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Biomedical subjects

J Taxi

Publications and source records attributed to J Taxi.

At least 37 records · Page 2Linked to original sources
PubMed1988

[The significance of a positive reaction to anti-serotonin (5-HT) in certain hypothalamic neurons of the rat during the perinatal period].

In this study, two regions containing 5-HT immunopositive neurons were observed in the hypothalamus of fetal (18th fetal day) and neonatal rats (9th postnatal day) after pretreatment with the monoamine oxidase inhibitor, pargyline, and the amino acid precursor of the 5-HT synthesis, l-tryptophan. They were localized in the anterolateral hypothalamus and the dorso-medial hypothalamic nucleus. Immunostaining was completely blocked by the preliminary injection of fluoxetine, a specific uptake inhibitor of the serotoninergic neurons. Thus, the 5-HT immunostaining of hypothalamic neurons reported in this study is accounted for by the specific uptake of the 5-HT from the environment rather than by its synthesis from l-tryptophan.

Animals↗
PubMed1987

Ultrastructural evidence for a functional unit between nerve fibers and type II cerebral mast cells in the cerebral vascular wall.

By histofluorescence microscopic examinations of pial arteries from rats and rabbits, we have observed that the routes of adrenergic fibers were apparently organized along successive sites of granular autofluorescent cells present in the adventitia. Subsequent electron microscopic studies showed that these cells were often situated in close apposition (80 to 200 nm) to the adventitial nerve bundles. The granular cells and nerve varicosities were frequently enclosed within the same basement membrane, with a membrane-to-membrane distance as small as 20 nm. However, no clear membrane differentiation was seen. These granular cells were identified histochemically by staining with Sudan Black, Oil Red O, Toluidine Blue, Alcian Blue, together with ultrastructural and pharmacological methods (48/80 compound and carbachol intracarotid infusions). The cells, many of which contained large amounts of lipids, showed morphological ultrastructural and pharmacological similarities to peripheral mast cells. Nerve bundles contained two types of varicosities: some of them degenerated after superior cervical ganglionectomy and were thus of sympathetic origin, whereas the others contained small clear vesicles (probably cholinergic) and/or large dense-cored vesicles (probably peptidergic). As we have shown that cholinomimetics induce exocytosis of these granular cells, the close relationship between these cells and the nerve fibers may indicate a neurogenic control of the cerebrovascular mast cell secretion. As these cells contain potent vasoactive substances, this relationship may be of importance in the genesis of physiological or pathological cerebrovascular events which are, as yet, poorly understood.

Animals↗
PubMed1986

The innervation of the myometrium of the cynomolgus monkey (Macaca fascicularis). A quantitative electron-microscopic study.

The autonomic innervation of the myometrium of Macaca fascicularis consists of bundles of unmyelinated nerve fibres running between the smooth muscle cells, and is therefore considered to be of the "fascicular (= unitary) type". Close contacts between nerve fibres and smooth muscle fibres were not found. Modification of the chromaffin method according to Tranzer and Richards made it possible to visualize the heterogeneity of the nerve fibres in a single bundle. The following fibre types were found to coexist: (1) noradrenergic fibres containing "synaptic" vesicles with a dense granule, (2) cholinergic fibres containing empty "synaptic vesicles", and (3) non-adrenergic non-cholinergic (NANC) fibres containing only or predominantly large dense-cored vesicles, which do not react with this method. Noradrenergic fibres are the most numerous (around 60%), followed by NANC fibres (30%) and cholinergic elements (around 10%). The distribution of these three types is similar in the cervix, the isthmus and the body of the uterus in pregnant and non-pregnant females.

Adrenergic Fibers↗
PubMed1986

Development of the hypothalamic serotoninergic system during ontogenesis in rats. Immunocytochemical and radioautographic study.

The development of the hypothalamic serotoninergic system has been studied in rats from the 14th fetal till the 9th postnatal day. Serotoninergic elements were detected with immunocytochemistry using antiserum to serotonin (5-HT) and radioautography following the injections of [3H]5-HT into the cerebral ventricles. Immunocytochemistry failed to recognize hypothalamic 5-HT neurons either in fetuses or in neonatal rats. Conversely, radioautography demonstrated sparse radioactively labeled cells, undifferentiated in appearance, at the 16th and 18th fetal days. Moreover, at the 18th fetal day an accumulation of radioactively labeled typical neurons appeared in the suprachiasmatic region. By the 9th postnatal day, practically all radioactively labeled cells looking like highly differentiated neurons were concentrated in the dorsomedial nucleus. As to nerve fibers, a small number of 5-HT-immunoreactive axons arising from the raphe nucleus were first detected in the hypothalamus at the 16th fetal day. Two days later, both 5-HT-immunoreactive and radioactively labeled fibers became widely distributed through the hypothalamus with especially high concentrations in and around the optic chiasma. By the 9th postnatal day, the frequency of 5-HT fibers increased considerably both in the anterior and middle hypothalamus. Some 5-HT fibers were apposed to unlabeled neurons and others abutted on the capillaries either in the organum vasculosum of the lamina terminalis or in the median eminence. The present morphologic study suggests that during the perinatal period the hypothalamic 5-HT system becomes developed enough to be involved in the regulation of some neuroendocrine functions.

Animals↗
PubMed1986

Molecular forms of acetylcholinesterase in mammalian smooth muscles.

A comparative study of the molecular forms of acetylcholinesterase (AChE) was made in various smooth muscles (intestine, vas deferens, ciliary body, iris, nictitating membrane retractor, ureter, arteries, anococcygeus muscles) of some mammals (cat, guinea-pig, rat, rabbit, mouse), seeking for a correlation between the presence of 16 S (asymmetric, tailed) form of AChE in smooth muscles and their type of innervation defined by morphological criteria, as well as by the nature of the main neurotransmitters involved in their neuroeffector junctions. Contrary to previous assertions, many smooth muscles contain 16 S AChE, although all those examined here exhibited a proportion clearly less than that of striated muscles. There are large species-specific and individual variations in the percentage of 16 S AChE. The highest percentages of 16 S AChE were found in ciliary and iris muscles, which are provided with an individual (= multiunit) cholinergic innervation. The vas deferens muscles, which are also individually, but noradrenergically innervated contain practically no 16 S AChE. In the muscles having a fascicular (= unitary) innervation, the differences are striking: 16 S AChE is in rather high amount in intestine muscle layers, whereas it is very low or virtually absent in ureter or arterial muscles. Thus, the type of innervation is not clearly involved in the amount of 16 S AChE present in smooth muscles. As for the nature of neurotransmitter a clear correlation exists only in the case of individual innervation, in which only one neurotransmitter is involved or largely predominant.

Acetylcholinesterase↗
PubMed1986

[Structural characteristics and innervation of chromaffin tissue in the adrenal gland of the axolotl].

Each adrenal gland of the Axolotl consists of a strip lying all along the medio-lateral edge on the ventral surface of the kidney. The gland is composed of interrenal cells (IC) and chromaffin cells (CC). The IC contained a great number of pleomorphic lipid droplets, smooth endoplasmic reticulum and elongated mitochondria with tubulo-vesicular cristae. Two types of CC, always disposed in clusters and exhibiting long cytoplasmic processes were described according to the electron density, size and shape of granules distributed in their cytoplasm; noradrenaline cells (NA) and adrenaline cells (A). The innervation and ultrastructural differences from the adrenal gland of other Anurans were discussed.

Adrenal Glands↗
PubMed1986

[Immunocytochemical and autoradiographic research on the growth of serotoninergic fibers to the cerebral ventricles in the perinatal period in rats].

Anatomical relationships between serotoninergic (5-HT) fibers and cerebral ventricles were studied in rats from the 16th fetal day until the 9th postnatal day with immunocytochemistry and radioautography. In the latter case, 5-HT neuronal elements were detected according to their specific uptake of intraventricularly injected 3H-5-HT. On the 16th fetal day, occasional 5-HT fibers first spread from the main place of their origin in the raphe nuclei to the dorsocaudal portion of the 3rd ventricle and aqueduct. Two days later, a more extensive network of 5-HT fibers appeared around the dorsal portion of the 3rd ventricle, whereas fibers only rarely penetrated fibers became noticeable in the lateral and 3rd ventricles. The functional significance of hypothalamic and ventricular 5-HT is discussed from the standpoint of its being either a modulator of growth and differentiation of the developing brain, or a factor involved in some specific neuroendocrine functions.

Aging↗
PubMed1985

Immunocytochemical and radioautographic study of serotonin projections to cerebral ventricles of perinatal rats.

Anatomical relationships between serotoninergic (5-HT) fibers and cerebral ventricles were studied in rats from the 16th fetal day until the 9th postnatal day with immunocytochemistry and radioautography. In the last case, 5-HT neuronal elements were detected according to their specific uptake of intraventricularly injected [3H]5-HT. At the 16th fetal day, occasional 5-HT fibers first spread from the main place of their origin in the raphe nuclei to the dorsocaudal portion of the 3rd ventricle and aqueduct. Two days later, a more extensive network of 5-HT fibers appeared around the dorsal portion of the 3rd ventricle whereas fibers only rarely penetrated toward its ventral portion. By the 9th postnatal day, extensive networks of supraependymal fibers became noticeable in the lateral ventricles and in the dorsal portion of the 3rd ventricle. In addition, a number of 5-HT fibers surrounded the infundibular and preoptic recesses and sometimes penetrated to the ventricular cavity. The functional significance of hypothalamic and ventricular 5-HT as a modulator of either the growth and differentiation of the developing brain or of some specific neuroendocrine functions is discussed.

Animals↗
PubMed1985

Localization of some neuropeptide- and serotonin-like immunoreactivities in the vegetative network of guinea pig spinal cord.

The localization of Substance P(SP)-, Methionine-Enkephalin(met-Enk)-, Somatostatin(SOM)- Serotonin(SER)-, Cholecystokinin(CCK)-, and Vasoactive intestinal polypeptide (VIP)-like immunoreactivity (-LIR) has been determined immunocytochemically in the thoracic spinal cord intermediate zone of male and female guinea pigs. All neuroactive substances studied are exclusively localized in nerve fibre varicosities and terminals building up the vegetative network of the thoracic spinal cord intermediate zone. This network is situated dorsally to the central canal as a longitudinal plate of approximate thickness of 90-100 microns. Immunoreactive fibres are observed in the two Fasciculi longitudinales laterales and the two Fasciculi longitudinales mediales which are interconnected by transverse and oblique peptide-containing bundles (the terminology used by Petras and Cummings 1972; Galabov and Davidoff 1976). All these bundles interconnect the nuclei intermediolaterales principales and funiculares, the nuclei intercalates spinales and the nuclei intercalates paraependimales in ipsi- and contralateral as well as in rostral and caudal direction. The neurones of these nuclei are surrounded by immunoreactive varicosities and terminals. The quantity of the immunoreactive structures and intensity of the staining varied for the different neuroactive substances. As to the origin of the vegetative network immunoreactive fibres three main possibilities exists: a). From primary afferent neurones situated in the dorsal root ganglia, which send their axons via the dorsal roots (mainly for SP and perhaps for CCK); b). From supraspinal neurones which send their axons descending in the white matter funiculi and in the fasciculi longitudinales laterales and mediales and c). From intrinsic spinal cord neurones, which send their neurites in ascending and descending directions, ipsi- and contralaterally and interconnect the spinal cord segments. The different origin of the vegetative network immunoreactive fibres as well as the complex innervation of the preganglionic sympathetic nerve cells in the intermediate zone of the spinal cord suggests that this network may play an important role in the integration of the central and peripheral vegetative nervous system as well as probably in the integration of the somatic and the vegetative nervous system.

Animals↗
PubMed1983

An in vivo and in vitro study of rabies virus infection of the rat superior cervical ganglia.

In the attempt to develop a homogeneous neuronal model to study rabies pathogenesis in vivo and in vitro, the superior cervical ganglia (SCG) were chosen because of their unique features. In vivo infection of the SCG was attempted by inoculation of fixed rabies virus into the anterior eye chamber. However, viral by this route as well as intracerebrally failed to infect this neuronal organ in adult rats whereas the infection was poorly efficient in 24 hours newborn rats. Dissociated cell cultures from the rat embryo SCG were infected in vitro and examined for the presence of rabies specific antigen and release of virus particles in the supernatant. Despite the presence of rabies nucleoprotein in the cytoplasm and the presence of typical Negri bodies, neurons from the rat SCG produced few particles as observed by electron microscopy and no increase in virus yields could be detected by titration of viral infectivity during the infectious cycle. Our observations indicate that although rabies virus is neurotropic as shown in previous studies, all neuronal tissues are not equally susceptible to this viral infection. The resistance of the SCG to rabies virus infection in vivo does not seems to be a lack of accessibility of this organ to infection since other authors had shown that it could be infected by herpes virus. Both in vitro and in vivo experiments show that although neurons from the SCG are susceptible to rabies virus infection, infected cells do not produce rabies infectious virions efficiently.

Animals↗
PubMed1976

Some cytochemical and cytological features of the so-called SIF cells of the superior cervical ganglion of the rat.

The properties of uptake and storage of dopamine and noradrenaline of the SIF cells of the superior cervical ganglion of the rat were tested, using the radioautographic method. Their ability to store exogenous catecholamines appears very poor under the present experimental conditions, in spite of the great number of storage vesicles they usually contain. This situation may be related either to the absence of a high affinity uptake mechanism in the SIF cell membrane or to a normal saturation of SIF cells in catecholamine. Cytological peculiarities of nerve terminals on SIF cells were pointed out. Dense patches attached to the inner face of the SIF cell membrane suggest a local release of vesicular contents, with further functional implications.

Animals↗