High correlations of norepinephrine, dopamine, and epinephrine and their major metabolite excretion rates

Serial Hydrolysis for the Simultaneous Analysis of Catecholamines and Steroids in the Urine of Patients with Alopecia Areata

Catecholamines and steroids are well-known neurotransmitters and hormones that rapidly change the excitability of neurons. Alopecia areata is a disease for which the exact cause is unknown, but it is considered to be associated with stress, and so the simultaneous analysis of catecholamines and steroids is required for the diagnosis of alopecia areata. Thus, we herein report the simultaneous analysis of catecholamines and steroids bearing different functional groups for the first time, during which it was necessary to carry out a serial hydrolysis procedure. Following hydrolysis of the urine samples to produce the free forms from the urinary conjugates, ethyl acetate extractions were carried out, and chemical derivatization was performed using dansyl chloride to increase the sensitivity of the liquid chromatography-tandem mass spectrometry method. The matrix effects and recoveries of this analytical method were validated, giving values of 85.4-122.9% and 88.8-123.0%, respectively. In addition, the method accuracy and precision were assessed, giving values of 0.4-21.5% and 2.0-21.6% for the intra-day and inter-day precisions, respectively. This validated method was then applied to identify differences between patients with and without alopecia areata, wherein the metanephrine content was found to be significantly higher in the alopecia areata patient group. This quantitative profiling method can also be applied to steroid-dependent diseases, as well as catecholamine-related diseases.

Assessment of O-methylated catecholamine levels in plasma and urine for diagnosis of autonomic disorders

The term 'metanephrines' is used to indicate the two catechol 3-O-methylated metabolites of epinephrine (E) and norepinephrine (NE): metanephrine and normetanephrine (NMN). The corresponding 3-O-methylated metabolite of dopamine is usually referred to as 3-methoxytyramine rather than 3-methoxydopamine and is not generally considered a "metanephrine". O-Methylation occurs outside the sympathetic neuron and neuroeffector junction. Metanephrines are products of the enzyme catechol-O-methyltransferase (COMT). Subsequent conjugation with sulfate or deamination by monoamine oxidase (MAO) followed by reduction to vanilmandelic acid (VMA) facilitates urinary excretion. For the clinician, measurement of normetanephrine provides an index of norepinephrine released during sympathetic nervous system activity, whereas metanephrine concentration provides an indication of adrenal medullary metabolism of epinephrine prior to its discharge into the circulation. Plasma epinephrine concentration is the preferable index of adrenal medullary epinephrine discharge. Pheochromocytomas, with their protean clinical manifestations, may be diagnostic challenges, but assay of metanephrines, especially plasma metanephrine, can be particularly helpful in diagnosis. These COMT metabolites may also help in elucidation of still undiscovered genetic and acquired disorders of catecholamine metabolism.

The relationship between plasma MHPG and NE: employing regression models in estimating centrally derived MHPG and peripheral NE turnover rate in panic disorder

Studies investigating the role of the noradrenergic system in the pathophysiology of anxiety have focused on measuring plasma 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) levels. Fewer studies have examined norepinephrine levels. Basal plasma norepinephrine and free MHPG levels were simultaneously measured in 33 normal controls and 20 panic disorder (PD) patients. Norepinephrine levels were similar in patients and controls, but MHPG levels were significantly lower in patients (13.34 +/- 3.22 vs 18.37 +/- 4.49 pmol ml-1, p < 0.0001). Norepinephrine correlated significantly with plasma MHPG levels in controls (r = 0.538, p < 0.0001) and patients (r = 0.645, p < 0.002). Patients had a trend toward a lower y-intercept than controls, suggesting a lower contribution by the CNS to MHPG pool plasma levels (9.18 vs 12.51, p < 0.08). Norepinephrine turnover rate was similar in patients and controls. We propose that the dysregulation in the noradrenergic system in PD may be akin to animal studies of acute-on-top-of-chronic stress paradigms, whereby chronic stress results in normal or decreased basal NE turnover and sensitized responses to recurrent stresses.

Reward dependence is positively related to urinary monoamines in normal men

According to Cloninger, three major personality dimensions, novelty seeking, harm avoidance, and reward dependence, are dependent on central monoaminergic systems. This study examined the relationship between the urinary levels of different monoamines and the above personality dimensions. Fifty normal men answered the Tridimensional Personality Questionnaire (TPQ); their levels of dopamine, norepinephrine, epinephrine, normetanephrine, metanephrine, 3-methoxy-4-hydroxyphenylglycol, vanilmandelic acid, homovanilic acid, and serotonin metabolite 5-hydroxyindolacetic acid were measured in urine on two consecutive nights. Significant and positive correlations were found between reward dependence, 3-methoxy-4-hydroxyphenylglycol, and epinephrine (r = .50 and r = .51, respectively). Monoamine levels explained 44% of the variance of reward dependence. Cluster analysis identified three groups of subjects presenting specific patterns of monoamine excretion. The TPQ scores could discriminate among subjects belonging to these clusters. These results point out a narrow relationship between urinary monoamine excretion and the basic personality dimension of reward dependence.

Urinary catecholamines and plasma hormones predict mood state in rapid cycling bipolar affective disorder

Over the course of 1 year, a patient with a rapid cycling bipolar affective disorder was followed at weekly intervals to examine whether plasma hormones and urinary catecholamines could predict current or future mood. Higher cortisol levels were found to predict depressed mood 3 days after blood sampling, higher urinary dopamine predicted a manic mood 3 days after blood sampling, urinary norepinephrine was associated with severity of current mood and prolactin was lower with concurrent depressed mood. In multivariate analyses of mood against cortisol, prolactin and three urinary catecholamines, > 50% of the variance in mood state in 3 days was explained by combinations of these biologic measures, especially cortisol and urinary dopamine, while all five biologic variables contributed to explaining 50% of the variance in current mood state. Based on the interrelationships between urinary dopamine, norepinephrine and mood, we postulate the existence of an overcompensating mechanism which is reflected in opposing correlations between urinary dopamine and norepinephrine with mood, despite the two urinary catecholamines being positively correlated.

Cultured human keratinocytes as a model for studying the dopamine metabolism in schizophrenia

The dopamine hypothesis is the major etiological hypothesis of schizophrenia which proposes that enhanced central nervous system dopaminergic activity is the causative factor for this disease. The hypothesis remains unproven despite decades of research. The major difficulty in studying the disease is due to the unavailability of a suitable animal model. Studies with human blood, cerebrospinal fluid or post-mortem brains lead only to inconclusive results, due to the effects of medication and other environmental factors. No extra-neuronal cells, with the exception of adrenal medulla, have been reported to contain a dopamine metabolic pathway. Literature evidence and our own study suggest that human keratinocytes express the enzymes to synthesize and degrade dopamine. We have compared the properties of tyrosine hydroxylase, the rate-limiting enzyme, from mouse striatum and from human skin keratinocytes cultured in vitro. Moreover we could also detect dopamine beta hydroxylase and catechol-o-methyl transferase in keratinocytes. We propose that human keratinocytes cultured in vitro can be used to study the relevance of dopamine metabolism to schizophrenia under controlled conditions avoiding the effects of medication and other environmental factors.

Noradrenergic and adrenergic functioning in autism

A neurochemical assessment of noradrenergic and adrenergic functioning was carried out with autistic patients and normal control individuals. Norepinephrine and related compounds were measured in autistic (n = 17 unmedicated, 23 medicated; age range 9-29 years old) and normal controls (n = 27; age range 9-36 years old). Plasma levels and urinary excretion of 3-methoxy-4-hydroxy-phenylglycol (MHPG) were measured, as were urinary excretion rates of norepinephrine (NE), epinephrine (EPI), and vanillylmandelic acid (VMA). No significant group mean differences were seen between the autistic and control groups. In both the autistic and control groups urinary excretion rates of norepinephrine and epinephrine were substantially higher in the afternoon-evening (5-11 PM) compared to the overnight (11 PM-7 AM) collection period. Based on our neurochemical assessment, marked abnormalities in basal noradrenergic functioning do not appear to be present in autism.

The biology of personality

Historically, models of personality have generally postulated, or assumed, a link with biology. This century has witnessed a major revision of these ideas with both behavioural and psychoanalytic theorists emphasising life experiences as being largely responsible for behaviour as adults. Challenges to this assumption of the overwhelming importance of life experiences are reviewed. An extensive body of data now exists suggesting that biology contributes significantly to individual variability. This biological contribution occurs at a relatively low level in the central nervous system, best defined as temperament. Further research has suffered from the lack of a cohesive psychobiological model. Cloninger's tridimensional theory of personality is presented as a model which attempts to bridge the gap between theoretical temperamental traits, neurotransmitter function and clinical psychiatry. It is to be hoped that new theoretical models will be formulated which will focus on the importance of temperamental variables in psychiatric disorders.

Endocrine and amine responses to D,L-fenfluramine in normal subjects

To investigate indirectly the central neurotransmitter mechanisms of D,L-fenfluramine-induced hormone release, prolactin, adrenocorticotropic hormone, cortisol, growth hormone, 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5HIAA) responses to D,L-fenfluramine (60 mg, oral) were examined in a single-blind, placebo-controlled trial in 14 normal subjects. As compared with placebo, D,L-fenfluramine significantly increased both prolactin and cortisol. There was a significant correlation between the cortisol and prolactin responses. HVA levels were also significantly increased, but there were no changes in MHPG or 5HIAA. The elevation in HVA significantly correlated with increases in both prolactin and cortisol. These findings are consistent with recent animal studies suggesting that D,L-fenfluramine-induced prolactin and cortisol release may be mediated, at least in part, by catecholaminergic systems.