Serum DBH Research Articles

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.

An Attempt to Evaluate Autonomic Nervous Functions in Workers Exposed to Vibration : Respiratory Arrhythmia and Serum DBH Activities

An Attempt to Evaluate Autonomic Nervous Functions in Workers Exposed to Vibration : Respiratory Arrhythmia and Serum DBH Activities

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.

Biochemical indices of sympathetic activity in migraine.

Plasma levels of adrenaline, noradrenaline, cAMP, free fatty acids and serum DBH, were estimated in a group of ten migrainous patients before, during and after a migraine attack. All parameters, apart from adrenaline, showed a statistically significant elevation during the headache period. As the blood concentration of the above substances taken in combination is the most reliable index of sympathetic activity available at present, these findings indicate that there is considerable sympathetic dysfunction during the migraine attack.

Failure of naloxone to antagonize metoclopramide induced prolactin rise.

Seven subjects aged 21--54 years were investigated. Serum PRL and DBH were estimated before and at 30, 60, 90 and 120 min after the administration of 20 mg clopropamide. The same parameters were estimated a second time when 0.4 mg naloxone was associated. PRL level increased and DBH decreased in all the patients in both investigations and no significant differences between the two occasions were detected. It is suggested that probably the two substances do not act on identical receptors.

Serum DBH and platelet MAO in patients with depressive disorders.

Km and V of serum dopamine-beta-hydroxylase and platelet monoamine-oxidase (MAO) were determined in the depressive and manic state as well as after recovery in patients with affective psychoses and in the depressive state of patients with neurotic depression. DBH and MAO values were measured also in age- and sex-matched controls. The Km and V values of each enzyme failed to differ between patients and healthy controls or between patients during and after an episode of illness. The ratio of V of serum DBH (tyramine as substrate) tended to be lower in patients independent of their psychopathological state than in controls. The findings fail to support the notion that characteristics of the peripheral enzymes measured provides a reliable indicator of a biological disposition to depression, but are consistent with the notion that the balance of monoamine may play a role in certain psychopathological states.

25] Radioimmunoassay and immunotitration of human serum dopamine β-hydroxylase

Publisher Summary This chapter describes the radioimmunoassay and immunotitration of human serum dopamine β-hydroxylase. Dopamine β-hydroxylase (DBH) is the enzyme that catalyzes the conversion of 3,4-dihydroxy-phenylethylamine (dopamine) to the neurotransmitter norepinephrine is released with catecholamines from vesicles in the adrenal medulla and sympathetic nerves, and is found circulating in blood. The immunotitration of DBH, like other immunotitration procedures, is based on the assumption that increasing quantities of antibody will be required to bind a given fraction of antigen as the quantity of antigen is increased. In practice, several different quantities of anti-DBH antibody are incubated with aliquots of the sample being analyzed. Antibody-bound and free DBH may be separated by precipitation of the anti-DBH antibody with a second antibody. Immunotitration of human serum DBH was performed with a two-stage procedure. Incubation tubes for the first stage contained 50 μl of human serum diluted 1:6 and 50 μl of rabbit serum diluted 1:250. The observation suggests the existence of a rare variant form of DBH with decreased enzymatic activity per molecule of enzyme protein. This observation was facilitated by the ability to assay many samples simultaneously and could not have been made without the ability to measure DBH protein.

Dopamine-β-hydroxylase in a biracial community: Demographic, cardiovascular and familial factors

The characteristics of dopamine-β-hydroxylase (DBH) distribution in a total community-based sample ( N = 330) are presented. DBH activity was measured in duplicate by spectrophotometric assay in a random sequence of aliquots. DBH values were higher in white than in black residents of Evans County; sex- and age-related changes were also observed. Similarity of DBH enzymatic activity was found between genetically related individuals, but not between spouses. Determination of DBH on samples from a 7- and 15-yr follow-up of this cohort revealed long-term stability of DBH enzymatic activity and marked tendency for individual ‘tracking’ of DBH values. Serum DBH was not associated with blood pressure levels in each cross-sectional examination, nor was DBH predictive of blood pressure changes over the period of follow-up.

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.

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.

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.

Catecholamine metabolism in familial amyloid polyneuropathy.

In order to evaluate the involvement of the peripheral autonomic nervous system in the pathogenesis of type 1 familial amyloid polyneuropathy, the urinary excretion rates of catecholamines and serum dopamine-beta-hydroxylase (DB/) activity were examined in 22 patients at various clinical stages. Changes in both indices were closely linked to the progression of the illness; urinary excretion rates of catecholamines were first decreased in patients suffering from moderate autonomic dysfunction, while serum DBH activity was significantly reduced only in patients with far advanced disease. These findings suggested that patients with advanced disease might be suffering from a chronic deficiency of catecholamines in the peripheral sympathetic nerves. Administration of L-dopa, however, failed to improve the clinical manifestations.

Changes of serum DBH activity during cardiopulmonary bypass in patients.

Changes of serum DBH activity during cardiopulmonary bypass in patients.

Changes in the Metabolism of Biogenic Amines in Alcoholism—Especially Regarding CSF Monoamine Metabolites and Serum DBH Activity

Concentrations of the major metabolites of biogenic amines in cerebrospinal fluid and activity of serum dopamine-beta-hydroxylase in abstinent alcoholics were measured, suggesting that withdrawal symptoms of alcoholics were based on the abnormality of serotonin and dopamine metabolism in the body.

Serum Dopamine-β-Hydroxylase Activity Does Not Reflect Sympathetic Activation During Hypoglycemia*

The relationship between serum dopamine-beta-hydroxylase (DBH) activity and sympathetic nervous system activation in response to insulin-induced hypoglycemia was investigated in healthy young male and female volunteers. Serum DBH activity and glucose levels were measured in blood samples obtained 30 min before and 90 min after the iv administration of regular insulin or placebo. All subjects developed significant hypoglycemia in response to the insulin and manifested signs of sympathetic activation, including increased heart rate, diaphoresis, and lightheadedness. However, despite obvious clinical manifestations of increased sympathetic activity, none of the subjects exhibited a significant alteration in serum DBH activity either in comparison to baseline or placebo values. These data question the suitability of serum DBH measurements for assessing adrenomedullary function in man.

Serum dopamine-beta-hydroxylase in schizophrenic patients.

Abstract— Dopamine‐β‐hydroxylase (DBH) activity in serum was decreased significantly in schizophrenic patients (16.17 ± 12.60 μmol/min/1 of serum, mean ± S.D., n = 149) when compared with that of normal controls (42.53 ± 30.94 μmol/min/1 of serum, mean ± S.D., n= 153) and neurotic patients. Long duration of disease did not cause any significant changes in serum DBH activity except a tendency for increase in patients of lodger than 18 years duration. We also examined the possibility that the serum DBH deficiency in the schizophrenic group was an artifact of treatment with antipsychotic drugs, especially phenothiazines. No significant difference was observed between the patients treated with the drugs and the patients not receiving the drugs.

Fluorescence assay for dopamine β-hydroxylase activity in human serum by high-performance liquid chromatography

As a model for the assay of enzyme activity by high-performance liquid chromatography, a simple, sensitive and specific fluorescence assay for dopamine β-hydroxylase (DBH) activity was devised using o-phthalaldehyde as reagent. Tyramine was used as a substrate and was incubated under optimal conditions. Endogenous inhibitors in the enzyme preparation were completely inactivated by addition of N-ethylmaleimide and a small amount of Cu 2+. After isolating the amines on a small Dowex 50 column, the eluate was analyzed fluorometrically by high-performance liquid chromatography. The product, octopamine, was eluted prior to and completely separated from tyramine, and the height of the fluorescence peak gave the amount of enzymatically formed octopamine. DBH activity in serum obtained from the umbilical vein was much lower than the activity in adult human serum. Normal values of serum DBH activity from 153 subjects (1–74 years) showed a mean and standard deviation of 42.5 ± 30.9 and 34.3 ± 18.2 μmol/min/liter of serum at 37°C, before and after computation by the method of Hoffmann. Male serum had a slightly higher activity than female serum. Serum DBH activity rapidly increased during the first 10 years after birth, gradually increased up to an optimum at 40–50 years, and then decreased.