the ultrastructural level, a dopaminergic neuron which has been previously identified by light microscopy. Primary cultures of virtually pure mesencephalic neurons from mouse embryos were obtained. These cultures were kept for 6 days, then incubated with tritiated dopamine, fixed and embedded in Epon. The dopaminergic neurons were firstly visualized by radioautography directly through Epon blocks in toto by light microscopy. In a second step, ultrathin sections of the identified dopaminergic cells were prepared and the neurons observed at the electron microscopy level. The dopaminergic nature of these neurons was regularly checked by radioautographic control on some selected ultrathin sections.

Animals↗
PubMed1983

Inhibition of brain adenylate cyclase by A1 adenosine receptors: pharmacological characteristics and locations.

When tested under conditions reducing the endogenous production of adenosine (presence of adenosine deaminase (ADA) 1.6 IU/ml; and deoxyadenosine triphosphate (d-ATP), and in the presence of both NaCl and GTP, the ADA-resistant analog phenylisopropyladenosine (PIA) inhibited the adenylate cyclase of several brain tissues. These tissues included: (1) 5 brain areas of adult rats (frontal and parietal cortex, cerebellum cortex, hippocampus and striatum)--hypothalamus and mid-brain adenylate cyclases were not inhibited by PIA; (2) astrocytes in primary cultures prepared from cerebral cortex of newborn mice; and (3) neurons in primary cultures prepared from striata of 15-day-old mouse embryos. The specificity profile of the adenosine receptor involved in the inhibition was determined in astrocytes. It was typical of an A1 adenosine receptor (high affinity of PIA; Ka app: 9 +/- 5 X 10(-9) M (n = 4) compared to the affinity of 5'-N-ethylcarboxamide adenosine (NECA); Ka app: 1.3 +/- 0.6 X 10(-7) M (n = 3). There was an excellent correlation between the affinities of several adenosine agonists and antagonists for A1 receptors coupled with an adenylate cyclase in astrocytes and for the receptors labeled with N6-cyclohexyl-[3H]adenosine in brain cortex. In adult rat striatum as well as in astrocytes and striatal neurons in culture the adenylate cyclase was inhibited by low PIA concentrations through A1 receptors and stimulated by higher concentrations through A2 receptors. In contrast, A2 receptors were not detected in adult rat cerebral cortex. In adult rat striatum, A1 and dopamine receptors coupled with an adenylate cyclase seemed to be located on different cell populations. In contrast, in astrocytes A1 and beta-adrenergic receptors coupled with adenylate cyclase were apparently located on the same cells.

Adenosine↗
PubMed1983

Microheterogeneity of tubulin proteins in neuronal and glial cells from the mouse brain in culture.

The microheterogeneity of the alpha and beta isoforms of tubulin in brain cells in culture was studied. The cells were prepared from two precise regions of the embryonic mouse brain (ED15), the striatum and the mesencephalon. It was possible to maintain virtually pure cultures of neuronal or glial cells up to 1 and 4 weeks in vitro, respectively. The tubulin heterogeneity of striatal and mesencephalic neurons was found to be very similar after a few days in culture. More precise examination of pure neurons from the striatum revealed that their tubulin content after 7 days in vitro exhibited the same degree of complexity as a control extract from a 4 day-old mouse brain. In fact, we could detect the presence of at least six alpha and nine beta tubulin isoforms. Among these isoforms a specific family of beta proteins (beta' tubulin) and the more acidic alpha proteins were present. Since these isoforms have, up to now, been found only in tubulin extracts prepared from the nervous system, our experiments suggest that they belong to the neuronal subpopulation of this tissue. This point is reinforced by their complete absence from the tubulin proteins extracted from pure glial cells even after several weeks in vitro. These results lead us to propose that brain tubulin microheterogeneity is associated with the presence of neurons and not of glia and may, therefore, play a specific role in maintaining neuronal shape and function.

Animals↗
PubMed1983

Biogenic amines and adenosine-sensitive adenylate cyclases in primary cultures of striatal neurons.

Primary cultures of virtually pure striatal neurons from 16-day-old mouse embryos can be obtained using a serum-free chemically defined medium. Membranes prepared from these cells contain dopamine, beta-adrenergic, serotonin and adenosine sensitive adenylate cyclases. The pharmacological properties of the dopamine receptors are similar to those found for D1 receptors in adults except for the apparent affinities for agonists which were 5-10 times higher in fetal neurons. Beta-adrenergic receptors of striatal and cerebellar fetal neurons are of the beta 1-subtype as indicated by their identical affinity for adrenaline and noradrenaline and by their homogeneous, high affinity for practolol (Ki = 1.3 X 10(-6)M). Adenosine and serotonin sensitive adenylate cyclases present classical characteristics. An extensive study of the additive effects of the 4 neurotransmitter-sensitive adenylate cyclases indicates that: (1) part of the neurons bear more than one type of biogenic amine receptors; (2) the serotonin receptors are always associated with adenosine receptors on the same neurons; (3) adenosine- and dopamine-sensitive adenylate cyclases are additive. From this it can be concluded that as far as their adenylate cyclases-linked amine receptors are concerned, a maximal number of 15 types of neurons are present in these striatal cell cultures.

Adenosine↗
PubMed1983

Specific influence of striatal target neurons on the in vitro outgrowth of mesencephalic dopaminergic neurites: a morphological quantitative study.

In previous studies, we have shown that dissociated dopaminergic neurons from embryonic mouse in co-culture with striatal target neurons take up and synthesize dopamine to a greater extent. We now report that striatal target cells influence the morphology of dopaminergic neurons as well. In co-culture, the total length of neuritic arborization visualized by autoradiography is reduced when compared to cultures of mesencephalic neurons alone or to co-cultures with cerebellar cells. Experiments performed in the presence of striatal glial cells at the same density as striatal neurons or with media conditioned with striatal glia or neurons suggest that striatal neurons regulate dopaminergic afferent growth in vitro through specific neuro-neuronal interactions.

Animals↗
PubMed1982

Long-term development of mesencephalic dopaminergic neurons of mouse embryos in dissociated primary cultures: morphological and histochemical characteristics.

In 13 and 15 day-old mouse embryos mesencephalic dopaminergic neurons could already be visualized at the level of the mesencephalic flexure by tyrosine hydroxylase immunocytochemistry at day 13. At this time, noradrenergic cells in the locus coeruleus area were not detectable. In most in vitro experiments, dissociated mesencephalic cells of 13 day-old embryos were grown in presence of serum. Four approaches were used to identify the dopaminergic neurons in vitro: fluorescence histochemistry of newly taken up exogenous norepinephrine, radioautography after labelling with (3H) dopamine, tyrosine hydroxylase-like immunoreactivity and fluorescence histochemistry of endogenous stores of catecholamines. Control experiments performed at various times in vitro with selective inhibitors of amine transport into dopaminergic, noradrenergic and serotoninergic neurons indicated that only dopaminergic neurons were detected by these various approaches, noradrenergic neurons being virtually absent from the cultures. The uptake of exogenous norepinephrine was detected already 24 h after plating and preceded the appearance of tyrosine hydroxylase-like immunoreactivity (48 h). The number of neurons revealed by these two techniques increased up to 4 and 10 days, respectively. Endogenous stores of dopamine were only seen after three weeks in vitro by fluorescence histochemistry. At this time, the same number of neurons was revealed whatever the method used. The presence of striatal target cells (co-cultures) affected neither the sequential appearance of the markers nor the number of dopaminergic cells. The two main types of dopaminergic neurons (fusiform and multipolar) described in vivo both in the substantia nigra (A9) and the ventral tegmental area (A10) of adult animals were identified in vitro and their development into well-differentiated neurons can be followed for up to six weeks. This in vitro system seems, therefore, to be particularly suitable for biochemical and electrophysiological studies of these dopaminergic neurons.

Animals↗
PubMed1982

Gluteal myoplasty for sphincter replacement: principles, results and prospects.

The treatment of anal incontinence following anorectal malformations and their treatment can be done even if the colic pull-down has been carried out of the levatori ani muscle sling. The use of the gluteus maximus encircling the neorectum with a contractile muscular ring provides an active control of continence, and reverses the anorectal angulation. The rationale of the myoplasty has been pointed out and our first resulted analyzed. The use of voluntary contraction limits the scope of an operation whose effects can be lost during sleep. But the voluntary daytime control makes it possible for the patient to take part in school, occupational or sportive activities.

Anal Canal↗
PubMed1982

Specific binding of an immunoreactive and biologically active 125I-labeled substance P derivative to mouse mesencephalic cells in primary culture.

Binding characteristics of 125I-labeled Bolton-Hunter substance P ([125I]BHSP), a radioactive analogue of substance P, were studied with mesencephalic primary cultures prepared from embryonic mouse brain. Nonspecific binding represented no more than 20% of the total binding observed on the cells. In contrast, significant specific binding--saturable, reversible, and temperature-dependent--was demonstrated. Scatchard analysis of concentration-dependent binding saturation indicates a single population of noninteracting sites with a high affinity (Kd = 169 pM). Substance P and different substance P analogues were tested for their competitive potencies with regard to [125I]BHSP binding. BHSP itself, substance P, (Tyr8)-substance P, and (nor-Leu11)-substance P strongly inhibited the binding. Good inhibition was also obtained with physalaemin and eledoisin, two peptides structurally related to substance P. When substance P C-terminal fragments were tested for their ability to compete with [125I]BHSP binding, a good relationship was found between competitive activity and peptide length. Regional distribution of [125I]BHSP binding sites was found using primary cultures obtained from different regions of embryonic mouse brain. Mesencephalic, hypothalamic, and striatal cultures had the highest [125I]BHSP binding capacities, whereas cortical, hippocampal, and cerebellar cells shared only little binding activity. Finally, when mesencephalic cells were grown under conditions impairing glial development, [125I]BHSP binding was not affected, demonstrating that binding sites are located on neuronal cells.

Animals↗
PubMed1980

Effect of striatal cells on in vitro maturation of mesencephalic dopaminergic neurones grown in serum-free conditions.

It is well documented that target cells can regulate the morphological and biochemical development of peripheral afferent neurones, but little is known about the existence of such regulatory mechanisms in the central nervous system. We therefore investigated previously the influence of striatal target cells on the maturation in vitro of nigrostriatal dopaminergic neurones, which survive in culture for more than 5 weeks, develop dense arborizations and both take up 3H-dopamine (DA) by a high-affinity specific process and synthesize 3H-DA from 3H-tyrosine. Furthermore, depolarization by potassium or veratridine stimulates the release of DA through a calcium-dependent mechanism and tetrodotoxin prevents the veratridine-evoked release of the transmitter. Both the number of 3H-DA uptake sites and the capacity for 3H-DA synthesis were at least doubled when the neurones were cultured with target cells from the striatum. To determine whether glial cells which proliferate in serum-complemented medium are partly responsible for the maturation of dopaminergic neurones and/or for the effect of striatal cells, we have now repeated the experiment using serum-free medium in which virtually pure neuronal populations can be obtained. The reduction in the number of glia did not affect either the maturation of dopaminergic cells alone, or the effect of striatal cells. Autoradiographic analysis of the number of dopaminergic cells strongly suggests that the stimulatory effect is related to increased capacities of 3H-DA uptake and synthesis per dopaminergic neurone.

Animals↗
PubMed1980

[Role of cell-milieu interactions in the differentiation of nerve cells].

In this review some aspects of nerve cell development are studied from the point of view of the role of the environment on differentiation processes. In the first part, attention is focused on the early stages, with special emphasis on the commitment of the cells coming from the neural crest to acquire and keep a specialized phenotype. In the second part, attempts were made to understand the mechanisms of action of specific growth factors, the Nerve Growth Factor (NGF) being taken as a model molecule. Information presently available is presented on factors that may be implicated in the development of cell types other than those NGF-sensitive, with considerations as to whether the notion of specific growth factors can be generalized to all nervous cell types or not.

Animals↗
PubMed1979

In vitro maturation of mesencephalic dopaminergic neurons from mouse embryos is enhanced in presence of their striatal target cells.

Long-term survival of mesencephalic and striatal cells from mouse embryos in dissociated primary cultures is described. Catecholaminergic neurons in mesencephalic culutres were identified histochemically and by measuring [3H]dopamine uptake and synthesis from [3H]tyrosine. According to experiments using specific inhibitors of catecholamine uptake, at least two-thirds of the catecholaminergic neurons are dopaminergic. These neurons differentiated whether or not striatal target cells were present, but striatal cells stimulated the development of the dopaminergic neurons. [3H]Dopamine uptake was increased by at least 2-fold regardless of the age of the cocultures (4-15 days). Enhanced [3H]dopamine synthesis was also observed (at least 2-fold) at later times (12-15 days).

Animals↗