DBH Activity Research Articles

Genetic regulation of catecholamine synthesis, storage and secretion in the spontaneously hypertensive rat

Understanding catecholamine metabolism is crucial for elucidating the pathogenesis of hereditary hypertension. Here we integrated transcriptional and biochemical profiling with physiologic quantitative trait locus (eQTL and pQTL) mapping in adrenal glands of the HXB/BXH recombinant inbred (RI) strains, derived from the spontaneously hypertensive rat (SHR) and normotensive Brown Norway (BN.Lx). We found simultaneous down-regulation of five heritable transcripts in the catecholaminergic pathway in young (6 weeks) SHRs. We identified cis-acting eQTLs for Dbh, Pnmt (catecholamine biosynthesis) and Vamp1 (catecholamine secretion); enzymatic activities of Dbh and Pnmt paralleled transcripts, with pQTLs for activities mirroring eQTLs. We also detected trans-regulated expression of Vmat1 and Chga (both involved in catecholamine storage), with co-localization of these trans-eQTLs to the Pnmt locus. Pnmt re-sequencing revealed promoter polymorphisms that result in decreased response of the transfected SHR promoter to glucocorticoid, compared with BN.Lx. Of physiological pertinence, Dbh activity negatively correlated with systolic blood pressure in RI strains, whereas Pnmt activity was negatively correlated with heart rate. The finding of such cis- and trans-QTLs at an age before the onset of frank hypertension suggests that these heritable changes in biosynthetic enzyme expression represent primary genetic mechanisms for regulation of catecholamine action and blood pressure control in this widely studied model of hypertension.

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.

Dopamine-ß-hydroxylase (DBH), its cofactors and other biochemical parameters in the serum of neurological patients in Bangladesh

Dopamine-ß-hydroxylase (DBH) is a neurotransmitter synthesizing enzyme which catalyzes the formation of norepinephrine from dopamine. It is found in all cells that produce epinephrine and norepinephrine (catecholamines). Up to now no study has been done on the level of DBH and its co-factors in the serum of neurological patients in Bangladesh. This tempted us to do this research on DBH in Bangladeshi neurological patients. In this study, we measured the level of DBH activity in the serum of patients of three different age groups (8–14yrs, 20–40yrs and 45–60yrs) suffering from neurological diseases.

Association study between the −1021C/T polymorphism of the dopamine-β-hydroxylase gene promoter and personality traits in healthy subjects

Dopamine and norepinephrine are implicated in the characterization of personality traits. Dopamine-β-hydroxylase (DBH) is the enzyme responsible for conversion of dopamine to norepinephrine, and thus plays an important role in controlling dispositions of these neurotransmitters. Previous studies have shown that the −1021C/T polymorphism of the DBH gene promoter influences plasma DBH activity. Therefore, we examined the association between the −1021C/T DBH polymorphism and personality traits in 627 Japanese healthy volunteers. The DBH genotypes were identified by a PCR-RFLP method, and personality traits were assessed by the Temperament and Character Inventory (TCI). In the two-factor analysis of covariance with the DBH genotype and sex as factors and with age as a covariate, there was no main effect of the DBH genotype on any TCI score, while the interaction between the factors was significant in harm avoidance. In the post hoc analysis, the group with the T allele predictive of lower DBH activity had higher scores of harm avoidance than that without the T allele in females ( p = 0.006), but not in males. The present study suggests that the −1021C/T DBH polymorphism affects the personality trait of harm avoidance in healthy females.

Normal plasma dopamine-beta-hydroxylase in non-treated and treated Parkinson patients.

Plasma dopamine-beta-hydroxylase activity (DBH) was estimated in 50 drug-free Parkinson patients, 30 of whom had never been treated, in 26 patients treated chronically with L-Dopa, and in 44 controls. 22 of the drug-free patients were examined again after two weeks treatment with L-Dopa plus decarboxylase inhibitor. In disagreement with other reports, no differences were found among the groups and no change in the enzyme activity occurred after treatment, although urinary homovanillic acid increased 20 fold. Low DBH activities could not be attributed to the age of onset or duration of illness, main symptom, depression, autonomic disturbances, or duration of drug treatment. The only difference was found in patients with dementia associated to their illness, who showed low enzyme activities.

Norepinephrinergic afferents and cytology of the macaque monkey midline, mediodorsal, and intralaminar thalamic nuclei

The midline and intralaminar thalamic nuclei (MITN), locus coeruleus (LC) and cingulate cortex contain nociceptive neurons. The MITN that project to cingulate cortex have a prominent innervation by norepinephrinergic axons primarily originating from the LC. The hypothesis explored in this study is that MITN neurons that project to cingulate cortex receive a disproportionately high LC input that may modulate nociceptive afferent flow into the forebrain. Ten cynomolgus monkeys were evaluated for dopamine-beta hydroxylase (DBH) immunohistochemistry, and nuclei with moderate or high DBH activity were analyzed for intermediate neurofilament proteins, calbindin (CB), and calretinin (CR). Sections of all but DBH were thionin counterstained to assure precise localization in the mediodorsal and MITN, and cytoarchitecture was analyzed with neuron-specific nuclear binding protein. Moderate-high levels of DBH-immunoreactive (ir) axons were generally associated with high densities of CB-ir and CR-ir neurons and low levels of neurofilament proteins. The paraventricular, superior centrolateral, limitans and central nuclei had relatively high and evenly distributed DBH, the magnocellular mediodorsal and paracentral nuclei had moderate DBH-ir, and other nuclei had an even and low level of activity. Some nuclei also have heterogeneities in DBH-ir that raised questions of functional segregation. The anterior multiformis part of the mediodorsal nucleus but not middle and caudal levels had high DBH activity. The posterior parafascicular nucleus (Pf) was heterogeneous with the lateral part having little DBH activity, while its medial division had most DBH-ir axons and its multiformis part had only a small number. These findings suggest that the LC may regulate nociceptive processing in the thalamus. The well established role of cingulate cortex in premotor functions and the projections of Pf and other MITN to the limbic striatum suggests a specific role in mediating motor outflow for the LC-innervated nuclei of the MITN.

Prognostic significance of biochemical heterogeneity of catecholaminergic clones in neuroblastoma

Background/Purpose Genetic heterogeneity of neuroblastic tumors leads to biochemical changes that manifest themselves in different symptoms and clinical courses, which may vary from spontaneous regression and remission to progression with fatal outcome. Methods To test the hypothesis that ratios of dopamine (DA) to noradrenaline and of DA to vanillylmandelic acid reflect the composition of adrenergic clones and tumor heterogeneity, we determined urinary DA/noradrenaline and DA/vanillylmandelic acid ratios that presumably reflect DA- β-hydroxylase (DBH) activity and the prognostic values thereof. Results Based on catecholamine metabolism, 4 model situations were defined: ( a) complete block of DBH in all cells; ( b) block of DBH in some cells; ( c) a different enzymatic block; and ( d) normal DBH activity in the population of tumor-forming cells. Normal DBH activity was encountered most frequently in children younger than 2 years and in tumors representing favorable prognostic stages (I, II, and IVS). Surviving children with stage IV neuroblastoma presented with tumors composed primarily of cells without the DBH block. Further stratification of 2 prognostically poor groups (stages IV and III + IV) was possible with respect to DBH activity. Conclusions Differential production of neurotransmitters in a population of tumor cells may be explained in terms of tumor heterogeneity.

Effect of Estrogens with ERα or ERβ on Transcriptional Regulation of Catecholamine Biosynthetic Enzymes

Estrogen is proposed to be responsible for some of the gender specific differences in susceptibility to several disorders relating to catecholaminergic systems. Previously, administration of estrogen to rats in vivo was found to alter mRNA levels of catecholamine (CA) biosynthetic enzymes, TH and DBH, as well as GTPCH, rate limiting for tetrahydrobiopterin (cofactor for TH, TPH and NOS). However, there were differences depending on the dose and mode of administration and the tissue examined. Prolonged estrogen injections also attenuated some of the stress triggered changes in gene expression of CA biosynthetic enzymes. Since the different responses might reflect changes in ER subtype expressed, we transfected PC12 cells with either ERα or ERβ and reporter vectors for TH, DBH or GTPCH. Treatment with 2.5-20 nM 17 β-estradiol (E2) elevated TH, DBH or GTPCH promoter driven luciferase activities with ERα. However, with ERβ, E2 decreased TH, and increased DBH and GTPCH promoter activities. The promoter elements involved are being identified. We examined the combined response to E2 and elevated cAMP. Their effects were additive on DBH promoter activity. However E2 attenuated the elevation of TH and GTPCH transcription in response to cAMP analogs with either ER. Thus, the ER subtype expressed can influence transcriptional regulation of CA systems.

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.

HAND2 synergistically enhances transcription of dopamine-β-hydroxylase in the presence of Phox2a

Noradrenergic neuronal identity and differentiation are controlled by cascades of transcription factors acting downstream of BMP4, including the basic helix–loop–helix DNA binding protein HAND2 and the homeodomain factor Phox2a. Dopamine-β-hydroxylase (DBH) is the penultimate enzyme required for synthesis of norepinephrine and is thus a noradrenergic cell type-specific marker. We have examined the interaction of HAND2 and Phox2a at the DBH promoter. Using transient transfection of P19 or NT-2 cells, HAND2 is shown to synergistically enhance Phox2a-driven transcriptional activity at the DBH promoter, an effect that is enhanced by cAMP. While mutation of the Phox2a homeodomain binding sites HD1, HD2, and HD3 results in the loss of HAND2/Phox2a transactivation of DBH, it is the interaction of HAND2/Phox2a at the CRE/AP1-HD1/2 domains in the DBH enhancer that are required for synergistic activation by HAND2. We find that HAND2 functions as a transcriptional activator without directly binding to E-box sequences in the DBH promoter, suggesting that HAND2-mediated DBH activity occurs by protein–protein interactions with other transcriptional regulators. Although we were unable to detect interaction of HAND2 and Phox2a in IP/Western blots, HAND2 synergistic activation of DBH is blocked by E1A, suggesting that HAND2 interacts with CBP (cAMP response element binding protein) in this transcriptional complex. In the presence of the putative HAND2 dimerization partner, E12, synergistic activation of DBH transcription is titrated away, suggesting that HAND2 does not functionally dimerize with E12 in the DBH transcription complex. Our data suggest that HAND2 regulates cell type-specific expression of norepinephrine in concert with Phox2a by a novel mechanism.

A genotype-controlled analysis of plasma dopamine β-hydroxylase in healthy and alcoholic subjects: evidence for alcohol-related differences in noradrenergic function

Background Norepinephrine and dopamine mediate important aspects of alcoholism and alcohol withdrawal. Dopamine-β-hydroxylase (DβH) converts dopamine to norepinephrine. A recent study demonstrated a strong association between variance in plasma DβH activity and a novel polymorphism (DBH-1021C→T) at the structural locus (DBH) encoding DβH protein. Methods Our study investigated whether the DBH-1021C→T polymorphism and plasma DβH activity were associated with alcoholism or with delirium tremens (DT) during alcohol withdrawal by analyzing 207 German alcoholic and 102 healthy control subjects. We also examined the influence of the polymorphism on enzyme activity. Results Mean (+SD) plasma DβH activity measured in alcoholic subjects abstinent was significantly lower than that observed in control (27.7 + 16.7 vs. 35.6 + 18.8; p = .01). It did not differ between subjects with DT during withdrawal and subjects with mild withdrawal symptoms. The T allele of the DBH-1021C→T polymorphism was significantly associated with lower plasma DβH activity. None of the alleles or genotypes were associated with alcoholism or DT. Conclusions The data indicate that the alcoholism-related reduction in plasma DβH activity is independent of genotype at DBH-1021C→T and replicate the finding that DBH-1021C→T is strongly associated with plasma DβH activity in a native Western European population.

Genotype-controlled analysis of plasma dopamine β-hydroxylase activity in psychotic unipolar major depression

Background: Plasma activity of dopamine β-hydroxylase (DβH), the enzyme that converts dopamine to norepinephrine, is reportedly lower in patients with unipolar major depression with psychotic features (UDPF) than in those with nonpsychotic unipolar major depression (UD). Plasma DβH is under genetic control by the structural locus encoding DβH protein, DBH. This study tested the hypothesis that diagnosis-specific allelic variation at DBH accounts for lower plasma DβH in UDPF. Methods: Plasma DβH activity was measured in samples from patients with UDPF ( n = 33) and UD ( n = 45). Genotypes were determined at several functional DBH polymorphisms, including C-1021T, a single nucleotide polymorphism (SNP) in the proximal 5′ region that associates with variation in plasma DβH activity. Results: Mean plasma DβH activity was significantly lower in UDPF than in UD. Genotyping at DBH did not reveal genetic associations distinguishing UDPF from UD. A two-way analysis of variance showed significant effects of genotype and diagnostic group but no significant interaction. Conclusions: Although the effects of the diagnosis of UDPF, and of DBH allele status, on plasma DβH activity were replicated, the lower plasma DβH in patients with UDPF was not accounted for by DBH genotype. Several explanations for this result are possible. First, other variants at DBH, or at other loci, could account for the findings. Second, nongenetic factors could account for the differences in plasma DβH. In this regard, we hypothesize that abnormal regulation of hypothalamic-pituitary-adrenal function in UDPF lowers expression of DβH protein, which could in turn alter the ratio of dopamine and norepinephrine in noradrenergic neurons, thereby promoting development of psychotic symptoms.

A polymorphism in the dopamine β-hydroxylase gene is associated with “paranoid ideation” in patients with major depression

Background: Increased dopaminergic activity may play a primary role in psychotic depression. Dopamine β-hydroxylase (DβH) catalyses the key step in biosynthesis of the neurotransmitter noradrenaline from dopamine, and low DβH activity is a possible risk factor for developing psychotic depression. An exon 2 polymorphism (DBH∗444 g/a) of the DβH gene (DBH) is significantly associated with both serum and cerebrospinal fluid levels of DβH. Methods: We determined the genotype of the DBH∗444g/a polymorphism in a cohort of 164 patients with major depression and examined the association of this polymorphism with paranoid ideation, interpersonal sensitivity, and psychoticism on the Hopkins Symptom Checklist. Results: Patients who possessed the A allele were significantly more likely to have higher scores for interpersonal sensitivity and paranoia than patients without the A allele ( p = .004 and p = .048, respectively), suggesting that this allele may predispose patients to paranoia in major depression. In addition, we found an association between prolactin levels in men and DBH∗444 g/a genotype such that homozygous G individuals displayed significantly higher levels than homozygous A or heterozygote individuals. Conclusions: Depressed patients with the GG genotype of DβH have lower scores for interpersonal sensitivity and paranoid ideation. The GG genotype may be protective against the development of psychosis in the presence of a major depressive episode.

Angiotensin II Increases Vesicular Trafficking in Live Noradrenergic Brain Neurons

P1 Angiotensin II (Ang II) interacts with the AT 1 receptor subtype and stimulates turnover of norepinephrine (NE) by regulating its synthesis, release, and uptake. The cellular mechanism by which Ang II regulates this neurotransmission is not well understood. The aim of this study was to test the hypothesis that Ang II increases vesicular trafficking to increase synaptic release of NE. cDNA encoding full length rat dopamine beta-hydroxylase (DβH) fused to Green Fluorescence Protein (GFP) was cloned in pCl-Neo vector under the control of CMV promoter and used to tag synaptic vesicles. Transfection of cells with this plasmid resulted in the expression of green fluorescence and GFP-DβH fusion protein which was functional as judged by an increase in DβH activity. Transfected neurons expressed bright green fluorescence representing GFP-DβH that was predominantly localized in the cell soma. Few neurites also displayed the fluorescence. Real time confocal microscopic examination of live neurons indicated that Ang II caused a time-dependent increase in both the intensity and the number of neurites depicting green fluorescence. An increase in GFP-DβH in the neurites became apparent within one minute and persisted for 15-20 minutes. A 2.5 fold increase in the GFP-DβH positive neurites was observed by 100 nM Aug II in 15 min [control, 2±0.5 (n=20) versus Ang II treatment, 5±0.4 (n=25)]. Ang II-induced GFP-DβH redistribution was punctate, co-localized with synaptophysin and was blocked by losartan, and not by PD123319. Release of Ang II induced NE paralleled its effect on GFP-DβH distribution. PMA treatment caused translocation of GFP-DβH in a fashion comparable with Ang II. In addition, inactivation of protein kinase C by a prolonged incubation of neurons with PMA, completely blocked the translocation of GFP-DβH from the cell body to neurites. These observations demonstrate that Ang II stimulates trafficking of NE vesicles by a PKC-dependent mechanism. Thus, an increased trafficking of NE containing vesicles from the neuronal cell body to the neurites may be key to Ang II stimulated release of NE from a noradrenergic neuron.

Angiotensin II Increases Vesicular Trafficking in Live Noradrenergic Brain Neurons

P1 Angiotensin II (Ang II) interacts with the AT 1 receptor subtype and stimulates turnover of norepinephrine (NE) by regulating its synthesis, release, and uptake. The cellular mechanism by which Ang II regulates this neurotransmission is not well understood. The aim of this study was to test the hypothesis that Ang II increases vesicular trafficking to increase synaptic release of NE. cDNA encoding full length rat dopamine beta-hydroxylase (DβH) fused to Green Fluorescence Protein (GFP) was cloned in pCl-Neo vector under the control of CMV promoter and used to tag synaptic vesicles. Transfection of cells with this plasmid resulted in the expression of green fluorescence and GFP-DβH fusion protein which was functional as judged by an increase in DβH activity. Transfected neurons expressed bright green fluorescence representing GFP-DβH that was predominantly localized in the cell soma. Few neurites also displayed the fluorescence. Real time confocal microscopic examination of live neurons indicated that Ang II caused a time-dependent increase in both the intensity and the number of neurites depicting green fluorescence. An increase in GFP-DβH in the neurites became apparent within one minute and persisted for 15-20 minutes. A 2.5 fold increase in the GFP-DβH positive neurites was observed by 100 nM Aug II in 15 min [control, 2±0.5 (n=20) versus Ang II treatment, 5±0.4 (n=25)]. Ang II-induced GFP-DβH redistribution was punctate, co-localized with synaptophysin and was blocked by losartan, and not by PD123319. Release of Ang II induced NE paralleled its effect on GFP-DβH distribution. PMA treatment caused translocation of GFP-DβH in a fashion comparable with Ang II. In addition, inactivation of protein kinase C by a prolonged incubation of neurons with PMA, completely blocked the translocation of GFP-DβH from the cell body to neurites. These observations demonstrate that Ang II stimulates trafficking of NE vesicles by a PKC-dependent mechanism. Thus, an increased trafficking of NE containing vesicles from the neuronal cell body to the neurites may be key to Ang II stimulated release of NE from a noradrenergic neuron.

A haplotype at the DBH locus, associated with low plasma dopamine beta-hydroxylase activity, also associates with cocaine-induced paranoia.

Low levels of dopamine beta-hydroxylase (DbetaH) protein in the plasma or cerebrospinal fluid (CSF) are associated with greater vulnerability to positive psychotic symptoms in several psychiatric disorders. DbetaH level is a stable, genetically controlled trait. DBH, the locus encoding DbetaH protein, is the major quantitative trait locus controlling plasma and CSF DbetaH levels. We therefore hypothesized that DBH variants or haplotypes, associated with low levels of DbetaH in the plasma, would also associate with greater vulnerability to cocaine-induced paranoia. To test this hypothesis, we first showed that a di-allelic variant, DBH*5'-ins/del, located approximately 3 kb 5' to the DBH transcriptional start site, significantly associates with plasma DbetaH activity in European-Americans (n = 66). Linkage disequilibrium analysis of that polymorphism and DBH*444g/a, another di-allelic variant associated with DbetaH levels, demonstrated that alleles of similar association to DbetaH levels are in positive disequilibrium. We then estimated DBH haplotype frequencies in cocaine-dependent European Americans rated for cocaine-induced paranoia (n = 45). As predicted, the low-DbetaH-associated haplotype, Del-a, was significantly more frequent (P = 0.0003) in subjects endorsing cocaine-induced paranoia (n = 29) than in those denying it (n = 16). Comparison to control haplotype frequencies (n = 145 healthy European-Americans) showed that the association predominantly reflected under-representation of Del-a haplotypes in those denying cocaine-induced paranoia. We conclude that: (a) the two DBH polymorphisms we studied are associated with plasma DBH levels; (b) those two polymorphisms are in significant linkage disequilibrium in European Americans, with alleles of similar association to DbetaH levels in positive disequilibrium; and (c) the haplotype associated with low DBH activity is also associated with cocaine-induced paranoia. Molecular Psychiatry (2000) 5, 56-63.

The condensed matrix of mature chromaffin granules. The soluble form of dopamine beta-hydroxylase is catalytically inactive.

The important finding in the present study is not the latency per se (Fig. 1) but that the latency was highly dependent on the granule protein concentration and essentially absent at a granule concentration of 2 mg protein/mL (Fig. 2). The lack of latency at high granule protein concentration most likely reflects the decrease in homospecific DBH activity by increasing matrix protein concentration as shown in Fig. 3. As the matrix- dependent inhibition is present in an extensively dialysed matrix fraction containing molecules ≥30 kDa (defined by the preparation procedure), even after heat-treatment, we conclude that the heat-stable acidic matrix glycoproteins (chromogranins) are responsible for the inhibition. A matrix fraction largely free of chromogranin A (precipitated by 35 mM Ca2+ at pH 5.5) as well as a preparation of redissolved precipitated matrix proteins (enriched in chromogranin A) also inhibited sDBH. This indicates that the matrix-dependent inhibition of sDBH results from the combined effect of several proteins identified in the matrix (Fischer-Colbrie et al., 1987). As the matrix-dependent inhibition of sDBH was largely overcome by high salt concentration (Fig. 4), we suspect that electrostatic interactions between sDBH and the chromogranins (Hogue-Angeletti 1977; Helle et al., 1978) inhibit the sDBH by an unknown mechanism. It should be noted that the mechanism behind the anion-activation of purified sBDH is also unknown (Craine et al., 1973).

Studies of Copper Complexes Displaying N(3)S Coordination as Models for Cu(B) Center of Dopamine beta-Hydroxylase and Peptidylglycine alpha-Hydroxylating Monooxygenase.

We describe the studies of new copper complexes [MeSPY2]CuPF(6), 2, and [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, as models for the Cu(B) center of dopamine beta-hydroxylase and peptidylglycine alpha-hydroxylating monooxygenase. The structure of [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, has been established by X-ray crystallography. The copper coordination exhibits a square pyramidal geometry where the equatorial plane is occupied by the SCH(3) group and three nitrogen atoms (tertiary amine, one pyridine, and acetonitrile solvent), whereas the axial position binds the second pyridine. Using FEFF calculations and multiscattering interaction, EXAFS refinements show that the SMe group lies in the coordination sphere of copper complexes [MeSPY2]CuPF(6), 2, and [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3. While [MeSPY2]CuPF(6), 2, reacts with dioxygen in dichloromethane without oxidation of the ligand, we observed an oxidation of the sulfide ligand when [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, reacts with hydrogen peroxide in methanol. Considering results, we propose that Met(314), crucial for DBH and PHM activity, could be the site of the H(2)O(2) (or ascorbate) inactivation by oxidation to the sulfoxide group.

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.

The effect of dietary protein source on biochemical indices of stress in stress-susceptible pigs

The porcine stress syndrome (PSS) is responsible for major economic losses to the swine industry. The present study was performed to determine if 8-wk-old pigs representing each of three genotypes (NN = homozygous noncarrier, Nn = heterozygous carrier, nn = homozygous carrier) with respect to the PSS, differ in selected biochemical indices related to stress (exp. 1), and to examine if these indices are affected during 5 wk of dietary adaptation to a cereal-based swine diet (control diet) or to a feed containing casein, a higher quality protein (exp. 2). The first experiment demonstrated that nn and Nn 8-wk-old female pigs have a significantly greater glycemic response to a blood sampling stressor than do NN female pigs. In contrast, no genotype differences in glycemic response were observed within young male pigs. Pigs of nn genotype also demonstrated a significantly greater plasma dopamine-β-hydroxylase (DBH) activity than did the NN pigs. Results of the second experiment revealed that pigs of the nn and Nn genotypes experienced a greater glycemic response to the initial blood sampling stressor than did the NN pigs. Compared with initial levels, upon the sixth weekly blood sampling stressor the nn and Nn pigs experienced reduced plasma glucose concentration irrespective of diet, while no change in glycemic response was observed in the pigs of the NN genotype. Finally, the DBH activity of the Nn pigs adapted for 2 wk to the casein diet was found to be reduced when compared to control-adapted Nn pigs. This study suggests that in addition to genotype differences, regular exposure to stress combined with dietary adaptation to feed containing a higher quality protein (casein) may confer increased resistance to stress in pigs of the Nn genotype. Key words: Pigs, stress, dietary protein, glycemia, dopamine-β-hydroxylase