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L Denoroy

Publications and source records attributed to L Denoroy.

At least 91 records · Page 5Linked to original sources
PubMed1989

Adrenergic neurons in the nucleus tractus solitarius receive GABAergic synapses. Demonstration by dual immunocytochemistry in the rat.

By means of a dual immunocytochemical labeling for phenylethanolamine-N-methyltransferase and glutamate decarboxylase, synaptic associations between adrenaline-synthesizing neurons and GABAergic terminals are demonstrated in the medial nucleus tractus solitarius of the rat. These relationships could constitute an anatomical substrate for the presumed role of GABA in modulation of baroreceptor reflexes at this level.

Adrenergic Fibers↗
PubMed1989

Double antigen localization of two catecholamine enzymes and GABA in amacrine cells of the rat retina in semi-thin sections.

A double immunohistochemical labeling technique was developed with two immunoperoxidase reactions performed before and after embedding in epoxy resin using two different chromogens: diaminobenzidine (yellowish brown color) and diaminobenzidine + nickel ammonium sulfate (black color). The two catecholamine enzyme immunoreactivities (phenylethanolamine-N-methyltransferase, and tyrosine-hydroxylase) were not found in the same cells, while gamma-aminobutyric acid (GABA) immunoreactivity was observed in large tyrosine-hydroxylase immunoreactive cells, but not in phenylethanolamine-N-methyltransferase immunoreactive cells.

3,3'-Diaminobenzidine↗
PubMed1989

Possible increase of dopamine-beta-hydroxylase activity in the locus ceruleus of paranoid schizophrenic patients: a preliminary post-mortem study.

Five schizophrenic brains and seven control brains were compared for phenylethanolamine-N-methyl-transferase and dopamine-beta-hydroxylase activities. The two groups were comparable in age, sex, and post-mortem delay before autopsy. A radioenzymatic assay showed a statistically significant increase of dopamine-beta-hydroxylase activity in the rostral part of the locus ceruleus in the schizophrenic brains.

Adult↗
PubMed1989

[Immunohistochemical absence of adrenergic neurons in the dorsal part of the solitary tract nucleus in sudden infant death].

The immunohistochemical distribution of TH and PNMT containing neuronal elements was investigated utilizing peroxidase anti-peroxidase methods in newborn control and sudden infant death syndrome (SIDS) brainstems. The TH immunoreactive neurons, within the medulla oblongata, displayed a similar distribution in both control and SIDS tissue. However, PNMT immunoreactive neurons seen in the dorsal part of the nucleus of tractus solitarius in control tissue were not observed in SIDS tissue. This alteration of adrenergic neurons in the dorsal part of NTS (region reported to be implicated in the control of blood pressure and respiration) could explain the cardiorespiratory disorders in SIDS.

Epinephrine↗
PubMed1988

Immunohistochemical and biochemical evidence for the presence of serotonin in amphibian adrenal chromaffin cells.

The presence of serotonin (5-HT) in chromaffin cells of the frog adrenal (inter-renal) gland has been demonstrated both by immunocytochemical and biochemical techniques. Using antisera against 5-HT and tyrosine hydroxylase (TH) on consecutive sections, we found by means of the indirect immunofluorescence technique that a majority of chromaffin cells were also immunopositive for 5-HT. When antibodies to 5-HT and phenylethanolamine-N-methyltransferase (PNMT) were applied on consecutive sections, 5-HT-like immunoreactivity was observed in almost all epinephrine-producing cells which represented about 90% of the total chromaffin cells. No 5-HT-containing fibres could be detected. At the ultrastructural level, using a pre-embedding procedure associated with gold-silver intensification of the immunoperoxidase reaction, 5-HT-immunoreactivity was visualized in secretory vesicles essentially located in the periphery of epinephrine cells. Combination of high performance liquid chromatography and electrochemical detection showed the presence of both 5-HT and its metabolite 5-hydroxyindolacetic acid (5-HIAA) in frog adrenal extracts. Transection of the splanchnic nerve enhanced 5-HT immunoreactivity and augmented the amount of 5-HT in adrenal extracts. Taken together, these results indicate that epinephrine-producing cells of the frog adrenal contain significant amounts of serotonin. The observation of the storage of 5-HT in secretory vesicles of epinephrine cells suggests that serotonin may be released with catecholamines under stress conditions.

Adrenal Medulla↗
PubMed1988

Anatomy of the adrenergic system in the medulla oblongata of the tree shrew: PNMT immunoreactive structures within the nucleus tractus solitarii.

The adrenergic system in the medulla oblongata of tree shrews was investigated by immunocytochemistry with an antibody against phenylethanolamine-N-methyltransferase. Two groups of adrenergic cells, which are equivalent to those of other species, were detected: Group C1 in the ventrolateral medulla and group C2 in the dorsomedial medulla. Adrenergic cells in C1 are located around the lateral reticular nucleus or between its subdivisions. They are mostly multipolar with branched processes. In group C2, some immunoreactive cell bodies smaller than those in C1 and many nerve terminals are found in the motor nucleus of the vagus, but most of the adrenergic cells and fibers are observed in the nucleus tractus solitarii. The cytoarchitecture of this nucleus resembles that described before for the rhesus monkey. In contrast to the rat, the subnucleus gelatinosus, which according to other authors receives cardiac and gastric afferents, is a prominent structure in immunocytochemically as well as conventionally stained sections. Adrenergic cell bodies and their fibers form a ring around this nucleus, but no immunoreactive structures are found within it. In the dorsomedial part of the nucleus tractus solitarii, adrenergic neurons are accumulated. They are often located in close proximity to blood vessels. Elongated immunoreactive neurons in the medial subdivision of the nucleus also seem to project in the direction of the dorsal area. Our data give new information about the adrenergic system in the medulla oblongata, especially in the nucleus tractus solitarii of the tree shrew, a species that provides a useful model of a small primate brain.

Animals↗
PubMed1988

Immunohistochemistry of tyrosine hydroxylase and phenylethanolamine N-methyltransferase in the human brain stem: description of adrenergic perikarya and characterization of longitudinal catecholaminergic pathways.

Using immunocytochemical method in conjunction with antibodies to tyrosine hydroxylase and phenylethanolamine N-methyltransferase, catecholaminergic cell groups and axon pathways are mapped in the human hind brain. Adrenergic perikarya are located mainly in the rostral medulla, as in lower animals, and contribute a subset of axons to the main longitudinal catecholaminergic bundle which runs through the medulla oblongata, pons and midbrain such as the dorsal part of the central nucleus of the medulla oblongata, the parvocellular reticular formation ventromedial to the facial nerve and ventrolateral to the locus coeruleus. Adrenergic terminals are present in the locus coeruleus and other medullary and pontine structures. The locus coeruleus contains only tyrosine hydroxylase-immunoreactive cells and appears to be the source of a discrete dorsal catecholaminergic bundle which runs through the central tegmental field just ventrolateral to the periaqueductal gray of the rostral pons and mesencephalon and which does not contain adrenergic axons. A ventral catecholaminergic bundle arising in the medullary cells does contain a subset of adrenergic axons in the mesencephalic tegmental field. These two longitudinal axon bundles run near each other in the mesencephalic reticular formation. Additional descriptions are provided of catecholaminergic axons near the dorsal and ventral surface of the human medulla.

Adrenergic Fibers↗
PubMed1987

Immunohistochemical evidence for the adrenergic medullary longitudinal bundle as a major ascending pathway to the hypothalamus.

Three weeks after unilateral electrolytic lesion of the longitudinal axon bundle in the medulla oblongata of the rat, we observed a decrease in the number of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive (IR) nerve fibers in virtually all the regions of the diencephalon ipsilaterally to the lesion, especially in the dorsomedial nucleus and the paraventricular nucleus of the hypothalamus. These results indicate that the hypothalamic PNMT-IR terminal-like fibers originate in the ipsilateral medulla oblongata presumptive adrenaline-containing (Ad) neurons especially through ascending projections provided in majority by the longitudinal axon bundle. Further, no PNMT-IR cell bodies were detected in the hypothalamus even after colchicine treatment.

Adrenergic Fibers↗
PubMed1987

Descending phenylethanolamine-N-methyltransferase projections to the monkey spinal cord: an immunohistochemical double labeling study.

In the present study, we determined that a population of spinally projecting neurons in the monkey brainstem also contained the enzyme phenylethanolamine-N-methyltransferase (PNMT). Following bilateral placements of horseradish peroxidase (HRP) in the cervical spinal cord, brainstem sections containing retrogradely labeled cells were immunohistochemically stained for PNMT. Single labeled PNMT-positive cells were found in a distinctive pattern in the dorsomedial and ventrolateral medulla. A population of double labeled cells was observed in the latter group only. This population was dispersed among other single labeled HRP and single labeled PNMT neurons. Possible functional roles of descending PNMT cells include involvement in sympathetic control of cardiovascular mechanisms and/or tonic descending inhibition of dorsal horn neurons.

Animals↗
PubMed1987

Immunohistochemical evidence for the adrenergic medullary longitudinal bundle as a major ascending pathway to the locus coeruleus.

The present study describes the first experimental evidence for a direct projection of the medulla oblongata adrenergic (Ad) neurons to the rat pontine structures by using the indirect immunoperoxidase technique. Three weeks after unilateral electrolytic lesion of the longitudinal axon bundle in the medulla oblongata, the morphological changes of the phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive (IR) structures located in the rat brainstem have been analysed. In the lesioned rats we observed a decrease in the number of PNMT-IR structures in virtually all regions of the brainstem ipsilateral to the lesion, especially in the locus coeruleus (LC). These results indicate that the PNMT-IR terminal-like fibers of the LC are derived from the ipsilateral medulla oblongata Ad neurons and are mainly provided by the longitudinal axon bundle.

Adrenergic Fibers↗
PubMed1987

Electron-microscopic characterization of adrenergic axon terminals in the diencephalon of the rat.

The fine structure of adrenergic axon terminals was examined in the paraventricular nucleus of the thalamus (PNT) and in the hypothalamic arcuate nucleus-median eminence (ARC-ME) complex by use of phenylethanolamine-N-methyl transferase (PNMT) immunocytochemistry. In the PNT, immunoreactive terminals formed a dense and well-circumscribed plexus. In the ARC, labeled varicosities were less numerous and more evenly distributed. In the ME, they were scarce and confined to the inner zone. In all these areas, the diameter of immunoreactive varicosities ranged between 0.2 and 1.3 micron; in the ME and in the transitional zone between the ARC and the ME, a population of larger boutons (greater than 2 microns) was also visible. All immunoreactive varicosities exhibited densely packed small, clear vesicles associated with a few large granular vesicles. In the PNT and the ARC, but not in the ME, they formed synaptic contacts with dendritic elements and were occasionally apposed to neuronal cell bodies. These axo-somatic appositions showed no junctional specializations. In the ME and transitional zone, immunoreactive terminals were frequently juxtaposed to, and occasionally established differentiated synaptic contacts with, tanycytes. These data support a transmitter role for adrenaline in the diencephalon and suggest that adrenaline plays a role in hypothalamo-hypophysiotropic regulation through interactions with neural and glial elements.

Animals↗
PubMed1987

Catecholamine synthesizing enzyme activity in brainstem areas from victims of sudden infant death syndrome.

In order to investigate whether central catecholaminergic neurons are altered in sudden infant death syndrome (SIDS), the activities of dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) were determined in nine brainstem areas from 19 victims of totally unexplained SIDS (tSIDS), 9 victims of partially unexplained SIDS (pSIDS) and 8 control infants. The distinction between tSIDS and pSIDS was made according to the results of the autopsy. They were totally negative for the tSIDS victims, while minor pathological alterations were found in pSIDS victims. In both tSIDS and pSIDS victims, the PNMT activity was significantly decreased in the medullary C2m and C21 areas and in the nucleus medullae oblongatae centralis. In the C21 area only DBH activity was decreased. Further, in the nucleus ambiguus PNMT activity was decreased in tSIDS, while DBH was lowered in pSIDS victims. No significant modifications were found in the areas from the dorso-lateral pons (locus coeruleus, Kolliker Fuse and parabrachialis nuclei). Thus, in the two groups of SIDS victims the capacity to synthesize adrenaline was decreased in some medullary areas. It is considered that these biochemical alterations are related to the abnormal central respiratory and arousal control, which is thought to be present in SIDS.

Brain Stem↗
PubMed1986

Biochemical evidence for an interaction between adrenaline and noradrenaline neurons in the rat brainstem.

In this study, we sought to determine if there was an interaction between the C2 adrenaline-containing (A) neurons of the rat medulla oblongata and the noradrenaline-containing (NA) cell bodies of the locus coeruleus (LC). For this purpose, the biochemical response of the NA cell bodies of the LC after a lesion of the C2 region was studied by using as markers the in vitro activities of the catecholamine synthesizing enzymes: tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT). An increase in TH activity, not associated with any change in DBH or PNMT activity, was found in the LC (+104%, P less than 0.001) 4 days after a bilateral electrolytic lesion (3 mA for 5 s) of the C2 region. Conversely, the electrolytic lesioning of the neighboring A2 region of NA neurons did not modify the TH activity of the LC. These results suggest the existence of an ascending adrenergic inhibitory control of the NA cell bodies of the LC.

Afferent Pathways↗
PubMed1986

Regional specialization of the rat retina: catecholamine-containing amacrine cell characterization and distribution.

The distribution of catecholaminergic amacrine cells has been investigated in rats by means of immunohistochemical labelling of wholemounted retinas. Two groups of catecholamine-containing cells could be distinguished on the basis of their catecholamine and biosynthetic enzyme content. Both groups could be stained with an anti-tyrosine hydroxylase (TH) antiserum. The first group was composed of large, strongly TH-immunoreactive stellate amacrine cells, located principally in the innermost row of the inner nuclear layer (INL) and sending processes to the outermost sublamina of the inner plexiform layer (IPL). Some were displaced in the IPL or in the ganglion cell layer (GCL). This first group of cells can be regarded as dopaminergic since they were also stained by an anti-dopamine (DA) antiserum. The second group was composed of small, weakly TH-positive cell bodies, located slightly more sclerad within the INL. Their processes were usually not labelled with anti-TH. Identical cells could be better visualized with an anti-phenylethanolamine-N-methyltransferase (PNMT) antiserum. Their processes were observed in the middle sublamina of the IPL. A great number of these cells were displaced in the GCL. They could be regarded as epinephrine cells. Concerning the density and distribution throughout the retina a striking difference was observed between the superior and inferior halves of the retina, whereas a lower difference was observed between the nasal and temporal regions. Almost all the PNMT-immunoreactive cells were located throughout the upper retina, whereas the DA-cells were especially concentrated in the upper temporal quadrant. The distribution of the DA cells parallels that of the ganglion cells whose density is also maximal in the upper temporal retina.

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

Distribution of PNMT-immunoreactive neurons in the cat medulla oblongata.

The distribution and morphology of presumptive adrenaline neurons in the cat medulla oblongata were studied in conjunction with the indirect immunoperoxidase technique utilizing antibody raised against bovine adrenal phenylethanolamine-N-methyltransferase (PNMT), an enzyme which converts noradrenaline to adrenaline. Small PNMT-immunoreactive (IR) perikarya are located in the dorsomedial part of the medulla (C2 group) extending from P17 to P12, and larger ones in the ventrolateral part (C1 group) from P11 to P9 of the caudorostral extent. In the rostral medulla (P11-10), larger cells extended more dorsally in the lateral tegmental field, where only a few catecholamine cells are localized. No midline PNMT-IR cells were identified corresponding to C3 cell group in the rat. Distinct longitudinal PNMT-IR axon bundles can be traced through the dorsal part of the lateral tegmental field. Comments are made on the relative localizations of the PNMT-IR and DBH-IR cells, as well as on species differences in comparison with the results reported in the rat.

Adrenal Glands↗
PubMed1986

Co-localization of tyrosine hydroxylase and phenylethanolamine-N-methyltransferase immunoreactivity in the rat retina: a re-examination using double labeling on semi-thin sections.

The precise morphology and distribution of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive cells has been observed and compared with the previously described tyrosine hydroxylase (TH)-immunoreactive cells, in the rat retina. The PNMT-positive cells are small amacrine neurons, located either in the inner nuclear layer or in the ganglion-cell layer. They send processes mainly to the middle sublayer and to a lesser extent to the outermost sublayer of the inner plexiform layer. They resemble the small TH-positive bouquet cells described previously. In order to ascertain the relationship between PNMT-positive cells and TH-positive bouquet cells, a double immunohistochemical labeling technique, using anti-TH and anti-PNMT antisera, has been developed on semi-thin sections. The result of these experiments clearly indicate that the populations of TH-positive cells and PNMT-positive (presumably epinephrinergic) cells are separated. The absence of TH enzyme in the PNMT-positive cells raises the question of the enzymatic activity of PNMT, which appears to be different from the classical pathway of catecholamine biosynthesis in the retina.

Animals↗