Serum DBH Activity Research Articles

Human Bacterial Artificial Chromosome (BAC) Transgenesis Fully Rescues Noradrenergic Function in Dopamine β-Hydroxylase Knockout Mice.

Dopamine β-hydroxylase (DBH) converts dopamine (DA) to norepinephrine (NE) in noradrenergic/adrenergic cells. DBH deficiency prevents NE production and causes sympathetic failure, hypotension and ptosis in humans and mice; DBH knockout (Dbh -/-) mice reveal other NE deficiency phenotypes including embryonic lethality, delayed growth, and behavioral defects. Furthermore, a single nucleotide polymorphism (SNP) in the human DBH gene promoter (-970C>T; rs1611115) is associated with variation in serum DBH activity and with several neurological- and neuropsychiatric-related disorders, although its impact on DBH expression is controversial. Phenotypes associated with DBH deficiency are typically treated with L-3,4-dihydroxyphenylserine (DOPS), which can be converted to NE by aromatic acid decarboxylase (AADC) in the absence of DBH. In this study, we generated transgenic mice carrying a human bacterial artificial chromosome (BAC) encompassing the DBH coding locus as well as ~45 kb of upstream and ~107 kb of downstream sequence to address two issues. First, we characterized the neuroanatomical, neurochemical, physiological, and behavioral transgenic rescue of DBH deficiency by crossing the BAC onto a Dbh -/- background. Second, we compared human DBH mRNA abundance between transgenic lines carrying either a “C” or a “T” at position -970. The BAC transgene drove human DBH mRNA expression in a pattern indistinguishable from the endogenous gene, restored normal catecholamine levels to the peripheral organs and brain of Dbh -/- mice, and fully rescued embryonic lethality, delayed growth, ptosis, reduced exploratory activity, and seizure susceptibility. In some cases, transgenic rescue was superior to DOPS. However, allelic variation at the rs1611115 SNP had no impact on mRNA levels in any tissue. These results indicate that the human BAC contains all of the genetic information required for tissue-specific, functional expression of DBH and can rescue all measured Dbh deficiency phenotypes, but did not reveal an impact of the rs11115 variant on DBH expression in mice.

Dopamine-β-Hydroxylase (DBH), Its Cofactors and Other Biochemical Parameters in the Serum of Neurological Patients in Bangladesh

Dopamine-β-hydroxylase (DBH) is a neurotransmitter synthesizing enzyme which catalyzes the formation of norepinephrine from dopamine. In this study, we measured the level of DBH activity in the serum of patients of three different age groups (8-14 yrs, 20-40 yrs and 45-60 yrs) suffering from neurological diseases. Serum DBH activity was measured in 38 neurological patients and 38 normal individuals in order to determine significant variables for its potential use to diagnose the neurological patients. It was found that the DBH activity decreased in the patients of all age groups. A considerable decrease in activity was observed in the patients of 8-14 yrs age group (14.2 nmoles/min/ml in patients compared to the normal value of 22.6). A significant decrease in activity was found in the 20-40 yrs age group (23.4 nmoles/min/ml in patients compared to the normal value of 33.0). The decrease in DBH activity was also found in the patients of 45-60 yrs age group but to a lesser extent (26.4 nmoles/min/ml in the patients compared to the normal value of 30.2).The kinetic studies of DBH exhibited an increase of Km value and a decrease in Vmax in the neurological patients. Serum copper and ascorbic acid levels (cofactors of DBH) were found to be decreased in neurological patients and hence are in agreement with the decrease in DBH activity in these patients. Other parameters such as glucose and cholesterol levels increased, protein and zinc levels decreased and ALT, AST, creatinine and urea content remained nearly unchanged in the patients' serum.

A functional polymorphism regulating dopamine β‐hydroxylase influences against Parkinson's disease

A functional --1021C --> T polymorphism in the dopamine beta-hydroxylase gene has been demonstrated to regulate plasma DBH activity. We report that individuals with genetically determined low serum DBH activity (genotype T/T) have protection against Parkinson's disease (p = 0.01). In particular, we observed an underrepresentation of the T/T genotype odds ratio = 0.46 (CI = 0.27-0.8). Rather than identifying a haplotype, or a marker in linkage disequilibrium with the risk variant, this to our knowledge is the first report directly linking PD susceptibility with a proven functional variant.

A study of the relationship between the DBH activity in serum and a MspI polymorphic site in intron 9 of the human DBH gene in schizophrenia

Intron 9 of the human dopamine β-hydroxylase (DBH) gene was amplified using a long PCR procedure in unrelated patients with schizophrenia and unrelated control subjects. MspI digestion of the PCR fragments showed a two allele polymorphism, A1 and A2. Kruskal-Wallis analysis revealed a significant difference in serum DBH activity among the three groups carrying the A1/A2 genotype, the drug-free and drug-treated patients, and the control subjects ( H= 12.2, df=2, p<0.005), and also a significant difference among the three subgroups of drug-treated patients carrying the genotype of A1/A1, A2/A2 or A1/A2 ( H=10.4, df=2, p<0.01). The present results suggest that the MspI polymorphic site in intron 9 of the human DBH gene may be associated with alterations of DBH activity in schizophrenia and with the influence of neuroleptic drugs on the DBH activity as well.

Are gender differences genetically related to catecholamine metabolism in schizophrenia?

Serum homovanillic acid (HVA) and norepinephrine (NE), serum dopamine-β-hydroxylase (DBH), platelet monoamine oxidase (MAO), and erythrocyte catechol-O-methyltransferase (COMT) have been measured in 86 healthy parents of schizophrenic patients and 36 normal control subjects. The t-test showed that serum HVA concentration was significantly higher in mothers of female patients than in mothers of male patients ( p < .05); Kruskal-Wallis analysis revealed a significant difference in erythrocyte COMT activity among the mothers of male patients, mothers of female patients and female control subjects ( H = 8.7, df = 2, p < .02); and the Mann-Whitney test demonstrated that erythrocyte COMT activity was significantly increased in mothers of male patients as compared with female control subjects ( p < .01), but there were no significant differences in the HVA concentration and COMT activity between the fathers of male and female patients, and male control subjects. There were no significant changes in serum NE concentration, serum DBH and platelet MAO activity in these subjects. The present study suggests that catecholamine metabolism in mothers of schizophrenic patients may play a genetic role in the gender differences of schizophrenia.

Studies on concentrations of NA and HVA and activity of DBH in the serum from schizophrenic patients, first-degree relatives and normal subjects

The serum noradrenaline (NA), homovanillic acid (HVA) and dopamine β-hydroxylase (DBH) have been examined in neuroleptic-free and -treated patients, healthy first-degree relatives of the patients and normal subjects. Analysis of variance (ANOVA) revealed significant differences in the concentrations of serum NA( F = 2.91, p < 0.05) and HVA( F = 3.58, p < 0.05), and in the activity of serum DBH( F = 2.77, p < 0.05) among the four groups. The serum NA was significantly higher in neuroleptic-free patients (475±220pg/ml, n = 18), than in healthy first-degree relatives (343±189 pg/ml, n = 37, p < 0.05) or in normal subjects (354±111 pg/ml, n = 17, p < 0.05), and it also was significantly higher in neuroleptic-treated patients (442±223 pg/ml, n = 58) than in healthy first-degree relatives ( p < 0.05) or in normal subjects ( p < 0.05). There was a trend towards high serum HVA in neuroleptic-free patients (11.3±6.3 ng/ml, n = 17) compared with the other three groups. The serum DBH activity was high in neuroleptic-free patients (31.2±15.6 nmol/ min/ml, n = 17), and significantly in comparison with those treated with neuroleptic drugs (21.6±10.9 nmol/ min/ml, n = 56, p < 0.05). There was a significant negative correlation between HVA concentration and DBH activity in the serum from neuroleptic-free patients ( r = −0.64, n = 16, p < 0.01), and there appeared to be three subgroups with alterations of serum DBH activity and HVA concentration. The concentrations of serum HVA or NA, or the activity of serum DBH did not correlate with the severity of illness. These results suggest that disturbances of metabolic pathways of catecholamines may be involved in schizophrenia and that this group of schizophrenic patients may be heterogeneous in neurochemistry.

No change in serum dopamine-β-hydroxylase activity in workers exposed to trichloroethylene

To determine whether occupational exposure to trichloroethylene (TCE) influences sympathetic nerve activity, serum dopanine-β-hydroxylase (DBH) activities were analyzed in 84 male workers exposed to TCE and 83 male age-matched controls. The workers were exposed to about 22 ppm TCE in air. There were no significant differences between the mean serum DBH activity levels for the exposed workers and the corresponding controls. No significant correlation was found between the serum DBH activities and the urinary TCE-metabolite levels or the duration of employment of the workers. The results suggest that chronic occupational exposure to TCE did not influence sympathetic nerve activity of the workers.

Serum dopamine-β-Hydroxylase activity and alcohol withdrawal symptoms

Fifty male alcoholics had serum dopamine-β-hydroxylase (DBH) activity, and serum prolactin (PRL) levels measured on the day of withdrawal, and 22 of them also on days 7 and 28 after it. The obtained values were related to the development of withdrawal symptoms. Treatment was begun with meprobamate on the first day of withdrawal, and from day 7 it was completed with disulfiram (250 and 500 mg/day, respectively). Serum DBH activity decreased significantly by day 7, however a further fall of it occurred by day 28 only in patients receiving high doses (500 mg) of disulfiram. PRL levels rose over the period of withdrawal which reached significance level on day 28. No correlation was found between serum DBH activity and the severity of withdrawal symptoms. Serum DBH activity did not differ from that of the healthy controls at either point of time, while serum PRL level was significantly elevated throughout the period of the study.

肥満と血清Ｄｏｐａｍｉｎｅ‐β‐ｈｙｄｒｏｘｙｌａｓｅ活性

The relationship between obesity index and serum dopamine-β-hydroxylase (DBH) activity, which was considered to be a useful index as a sympathetic nerve activity, was examined on 55 males and 61 females over 19 years old who lived in Shiramine-village, Ishikawa Prefecture. The results obtained were as follows. 1) Frequency of obese persons, whose obesity indexes were over +10%, in females 2) Significant negative correlation between obesity index and serum DBH activity was observed in females. However, there was no significant correlations between them in males.was significantly high, compared with that in males. 3) The serum DBH activities in the obese females under 39 years old were significantly low, compared with that in non-obese females . The serum DBH activities in nonobese females tended to decrease with age. However, in obese females, the changes of the serum DBH activities with age were not observed. These results suggests that the sympathetic nerve activity in obese females might be depressed from youth.

Dopamine-β-hydroxylase activities in serum and cerebrospinal fluid of aged and demented patients

Age-related changes in dopamine-β-hydroxylase (DBH) activities in serum and cerebrospinal fluid (CSF) were determined. In normal subjects, serum DBH activity increased gradually from the 3rd to the 8th decade, but decreased prominently in the 9th decade. DBH activity in CSF did not differ between younger and older subjects. Serum DBH activity decreased significantly in senile dementia of Alzheimer's type (SDAT, 12.2 ± 8.8 nmoles/min/ml , P < 0.05), but not in multi-infarct dementia (MID, 13.9 ± 9.1 nmoles/min/ml ) compared to control subjects ( 17.1 ± 9.5 nmoles/min/ml ). The decrease of serum DBH in SDAT was more prominent in patients with severe dementia and/or severe brain atrophy. DBH activity in CSF was much lower than that in serum and did not correlate with each other. DBH activity in CSF obained from SDAT patients ( 1.60 ± 0.94 nmoles/h/ml ) and from MID patients ( 2.01 ± 0.99 nmoles/h/ml ) were both lower than that from other neurological diseases without dementia ( 4.04 ± 3.81 nmoles/h/ml ). DBH in CSF from SDAT patients was significantly lower ( P < 0.05) than that from controls, but that from MID did not differ from controls. Noradrenergic nervous dysfunction is partly associated with pathophysiology and life expectancy of senile dementia of Alzheimer's type (SDAT).

Comparative analysis of indices of central dopaminergic functions in man

Various postulated indices of central dopaminergic activity - cerebrospinal fluid (CSF) dopamine (DA), dihydroxy-phenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), plasma NA, serum prolactin, serum dopamine-β-hydroxylase (DBH), and platelet monoamine oxidase (MAO) activity - were measured in 30 drug-free inpatients. The mean values and the ranges were similar to those described in the literature. Plasma NA showed significant positive correlation with age. Significant positive correlation was found between CSF DA and its metabolites DOPAC and HVA. Serum DBH activity showed a slight but significant inverse correlation with CSF DA and its two metabolites. CSF NA showed a significant positive correlation with CSF DOPAC, but only in females. Serum DBH activity had no significant correlation either with CSF or with plasma NA levels. These findings suggest that either CSF HVA or DOPAC and DA may be useful indicators of DA metabolism in humans. Serum DBH activity may be in relationship with the central dopaminergic functions.

Reduced serum dopamine-beta-hydroxylase activity in paranoid schizophrenics.

The serum dopamine-beta-hydroxylase activity of 134 carefully selected paranoid schizophrenic patients was compared with that of 118 normal controls. Significantly reduced serum DBH activity found in the schizophrenic group in comparison to the control group could not be brought into relationship with the patients' age, nor with neuroleptic treatment. Manic depressive patients showed values similar to the normal control group. It is discussed that mainly genetically determined low serum DBH activity may be related to the hyperdopaminergic pathomechanism of paranoid schizophrenia.

Serum dopamine β-hydroxylase activity in non-human primates: phylogenetic and genetic implications

1. Serum dopamine β-hydroxylase (DBH) activity is one to two orders of magnitude higher in man than in any other species previously studied. The high levels of human serum DBH are associated with the inherited allele DBH H. 2. DBH activity was measured in serum from gorillas, chimpanzees, orangutans, gibbons, rhesus monkeys and squirrel monkeys in an attempt to determine how recently in the course of evolution the allele DBH H had originated. 3. Of the non-human primates tested, only gorillas had high levels of serum DBH activity comparable to those found in man. 4. The genetic polymorphism responsible for elevated serum DBH in man is probably of very recent evolutionary origin.

Assay of dopamine β-hydroxylase in human serum as a modification of the assay for the enzyme in rat serum by high-performance liquid chromatography

Dopamine h 3,4-dihydroxyphenylethylamine, ascorbate : oxygen oxidoreductase (P-hydroxylating), EC 1_14_17.1] catalyzes the P-hydrosylation of doparnine, the Iast step in the biosynthesis of norepinephrine. The enzyme is released with catecholamines into the blood stream from the peripheral sympathetic nerve endings [I J , and its activity in human serum may reflect the degree of diseases accompanying changes in the Ievel of serum DBH activity, such as hypertension and renal and neurological diseases [Z] , and has therefore drawn much attention from clinical and biomedical investigators. We reported recently a sensitive method for the assay of DBH in rat serum based on the following principle_ Octopamine formed enzymatically from the substrate tyrarnine, is separated by Dowex 5OW-X4 column chromatography and oxidized with periodate to p-hydroxybenzaldehyde, which is then converted into a fluorescent compound with 2,2’-dithiobis(laminonaphthaIene) (DT_k?S)_ The compound, after extraction with n-hexane--chloroform, is separated by normal-phase high-performance liquid chromatography (HPLC) on LiChrosorb Alox T with fluorescence detection using n-hexane-chloroform containing a small amount of acetic acid as mobile phase [3]. DBH activity in human serum is much higher than that in rat serum; and the optimal conditions of the reaction with the enzyme in human serum were found to be slightly different from those with the enzyme in rat serum. Thus, the reported DBH assay method has been applied to the assay of the enzyme in a minute of human serum with some modifications_

Catecholamine-thyroid Hormone Interactions: III. Serum DBH Activity and Thyroxine in Euthyroid Subjects

Catecholamine-thyroid Hormone Interactions: III. Serum DBH Activity and Thyroxine in Euthyroid Subjects

Longitudinal Assessment of MAO-, COMT-, and DBHActivity in Patients with Bipolar Depression

This study was carried out to determine whether the activity of regulatory enzymes for biogenic amines are state variables or trait variables for bipolar depression. The activity of MAO, COMT, and DBH in platelets, RBC and serum, respectively, was measured repeatedly in patients with bipolar depression and in matched control subjects. An increase in MAO activity was observed in patients compared to controls, while MAO activity was unrelated to the patient's psychopathological state. COMT activity was higher in female patients than in female controls and was lower in male patients than in male controls, but it failed to be related to the psychopathological state of patients. Relevant differences in serum DBH activity failed to occur either between patients and controls, or in patients during different states of their illness. The findings suggest that the activity of MAO and COMT are trait variables for bipolar depression, while DBH activity is neither a state variable nor a trait variable. it is discussed why only longitudinal studies in contrast to conventional cross-sectional assessments allow a distinction between state and trait variables.

Serum Dopamine-β-Hydroxylase Activities in the Various Disorders with Symptoms of Dizziness or Vertigo

Serum dopamine-β-hydroxylase (DBH) activities were examined in 110 patients complaining of dizziness or vertigo. The enzyme was measured by the photometric assay method of Nagatsu and Udenfriend.The mean serum DBH activity of 17 patients was 16.1±8.3 units and there was no significant difference from findings in the normal controls (18.2±6.7 units).Dizziness and vertigo were often complained of by patients with cerebrovascular diseases, particularly thrombosis of the posterior cerebral artery or vertebro-basilar insufficiency, as well as other neurological diseases such as spino-cerebellar degeneration, normal pressure hydrocephalus, cerebellar hemorrhage, cerebellar tumor, Parkinson's disease, essential tremor, amyotrophic lateral sclerosis etc.Computed tomography (CT) of the brain was performed on 71 patients. Serum DBH activities in the patients with normal CT scan findings exhibited no significant change, while activities in patients with CT findings of cerebral atrophy, cerebellopontine atrophy and localized low density areas exhibited comparatively low values.In the dysautonomic patients with dizziness or vertigo, the serum DBH activities exhibited wide varieties, but there were 5 with values under 5 units.No significant change was seen on the enzyme activity during attacks of vertigo or after the caloric test, in the same individual.

Dopamine beta-hydroxylase in health and disease.

DBH is a copper-containing oxygenase that catalyzes the hydroxylation of the beta carbon of a wide variety of phenylethylamine derivatives using molecular oxygen ascorbate as cofactors. It is a glycoprotein with a molecular weight of 290,000 and consists of four identical subunits, each with a single copper atom and 5% carbohydrate by weight. The enzyme is a constituent of catecholamine storage vesicles in chromaffin cell and adrenergic neurons in the peripheral and central nervous system where it functions to synthesize noradrenaline from dopamine. Although endogenous inhibitors have been isolated, they have not been demonstrated to have a physiological function, and the kinetics of the enzyme in vitro and in vivo suggest that the enzyme is not a rate limiting step in catecholamine synthesis under normal conditions. DBH exists in both a soluble form within vesicles and as a constituent of their membranes with its active site directed inward. The significance of the partition of the enzyme into soluble and membrane forms is not understood, although the soluble form has a fivefold greater homospecific activity. DBH has been one of the most intensively investigated enzymes in neurochemistry for several reasons. It is a readily assayable constitutent of catecholamine storage vesicles and, as such, provides a convenient biochemical marker for subcellular fractionation work and studies of the cellular regulation of catecholamine synthesis, storage, and release. The adrenal medulla is a rich source of the enzyme for purification, and the purified enzyme is highly antigenic, thereby enabling the use of several immunological techniques to study the cellular dynamics of the enzyme and the organelles in which it is located. These include radioimmunoassay, immunohistochemistry, and cytochemistry. This review firstly summarizes the present state of knowledge concerning the molecular properties of DBH. It then describes the tissue, cellular, and subcellular localization of the enzyme and its physiological regulation. The remainder of the review concentrates on those aspects of research on DBH in which the authors have participated that have led to general advances such as the development of the concept of homospecific activity, the introduction of immunohistochemistry for the localization of enzymes involved in transmitter metabolism, the release of macromolecules from synaptic vesicles during the process of exocytosis, the use of antibodies to DBH administered in vivo to study the fate of synaptic vesicle membranes and to produce specific immunological lesions of noradrenergic nerves in the peripheral and central nervous system, the genetic, environmental, and physiological determinants of serum DBH activity as an index of sympathetic function in animals and man, and the question of its diagnostic value in disease.

Characterization of the basis for differences in serum DBH activity in immature and adult rats by use of homologous antibody.

Abstract– Rat serum dopamine‐β‐hydroxylase (DBH) activity decreased 5‐7‐fold between 15 and 60 days of age. Immunoprecipitation performed with homologous antibody (guinea‐pig anti‐rat adrenal DBH) showed that during this time period the quantity of antibody necessary to precipitate 50% of the enzymatic activity (AD50) decreased 5‐fold from 0.25 to 0.05 μl/ml. The biochemical properties of rat serum DBH at 15 and 60 days of age were compared to test the hypothesis that there might be different biochemical forms of the enzyme in the blood of immature and adult rats. Thermal stability, apparent Km for tyramine, electrophoretic mobility, pH optima and elution profile on gel filtratioh chromatography were all found to be similar for rat serum DBH at both ages. On the basis of homospecific activity and multiple similarities in biochemical characteristics, it appears that differences in serum activity at the two ages reflect differences in the steady‐state levels of enzyme.To determine the turnover of serum DBH in the two age groups, the recovery of enzyme activity was monitored after acute clearance of the circulating pool of DBH by treatment with the homologous antiserum. Immunotitration of DBH activity in vivo indicated that the total pool of serum enzyme was 4‐fold greater in the mature rat than in 4‐day‐olds. After treatment of adult rats with 2μl of homologous antiserum, serum DBH activity was reduced by 85% with a half‐life of recovery of 3.0 ± 0.6 days; the estimated fractional rate of degradation was 0.23 ± 0.06 day−1 and the rate of entrance was 2.3 ± 0.2 units/ml/day. After treatment of 4‐day‐old rats with 1 μl of homologous antiserum, serum DBH activity was reduced by 95% with a half‐life of recovery of 3.3 ± 0.5 days: the estimated average fractional rate of degradation was 0.22 ± 0.06 day−1 and the average rate of entrance was 10.7 ± 1.6 units/ml/day. Thus, the several‐fold difference in steady‐state levels of serum DBH in rat pups as compared to adult rats appears to be due to greatly increased rates of entrance of the enzyme in the immature rats.

A study of the possible relationship of serum dopamine-beta-hydroxylase activity with diabetic neuropathy.

Serum DBH activity in a normal population of 58 individuals shows a gaussian distribution, on the opposite to what happens in a population of 100 diabetics. These two populations also differ statistically by the analysis of variance. However it was round that it is not possible to correlate serum DBH neither with insulin administration, type of diabetes, duration of disease, nor with the severity of the involvement of the peripheral nerves. It is hypothesized that the variation of DBH in diabetics may have a multifactorial cause, resulting from several metabolic and circulatory alterations that accompany the disease.