Competitive inhibition of pryidoxal phosphate action by toxopyrimidine phosphate in the tyrosine decarboxylase system.
Explore the source record for details and available documents.
SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
The coexistence of immunoreactivities for glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) and substance P (SP) was revealed in the hamster main olfactory bulb, using the peroxidase-antiperoxidase immunohistochemical method. Adjacent 40 micron thick Vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning were identified at the paired surfaces of two consecutive sections. The coexistence of the immunoreactivities for 1) TH and GAD, 2) TH and SP and 3) GAD and SP in the same cells could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. About 70% of TH-like immunoreactive (TH-LI) neurons in the periglomerular region also contained GAD-like immunoreactivity, whereas about 45% of GAD-LI ones were also TH-like immunoreactive. Furthermore, almost all (more than 95%) of SP-LI neurons contained both GAD-like and TH-like immunoreactivities. These observations indicate that in the periglomerular region of the hamster main olfactory bulb, some neurons (about 9% of all neurons containing TH-like and/or GAD-like immunoreactivities) may contain three different categories of neuroactive substances, that is, amino acid (GABA), amine (dopamine) and peptide (SP).
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The present study was designed to investigate the modulatory role of dietary curcumin on (i) azoxymethane (AOM)-induced ornithine decarboxylase (ODC), tyrosine protein kinase (TPK) and arachidonic acid metabolism in liver and colonic mucosa of male F344 rats, (ii) in vitro arachidonic acid metabolism in the liver and colonic mucosa and (iii) AOM-induced aberrant crypt foci (ACF) formation in the colon of F344 rats. At 5 weeks of age groups of animals were fed one of the experimental diets containing 0 or 2000 p.p.m. curcumin. Two weeks later all the animals except the vehicle-treated groups were given s.c. injections of AOM, 15 mg/kg body wt, once weekly for 2 weeks. The animals intended for biochemical study were killed 5 days later and the colonic mucosa and liver were analyzed for ODC, TPK, lipoxygenase and cyclo-oxygenase metabolites. The animals intended for ACF study were killed 9 weeks later and analyzed for ACF in the colon. The results indicated that in saline-treated animals dietary curcumin significantly inhibited the ODC (P < 0.001) and TPK (P < 0.05) activities in the liver and colonic mucosa. Dietary curcumin significantly decreased the levels of AOM-induced ODC activity in the liver and colon (P < 0.0001) and TPK activity in the liver and colon (P < 0.01-0.0001) and the formation of 5(S)-, 8(S)-, 12(S)- and 15(S)-hydroxyeicosatetraenoic acids (HETEs) in the liver and colon (P < 0.0001). Also, curcumin suppressed AOM-induced prostaglandin (PG) and thromboxane (Tx) formation in the liver (PGE2, PGF2 alpha, PGD2, 6-keto-PGF1 alpha and TxB2 to 40, 59, 55, 53 and 39% respectively) and in the colon (PGE2 and PGF2 alpha to 39 and 41% respectively). Further, dietary curcumin reduced the in vitro formation of HETEs, PGs and Tx in a dose-dependent manner. AOM-induced colonic ACF were significantly (P < 0.001) inhibited in the animals fed the curcumin diet. The results of the present study indicate that curcumin, present in turmeric, inhibits AOM-induced colonic preneoplastic lesions and other cellular events relevant to colon carcinogenesis.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To improve basic knowledge about the neurochemical organization of the urodele brain, and to study discrepancies in the localization of monoaminergic markers, we immunohistochemically charted the distribution of four such markers (tyrosine hydroxylase, aromatic L-amino acid decarboxylase, dopamine, and serotonin) in the axolotl (Ambystoma mexicanum) forebrain. Catecholaminergic and serotoninergic systems were found in similar locations to those seen in other Urodela. As seen in other vertebrates, the localization of the different monoaminergic markers reveals some inconsistencies. Cells that are exclusively tyrosine hydroxylase-immunoreactive are observed in the olfactory bulb, anterior olfactory nucleus/nucleus accumbens region, the epichiasmatic portion of the preoptic nucleus, and in the pars intercalaris thalami, whereas cells that are only labelled by aromatic L-amino acid decarboxylase are seen in the anterior olfactory nucleus/nucleus accumbens region, the bed nuclei of the anterior commissure, the posterior portion of the preoptic nucleus, the ventral hypothalamus, and the pars intercalaris thalami. The presence of cells solely serotonin (5-HT)-immunoreactive is suggested for the nucleus infundibularis dorsalis. Conversely, there were no areas that appeared to be exclusively immunoreactive for dopamine. Double-labelling for aromatic L-amino acid decarboxylase/tyrosine hydroxylase and aromatic L-amino acid decarboxylase/serotonin, together with cell counting, confirmed the existence of neurons that express only one monoaminergic marker in amphibian, supporting the hypothesis that these cells are universally present in the central nervous system of vertebrates.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the selective loss of dopaminergic neurons in the substantia nigra. This loss leads to complete dopamine depletion in the striatum and severe motor impairment. It has been demonstrated previously that a lentiviral vector system based on equine infectious anemia virus (EIAV) gives rise to highly efficient and sustained transduction of neurons in the rat brain. Therefore, a dopamine replacement strategy using EIAV has been investigated as a treatment in the 6-hydroxydopamine (6-OHDA) animal model of PD. A self-inactivating EIAV minimal lentiviral vector that expresses tyrosine hydroxylase (TH), aromatic amino acid dopa decarboxylase (AADC), and GTP cyclohydrolase 1 (CH1) in a single transcription unit has been generated. In cultured striatal neurons transduced with this vector, TH, AADC, and CH1 proteins can all be detected. After stereotactic delivery into the dopamine-denervated striatum of the 6-OHDA-lesioned rat, sustained expression of each enzyme and effective production of catecholamines were detected, resulting in significant reduction of apomorphine-induced motor asymmetry compared with control animals (p < 0.003). Expression of each enzyme in the striatum was observed for up to 5 months after injection. These data indicate that the delivery of three catecholaminergic synthetic enzymes by a single lentiviral vector can achieve functional improvement and thus open the potential for the use of this vector for gene therapy of late-stage PD patients.
This study was aimed at showing the distribution and projection of the medullary cardiovascular control neurons that contain a standard neurotransmitter or a related enzyme in the rat. A small amount of HRP was injected into either the depressor area of the caudal ventrolateral medulla (D-CVLM) or the pressor area of the rostral ventrolateral medulla (P-RVLM). Using an immunohistochemical method, we identified HRP-labelled neurons which were stained with antiserum to glutamate (Glu), glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) or phenylethanolamine N-methyltransferase (PNMT). Our findings are summarized as follows. (1) The Glu-containing neurons in the nucleus tractus solitararii (NTS) project to the D-CVLM (n = 279, 100% assumed as a standard value) and P-RVLM (n = 225, 81% against the standard), indicating divergent excitatory projection. (2) The GAD-containing neurons in the NTS (n = 74, 27% against the standard) project to the P-RVLM, indicating the convergent inhibitory projection. (3) The projections of the TH-containing neurons from the NTS (n = 19, 7% against the standard) and CVLM (n = 4, 1% against the standard) to the P-RVLM are weaker than those of the GAD-containing neurons, suggesting that the catecholaminergic neurons play a minor role in inhibition of the sympathetic activity of the P-RVLM neurons. These results suggest that the glutamatergic NTS neurons excite both the P-RVLM and D-CVLM neurons, and the gamma-aminobutyric acid (GABA)ergic NTS and CVLM neurons inhibit the sympathetic activity of the P-RVLM neurons.
Neurotransmitter-related messenger RNAs were detected by in situ hybridization in sections of rat and mouse brains by using 35S-radiolabelled RNA probes transcribed from cDNAs cloned in SP6 promoter-containing vectors. The distribution of messenger RNAs for glutamic acid decarboxylase, tachykinins (substance P and K), and tyrosine hydroxylase was examined in the striatum, pallidum, and substantia nigra. Dense clusters of silver grains were observed with the RNA probe complementary of the cellular messenger RNA for glutamic acid decarboxylase (antisense RNA) over most large neurons in the substantia nigra pars reticulata and medium-sized to large neurons in all pallidal subdivisions. A few very densely and numerous lightly labelled medium-sized neurons were present in the striatum. Among the areas examined, only the striatum contained neurons labelled with the antisense tachykinin RNA. Most of these neurons were of medium size, and a few were large. With the antisense tyrosine hydroxylase RNA, silver grains were found over neurons of the substantia nigra pars compacta and adjacent A10 and A8 dopaminergic cell groups. No signal was observed with RNAs identical to the cellular messenger RNA for glutamic acid decarboxylase or tachykinin (sense RNA). These results show a good correlation with immunohistochemical studies, suggesting that documented differences in the distribution and the level of glutamic acid decarboxylase, tyrosine hydroxylase, and substance P immunoreactivities in neurons of the basal ganglia are related to differences in the level of expression of the corresponding genes rather than to translation accessibility, stability, or transport of the gene products.
Epidemiological and laboratory animal model studies suggest that the effect of dietary fat on colon carcinogenesis depends on the amount and its type. In the present study, we investigated the modulating effect of high-fat diets rich in omega-3, omega-6 and omega-9 fatty acids on liver, colon and small intestine mucosal ornithine decarboxylase (ODC) and tyrosine-specific protein kinase (TPK) activities and plasma, liver and colon mucosal prostaglandin E2 (PGE2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) levels in male F344 rats. At 6 weeks of age, groups of animals were fed the low-fat diet containing 5% corn oil (LFCO), or high-fat diets containing 23.5% corn oil (HFCO), 23.5% olive oil (HFOO) and 20.5% fish oil + 3% corn oil (HFFO). Two weeks later, all animals except the vehicle-treated groups received azoxymethane (AOM) s.c. once weekly for 2 weeks at a dose rate of 15 mg/kg body wt. All animals were killed 5 days later and liver, colon and small intestine mucosa were analyzed for ODC, TPK and PGs and plasma for PGs. Carcinogen treatment enhanced the ODC and TPK activities (P < 0.0001) in the liver and colon of animals, irrespective of dietary treatment. Dietary HFCO compared with LFCO significantly increased the ODC (P < 0.01) and membrane TPK (P < 0.05) activities in the liver and colon of carcinogen-treated animals, whereas the HFOO and HFFO diets significantly (P < 0.002) suppressed the ODC and membrane TPK (P < 0.05) activities in the liver and colon mucosa compared with the HFCO diet. Carcinogen treatment also significantly (P < 0.01) increased the PG levels in plasma, liver and colon. Feeding of the HFFO diet significantly suppressed both the basal levels and ex vivo production of PGE2 and 6-keto PGF1 alpha levels compared with the HFCO diet, whereas the HFOO diet only decreased PGE2 in liver and colon. These results thus demonstrate that high levels of corn oil in the diet increase colon and liver ODC, TPK and PGs whereas high dietary levels of fish oil and olive oil suppress these activities.
A method for producing solid tumors in rat liver or spleen by local inoculation of Yoshida sarcoma or Hirosaki sarcoma was developed by careful selection of rat strains. After development of the tumor, the liver was isolated and perfused with a mixture of calf serum and fluorocarbon. Addition of corticoid hormone to the perfusion fluid induced tyrosine aminotransferase in normal tissue of the liver and to a lesser degree in the tumor tissue. Corticoid did not cause any detectable induction of thymidine kinase in normal tissue of the liver, but caused slight but definite induction of the enzyme in the tumor tissue. Ornithine decarboxylase was induced in the normal tissue by perfusion with serum alone, even without corticoid, but no enzyme induction was observed in the tumor tissue. The low level of this enzyme found in solid tumor tissue might be due to the fact that the enzyme was measured in the late period of tumor growth, because, in experiments with ascites tumor cells, higher enzyme activities were observed in the early period of growth.