Dopamine-beta-hydroxylase in postural tachycardia syndrome

Norepinephrine is frequently elevated in postural tachycardia syndrome (POTS), a syndrome of heterogeneous etiology characterized by a >30 beats/min increase in heart rate with standing. Norepinephrine is synthesized from dopamine by dopamine-beta-hydroxylase (DBH). The results of a preliminary study suggested that the T allele frequency of the DBH -1021C-->T polymorphism is elevated in POTS. This allele correlates with low DBH activity and might predict reduced serum DBH activity in patients with POTS. To test the hypothesis that low DBH activity and the underlying -1021C-->T polymorphism are associated with increased susceptibility to POTS, we measured serum DBH activity in POTS and determined its relationship to the DBH genotype and plasma norepinephrine. Serum DBH was similar for 83 normal volunteers and 42 patients with POTS: median (range) = 22.5 (0.5-94.2) and 19.6 (0.1-68.8) nmol.min(-1).ml(-1), respectively (P = 0.282). The genotype frequencies for 254 control and 157 POTS patients were not different between groups ( approximately 63% CC genotype and approximately 5% TT genotype, P = 0.319). The T allele associated with lower serum DBH in both groups [control serum DBH = 15.7 (SD 12.3) and 35.1 nmol.min(-1).ml(-1) (SD 18.6) for T carriers and noncarriers, respectively; POTS serum DBH = 8.2 (SD 5.6) and 28.5 nmol.min(-1).ml(-1) (SD 14.7) for T carriers and noncarriers, respectively]. High DBH in POTS was linked to elevated plasma levels of norepinephrine. Although DBH activity and genotype are unlikely to be primary determinants of susceptibility to POTS, differences in DBH activity in POTS may reflect differences in the level of sympathetic activation.     

Hemolytic complement in nonhuman primates

Hemolytic serum complement activity was quantitatively compared in baboons, squirrel monkeys, cebus monkeys, and cotton-top marmosets. Squirrel monkeys showed the highest activity, and marmosets had the lowest activity. The complement level in squirrel monkeys and tenfold greater than marmosets and almost four times higher than that of man. Cebus monkeys had levels most similar to that of man while the baboon exhibited activity almost as low as that of the marmoset.     

Human serum dopamine beta-hydroxylase: correlation of enzymatic activity with immunoreactive protein in genetically defined samples.

An antibody against human adrenal dopamine beta-hydroxylase (DBH) was used to quantitate immunoreactive DBH protein in human serum by an immunoprecipitation technique. A significant correlation was found between DBH enzyme activity and immunoreactive DBH protein in randomly selected serum samples (r = 0.94; N = 38; p less than .001). Studies of sera from obligate heterozygotes and individuals homozygous for the allele responsible for very low serum DBH enzymatic activity were compatible with a genetically mediated decrease in the quantity of circulating DBH protein in these subjects.     

Inheritance of very low serum dopamine-beta-hydroxylase activity.

Serum dopamine-beta-hydroxylas (DBH) activity was measured in blood samples obtained from 841 children ages 6-12, 277 adults subjects, and 114 relatives of children with serum DBH activity of less than 50 units. Approximately 4% of the children and 3% of the adult subjects tested had very low sweum DBH activity (50 units or less). Because these subjects appeared to make up a separate subgroup within the population and because of a striking familial aggregation of subjects with very low enzyme activity, serum DBH activity was measured in blood obtained from members of 22 families of probands with very low serum enzyme activity. The results of sibship and pedigree analyses of the data were compatible with autosomal recessive inheritance of very low serum DBH activity. Unaffected parents of probands had serum DBH activity intermediate between that found in affected individuals and in control population. No significant correlation of serum DBH activity with either systolic or diastolic blood pressure was found in this randomly selected population of children.     

Elevation of Serum Dopamine-β-hydroxylase Activity with Forced Immobilization

THE formation of the neurotransmitter noradrenaline from 3,4-dihydroxyphenylethylamine (dopamine) is catalysed by the enzyme dopamine-β-hydroxylase (DBH)¹. This enzyme is associated both with the catecholamine-containing chromaffin granules in the adrenal medulla^2,3 and with the vesicular structures in sympathetic nerve terminals which contain catecholamines⁴. Furthermore, DBH activity is released with catecholamines into the perfusate after stimulation of either the isolated perfused adrenal gland⁵ or the isolated perfused spleen^6–8. DBH activity has been reported in the serum of both man and the rat^9,10. This activity is similar to adrenal and sympathetic nerve DBH activity with regard to cofactor requirements, oxygen requirement and kinetic characteristics^9,10. It has been suggested that serum DBH activity might be present as a result of release of enzyme with catecholamines from the adrenal glands and sympathetic nerves. If this is the case, serum DBH activity might be a useful and convenient index of sympathetic-adrenal activity. The work described here was undertaken to investigate both the source of the serum DBH and the effect on this activity of forced immobilization, a procedure which has been used as a model of stress and which has been shown to release catecholamines from the adrenal gland and increase catecholamine excretion¹¹.     

Occurrence and frequency of transmission of naturally occurring simian retroviral infections (SIV,STLV, and SRV) at the CIRMF Primate Center,Gabon

Abstract: Among the primates held at the CIRMF Primate Center, Gabon, no serological sign of SIV infection could be demonstrated in 68 cynomolgus monkeys, 60 chimpanzees, nine gorillas, and 12 sun-tailed monkeys, while seven of 102 mandrills and six of 24 vervets were infected with SIV. Six mandrills, seven vervets and ten cynomolgus monkeys exhibited a full HTLV type 1 Western blot profile. The sera of two gorillas and one chimpanzee presented with a positive but not typical HTLV Western blot profile. The sera of the gorillas lacked p24 antibodies, and the chimpanzee had a Western blot profile evocative of HTLV-II. All attempts to amplify viruses from these animals by PCR were unsuccessful. Two other chimpanzees and seven gorillas presented with indeterminate HTLV Western blot profiles. In the mandrill colony, only male animals were STLV seropositive and no sexual transmission to females was observed. SIV infection was also more frequent in male than female mandrills and sexual transmission appeared to be a rare event. No SRV infection was observed in macaques.     

Family studies of plasma dopamine-beta-hydroxylase thermal stability.

There are large individual variations in the thermal stability of human plasma dopamine-beta-hydroxylase (DBH). These variations are a characteristic of the DBH molecule itself. Individual subjects may be classified as those with thermolabile and those with thermostable plasma DBH. Of 362 randomly selected unrelated children, 8.01%, and of 238 randomly selected unrelated adult subjects, 5.46% had thermolabile plasma DBH. There was not a significant correlation of DBH thermolability with either sex or age on the basis of data from 230 adults and children in 53 randomly selected families. Subjects with thermolabile DBH had basal enzyme activity only about 55% of that in subjects with stable enzyme. There was not a direct relationship between DBH thermolability and the allele DBHL, the presence of which results in very low basal enzyme activity. There was a significant familial aggregation of the trait of DBH thermolability, but there was not a significant correlation of this trait among spouses. Although preliminary pedigree evaluation raised the possibility of monogenic inheritance of the trait of DBH thermolability by an autosomal recessive mechanism, three separate families in which both parents had thermolabile enzyme included offspring with thermostable DBH. All five of these offspring had very low basal plasma DBH and were presumed to be homozygous for the allele DBHL. These observations raised the possibility that the trait of plasma DBH thermolability may be inherited, and that there may be an interaction between the locus or loci responsible for thermal stability and the locus DBH.     

Cortisol metabolism in the Bolivian squirrel monkey (Saimiri boliviensis boliviensis)

New World squirrel monkeys (Saimiri spp.) have high circulating cortisol levels but normal electrolytes and blood pressures. The goal of the present study was to gain insight into adaptive mechanisms used by Bolivian squirrel monkeys to minimize the effects of high cortisol on mineralocorticoid receptor (MR) activity and electrolyte and water balance. Aldosterone levels in serum from 10 squirrel monkeys were 17.7 +/- 3.4 ng/dl (normal range in humans, 4 to 31 ng/dl), suggesting that squirrel monkeys do not exhibit a compensatory increase in aldosterone. The squirrel monkey MR was cloned and expressed in COS-7 cells and found to have similar responsiveness to cortisol and aldosterone as human MR, suggesting that squirrel monkey MR is not inherently less responsive to cortisol. To determine whether altered metabolism of cortisol might contribute to MR protection in squirrel monkeys, serum and urinary cortisol and cortisone were measured, and a comprehensive urinary corticosteroid metabolite profile was performed in samples from anesthetized and awake squirrel monkeys. The levels of cortisone exceeded those of cortisol in serum and urine, suggesting increased peripheral 11beta-hydroxysteroid dehydrogenase 2 activity in squirrel monkeys. In addition, a significant fraction (approximately 20%) of total corticosteroids excreted in the urine of squirrel monkeys appeared as 6beta-hydroxycortisol, compared with that in man (1%). Therefore, changes in cortisol metabolism likely contribute to adaptive mechanisms used by Bolivian squirrel monkeys to minimize effects of high cortisol.     

Changes of dopamine-beta-hydroxylase activity during ontogenesis in healthy subjects and in an experimental model (rats)

In children and adolescents (250 healthy subjects) serum dopamine-beta-hydroxylase (DBH) activity (23.9+/-5.2 to 57.1+/-17.5 micromol/min/ml) increases with the age between 3-10 years, later it decreases approximately by the age of 10-14 years. At the age of 21 to 60 years DBH level is stable. Our study described decreasing DBH activity in adolescents at the age of 10-14 years in the studied sample of healthy persons. Experimental animals (200 Wistar rats, 5-120 days old) show the same trend of enzymatic activity, similarly as in humans. DBH activity in rats is between 0.85+/-0.1 to 2.8+/-0.05 micromol/min/ml. This activity is highest in 5-day-old rats; it decreases till the age of 14 days and increases mainly in 14- to 35-day-old animals. Decrease of DBH activity in rats between 35 to 40 days is significant and corresponds to the reduction of DBH activity in adolescent humans (10-14 years). Adult rats (aged 90-120 days) show a stable DBH activity. DBH activity intermediately decreases in 10- to 14-year-old children. This decrease corresponds to the intermediate developmental changes of electrophysiological parameters (decreasing EEG activity in healthy adolescents occurs in 10-14 years old children). Puberty is coupled with intermediate decreasing of DBH activity in man and also in experimental animals in the period of prominent psychological and physiological changes.     

Androgen resistance in squirrel monkeys (Saimiri spp.)

The goal of this study was to understand the basis for high androgen levels in squirrel monkeys (Saimiri spp.). Mass spectrometry was used to analyze serum testosterone, androstenedione, and dihydrotestosterone of male squirrel monkeys during the nonbreeding (n = 7) and breeding (n = 10) seasons. All hormone levels were elevated compared with those of humans, even during the nonbreeding season; the highest levels occurred during the breeding season. The ratio of testosterone to dihydrotestosterone in squirrel monkeys is high during the breeding season compared to man. Squirrel monkeys may have high testosterone to compensate for inefficient metabolism to dihydrotestosterone. We also investigated whether squirrel monkeys have high androgens to compensate for low-activity androgen receptors (AR). The response to dihydrotestosterone in squirrel monkey cells transfected with AR and AR-responsive reporter plasmids was 4-fold, compared with 28-fold in human cells. This result was not due to overexpression of cellular FKBP51, which causes glucocorticoid and progestin resistance in squirrel monkeys, because overexpression of FKBP51 had no effect on dihydrotestosterone-stimulated reporter activity in a human fibroblast cell line. To test whether the inherently low levels of FKBP52 in squirrel monkeys contribute to androgen insensitivity, squirrel monkey cells were transfected with an AR expression plasmid, an AR-responsive reporter plasmid, and a plasmid expressing FKBP52. Expression of FKBP52 decreased the EC50 or increased the maximal response to dihydrotestosterone. Therefore, the high androgen levels in squirrel monkeys likely compensate for their relatively low 5 alpha-reductase activity during the breeding season and AR insensitivity resulting from low cellular levels of FKBP52.     

Dopamine beta-hydroxylase in rat serum and lymph: changes with age and effect of cold exposure.

The pH optimum for rat serum dopamine beta-hydroxylase (DBH) (3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating)(EC 1.14.17.1) was 4.0 in acetate buffer; other requirements were as reported by others. DBH activity in serum of 20-day-old fetuses is slightly higher than in that of their mothers. Levels of the enzyme in blood a few hours after birth are almost five times greater than in the adult, remain high during the suckling period, then drop rapidly during the 4th week after birth to about three times the adult level, which is then slowly reached over the next few weeks. These fluctuations in serum DBH activity coincide with the period of intense development and maturation of the sympathetic nervous system. There was not significant effect of cold exposure on blood DBH activity when newborn, suckling, weanling or adult warm- and cold-acclimated rats were exposed to cold. Similarly, exposure to cold that elicited two- to three-fold increases in O2 consumption failed to increase DBH activity in thoracic duct lymph. Therefore serum and lymph DBH activities are not sensitive indices of sympathetic secretory activity in the intact rat.     

Changes of plasma dopamine-beta-hydroxylase activity and other plasma constituents during the cold pressor test

The effect of the cold pressor test on plasma DBH activity in ten healthy human subjects was investigated. Parallel changes of other plasma constituents were ascertained as well. Plasma DBH activity rose by over ten per cent in six of the sen subjects and declined by 14 per cent or more in two subjects; the correlations of altertions in DBH activity with changes of high molecular weight plasma constituents were high (r=0.565 to 0.902); correlations with blood urea nitrogen and plasma glucose were low (r=0.002 to 0.248). The results suggest that factors other than neuronal DBH release may be important in alterations of plasma DBH activity following $\text{acute}$ stresses produced by the cold pressor test in man.     

Renin angiotensin aldosterone axis, including aldosterone binding globulin and blood pressure in three species of nonhuman primates

Variables of renin-angiotensin-aldosterone axis with inclusion of protein binding to specific plasma globulin (ABG), plasma cortisol, and the blood pressure (BP) were measured in 24 chimpanzees, 4 gorillas, and 16 cynomolgus monkeys. ABG activity was readily detected in plasma from the primates. In chimpanzees and gorillas, all the variables under baseline conditions were similar to those in humans. In cynomolgus (Macaca fascicularis), both the ABG binding capacity for aldosterone and the diastolic or systolic BP were significantly higher (p less than 0.001 and p less than 0.01 respectively) than in chimpanzees and gorillas.     

Rh gene evolution in primates: study of intron sequences

By amplification and sequencing of RH gene intron 4 of various primates we demonstrate that an Alu-Sx-like element has been inserted in the RH gene of the common ancestor of humans, apes, Old World monkeys, and New World monkeys. The study of mouse and lemur intron 4 sequences allowed us to precisely define the insertion point of the Alu-Sx element in intron 4 of the RH gene ancestor common to Anthropoidea. Like humans, chimpanzees and gorillas possess two types of RH intron 4, characterized by the presence (human RHCE and ape RHCE-like genes) or absence (human RHD and ape RHD-like genes) of the Alu-Sx element. This led us to conclude that in the RH common ancestor of humans, chimpanzees, and gorillas, a duplication of the common ancestor gene gave rise to two genes, one differing from the other by a 654-bp deletion encompassing an Alu-Sx element. Moreover, most of chimpanzees and some gorillas posses two types of RHD-like intron 4. The introns 4 of type 1 have a length similar to that of human RHD intron 4, whereas introns 4 of type 2 display an insertion of 12 bp. The latest insertion was not found in the human genome (72 individuals tested). The study of RH intron 3 length polymorphism confirmed that, like humans, chimpanzees and gorillas possess two types of intron 3, with the RHD-type intron 3 being 289 bases shorter than the RHCE intron 3. By amplification and sequencing of regions encompassing introns 3 and 4, we demonstrated that chimpanzee and gorilla RH-like genes displayed associations of introns 3 and 4 distinct to those found in man. Altogether, the results demonstrate that, as in humans, chimpanzee and gorilla RH genes experienced intergenic exchanges.     

The Skin of Nonhuman Primates

SYNOPSIS What distinguishes man from all other primates is hisarchaic hair cover Nearly all the details that make his skinunique aie traceable to this single fact In vatious degrees,allnonhuman primates have a good pelage,which is characterizedby some morphological and physiological similarities but oftendiffers even between closely relatedspecies It can be thickor thin,short or long woolly or shaggy, dense oi sparse, andit assumes many varied colors All primates have dermitoglyphicson their faction surfaces they are also present on the volarsurface of the tail of some New World monkeys ind on the knucklepads of chimpanzees and gonllas The epidermis is uniformly thinand has little undersculpture Every species of primate has epideimaland dermal melinocytes which are often relatively distinct fromall otheis Eccrine sweat glmds are found on the fnction surfacesof all species, but onlv the tiue piehensile tailed New Worldmonkeys andOld World monkeys and apes have them also in thehairy skin Although chimpanzees and gorillas have more ercunethan apocrine glands in their bodies, in neither do the sweatglands respond to heat stimulation as they do in man All primateshavenumerous apocrine glands in the hany skin, but only man,the chimpanzee, and gorilla have an axillaiy organ The OideiPrimates is large and heteiogeneous most species have some commoncutaneous featuies but the details in each are so distinct asto preclude generalizations     

Increased production of 11beta-hydroxysteroid dehydrogenase type 2 in the kidney microsomes of squirrel monkeys (Saimiri spp.)

In squirrel monkeys (Saimiri spp.), cortisol circulates at levels much higher than those seen in man and other Old World primates, but squirrel monkeys exhibit no physiologic signs of the mineralocorticoid effects of cortisol. These observations suggest that squirrel monkeys have mechanisms for protection of the mineralocorticoid receptor (MR) from these high levels of cortisol. We previously showed that the serum cortisol to cortisone ratio in these animals is low relative to that in human serum, suggesting that production of the MR protective enzyme, 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), is increased in squirrel monkeys. Here, we directly evaluate whether increased production of 11beta-HSD2, which inactivates cortisol to cortisone, is a mechanism for protection of MR. In vitro assays showed that 11beta-HSD2 activity in squirrel monkey kidney microsomes was 3 to 7 times higher than that seen in kidney microsomes from pig or rabbit. 11beta-HSD2 protein detected by Western blot analysis was 4 to 9 times greater in squirrel monkey microsomes than in pig or rabbit microsomes. Comparison of the effect of expression of either human or squirrel monkey 11beta-HSD2 on MR transactivation activity showed similar inhibition of MR response to cortisol by both enzymes, indicating that the intrinsic activities of the human and squirrel monkey enzymes are similar. These findings suggest that one mechanism by which squirrel monkeys protect the MR from activation by high cortisol levels in the kidney is by upregulation of 11beta-HSD2 activity through increased production of the enzyme.     

Blood dopamine beta-hydroxylase activity and noradrenaline levels in the developing white rat.

Dopamine beta-hydroxylase (DBH) (3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating) (EC 1.14.17.1) activity in serum of blood obtained by decapitation of white rats at 19, 20, and 21 days in utero, immediately after birth, and postnatally to 70 days, was measured. Noradrenaline (NA) and DBH in plasma from undisturbed, cannulated, postweaning rats were also assayed. During the last few days in utero and the first 2 postnatal days serum DBH activity tripled and then remained elevated during the suckling period. Upon weaning, serum DBH activity declined at first precipitously and then more slowly, until the adult level was reached around 70 days of age. This postweaning decrease in DBH activity was also observed with the cannulated animals. In contrast, plasma NA levels remained low and constant throughout the postweaning period. In suckling rats treated with 6-hydroxydopamine from 2 to 12 days of age, serum DBH activity decreased to less than half its initial value by day 8. It is suggested that the observed changes in serum DBH activity in fetal and postnatal rats reflect ontogenetic changes in sympathetic nerve terminals and that they are probably not correlated with release of NA.     

Trichobilharzia ocellata: influence of infection on the interaction between the dorsal body hormone, a female gonadotropic hormone, and the follicle cells in the gonad of the intermediate snail host Lymnaea stagnalis

Activation of adenylate cyclase (AC)-cAMP system in follicle cells of Lymnaea stagnalis by the gonadotropic dorsal body hormone (DBH) is inhibited by schistosomin, an agent present in hemolymph of snails infected with Trichobilharzia ocellata. AC activation was determined enzyme cytochemically. This conclusion is based on the observation that the percentage of oocytes with AC-positive follicle cells in gonads incubated in the presence of schistosomin, i.e., in serum of infected snails (IS) with DBH, is significantly lower than that in gonads incubated in the absence of schistosomin, i.e., in serum of noninfected snails (NS) with DBH. Follicle cells in gonads preincubated in the absence of schistosomin, i.e., in NS, and subsequently incubated with freshly dissolved DBH showed a considerably lower response to DBH than those in not preincubated gonads. This indicates that the number of receptors for DBH on follicle cells had decreased during preincubation. The response to DBH also appeared to decrease when the hormone was preincubated in NS. This indicates that the activity of DBH decreases during preincubation. These data make it impossible to answer the question of whether or not schistosomin acts as an antagonist of DBH at the receptor level.