Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possible role that the hypothalamic arcuate nucleus might play in mediating the increase in paraventricular nucleus corticotropin-releasing hormone mRNA levels following adrenalectomy was investigated in two series of experiments. In the first series in situ hybridization histochemistry was used to quantify levels of eight accurate nucleus neuropeptide and neurotransmitter mRNAs in neurons that potentially relay adrenal steroid feedback to the paraventricular nucleus. In the second series of experiments, arcuate neuropeptidergic projections to the hypothalamic paraventricular nucleus were characterized using retrograde tracing in combination with in situ hybridization histochemistry. Despite an increase in paraventricular nucleus corticotropin-releasing hormone (60%) and pituitary proopiomelanocortin mRNA levels (sixfold), arcuate mRNA levels for proopiomelanocortin, neuropeptide Y, somatostatin, galanin, dynorphin, tyrosine hydroxylase, glutamate decarboxylase, and the glucocorticoid receptor were unchanged 14 days following adrenalectomy. Neuropeptidergic characterization of arcuatoparaventricular projections was achieved by injection of the retrograde tracer fluorogold into the paraventricular nucleus; retrogradely labeled neurons were characterized with polyclonal antisera against fluorogold in combination with oligonucleotide probes directed against neuropeptide Y, proopiomelanocortin, or somatostatin. Out of these three arcuate neuropeptide Y mRNA was contained in 18% of the fluorogold-positive neurons in the arcuate, proopiomelanocortin mRNA was contained in 8%, and somatostatin mRNA was contained in 6%. Overall, the results from both experiments suggest that the arcuatoparaventricular neuropeptide Y, proopiomelanocortin, and somatostatin projections are not sensitive to a chronic (14 day) lack of adrenal steroids. These projections as well as the other arcuate neurotransmitter and neuropeptide systems appear not to contribute to the persistent elevations in paraventricular nucleus corticotropin-releasing hormone mRNA levels or pituitary proopiomelanocortin mRNA levels found in 14 day adrenalectomized rats.
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PMID:Arcuate nucleus neurons that project to the hypothalamic paraventricular nucleus: neuropeptidergic identity and consequences of adrenalectomy on mRNA levels in the rat. 759 46

1. The aim of this study was to investigate the neurochemical effects and measure the anatomical spread of infusion of c-fos antisense (AS) DNA into the striatum. 2. Rats were anesthetized and infused in opposing striata with c-fos AS and c-fos sense (S) DNA. Ten hours later they were injected with apomorphine (2 mg/kg, i.p.) and 20 min later they were overdosed with sodium pentobarbital and their brains either perfused or frozen. Vibratome-cut sections were immunostained for the detection of c-fos, JunB, Krox 24, somatostatin, substance P, dynorphin, tyrosine hydroxylase, and enkephalin. Cryostat-cut sections from the caudate were immunostained for the detection of c-fos, JunB, and Krox 24, as well as in situ hybridization for proenkephalin mRNA. Sections from the globus pallidus were used for the autoradiographic localization of D2 dopamine and A2a adenosine receptors. Sections from the substantia nigra were used for the autoradiographic localization of D1 dopamine and cannabinoid receptors. A second group of rats were injected in opposing striata with biotin-labeled c-fos AS DNA and c-fos S DNA. Ten hours later they were challenged with apomorphine (2 mg/kg, i.p.) and 20 min later brains were either perfused or frozen. Sections from these brains were cut throughout the rostral-caudal extent of the forebrain and the biotin labeled AS DNA was localized. 3. Krox 24 was expressed at high levels on the sense side of the brain in the striatum and overlying neocortex. However, on the AS-injected side there was a reduction in Krox 24 expression in striatum and overlying cortex. The biotin-labeled AS studies confirmed that the striatal infusion spread throughout the dorsal striatum as well as the overlying neocortex. We did not detect any changes in neurotransmitter receptors, neuropeptides, or tyrosine hydroxylase in AS/S-injected rat brains. 4. These results demonstrate that c-fos AS reduces Krox 24 expression in striatal and neocortical neurons but does not change the expression of a number of other proteins involved in basal ganglia function. Whether this effect is due to nonspecific actions of c-fos AS or to its effects on a component of the transduction pathway responsible for basal Krox 24 expression (NMDA receptors?) is unknown.
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PMID:c-fos antisense reduces expression of Krox 24 in rat caudate and neocortex. 762 2

Although oligonucleotide probes are useful for in situ hybridization, their low sensitivity compared to riboprobes and cDNA remains a problem. We have systematically examined the protocols to provide a general procedure that increases the sensitivity of oligoprobes for light and electron in situ hybridizations by using mixtures of multiple non-overlapping oligonucleotides (multi-oligoprobes). The protocol achieves these improvements with both radioactive and non-radioactive oligoprobes. With 33P-labeled probes in a semiquantitative assay, we found that mixtures of up to six vasopressin-directed multi-oligoprobes, each employed at saturating concentration, led to an additive signal with no significant increase of the background. Using this approach with non-radioactive oligoprobes, we were able to detect in the hypothalamus several low or moderately abundant mRNAs, such as vasopressin heterogeneous nuclear RNA and the galanin, dynorphin, and tyrosine hydroxylase mRNAs. Moreover, we showed that multi-oligoprobes used in a pre-embedding procedure were suitable for studying the ultrastructural compartmentalization of moderately abundant mRNAs. Finally, with the same basic approach we demonstrated that two sets of multi-oligoprobes can be combined for simultaneous detection of two different mRNAs using fluorescent dyes, making this approach suitable for high-resolution confocal analyses. Overall, our data demonstrate that multi-oligoprobes provide a sensitive tool of choice for various applications in which both well-preserved morphology and high sensitivity are needed. In particular, these probes appear ideal for study of the comparative subcellular localization of mRNAs at both the light and the electron microscopic level.
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PMID:Enhanced sensitivity for light and electron microscopic in situ hybridization with multiple simultaneous non-radioactive oligodeoxynucleotide probes. 762 44

Four types of substance P-immunoreactive structures have been distinguished in the rat superior cervical ganglion by double-immunofluorescence microscopy: (1) A major population of mainly varicose fibres enmeshed singly-scattered neuronal perikarya, some of which contained vasoactive intestinal polypeptide-immunoreactivity. These substance P-immunoreactive fibres did not contain colocalized calcitonin gene-related peptide (CGRP) and were absent after transection of the cervical sympathetic trunk. (2) A rather small substance P-immunoreactive fibre population with colocalized calcitonin gene-related peptide-immunoreactivity was distributed in a patchy manner and disappeared after cutting the postganglionic branches. (3) Most of the intraganglionic small intensely fluorescent (SIF) cell clusters were intensely substance P-immunoreactive. SIF cells were not visibly changed in number and fluorescence intensity by either surgical procedure. (4) Immunoreactivity was not visible in principal ganglionic neurons of control ganglia, but occurred in cell bodies after pre- as well as after postganglionic nerve transection. Some of the substance P-immunolabelled perikarya in addition revealed immunostaining to antisera against the catecholamine-synthesizin enzyme tyrosine hydroxylase or against the neuropeptides leu-enkephalin and vasoactive intestinal polypeptide, respectively. The results strongly suggest that, in addition to a substance P-containing preganglionic input (1), and a supply by substance P-containing sensory axon collaterals (2), the superior cervical ganglion of the rat gives origin to a paraganglionic (3) and a postganglionic (4) substance P-immunoreactive intrinsic system, the latter becoming visible only after disconnection of the sympathetic pathway.
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PMID:Immunohistochemical evidence from co-localization and denervation studies for four types of substance P-containing nervous structures in the rat superior cervical ganglion. 768 95

Applying double-labelling immunofluorescence, the peptide content of solitary and clustered small intensely fluorescent (SIF) cells, identified by an antiserum to a selective membrane glycoprotein marker, synaptophysin, was correlated with the presence of catecholamines in the rat superior cervical ganglion. Most of synaptophysin-immunoreactive solitary and clustered SIF cells apparently contained dopamine (indicated by tyrosine hydroxylase-TH) but not noradrenaline (indicated by dopamine-beta-hydroxylase-DBH). Frequently, immunoreactivities for substance P or rarely, neuropeptide Y were colocalized in TH-immunolabeled cells of both types. Immunostaining for vasoactive intestinal polypeptide was found only in solitary SIF cells and was visible in TH-immunoreactive, as well as in TH-nonreactive cells. Very few solitary SIF cells were TH- and DBH-immunoreactive. Solitary and clustered SIF cells, as a rule, were encircled by leu-enkephalin-positive fibres which were also met-enkephalin-arg6-phe7-immunoreactive, indicating proenkephalin as precursor. SIF cells were additionally approached by varicose fibres which contained immunoreactivity for calcitonin gene-related peptide (CGRP) but not for enkephalins. As observed by immuno-electronmicroscopy, fibres that were immunostained for leu-enkephalin or CGRP, deeply invaginated into SIF cell somata. In addition to close membrane appositions, CGRP-immunolabeled fibres exhibited efferent synaptic contacts wih elements of SIF cell clusters. SIF cells were non-reactive to enkephalin-antisera in control ganglia and after transection of the postganglionic nerves (axotomy); but both types exhibited leu-enkephalin in preganglionically transected ganglia (decentralization) in which enkephalin-immunoreactive fibre baskets were absent. Synthesis of enkephalin in SIF cells after decentralization was confirmed by in situ hybridization demonstrating intracytoplasmic proenkephalin messenger-RNA. The findings are indicative for a differential neurochemical equipment of SIF cells in the rat superior cervical ganglion, which mainly is independent to a topographical classification. Moreover, they demonstrate the involvement of two neuropeptides in preganglionic SIF cell innervation. Finally, the observations indicate the capacity of SIF cells for proenkephalin-expression in response to preganglionic denervation.
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PMID:Neurochemistry, connectivity and plasticity of small intensely fluorescent (SIF) cells in the rat superior cervical ganglion. 768 94

Dynorphin and alpha-neoendorphin bind to the kappa subtype of opioid receptors and have been shown to inhibit the release of noradrenaline from cardiac sympathetic axons. The purpose of this study was to elucidate the endogenous localization of dynorphin and alpha-neoendorphin in the guinea pig heart. This goal was achieved by double- and triple-labelling immunofluorescence. Dynorphin- and alpha-neoendorphin-immunoreactive nerve fibers were numerous around coronary blood vessels and among cardiomyocytes. They also contained immunoreactivities to the rate-limiting enzyme of catecholamine synthesis tyrosine hydroxylase and to neuropeptide Y. These fibers disappeared in response to chemical sympathectomy (6-hydroxydopamine treatment). In contrast, substance P/calcitonin gene-related peptide-immunoreactive axons of sensory origin did not contain dynorphin and alpha-neoendorphin immunoreactivities and were unaffected by chemical sympathectomy. The findings demonstrate that immunoreactive dynorphin and alpha-neoendorphin are contained in postganglionic sympathetic nerve fibers innervating coronary blood vessels and cardiac muscle. Therefore, the inhibitory effect of these peptides upon noradrenaline release from the sympathetic terminal may well be an autoinhibitory feedback loop.
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PMID:Sympathetic noradrenergic fibers as the source of immunoreactive alpha-neoendorphin and dynorphin in the guinea pig heart. 770 29

Differences in behavioral and neurochemical responses to drugs of abuse and environmental stress have been observed between rats that have a greater locomotor response in a novel environment (high responders: HR) compared to those that have a low response to novelty (low responders: LR). This study examined nuclei associated with the nigrostriatal and mesolimbic systems for differences in mRNA content between HR and LR using Northern blot analysis. These brain regions were chosen because of their role in both drug abuse and stress responses. The mRNAs examined code for either peptide transmitters that interact with the dopaminergic system or components of the dopaminergic system that have not been previously examined for differences between HR and LR. HR rats had approximately 50% lower levels of mRNA for beta-preprotachykinin (PPT) in the core of the nucleus accumbens (NACC) compared to LR. No differences between HR and LR in mRNA levels for dynorphin (DYN), preproenkephalin (PPE), glutamic acid decarboxylase (GAD) or neurotensin (NT) were observed in the core of the NACC. In the shell region of the NACC, HR exhibited a 25% reduction in the level of mRNA for NT compared to LR. No differences between HR and LR in mRNA levels for PPT, DYN, PPE or GAD were observed in the shell of the NACC. In the medial frontal cortex and the dorsal striatum, no differences between HR and LR in mRNA levels for PPT, DYN, PPE, GAD or NT were found. In the substantia nigra and ventral tegmental area no differences between HR and LR in mRNA levels for tyrosine hydroxylase, GAD, cholecystokinin, or NT were noted.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The relationship between MRNA levels and the locomotor response to novelty. 787 16

Dynorphin facilitates conditioned place aversion and reduces locomotor activity through mechanisms potentially involving direct activation of target neurons or release of catecholamines from afferents in the nucleus accumbens. We examined the ultrastructural substrates underlying these actions by combining immunoperoxidase labeling for dynorphin 1-8 and immunogold silver labeling for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). The two markers were simultaneously visualized in single coronal sections through the rat nucleus accumbens. By light microscopy, dynorphin immunoreactivity was seen as patches of immunoreactive varicosities throughout all rostrocaudal levels of the nucleus accumbens. The dynorphin-immunoreactive terminals identified by electron microscopy ranged from 0.2 to 1.5 microns in cross-sectional diameter, contained numerous small (30-40 nm) clear vesicles, as well as one or more large (80-100 nm) dense core vesicles. From the dynorphin-immunoreactive terminals quantitatively examined in single sections, 74% (173/370) showed symmetric synaptic junctions mainly with large unlabeled dendrites. Of the dynorphin-immunoreactive terminals forming identifiable synapses, approximately 30% contacted more than one dendritic target. In addition, single dendrites frequently received convergent input from more than one dynorphin-labeled terminal. Irrespective of their dendritic associations, dynorphin-immunoreactive terminals also frequently showed close appositions with other axons and terminals; these included unlabeled (41%), TH-labeled (10%) or dynorphin-labeled axons (14%). In contrast to dynorphin-immunoreactive terminals, TH-labeled terminals formed primarily symmetric synapses with small dendrites and spines or lacked recognizable specializations in the plane of section analyzed. In some cases, single dendrites were postsynaptic to both dynorphin and TH-immunoreactive terminals. We conclude that dynorphin-immunoreactive terminals potently modulate, and most likely inhibit, target neurons in both subregions of the rat nucleus accumbens. This modulatory action could attenuate or potentiate incoming catecholamine signals on more distal dendrites of the accumbens neurons. The findings also suggest potential sites for presynaptic modulatory interactions involving dynorphin and catecholamine or other transmitters in apposed terminals.
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PMID:Dynorphin-immunoreactive terminals in the rat nucleus accumbens: cellular sites for modulation of target neurons and interactions with catecholamine afferents. 791 9

Heart rate is regulated by the autonomic nervous system but little is known about the pattern of innervation of the pacemaker in the sinoatrial node, or the subpopulations of nerves involved. Therefore in this study the pacemaker was located using electrophysiological methods and the pattern of innervation established by cholinesterase staining. In subsequent experiments, subpopulations of sympathetic, sensory and parasympathetic nerves were identified. Sympathetic nerves were labelled by glyoxylic acid-induced catecholamine fluorescence or an antiserum raised against tyrosine hydroxylase (TH). These experiments showed that the entire sinoatrial node was densely innervated by sympathetic axons, the majority of which were immunoreactive for neuropeptide Y (NPY). There were a few axons which were only immunoreactive for TH. Sensory nerves which were immunoreactive for both substance P (SP) and calcitonin gene-related peptide (CGRP) were also found throughout the sinoatrial node. In the absence of a selective marker for parasympathetic neurons, hearts were extrinsically denervated by placing them in organotypic culture to allow degeneration of extrinsic axons. In this way intrinsic parasympathetic neurons could be characterised. These experiments revealed several distinct populations of parasympathetic nerves which innervated only a small, discrete part of the sinoatrial node. These populations were immunoreactive for NPY, somatostatin (SOM) or vasoactive intestinal peptide (VIP) alone, or SOM combined with NPY, SOM with dynorphin B, and SOM with SP. These results highlight a remarkable difference in the pattern of innervation of the sinoatrial node by the sympathetic and parasympathetic nervous systems. Furthermore the presence of several distinct populations of autonomic cardiac neurons indicates a further complexity in neuronal regulation of heart rate.
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PMID:Innervation of the pacemaker in guinea-pig sinoatrial node. 801 78

Dynorphin and other kappa opioid agonists are thought to elicit aversive actions and changes in motor activity through direct or indirect modulation of dopamine neurons in ventral tegmental area (VTA) and substantia nigra (SN), respectively. We comparatively examined the immunoperoxidase localization of anti-dynorphin A antiserum in sections through the VTA and SN of adult rat brain to assess whether there were common or differential distributions of this opioid peptide relative to the dopamine neurons. We also more directly examined the relationship between dynorphin terminals and dopamine neurons in VTA and SN by combining immunoperoxidase labeling of rabbit dynorphin antiserum and immunogold-silver detection of mouse antibodies against tyrosine hydroxylase (TH) in single sections through the VTA and SN. Light microscopy showed dynorphin-like immunoreactivity (DY-LI) in varicose processes. These were relatively sparse in VTA and were unevenly distributed in the SN, with little labeling in the pars compacta (pcSN) and the highest density of DY-LI in the medial and lateral pars reticulata (prSN). Electron microscopy established that the regional differences were attributed to differences in density (number/unit area) of immunoreactive profiles. The profiles containing DY-LI were designated as axon terminals based on having diameters greater than 0.1 micron, few microtubules and many synaptic vesicles. In both the VTA and SN, the dynorphin-labeled terminals contained primarily small (35-40 nm) clear vesicles. These vesicles were rimmed with peroxidase immunoreactivity and were often seen clustered above axodendritic synapses. These synaptic specializations were usually symmetric; however a few asymmetric densities also were formed by immunoreactive terminals in both VTA and SN. Additionally, most of the dynorphin-labeled terminals contained 1-2, but occasionally 7 or more intensely peroxidase positive dense core vesicles (DCVs). Approximately 60% of the DCVs were located near axolemmal surfaces. The axolemmal surfaces contacted by immunoreactive DCVs were more often apposed to dendrites in the VTA; while in the SN other axon terminals were the most commonly apposed neuronal profiles. In both regions, a substantial proportion of the plasmalemmal surface in contact with the labeled DCVs was apposed to astrocytic processes.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Cellular substrates for interactions between dynorphin terminals and dopamine dendrites in rat ventral tegmental area and substantia nigra. 809 30


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