Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The afferent projections to the anterior medial preoptic area (MPA) from the brainstem have been studied, in female Wistar rats, by retrograde tracing with horseradish peroxidase (HRP). The HRP was injected by iontophoresis into the preoptic region containing the luteinizing hormone-releasing hormone (LHRH) perikarya. The brain sections including the MPA were reacted with diaminobenzidine (DAB) to reveal the injection site; the LHRH cells were then immunohistochemically identified using DAB with ammonium nickel sulphate. When the injection site incorporated the LHRH cells, the brainstem sections were reacted with the DAB nickel solution to detect lysosomal HRP and then immunohistochemically processed to locate the adrenaline-synthesizing cells using DAB alone. The results confirm the brainstem projections to the MPA from the central grey matter, ventral tegmental area, subcoeruleus area, the dorsal raphe nucleus, the lateral parabrachial nucleus, the raphe pontis nucleus, the raphe obscurus nucleus, the region of the paragigantocellular nucleus and the nucleus of the solitary tract. Given the considerable evidence implicating the ascending adrenergic systems in the regulation of LHRH, we focused our attention on the afferents from the locus coeruleus, area postrema and the adrenaline-synthesizing cell groups (C1-3). The only cells which were retrogradely labelled and immunopositive for phenylethanolamine N-methyltransferase were found in C3.
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PMID:Brainstem projections to the medial preoptic region containing the luteinizing hormone-releasing hormone perikarya in the rat. An immunohistochemical and retrograde transport study. 140 78

We have investigated the effect of adrenocorticotrophic hormone (ACTH) replacement after fetal hypophysectomy on the pattern of localization of enkephalin-containing peptides (enkephalins) and phenylethanolamine N-methyltransferase (PNMT) in the fetal sheep adrenal. We have also investigated the relative roles of the fetal pituitary and adrenal cortex in determining the extent of the interdigitation of the peripheral adrenaline (AD)-containing cells of the adrenal medulla with the inner zones of the adrenal cortex in the late gestation fetus. Fetal hypophysectomy (Hx; n = 12) or sham operations (n = 8) were performed at 109-118d. At 138 or 139d, ACTH (1-24) (10.5 micrograms/h) was infused intravenously for 72 h into 4 Hx fetuses (Hx + ACTH group). Saline was infused for 72 h into 4 Hx fetuses (Hx + Sal) and into 4 sham-operated fetal sheep (Intact + Sal). Fetal adrenal glands were collected at autopsy from 141/2d Intact + Sal, Hx + Sal and Hx + ACTH groups, from 4 intact fetal sheep at 145-147d gestation (145/7d Intact group) and 4 Hx fetal sheep at 147-164d gestation (147/64d Hx group). Adrenals were also collected from 4 newborn lambs at 10-12d after birth (10/12d Newborn group). Using the peroxidase-antiperoxidase immunocytochemical staining method, sections of adrenal glands (10-12 microns) from all groups were stained anti-PNMT. Sections of adrenal glands from the 141/2d groups were also stained separately with anti-dopamine-beta-hydroxylase (anti-D beta H) and anti-enkephalin (anti-ENK).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Different roles for the pituitary and adrenal cortex in the control of enkephalin peptide localization and cortico-medullary interaction in the sheep adrenal during development. 164 53

The presence of an adrenergic projection from the nucleus of the tractus solitarius (NTS) to the parabrachial nucleus (PB) was demonstrated by the immunocytochemistry combined with a retrograde tracing method. Numerous neurons containing both phenylethanolamine N-methyltransferase, a marker for adrenaline, and wheat germ agglutinin-conjugated horseradish peroxidase, a retrograde tracer, were detected in the dorsolateral part of the NTS at the level of the area postrema after injection of the tracer into the dorsal PB.
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PMID:Adrenergic projection from the caudal part of the nucleus of the tractus solitarius to the parabrachial nucleus in the rat: immunocytochemical study combined with a retrograde tracing method. 246 Jan 90

The somatic pressor reflex (SPR) elicited in anesthetized paralyzed rats by electrical stimulation of the sciatic or sural cutaneous afferent nerves produced an increase in arterial pressure ranging from 5 to 40 mmHg. Stimulation of femoral or tibial afferent nerves from muscle produced a depressor response. The SPR was not affected by midpontine transection but was eliminated either by hemisection of the lumbar spinal cord contralateral, but not ipsilateral, to the stimulated nerve or by electrolytic or kainic acid lesion of the contralateral, but not ipsilateral, rostral ventrolateral medulla (RVL). Stimulation of the brachial plexus elicited an SPR that was not eliminated by contralateral lumbar hemisection but was abolished by RVL lesion. RVL lesions consistently overlapped areas containing phenylethanolamine N-methyltransferase-labeled C1 adrenergic neurons. Kainic acid injections into the lateral reticular nucleus (LRN) did not affect the SPR. Neither contralateral nor ipsilateral electrolytic lesions of other autonomic areas including parabrachial nucleus, the nucleus tractus solitarii, the A5 region, or the inferior cerebellar peduncle (output pathway of the LRN) affected the reflex. In axonal transport studies using horseradish peroxidase, afferent terminals of the sciatic nerve were shown to overlap spinoreticular neurons in the dorsal horn retrogradely labeled from tracer injections in the RVL. We conclude that the SPR can be elicited in rats, that it is mediated by spinoreticular afferents traveling in the contralateral spinal cord, and that the C1 adrenergic area of the RVL is a critical region for the integration of the somatic pressor reflex.
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PMID:Neurons of rostral ventrolateral medulla mediate somatic pressor reflex. 246 48

Adrenergic neurons in the C1 region in the ventrolateral medulla oblongata send descending axons into spinal cord which terminate in thoracic and upper lumbar segments, overlapping the distribution of sympathetic preganglionic neurons. The present study was undertaken to determine whether adrenergic fibers synapse directly on preganglionic neurons which innervate the adrenal medulla and to examine the ultrastructure of these fibers during development. The ultrastructure and synaptology of adrenergic axons in the intermediolateral nucleus of mid-thoracic spinal cord were studied in 7-, 9-, 24-, 30-, 60-, and 90-day-old rats using immunocytochemical staining for phenylethanolamine N-methyltransferase, the epinephrine-synthesizing enzyme. Phenylethanolamine N-methyltransferase-immunoreactivity was observed in the cytoplasm of unmyelinated axonal varicosities and intervaricose segments in the neuropil of intermediolateral nucleus. Phenylethanolamine N-methyltransferase-immunoreactive synaptic boutons were filled with spherical electron-lucent vesicles and occasional larger dense-core vesicles. These boutons were observed to form symmetrical synaptic contacts with dendritic processes at all ages examined. Asymmetrical synapses on dendrites were also observed in adult rats. Axosomatic synaptic contacts were frequently observed in immature rats, but were never observed in adult rats. To determine whether adrenergic axons synapse on preganglionic neurons which project to the adrenal medulla, adrenal preganglionic neurons were retrogradely labeled with horseradish peroxidase and adrenergic axons were stained for phenylethanolamine N-methyltransferase-immunoreactivity. In young rats, phenylethanolamine N-methyltransferase-immunoreactive boutons were observed to form symmetrical axosomatic and axodendritic synaptic contacts with adrenal preganglionic neurons in intermediolateral nucleus. These contacts had already formed by postnatal day 7, the youngest age studied. In contrast, it was not possible to verify that adrenal preganglionic neurons receive adrenergic innervation in adult rats, since phenylethanolamine N-methyltransferase-immunoreactive boutons were only observed in contact with small diameter dendrites that were not retrogradely labeled by horseradish peroxidase. These studies demonstrate that adrenal preganglionic neurons receive adrenergic synapses prior to the first postnatal week. The initial synapses which form on preganglionic somata and proximal dendrites appear to reorganize late in development. It is suggested that these become more distally located as the dendritic tree matures. More generally, these observations suggest that adrenergic bulbospinal neurons are involved in central regulation of adrenal development and function.
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PMID:Phenylethanolamine N-methyltransferase-immunoreactive terminals synapse on adrenal preganglionic neurons in the rat spinal cord. 258 60

Adrenaline and gamma-aminobutyric acid (GABA) have been implicated in autonomic functions involving the intermediate and caudal portions of the medial nuclei of the solitary tracts (m-NTS). We sought to determine whether there was a cellular basis for direct intracellular or synaptic interactions between these transmitters in neurons in the m-NTS of rat brain by using dual-labeling immunocytochemical methods. Light microscopy revealed immunoautoradiographic labeling for the adrenaline-synthesizing enzyme phenylethanolamine N-methyltransferase (PNMT) in perikarya and processes in close proximity to cells demonstrating peroxidase reaction product for GABA. Electron microscopy of the intermediate m-NTS at the level of the area postrema further established the localization of immunoautoradiographic and peroxidase labels for PNMT and GABA in common as well as separate perikarya and dendrites. All axon terminals were labeled separately for PNMT and GABA. The PNMT-labeled terminals formed both symmetric and asymmetric synapses, whereas the GABA-labeled terminals formed exclusively symmetric synapses. Twenty-four percent (n = 42) of the PNMT- and 39% (n = 128) of the GABA-labeled terminals formed synaptic junctions on unlabeled soma and dendrites. Occasionally both types of terminals converged on a common unlabeled dendrite and on GABA-labeled dendrites. Only 3% of the PNMT- and 12% of the GABA-containing terminals formed synapses on PNMT-labeled soma and dendrites, whereas 7% of each type formed synapses with GABA-labeled profiles. The remaining labeled terminals lacked synaptic relations within the sections examined. The autoradiographic results were confirmed and extended by means of immunogold labeling for PNMT in combination with peroxidase-antiperoxidase localization of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD). GAD-labeled terminals formed symmetric synapses with dendrites that were either unlabeled or contained low levels of PNMT (gold particles) or PNMT and GAD. We conclude that in caudal, more cardiovascular portions of the NTS, adrenaline and GABA may coexist, but they are more commonly detected in separate populations of neurons having receptive sites for both transmitters and innervating certain common target neurons.
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PMID:Cellular substrates for interactions between neurons containing phenylethanolamine N-methyltransferase and GABA in the nuclei of the solitary tracts. 279 19

Co-localization of neurotensin and cholecystokinin in tyrosine hydroxylase-containing neurons in the nucleus tractus solitarius of the rat was demonstrated by immunocytochemistry with fluorescent double-staining combined with the peroxidase-antiperoxidase method. Co-localization of neurotensin/tyrosine hydroxylase or cholecystokinin/tyrosine hydroxylase was consistently found in small neurons in the region dorsomedial to the tractus solitarius at the level of the area postrema with high percentages of co-existence: 91.0% tyrosine hydroxylase-immunoreactive neurons contained neurotensin and 91.1% cholecystokinin, suggesting that they represent the same neurons. Accordingly, co-localization of neurotensin and cholecystokinin was assessed on tyrosine hydroxylase-containing neurons bisected into two adjacent sections, and then identified in a certain number of the catecholamine neurons in this region. Furthermore these catecholamine neurons exhibited immunoreactivity for an adrenaline-synthesizing enzyme, phenylethanolamine N-methyltransferase. It was concluded that catecholamine, in particular adrenaline, neurons, characterized by co-localization of neurotensin and cholecystokinin, established a distinct subpopulation in the catecholaminergic system in the dorsomedial medulla of the rat.
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PMID:Co-localization of neurotensin- and cholecystokinin-like immunoreactivities in catecholamine neurons in the rat dorsomedial medulla. 289 90

Adrenergic afferents from the rostral ventrolateral medulla are known to modulate the activity of noradrenergic neurons of the locus coeruleus (LC). The light and electron microscopic localization of a polyclonal antiserum directed against the adrenaline synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT) was used to determine the identity and targets of the adrenergic afferents to the LC of the rat brain. By light microscopy, varicose processes showing intense PNMT-like immunoreactivity (LI) were seen throughout the neuropil surrounding neuronal perikarya which in adjacent sections were shown to contain immunoreactivity for the noradrenaline synthesizing enzyme, dopamine-beta-hydroxylase. Electron microscopy confirmed that these labeled varicose processes were primarily axon terminals. Terminals containing PNMT-LI constituted 30% (141 out of 464) of all identifiable terminals within the LC. These terminals were 0.5-1.8 micron in diameter and contained many small, clear and from 2 to 10 larger dense-core vesicles. The targets of the terminals with PNMT-LI were principally unlabeled (i.e. non-PNMT-containing) perikarya and dendrites. The synaptic junctions on perikarya were rare and exclusively symmetric; whereas, those on proximal (large) dendrites were somewhat more numerous and included symmetric as well as asymmetric membrane specializations. However, the vast majority (85% from a total of 141) of the terminals with PNMT-LI formed asymmetric synaptic junctions on unlabeled distal (small) dendrites and dendritic spines. In rare instances, the PNMT-immunoreactive terminals also formed synaptic junctions with other similarly labeled terminals. These findings provide the first ultrastructural evidence that adrenergic terminals in the LC (1) are one of the more prevalent synaptic inputs to the principally noradrenergic neurons; (2) have both symmetric and asymmetric synaptic specializations conventionally associated with inhibition and excitation, respectively; and (3) may modulate other adrenergic terminals through presynaptic mechanisms. In addition to the varicose processes, light microscopy revealed diffuse PNMT-LI throughout the LC. The ultrastructural correlate of this labeling was seen as patches of peroxidase product within the cytoplasm of a few perikarya and dendrites and throughout the cytoplasm of astrocytes identified by their discrete bundles of microfilaments. The detection of PNMT-LI in cells that are not known to synthesize adrenaline is surprising and suggests either a functional diversity for PNMT or amino acid sequence homologies with related enzymes which are enriched in the LC.
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PMID:Ultrastructural localization of phenylethanolamine N-methyltransferase-like immunoreactivity in the rat locus coeruleus. 292 6

Atrial natriuretic polypeptide (ANP)-like immunoreactivity was found in the rat adrenal gland by using indirect immunofluorescence and peroxidase-antiperoxidase techniques. ANP-like immunostaining was present in most of chromaffin cells with varying degrees of immunoreactivity. The majority of medullary cells displayed very intense immunostaining, and several clusters revealed weaker immunostaining. No staining was found in the adrenal cortex or in the nerve fibers in this organ. In the consecutive sections treated for dopamine-beta-hydroxylase (DBH), apparently all medullary cells had intense immunofluorescence for DBH and its distribution pattern was very similar to that for ANP-like immunoreactivity. While phenylethanolamine N-methyltransferase (PNMT) immunoreactive cells largely corresponded to the intensely stained ANP-like immunoreactive cells, suggesting that adrenaline cells contained a large amount of ANP-like substance, noradrenaline cells contained a smaller amount of this substance than adrenaline cells. Ultrastructural study showed that end-products due to the immunoreaction with the ANP antiserum were primarily associating with chromaffin granules. In addition, the presence of ANP-like immunoreactivity was investigated in several sympathetic ganglia of the rat. No principal ganglion cells were ANP-positive, whereas a few small intensely fluorescent (SIF) cells were ANP-immunoreactive. The present findings suggest that catecholamines coexist with ANP which has a natriuretic and vasodilating effect, in adrenal medullary cells and SIF cells in several rat sympathetic ganglia, but not in principal ganglion cells.
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PMID:Immunoreactive atrial natriuretic polypeptides in the adrenal medulla and sympathetic ganglia. 294 73

The electron microscopic localization of the adrenaline-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT) was examined in the rostral ventrolateral medulla (RVL) of adult rats. The brains were fixed by perfusion with 3.75% acrolein and 2.0% paraformaldehyde in phosphate buffer. Coronal Vibratome sections through the RVL were immunocytochemically labeled using a rabbit polyclonal antiserum to PNMT and the peroxidase-antiperoxidase method. A semi-quantitative ultrastructure analysis revealed that the perikarya constituted 9% of the total immunoreactive profiles observed in the RVL. The labeled somata were large (18-24 microns) and were characterized by an indented nucleus and abundant cytoplasm with numerous mitochondria. An average of 136.8 +/- 11.6 mitochondria were present per 100 microns2 cytoplasm, which is 38% greater than the numbers found for PNMT-immunoreactive neurons in the nucleus of the solitary tract. Moreover, the labeled somata were often found in direct apposition to the basal lamina of small capillaries and neighboring astrocytic processes. The remaining labeled profiles were neuronal processes of which 72% were dendrites. Both the PNMT-labeled somata and dendrites received primarily symmetric contacts from unlabeled axon terminals. Only a few axons and terminals containing immunoreactivity for PNMT were observed. The axons were both unmyelinated and myelinated. The PNMT-immunoreactive terminals were characterized by a mixed population of vesicles and by the formation of synaptic junctions with both unlabeled dendrites and PNMT-labeled perikarya and dendrites. The ultrastructural morphology and proximity to blood vessels and glia suggest a high metabolic activity and possibly a chemosensory function of PNMT neurons in the RVL. The existence of myelinated and unmyelinated axons could imply that PNMT-containing neurons have different conduction velocities in efferent pathways to the spinal cord or other brain regions. Furthermore, the multiple types of synaptic interactions between labeled and unlabeled axons and dendrites support the concept that adrenergic neurons modulate and are modulated by neurons containing the same or other putative transmitters in the RVL.
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PMID:Phenylethanolamine N-methyltransferase-containing neurons in the rostral ventrolateral medulla of the rat. I. Normal ultrastructure. 330 Aug 45


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