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PubMedDate not supplied

Diurnal rhythms in ornithine decarboxylase activity and norepinephrine and acetylcholine synthesis and acetylcholine synthesis of rat submaxillary lymph nodes: effect of pinealectomy, superior cervical ganglionectomy and melatonin replacement.

The effect of pinealectomy, superior cervical ganglionectomy and melatonin replacement on diurnal variations in submaxillary lymph node ornithine decarboxylase activity, tyrosine hydroxylase activity and [3H]choline conversion to [3H]acetylcholine were examined in rats subjected to pinealectomy, bilateral superior cervical ganglionectomy or their respective sham-operations, and treated with Freund's complete adjuvant or its vehicle. In both immunized and nonimmunized sham-operated rats, significant diurnal variations in ornithine decarboxylase activity were detectable, with a maximum at 13.00 h (vehicle) or at 17.00 h (Freund's adjuvant). In rats subjected to pinealectomy, ornithine decarboxylase activity decreased by about half, still exhibiting significant diurnal variations with a maximum at 13.00 h. Abolition of circadian rhythmicity and depression of ornithine decarboxylase activity to about one third of controls were found in submaxillary lymph nodes of bilaterally superior cervical ganglionectomized rats. Administration of melatonin (30 micrograms/animal) in the late evening during 11 days counteracted the depressed levels and suppressed the amplitude of diurnal rhythmicity of ornithine decarboxylase in pinealectomized or bilaterally superior cervical ganglionectomized rats, as well as augmented enzyme activity in sham-operated controls. The amplitude and mean levels of 24-hour rhythms in submaxillary lymph node tyrosine hydroxylase activity and [3H]choline conversion to acetylcholine (that attained their maxima at 21.00-1.00 and 13.00-17.00 h, respectively) decreased significantly after pinealectomy, these effects being significantly counteracted by melatonin injection. Melatonin augmented tyrosine hydroxylase activity and acetylcholine synthesis in sham-pinealectomized rats. The results are compatible with the view that the pineal gland plays a role in circadian changes of immune responsiveness in lymphoid tissue via an immunopotentiating effect of melatonin on lymph node cell proliferation.

Acetylcholine↗
PubMed1993

Inhibitory effect of caffeic acid esters on azoxymethane-induced biochemical changes and aberrant crypt foci formation in rat colon.

Previous work from this laboratory established that caffeic acid esters, present in the propolis of honey bee hives, are potent inhibitors of human colon tumor cell growth, suggesting that these compounds may possess antitumor activity against colon carcinogenesis. The present study was designed to investigate (a) the inhibitory effects of methyl caffeate (MC) and phenylethyl caffeate (PEC) on azoxymethane (AOM)-induced ornithine decarboxylase (ODC), tyrosine protein kinase (TPK), and arachidonic acid metabolism in liver and colonic mucosa of male F344 rats, (b) the effects of caffeic acid, MC, PEC, phenylethyl-3-methylcaffeate (PEMC), and phenylethyl dimethylcaffeate (PEDMC) on in vitro arachidonic acid metabolism in liver and colonic mucosa, and (c) the effects of PEC, PEMC, and PEDMC on AOM-induced aberrant crypt foci (ACF) formation in the colon of F344 rats. At 5 weeks of age, groups of animals were fed diets containing 600 ppm MC or PEC (biochemical study) or 500 ppm PEC, PEMC, or PEDMC (ACF study). Two weeks later, all animals except the vehicle-treated groups were given s.c. injections of AOM, once weekly for 2 weeks. The animals intended for the biochemical study were sacrificed 5 days later and colonic mucosa and liver were analyzed for ODC, TPK, lipoxygenase, and cyclooxygenase metabolites. The animals intended for the ACF study were sacrificed 9 weeks later and analyzed for ACF in the colon. The results indicate that the PEC diet significantly inhibited AOM-induced ODC (P < 0.05) and TPK (P < 0.001) activities in liver and colon. The PEC diet significantly (P < 0.001) suppressed the AOM-induced lipoxygenase metabolites 8(S)- and 12(S)-hydroxyeicosatetraenoic acid (HETE). The animals fed the MC diet exhibited a moderate inhibitory effect on ODC and 5(S)-, 8(S)-, 12(S)-, and 15(S)-HETEs and a significant (P < 0.001) effect on colonic TPK activity. However, the MC and PEC diets showed no significant inhibitory effects on cyclooxygenase metabolism. In an in vitro study, caffeic acid and MC showed inhibitory effects on HETE formation only at a 100 microM concentration, whereas PEC, PEMC, and PEDMC suppressed in vitro HETE formation in a dose-dependent manner. AOM-induced colonic ACF were significantly inhibited in the animals fed PEC (55%), PEMC (82%), or PEDMC (81%). The results of the present study indicate that PEC, PEMC, and PEDMC, present in honey, inhibit AOM-induced colonic preneoplastic lesions, ODC, TPK, and lipoxygenase activity, which are relevant to colon carcinogenesis.

Animals↗
PubMedDate not supplied

Evidence for the existence of L-dopa- and dopamine-immunoreactive nerve cell bodies in the caudal part of the dorsal motor nucleus of the vagus nerve.

The precise neurochemical nature of tyrosine hydroxylase-immunoreactive neurons lying in the caudal part of the dorsal motor nucleus of the vagus nerve of the rat has been identified by immunohistochemistry of the catecholamines themselves. This region corresponds precisely to the area where tyrosine hydroxylase has been previously shown to be colocalized with choline acetyltransferase. Adjacent serial cryostat sections from the medulla oblongata and from the cervical spinal cord were treated either for choline acetyltransferase immunohistochemistry, aromatic L-amino acid decarboxylase and tyrosine hydroxylase immunolabelling or for tyrosine hydroxylase, dopamine, noradrenaline and L-dihydroxyphenylalanine (DOPA) immunostaining. The procedure involved the peroxidase-antiperoxidase method and an intensified diaminobenzidine reaction with imidazole. While no noradrenaline-positive cells were detectable in the dorsal motor vagal nucleus, tyrosine hydroxylase-, dopamine- and DOPA-immunoreactive perikarya were seen in the medial half of this nucleus, caudally the obex level. These results led us to conclude that these tyrosine hydroxylase-positive cells were effectively of dopaminergic nature and therefore that dopamine is a neurotransmitter contained in some neurons of the dorsal motor vagal nucleus. In the light of previous data showing colocalization of tyrosine hydroxylase and choline acetyltransferase in neurons of this portion of the nucleus, colocalization of dopamine with acetylcholine appears most likely. This might shed some light on the physiological consequences of dopamine action at target parasympathetic organs, such as the gastrointestinal tract.

Animals↗
PubMed1994

Aging diminishes gastric mucosal regeneration: relationship to tyrosine kinases.

BACKGROUND: Increased incidence of gastric ulcer observed in the aged could be partly attributed to increased susceptibility of the mucosa to various damaging agents together with impediment of the repair process. The present investigation was undertaken to compare the rate of mucosal regeneration and the role of tyrosine kinases in regulation of this process between young (4-month-old) and aged (24-month-old) rats during the first 24 hours after injury. EXPERIMENTAL DESIGN: Groups of young and aged rats were given intragastrically with either 2 M NaCl (1.5 ml/130 gm body weight), or an equivalent volume of water and killed 1, 6, and 24 hours later. Each animal was injected intraperitoneally with 5-bromo-2'-deoxyuridine (BrdU; 50 mg/kg) 1 hour before killing to assess proliferative activity by immunocytochemistry. The stomach (oxyntic gland area) was also evaluated by light microscopy for the extent of injury and subsequent regeneration, and mucosa assayed for ornithine decarboxylase and tyrosine kinase (Tyr-k) activity and tyrosine phosphorylation of membrane proteins. RESULTS: Although 2 M NaCl caused extensive damage to the gastric mucosa in both young and aged rats, as evidenced by the total loss of the surface epithelium at 1 hour postinjury, the degree of regeneration was faster in young animals. In young rats, gastric epithelium showed signs of regeneration at 6 hours postinjury and was essentially complete by 24 hours. In contrast, in aged rats, only intermittent surface cells were seen 24 hours after injury. In both age groups, injury resulted in stimulation of mucosal proliferative activity. However, whereas ornithine decarboxylase activity in both age groups was maximally stimulated (350% in young versus 80% in aged) at 6 hours after injury, the number of BrdU-positive cells in young rats increased steadily with time after injury. In contrast, aged rats showed a biphasic pattern in that the number of BrdU-positive cells/gland remained decreased for up to 6 hours, whereafter a steep rise occurred. At 24 hours after injury, the number of BrdU-positive cells/gastric gland in aged rats were found to be higher than in young rats (6 +/- 1.5 cells/gland in young rats versus 9 +/- 2.1 cells/gland in aged rats). The pattern of Tyr-k activity in young and aged rats after injury was found to be quite different from that observed for proliferative activity. In young rats, mucosal Tyr-k activity increased by about 60% at 1 hour after injury, then decreased slightly over the next 5 hours and increased again revealing a 120% rise at 24 hours postinjury. This was associated with a concomitant change in tyrosine phosphorylation of six membrane proteins with molecular weight (in kilodalton) of 30, 35, 50, 55, 60 and 70. In contrast, in aged rats, Tyr-k activity was increased only marginally (about 20%) during the first 6 hours, but at 24 hours postinjury it was found to be 70% above the control. In aged rats, injury produced no significant stimulation in tyrosine phosphorylation of gastric mucosal membrane proteins. CONCLUSIONS: We conclude that aging is associated with the diminished regenerative capacity of the gastric mucosa. This could partly be attributed to diminished activation of mucosal Tyr-k and decreased tyrosine phosphorylation of certain membrane proteins.

Aged↗
PubMed1990

Tyrosine hydroxylase containing neurons lacking aromatic amino acid decarboxylase in the hamster brain.

We have recently described populations of tyrosine hydroxylase-immunoreactive neurons in the hamster brain in regions not known to contain catecholamine cell bodies. In the present study, the nature of the tyrosine hydroxylase immunoreactivity in the hamster brain was determined. In addition, these tyrosine hydroxylase-immunoreactive cell groups were examined for their ability to express aromatic amino acid decarboxylase. Immunohistochemistry with two different antibodies to tyrosine hydroxylase identified immunoreactive cell bodies in regions known to contain catecholamine neurons, including the substantia nigra and locus ceruleus. In addition, tyrosine hydroxylase-immunoreactive neurons were observed in other regions, including the basal forebrain, inferior colliculus, lateral parabrachial nucleus, and dorsal motor nucleus of the vagus. Western blotting indicated that hamster brain contained only one immunoreactive molecule, very similar in size to rat tyrosine hydroxylase. Thus it is likely that the immunohistochemical studies stained authentic hamster tyrosine hydroxylase. Indeed, in situ hybridization studies using a synthetic oligonucleotide probe against tyrosine hydroxylase mRNA resulted in specific and heavy labelling of these novel tyrosine hydroxylase-immunoreactive neurons. When adjacent sections were stained with antibodies to aromatic amino acid decarboxylase, known catecholamine cell groups were stained. However, the novel tyrosine hydroxylase cell groups did not display any aromatic amino acid decarboxylase immunoreactivity. These results suggest that neurons are present in the hamster brain that are able to hydroxylate tyrosine to L-DOPA, but that lack the ability to decarboxylate aromatic amino acids to produce dopamine or other catecholamines.

Animals↗
PubMed1987

An aspect of the organization of the GABAergic system in the rat main olfactory bulb: laminar distribution of immunohistochemically defined subpopulations of GABAergic neurons.

The organization of the GABAergic system in the rat main olfactory bulb was investigated immunohistochemically using antisera against glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH), parvalbumin (PV) and methionin-enkephalin-Arg6-Gly7-Leu8 (ENK). Some GABAergic neurons were shown to contain TH immunoreactivity in the glomerular layer, PV immunoreactivity in the external plexiform layer and ENK-like immunoreactivity in the granule cell layer, indicating the stratified organization of the GABAergic subsystems.

Animals↗
PubMed1980

The decarboxylation of DOPA in the parkinsonian brain: in vivo studies on an animal model.

The site of decarboxylation of exogenously administered L-DOPA was studied in corpora striata of rats with near-total unilateral nigrostriatal lesions. After DOPA administration, the absolute increases in dopamine (DA) levels were lower in lesioned than in unlesioned striata, suggesting that, in the intact striatum, a major part of exogenous DOPA is decarboxylated in DA neurons. DOPA can also be decarboxylated outside DA neurons, however, as shown by our finding that relatively higher DOPA decarboxylase than tyrosine hydroxylase activity or DA concentration remains in striata after the nigrostriatal lesions. Also, the percentage increases in DA formation after DOPA administration were much higher in lesioned than in control striata. Rats with both raphé and nigrostriatal lesions failed to exhibit further reductions in striatal DOPA decarboxylase activity or diminished biochemical or behavioral (turning behavior) reactions to DOPA. Inhibition of the DOPA decarboxylase contained in brain capillary endothelial cells did not abolish DA formation in lesioned striata or circling behavior after DOPA administration. These findings all suggest an additional cell type in the striatum as the site of DOPA's decarboxylation in the absence of DA neurons.

Animals↗
PubMed1981

Enzyme induction in rat liver: the effects of Be2+ in vivo.

Rats given an LD50 dose of Be2+ showed reduced activities of ornithine decarboxylase and tyrosine aminotransferase in liver in response to dexamethasone induction. Control fed animals showed 'superinduction'. Be2+ also inhibited the uptake of [3H]orotic acid into rapidly labelled RNA of ribonucleoprotein particles extracted from liver nuclei in isomolar solutions at pH 8.0. Consistent with inhibition of cytoplasmic protein kinase reported previously (Kaser et al., 1980), the uptake of [32P]Pi into proteins in the ribonucleoprotein particles was also diminished.

Animals↗
PubMed2002

[Clinical, biochemical and immunological characteristic of diabetes type I, LADA, diabetes type II, and MODY patients].

Right classification of diabetes is important clinical issue. The aim of present study was to compare clinical, biochemical and immunological features, to analyze their practical use and to establish new decision tree which make the distinction between diabetes type 1, LADA, diabetes type 2 and MODY. We studied 97 not obese (mean BMI 26.3 +/- 4.9 kg/m2) patients aged 14 to 70 years, mean age 43 +/- 11.7 years, 53 women, 44 men. Mean duration of diabetes--2.3 +/- 4.3 years. We measured basal and stimulated C-peptide (6 minutes after 1 mg i.v. glucagon) (ELISA) and antibodies titers to glutamic acid decarboxylase--antiGAD65, tyrosine phosphatase-like molecule--IA2 and insulin--IAA (RIA). Autoimmune diabetes (LADA, type 1) was diagnosed with presence of one or more islet antigen antibodies. The highest frequencies had anti-GAD antibodies 33/97 (34%). The most complicated was to sort out group of patients with LADA. Comparison between this group and patients with diabetes type 2 have shown that BMI, co-existence of autoimmune disease, autoimmune markers and basal and stimulated C-peptide level measured at entry for the classification were useful in differentiation. Moreover we observed significantly lower C-peptide basal, stimulated and over basal level in group with MODY diabetes in comparison to diabetes type 2 patients. In the studied group were 5 patients with diabetes type 2 and obesity, in relatively young age. At the end there was one case of ADM (atypical diabetes mellitus). Clinical criteria for the classification of diabetes not always correlated with diagnosis. Autoimmune markers, basal and stimulated C-peptide were useful specially in differentiation between LADA and diabetes type 2 or diabetes type 1. Autoimmune diabetes co-existe with autoimmune disease. Proposed diagnostic scheme take for consideration presence of autoantibodies as well as C-peptide criteria.

Adolescent↗
PubMed1991

Double immunohistochemical detection of transmitter phenotype of proliferating cells using bromodeoxyuridine.

We describe a new method that can determine transmitter phenotype of proliferating nerve cells at a given age. The procedure is based on indirect sequential double antigen immunofluorescence histochemistry for transmitter-synthesizing enzymes (glutamic acid decarboxylase and tyrosine hydroxylase) and the thymidine analogue, bromodeoxyuridine. The method permits simple, rapid, and effective anatomical detection, and promises to reduce certain limitations inherent in a combination with tritiated thymidine autoradiography. Employing this technique, we observed that many striatal cells expressing gamma-aminobutyric acid (GABA) and nigral cells expressing dopamine undergo the final mitosis at embryonic days 13-14 in the rat.

Animals↗
PubMed1997

Regulation of tyrosine hydroxylase and aromatic L-amino acid decarboxylase by dopaminergic drugs.

We provide evidence that dopamine receptors differentially modulate tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the mouse striatum. The dopamine D1 receptor family (D1-like) antagonist, R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benazepine (SCH 23390), elevated aromatic L-amino acid decarboxylase activity and protein content in striatum, as well as the mRNA for the enzyme in midbrain. The dopamine D1-like receptor agonist, (+/-)-1-phenyl-2,3,4,5-tetrahydro-(1 H)-3-benzazepine-7,8-diol (SKF 38393), had no effect on aromatic L-amino acid decarboxylase. The dopamine D1-like drugs had no effect on tyrosine hydroxylase. In contrast, the dopamine D2 receptor family (D2-like) antagonists haloperidol and spiperone elevated both tyrosine hydroxylase and aromatic L-amino acid decarboxylase activities. The increase in aromatic L-amino acid decarboxylase activity was accompanied by elevated enzyme protein content but not mRNA. The dopamine D2-like receptor agonists, bromocriptine, quinpirole and (+/-)-7-hydroxydipropylaminotetralin (7-OH-DPAT), all decreased striatal tyrosine hydroxylase. Under the conditions used, bromocriptine and 7-OH-DPAT, but not quinpirole, decreased aromatic L-amino acid decarboxylase activity of striatum. Both the dopamine D1- and D2-like receptor antagonists enhanced the turnover of striatal dopamine to differing degrees, as judged by the ratio of acid metabolites of dopamine to dopamine. Taken together our results indicate that aromatic L-amino acid decarboxylase can be modulated independently of tyrosine hydroxylase.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1985

Acetylcholine and aromatic amine systems in postmortem brain of an infant with Down's syndrome.

Adult cases of Down's syndrome often show histologic and biochemical changes comparable to those seen in severe Alzheimer's disease, but it is not known whether these are congenital or acquired defects. Cell counts of the basal forebrain cholinergic system innervating the cortex in a 5.5-month-old male infant with Down's indicated about 50% of the number of cells expected at birth but this is in the range of cell numbers found in healthy middle-aged normals. The noradrenergic system of the locus ceruleus has the expected complement of cells for normal newborns. The activities of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), glutamate decarboxylase, and tyrosine hydroxylase in a number of brain regions are reported for this infant, two cases of crib death, and a group of normal adults. The regional distributions of the enzymes in the infants were generally as expected from adult control data except for that of ChAT in one of the two cases of crib death; the AChE activities seemed extraordinarily high, especially in the case of Down's syndrome. Data on the concentrations of the catecholamines, serotonin, and their metabolites are also given but, like the enzyme data, are difficult to interpret in the absence of controls for the neonatal period.

Acetylcholine↗
PubMed1994

Egg chorion tanning in Aedes aegypti mosquito.

The biochemical pathway of egg chorion tanning in the mosquito, Aedes aegypti, is described and compared with chorion protein crosslinking in Drosophila and silkmoths and the biochemical pathways of cuticular tanning in insects. Phenol oxidase, dopa decarboxylase and tyrosine are critical components involved in egg chorion tanning in A. aegypti. Tanning of the mosquito egg chorion is initiated following activation of phenol oxidase, which then catalyzes the hydroxylation of tyrosine to dopa and further oxidizes dopa and dopamine to their respective o-quinones. Because intramolecular cyclization is much slower in dopaminequinone than dopaquinone, the chance to react with external nucleophiles to participate in protein crosslinking reactions also is much greater in dopaminequinone than dopaquinone. This might partly explain the necessity for the involvement of dopa decarboxylase in mosquito chorion tanning. Intramolecular cyclization of dopaquinone and dopaminequinone to form dopachrome and dopaminechrome, respectively, the structural rearrangement of these aminochromes to produce 5,6-dihydroxyindole, and the subsequent oxidation of 5,6-dihydroxyindole by phenol oxidase also lead to melanin formation during egg chorion tanning.

Aedes↗
PubMed2002

Mutation of tyrosine 332 to phenylalanine converts dopa decarboxylase into a decarboxylation-dependent oxidative deaminase.

A flexible loop (residues 328-339), presumably covering the active site upon substrate binding, has been revealed in 3,4-dihydroxyphenylalanine decarboxylase by means of kinetic and structural studies. The function of tyrosine 332 has been investigated by substituting it with phenylalanine. Y332F displays coenzyme content and spectroscopic features identical to those of the wild type. Unlike wild type, during reactions with l-aromatic amino acids under both aerobic and anaerobic conditions, Y332F does not catalyze the formation of aromatic amines. However, analysis of the products shows that in aerobiosis, l-aromatic amino acids are converted into the corresponding aromatic aldehydes, ammonia, and CO(2) with concomitant O(2) consumption. Therefore, substitution of Tyr-332 with phenylalanine results in the suppression of the original activity and in the generation of a decarboxylation-dependent oxidative deaminase activity. In anaerobiosis, Y332F catalyzes exclusively a decarboxylation-dependent transamination of l-aromatic amino acids. A role of Tyr-332 in the Calpha protonation step that catalyzes the formation of physiological products has been proposed. Furthermore, Y332F catalyzes oxidative deamination of aromatic amines and half-transamination of d-aromatic amino acids with k(cat) values comparable with those of the wild type. However, for all the mutant-catalyzed reactions, an increase in K(m) values is observed, suggesting that Y --> F replacement also affects substrate binding.

Amines↗