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PubMed1993

Effects of acute and chronic lithium treatment on amphetamine-induced dopamine increase in the nucleus accumbens and prefrontal cortex in rats as studied by microdialysis.

The effects of acute and chronic administration of lithium (Li) on the basal levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5-HIAA), and the amphetamine-induced DA increase were assessed in the Nucleus Accumbens (NAC) and Prefrontal Cortex (PFC) by brain dialysis in freely-moving rats. Acute Li (2 meq/L) was locally administered by reverse dialysis. Chronic Li (2 meq/kg) was intragastrically administered for 14 days. No effect was observed after acute Li administration. However, after chronic Li administration, the basal levels of DOPAC and the amphetamine-induced DA increase in the NAC were significantly higher in the Li-treated rats than in the saline-treated controls. In the PFC, while the amphetamine-induced DA increase was not affected by chronic Li, the basal levels of DA and DOPAC were significantly decreased after Li administration. The effects of chronic Li in the NAC could be due to increased synthesis and/or decreased release of DA, whereas in the PFC the effects could be due to a decreased synthesis of DA. The absence of effects of acute Li administration is in agreement with the therapeutic inefficacy of the acute use of the cation. The changes observed after chronic treatment in the NAC and the PFC could be related to the effects of Li on mood disorders and cognitive functions, respectively.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1976

The distribution and metabolism of chlorpromazine in rats and the relationship to effects on cerebral monoamine metabolism.

Rats were injected with chlorpromazine (CPZ), 21 mumoles/kg (7.5 mg/kg) i.p., and killed after different time intervals up to 24 h. Mass fragmentographic methods were used to determine the levels of CPZ, monodemethyl-chlorpromazine (nor1-CPZ) and 7-hydroxy-chlorpromazine (7-OH-CPZ) in brain and blood and dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA) in the striatum. Significant correlations between the brain and blood concentrations of CPZ as well as its active metabolites and the levels of DOPAC and HVA were obtained at several time points. The similarity between the time curves for CPZ dominantly the unchanged drug in the brain which determines the acceleration of DA metabolism.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Effects of K+-stimulation and precursor loading on the in vivo release of dopamine, serotonin and their metabolites in the nucleus accumbens of the rat.

The in vivo efflux of endogenous 3,4-dihydroxyphenylethylamine (DA 5-hydroxytryptamine (5-HT), 3,4-dihydroxyphenyl-acetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5-HIAA) in the nucleus accumbens of the anesthetized rat was studied using a push-pull cannula. Local perfusion for 10 minutes with 35 mM K+ significantly (P less than 0.01) increased the release of DA and 5-HT, but not their metabolites, from their respective control levels of 0.95 and 0.04 pmol/15 min to 2.5 and 0.23 pmol/15 min. Exposure to 35 mM K+ a second and third time resulted in a decrement in the amount of stimulated release for both DA and 5-HT. This decrease was prevented by local perfusion for 10 minutes with 50 uM L-tyrosine and -tryptophan starting 30 minutes before each episode of depolarization. The baseline amounts of DOPAC, HVA and 5-HIAA observed in the perfusates were several fold higher than the basal levels found for 5-HT and DA. In the absence of precursors, the efflux of DOPAC, HVA and 5-HIAA decreased approximately 60, 40 and 25%, respectively, from the first to the last baseline fraction collected. Addition of precursors prevented the decrease for DOPAC and 5-HIAA but not for HVA. The data indicated that (a) the in vivo release of DA and 5-HT, along with their metabolites, could be simultaneously measured with the present procedure, and (b) when using the push-pull cannula, local perfusion with precursors may be necessary following periods of sustained and/or repeated stimulation in order to replenish the monoamine transmitter pools.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Analysis by HPLC-EC of metabolites of monoamines in fetal and postnatal rat brain.

High performance liquid chromatography with electrochemical detection (HPLC-EC) was adapted for the analysis of metabolites of monoamines (MA) in the developing brain of the rat. 3-Methoxy-4-hydroxy-phenyl-ethylene glycol (MOPEG), dihydroxy phenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA) were found in significant amounts in forebrain of the foetal rat from gestational day (GD) 17. The development pattern of the four metabolites was essentially similar in male and female animals. Except for transient fluctuations at around birth, concentrations of metabolites increased gradually throughout late gestation and early postnatal life. In late gestation and at birth the absolute amounts were small, while the concentrations were comparable to adult levels.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Acute administration of clozapine, thioridazine and metoclopramide increases extracellular DOPAC and decreases extracellular 5-HIAA, measured in the nucleus accumbens and striatum of the rat using in vivo voltammetry.

Changes in the extracellular levels of dihydroxyphenylacetic acid (DOPAC) and 5-hydroxy-indoleacetic acid (5-HIAA) after acute administration of clozapine (50 mg/kg s.c.), thioridazine (20 mg/kg s.c.) and metoclopramide (5 mg/kg s.c.), were monitored using in vivo voltammetry with micro-carbon electrodes implanted in the nucleus accumbens and striatum of the rat anaesthetised with halothane/N2O. Both clozapine and thioridazine increased extracellular levels of DOPAC in the striatum and the nucleus accumbens. The maximum increases with clozapine were 60% and 86% in the nucleus accumbens and striatum and 44% and 55% with thioridazine. Both neuroleptics also decreased the extracellular level of 5-HIAA in these regions of the brain. Metoclopramide increased the extracellular level of DOPAC in the nucleus accumbens (42%) and the striatum (57%) and significantly decreased the level of 5-HIAA in the nucleus accumbens. These results suggest that the two so-called atypical neuroleptics, clozapine and thioridazine, do not have selective effects on the metabolism of dopamine in vivo in the nucleus accumbens after acute administration. Furthermore, neuroleptic-induced increases in dopamine metabolism are accompanied by reciprocal decreases in 5-hydroxytryptamine metabolism in vivo.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Quantitative microdialysis of dopamine in the striatum: effect of circadian variation.

Two quantitative microdialysis methods were used to determine the concentration of extracellular dopamine in the anterior striatum of the rat. In the first method, the slow perfusion flow rate method, perfusion was at 57 nl/min and dialysate samples were collected every 90 min for 18 h and assayed for dopamine (DA), DOPAC (3,4-dihydroxy-phenylacetic acid), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5-HIAA). There was a significant increase in the concentration of dopamine during the dark cycle compared with the light cycle (14.7 +/- 1 nM vs. 9.3 +/- 0.7 nM; mean +/- SEM; P less than 0.0001), indicating possible circadian variations in the extracellular concentration of DA. There was a steady decrease in the level of DOPAC and HVA, and no change in the level of 5-HIAA. For the point of no-net-flux method, animals were perfused with 4 concentrations of DA or DOPAC, bracketing the extracellular concentrations. The extracellular concentrations of DA and DOPAC using this method were 10.2 +/- 1.7 nM and 17.4 +/- 2.6 microM, respectively. The in vivo recoveries for DA and DOPAC as derived from the slope of the linear regression curves were 72 +/- 3% and 43 +/- 5%. These values were shown to be significantly different (P less than 0.001). Both methods gave similar results for the level of DA in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

Hypericum perforatum L (St John's wort) preferentially increases extracellular dopamine levels in the rat prefrontal cortex.

The effects of hydro-alcoholic extracts of Hypericum perforatum L on extracellular serotonin (5-HT), noradrenaline (NA) and dopamine (DA) levels and the acidic metabolites (3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA)) were examined by in vivo microdialysis in the prefrontal cortex of awake rats. Thus, a single dose (60 mg kg(-1) i.p. or 300 mg kg(-1) p.o.) of H. perforatum increased DA concentrations to 165 and 140% of control values, respectively, and increased locomotor activity in nonhabituated rats. DOPAC and HVA levels were markedly reduced. 5-HT concentrations were elevated only moderately, while the NA levels were not affected by any treatment. The whole-tissue analysis revealed that hypericum increased, whereas the monoamine oxidase (MAO) A/B inhibitor phenelzine decreased DA and 5-HT turnover. The present data indicate that the mechanism of action of hypericum extract in vivo is more complex than the inhibition of monoamine reuptake or metabolism observed in vitro. The finding of preferential enhancement of DA transmission is in agreement with human studies measuring DA-mediated neuroendocrine responses.

Animals↗
PubMed1994

Assessment of the number and expression of P-type H(+)-ATPase genes in tomato.

Seven genomic fragments encoding isoforms of tomato (Lycopersicon esculentum) plasma membrane H(+)-ATPase were cloned and characterized. Genomic DNA gel-blot analysis indicated that probes corresponding to LHA1 through LHA7 hybridized to a common set of seven to nine restriction fragments at moderate stringency and to single, distinct fragments at high stringency. RNA gel-blot and polymerase chain reaction (PCR)-based RNA analyses indicated that LHA1, LHA2, and LHA4 transcripts were present in all organs examined (roots, hypocotyls, stems, immature leaves, mature leaves, green fruit, and red ripe fruit). LHA1 mRNA was present at similar abundance in all organs, LHA2 mRNA was most abundant in hypocotyls and leaves, and LHA4 mRNA was most abundant in roots and hypocotyls. RNA gel-blot and RNA-based PCR assays indicated that LHA3, LHA5, LHA6, and LHA7 mRNA was present at very low or nondetectable levels in all organs, suggesting that these genes are either expressed at very low levels or in organs not examined or that they are regulated by hormonal or environmental cues that were not tested. Indoleacetic acid (IAA) treatment of tomato hypocotyl segments resulted in modest changes in abundance of LHA1, LHA2, and LHA4 transcripts, but these changes were not correlated with the time course of IAA-induced growth. In addition, constitutively silent LHA genes were not activated by IAA. These results indicate that at least seven genomic sequences are present in tomato that may encode plasma membrane H(+)-ATPases, at least three of which are expressed relatively abundantly at the mRNA level.

Amino Acid Sequence↗
PubMed1979

Gibberellic Acid Activates Chromatin-bound DNA-dependent RNA Polymerase in Wounded Potato Tuber Tissue.

Chromatin-bound DNA-dependent RNA polymerases react upon wounding of white potato tuber tissues with an increase in activity, which is additionally enhanced to 300% in the presence of 0.1 micromolar gibberellic acid (GA(3)). 2,4-Dichlorophenoxyacetic acid is only weakly effective and indoleacetic acid not at all. Wounding and treatment with GA(3) affect template availability of chromatin only slightly. The hormone has no effect on chromatin-bound RNA polymerases, if added in vitro.The enzymes from intact, wounded, and hormone-treated tissues possess similar characteristics: their activity is dependent on the presence of all four ribonucleotides and a divalent cation such as Mg(2+) or Mn(2+). However, the sensitivity of the enzymes from different preparations toward alpha-amanitin differs. Total RNA polymerase activity of chromatin was inhibited by alpha-amanitin to about 44% in intact, to about 22% in wounded, and only 15% in GA(3)-treated tissues. The relative activities of polymerases I and II were estimated by varying the (NH(4))(2)SO(4) and alpha-amanitin concentrations in the assay system. It is evident that GA(3) preferentially stimulates polymerase I and hence ribosomal RNA synthesis. RNA polymerase II is but slightly affected by GA(3). Nearest neighbor frequency analysis revealed that the RNA synthesized by the enzymes from the intact tuber is different from that of wounded or GA(3)-treated tissues.

Journal Article↗
PubMed1991

Turnover of dopamine and serotonin and their metabolites in the striatum of aged rats.

Turnover of dopamine (DA), serotonin [5-hydroxytryptamine (5-HT)], and their metabolites has been measured in adult and aged rats. Turnover rates of 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxy-3-indoleacetic acid (5-HIAA) have been assayed from the disappearance rates after blocking by pargyline inhibition of monoamine oxidase (MAO) and from the accumulation rates by probenecid inhibition of the probenecid-sensitive transport system. DA and 5-HT turnover rates have been measured as accumulation rates of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively, after central decarboxylase inhibition by 3-hydroxybenzylhydrazine (NSD-1015) and as accumulation rates of DA and 5-HT after pargyline inhibition of MAO. The DA turnover rate after NSD-1015 was 23.9% lower in aged rats than in adults, whereas after pargyline there was no significant difference between the two age groups. The HVA fractional rate constant and turnover after pargyline were lower in aged rats than in adults, and HVA turnover after probenecid was higher in aged rats than in adults. The DOPAC-HVA pathway seems to be reinforced at the expense of DOPAC conjugation. In aged and adult rats whose 5-HT steady-state levels were not statistically different, the 5-HT turnover rate after pargyline and NSD-1015 treatment was lower in aged rats than in adults. An increase of 5-HIAA levels after pargyline and probenecid treatment in aged rats could be due to the handling stress.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Biogenic Amine Metabolites During Electroconvulsive Therapy of Melancholic Patients.

We assayed the urinary neurotransmitter metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxy-indoleacetic acid (5-HIAA) in unipolar depressed patients before and after a simulated electroconvulsive therapy ECT (SECT), and during course of 10 ECT sessions. A repeated measures analysis of variance (ANOVA) showed no significant changes in the three-metabolite excretion during the course of ECT. Planned comparisons performed after ANOVA revealed a trend for HVA and 5-HIAA levels to increase after SECT and a significantly higher MHPG excretion after the 10th ECT session. Seven depressed patients who responded favorably to ECT (reduction in Hamilton Rating Scale for Depression score of 50% or more) but not the seven nonresponders had significantly higher MHPG excretion after the final ECT compared to baseline levels. A significant relationship was found between low pretreatment MHPG excretion and therapeutic response.

Journal Article↗
PubMed2002

[Decreased beta-phenylethylamine in urine of children with attention deficit hyperactivity disorder and autistic disorder].

beta-phenylethylamine (PEA), a biogenic trace amine, acts as a neuromodulator in the nigrostriatal dopaminergic pathway and stimulates the release of dopamine. To clarify the mechanism of neurochemical metabolism in attention deficit hyperactivity disorder (ADHD), we measured the urine levels of PEA using gas chromatography-chemical ionization-mass spectrometry. The urinary levels of 3-methoxy-4-hydroxyphenyl glycol (MHPG), homovanillic acid (HVA), and 5-hydroxy-indoleacetic acid (5-HIAA) were determined by high performance liquid chromatography. Urine samples were collected in a 24 hour period. Findings were compared with those obtained from controls (N = 15), children with ADHD (N = 15), and children with autistic disorder (AD) (N = 5). The mean urinary levels of MHPG, HVA, and 5-HIAA in the children with ADHD were not significantly different from those of the controls or those with AD, whereas PEA levels were significantly lower in children with ADHD (11.23 +/- 13.40 micrograms/g creatinine) compared with controls (56.01 +/- 52.18 micrograms/g creatinine). PEA and MHPG levels in children with AD (14.75 +/- 14.37 micrograms/g creatine, 1.10 +/- 0.61 micrograms/mg creatine, respectively) were significantly decreased compared to controls (MHPG, 2.2 +/- 0.9 micrograms/mg creatine). The decreased urine PEA in children with ADHD and AD may suggest a common underlying pathophysiology. The decreased urine MHPG in children with AD might indicate the existence of an alteration in central and peripheral noradrenergic function.

Analysis of Variance↗
PubMed1990

Effect of amygdaloid kindled seizures during pregnancy on neonatal brain biogenic amines.

The effects of amygdaloid kindled seizures during pregnancy on the concentrations of noradrenaline (NE), dopamine (DA) and serotonin (5HT) and of their respective metabolites, 3-methoxy-4-hydroxyphenylglycol (MHPG), normetanephrine (NMN), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5HIAA), have been studied in the cerebral cortex, brain stem and cerebellum of rat offspring at birth. The levels of DA and NE were increased and those of HVA and MHPG were not modified in the cortex. The levels of DA, NE, 5HT, MHPG and 5HIAA were increased in the cerebellum. The brain stem presented a decrease in DA and 5HT levels, but increased MHPG and HVA levels. It is suggested that, in order to investigate possible changes in the biogenic amine levels on the postnatal period, carefully planned prospective studies are needed.

Animals↗
PubMed1978

[Levels of biogenic amines and their metabolites in rat whole brain after rapid tissue fixation with microwave irradiation (author's transl)].

Levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT), 3, 4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid were measured fluorometrically in the whole brain of rats killed either by decapitation or by 5kW microwave irradiation for 1.6 sec. which inactivates the relevant brain enzymes rapidly and irreversibly. There were statistically no differences in the levels of NE, DA, 5-HT and 5-HIAA between the two methods of sacrifice, while the level of DA increased slightly in irradiated brains. On the other hand, the level of DOPAC, an oxidative deaminated metabolite of DA, increased significantly and the level of HVA, a final metabolite of DA, reduced markedly in the irradiated brains compared to that in the decapitated brains, respectively. These findings suggest that the turnover rates for metabolism of DA at synaptic nerve terminals and synaptic clefts may be relatively rapid. Therefore, it may be concluded that rapid inactivation of the brain enzymes involved in metabolism of DA is necessary prior to analysis of DA and its metabolites and microwave irradiation is the most suitable method available at the present time.

Animals↗
PubMed1995

The PS-IAA4/5-like family of early auxin-inducible mRNAs in Arabidopsis thaliana.

The plant hormone auxin transcriptionally activates early genes. We have isolated a 14-member family of DNA sequences complementary to indoleacetic acid (IAA)-inducible transcripts in Arabidopsis thaliana. The corresponding genes, IAA1 to IAA14, are homologs of PS-IAA4/5 and PS-IAA6 from pea, Aux22 and Aux28 from soybean, ARG3 and ARG4 from mungbean, and AtAux2-11 and AtAux2-27 from Arabidopsis. The members of the family are differentially expressed in mature Arabidopsis plants. Characterization of IAA gene expression in etiolated seedlings demonstrates specificity for auxin inducibility. The response of most family members to IAA is rapid (within 4 to 30 minutes) and insensitive to cycloheximide. Cycloheximide alone induces all the early genes. Auxin-induction of two late genes, IAA7 and IAA8, is inhibited by cycloheximide, indicating requirement of protein synthesis for their activation. All IAA genes display a biphasic dose response that is optimal at 10 microM IAA. However, individual genes respond differentially between 10 nM and 5 microM IAA. Expression of all genes is defective in the Arabidopsis auxin-resistant mutant lines axr1, axr2 and aux1. The encoded polypeptides share four conserved domains, and seven invariant residues in the intervening regions. The spacers vary considerably in length, rendering the calculated molecular mass of IAA proteins to range from 19 kDa to 36 kDa. Overall sequence identity between members of the family is highly variable (36 to 87%). Their most significant structural features are functional nuclear transport signals, and a putative beta alpha alpha-fold whose modeled three dimensional structure appears to be compatible with the prokaryotic beta-ribbon DNA recognition motif. The data suggest that auxin induces in a differential and hierarchical fashion a large family of early genes that encode a structurally diverse class of nuclear proteins. These proteins are proposed to mediate tissue-specific and cell-type restricted responses to the hormone during plant growth and development.

Amino Acid Sequence↗