Modulation of neurotransmitter metabolism by dihydropyridine calcium channel ligands in mouse brain

The regional concentrations of dopamine, serotonin, dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindole acetic acid were measured in mouse brain following administration of the dihydropyridine calcium channel activator BAY K 8644, and antagonist, nifedipine. BAY K 8644 (1-8 mg/kg) produced dose- and time-dependent increases in dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid concentrations in the caudate, without altering dopamine and serotonin levels. No changes in 5-hydroxyindoleacetic acid concentration were observed in the raphe nuclei, hypothalamus, hippocampus and frontal cortex. Nifedipine (4 mg/kg) blocked BAY K 8644- (2 mg/kg) elicited increases in dihydroxyphenylacetic acid in the caudate. Furthermore, a higher dose of nifedipine (8 mg/kg) decreased dihydroxyphenylacetic acid and homovanillic acid, but did not affect dopamine, serotonin or 5-hydroxyindoleacetic acid concentrations, while a lower dose of nifedipine (2 mg/kg) significantly increased serotonin, 5-hydroxyindoleacetic acid and homovanillic acid, but did not affect dopamine and dihydroxyphenylacetic acid concentrations. The findings that both BAY K 8644 and nifedipine affect neurotransmitter metabolism in vivo in a dose-, time- and brain region-dependent manner, suggest that high-affinity dihydropyridine calcium channel binding sites play an important role in regulating neurotransmitter turnover in the central nervous system.     

Age changes in concentrations of monoamines and related substances in the cerebrospinal fluid]

We studied age changes of concentrations of thirteen substances including monoamines, their precursors and metabolites in the cerebrospinal fluid, using high performance liquid chromatography. Cerebrospinal fluid was obtained from 106 subjects without neurological diseases (44.2 +/- 17.3 years) who underwent minor operations under lumbar anesthesia. Concentrations of dopamine, norepinephrine, tyrosine and 3-methoxy-4-hydroxy-phenylalanine were significantly increased with age, while concentrations of other monoamine precursors and metabolites were unchanged. There was a significant positive correlation between concentrations of the following substances: dopamine and norepinephrine; tyrosine and tryptophan; tyrosine and 3-methoxy-4-hydroxy-phenylalanine; tyrosine and 5-hydroxytryptophan; homovanillic acid and 5-hydroxyindoleacetic acid. Norepinephrine concentrations were positively correlated with concentrations of 3-methoxy-4-hydroxy-phenylglycol, whereas dopamine concentrations were not with homovanillic acid concentrations. The significance of these results was discussed with regard to age changes of transmitter secretion and metabolism, the binding capacity of receptors and cerebrospinal fluid kinetics of the measured substances.     

Monoamine metabolism in the cerebrospinal fluid in Parkinson's disease: relationship to clinical symptoms and subsequent therapeutic outcomes

Summary We correlated monoamine concentrations in the cerebrospinal fluid from de novo (untreated) patients with Parkinson's disease with their clinical symptoms and therapeutic outcome after two years of L-dopa with/without other anti-parkinson medication. A significant correlation was found between the severity of some parkinsonian symptoms and the reduction in particular monoamines: Hoehn and Yahr's stage with dopamine, norepinephrine, and homovanillic acid: rigidity with dopamine; akinesia with dopamine and norepinephrine; freezing of gait with norepinephrine; and dementia with dopamine and homovanillic acid. Tremor had no correlations with the concentrations of the monoamines measured. Patients with dementia had a significantly increased level of epinephrine concentrations.Insufficient therapeutic responses of invidividual symptoms were associated with significantly decreased concentrations of particular monoamines before treatment: Hoehn and Yahr's stage with norepinephrine and epinephrine; akinesia with homovanillic acid and 5-hydroxyindoleacetic acid; and freezing of gait with dopamine, norepinephrine, homovanillic acid, and 5-hydroxyindoleacetic acid. These results suggest a significant correlation between the reduction in particular monoamines and the severity of some parkinsonian symptoms and their subsequent responses to L-dopa.     

5-Hydroxyindoleacetic acid and homovanillic acid in human cerebrospinal fluid below partial and complete spinal subarachnoid block

Concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were investigated by lumbar cerebrospinal fluid (CSF) of 21 patients with partial and total spinal subarachnoid block. HVA levels in CSF below a complete block were significantly lower and 5-HIAA levels were signigicantly higher than controls. Below a partial block, HVA levels were normal; 5-HIAA levels were higher than in patients with complete block. Possible explanations for these findings are discussed.     

Tryptophan hydroxylase and catechol-O-methyltransferase gene polymorphisms: relationships to monoamine metabolite concentrations in CSF of healthy volunteers

Concentrations of monoamine metabolites (MM) in lumbar cerebrospinal fluid (CSF) have been used extensively as indirect estimates of monoamine turnover in the brain. We investigated possible relationships between DNA polymorphisms in the tryptophan hydroxylase (TPH) and catechol-O-methyltransferase (COMT) genes and CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy volunteers (n = 66). Lower CSF 5-HIAA levels were found in men with the TPH U allele (p = 0.005), but not in women. A similar but less significant pattern was observed for CSF HVA. No relationship was found between the TPH polymorphism and CSF MHPG. COMT genotypes did not relate significantly to MM concentrations. The results suggest that TPH genotypes participate differentially in the regulation of serotonin turnover rate under presumed steady state in the central nervous system of men. Due to the uncertain functional relevance of the DNA polymorphism investigated and the many calculations performed, the results should be interpreted with caution until replicated.     

Effect of folic acid by mouth on cerebrospinal fluid homovanillic acid and 5-hydroxyindoleacetic acid concentration

Administration of 30 mg folic acid by mouth caused a significant fall in cerebrospinal fluid homovanillic acid concentration in 11 subjects. There was no significant change of 5-hydroxyindoleacetic acid concentration. The fall was less marked in five patients on anticonvulsant medication and failed to reach statistical significance. Neither homovanillic acid nor 5-hydroxyindoleacetic acid concentrations changed significantly when 15 mg folic acid was given in divided dosage for one, two, and four weeks. The effect appeared to be related to the height of serum-folate levels reached and to be independent of cerebrospinal fluid-folate levels, which did not change significantly. Possible mechanisms and their potential therapeutic application are discussed.     

Clomipramine treatment of obsessive-compulsive disorder. II. Biochemical aspects

Concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), the dopamine metabolite homovanillic acid, and the noradrenaline metabolite 4-hydroxy-3-methoxyphenyl glycol were measured in CSF before and after three weeks' treatment of severe obsessive-compulsive disorder with clomipramine hydrochloride. Patients who responded to clomipramine treatment had significantly higher CSF levels of 5-HIAA before treatment. The amelioration of obsessive-compulsive symptoms was positively correlated to the reduction of CSF concentrations of 5-HIAA during clomipramine treatment but negatively correlated to plasma concentrations of clomipramine. Reduction of CSF concentrations of 5-HIAA, which probably reflects drug action on central serotonin neurons, was maximal at a plasma clomipramine concentration of about 300 nmole/L. At higher levels, the reduction of CSF levels of 5-HIAA was smaller. The antiobsessive effect of clomipramine may be connected to its capacity to inhibit serotonin uptake.     

Platelet MAO activity and monoamine metabolites in cerebrospinal fluid in depressed and suicidal patients and in healthy controls

Platelet monoamine oxidase (MAO) activity and cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5HIAA), homovanillic acid (HVA), and 4-hydroxy-3-methoxyphenylglycol (HMPG) were simultaneously measured in 20 currently depressed patients, 11 recovered depressed patients, 15 nondepressed suicide attempters, and 42 healthy control subjects. Both 5HIAA and HVA were positively and significantly correlated to platelet MAO activity in the healthy subjects, but not in any of the patient groups. Suicide attempters had significantly lower CSF 5HIAA than nonsuicidal patients.     

Biogenic amines and their metabolites in brain tumor tissue

The concentrations of noradrenaline, 5-hydroxytryptamine, dopamine, 5-hydroxyindoleacetic acid and homovanillic acid were determined in the tissue of gliomas, meningiomas and neurinomas of the brain obtained during operations. Significantly higher levels of noradrenaline and 5-hydroxyindoleacetic acid were found in gliomas than in non-malignant tumours.     

Reye syndrome: monoamine metabolites in ventricular fluid

Concentrations of homovanillic acid (HVA) were markedly elevated in the ventricular fluid of 15 children with Reye syndrome (median, 887 ng per milliliter) compared to 7 controls (median, 282 ng per milliliter), but 5-hydroxyindoleacetic acid (5-HIAA) values were comparable (medians of 198 and 189 ng per milliliter, respectively). The ratio of 5-HIAA to HVA was significantly lower in patients with Reye syndrome (0.26) than in controls (0.51). Serial samples demonstrated wide fluctuations in HVA concentration, but not in that of 5-HIAA. Monoamine metabolite concentrations were not correlated with serum ammonia, increased intracranial pressure, morbidity, or mortality. Increased HVA in Reye syndrome may reflect cerebral ischemia and release of vasoactive amines (particularly dopamine) into the brain and cerebrospinal fluid (CSF).     

Effect of vagus nerve stimulation on cerebrospinal fluid monoamine metabolites, norepinephrine, and gamma-aminobutyric acid concentrations in depressed patients.

BACKGROUND: Vagus nerve stimulation (VNS) has shown promising antidepressant effects in treatment-resistant depression, but the mechanisms of action are not known. Cerebrospinal fluid (CSF) studies in epilepsy patients show that VNS alters concentrations of monamines and gamma-aminobutyric acid (GABA), neurotransmitter systems possibly involved in the pathogenesis of depression. METHODS: Twenty-one adults with treatment-resistant, recurrent, or chronic major depression underwent standardized lumbar puncture for collection of 12 mL CSF on three separate but identical procedure days during participation in the VNS D-02 clinical trial. All subjects remained on stable regimens of mood medications. Collections were made at baseline (2 weeks after surgical implantation but before device activation), week 12 (end of the acute-phase study), and week 24. Cerebrospinal fluid concentrations of norepinephrine (NE), 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) were determined with high-performance liquid chromatography. Concentrations of GABA were assayed with mass spectrometry. RESULTS: Comparison of sham versus active VNS revealed a significant (mean 21%) VNS-associated increase in CSF HVA. Mean CSF concentrations of NE, 5-HIAA, MHPG, and GABA did not change significantly. Higher baseline HVA/5-HIAA ratio predicted worse clinical outcome. CONCLUSIONS: Although several of the CSF neurochemical effects we observed in this VNS study were similar to those described in the literature for antidepressants and electroconvulsive therapy, the results do not suggest a putative antidepressant mechanism of action for VNS.     

Relationship of psychobiological variables to recidivism in violent offenders and impulsive fire setters. A follow-up study

Fifty-eight violent offenders and impulsive fire setters were followed up for an average of 3 years after release from prison. Recidivists who committed a new violent offense or arson had significantly lower cerebrospinal fluid 5-hydroxyindoleacetic acid and homovanillic acid concentrations and blood glucose nadirs after oral glucose challenge than did nonrecidivists. A discriminant analysis, based on the blood glucose nadir and cerebrospinal fluid 5-hydroxyindoleacetic acid concentration, correctly classified 84.2% of the subjects.     

Monoamine metabolites in CSF and suicidal behavior

Cerebrospinal fluid concentrations of the monoamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenyl glycol (MHPG) were measured in 30 psychiatric patients who had attempted suicide and 45 healthy volunteers. The suicide attempters had a significantly lower CSF 5-HIAA level than the controls, especially those who had made more violent attempts. After adjustment for differences in body height and age between controls and patients, the difference in 5-HIAA level became even more marked. Concentrations of 5-HIAA also were lower than normal in suicidal patients who were not diagnosed as depressed at the time of lumbar puncture, while HVA levels were lowered only in the depressives. A follow-up study of these and 89 more patients (depressed and/or suicidal) revealed a 20% mortality by suicide within a year after lumbar puncture in patients with a CSF-HIAA level below the median.     

Reliability of norepinephrine and major monoamine metabolite measurements in CSF of schizophrenic patients

Concentrations of norepinephrine, 3-methoxy-4-hydroxyphenylglycol, homovanillic acid, and 5-hydroxyindoleacetic acid (5-HIAA) were quantified in the CSF of 28 drug-free schizophrenic patients. Fifteen patients provided more than one drug-free sample on separate occasions. Considerable intraindividual variability over time was found in the concentrations of norepinephrine and these major monoamine metabolites in the repeated samples. This was not explained by assay errors or changes in the patient's global psychosis ratings. The variability in the present sample for CSF 5-HIAA concentrations was almost twice as wide as has been reported for patients with affective disorder. Variables that contribute much of the variability of norepinephrine and major monoamine metabolite concentrations in drug-free CSF samples from schizophrenic patients remain unknown and cannot be controlled.     

Hemiballismus: changes in cerebrospinal fluid

Concentrations of serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), and dopamine metabolites, homovanillic acid (HVA) and 3,4-dihydroxy-phenylacetic acid (DOPAC), were measured in the samples of cerebrospinal fluid of 5 patients with acute hemiballismus. The only significant change was the increased content of HVA compared to controls. This finding support the hypothesis on the increased dopamine turnover in hemiballismus and provide a rational basis for the present treatment with antidopaminergic agents.     

Serotonergic measures in suicide brain: the concentration of 5-HIAA, HVA, and tryptophan in frontal cortex of suicide victims.

Concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and tryptophan (TRP) were determined in the frontal cortex of individuals who died by suicide, homicide, accident, or the result of physical diseases. Females had significantly higher tryptophan concentrations than males. There was a significant correlation HVA and the interval between death to refrigeration of the body. Mean HVA levels were higher from noon to 5 PM. Suicide and homicide victims had significantly higher cortical HVA concentrations than those who died of physical disease but not accident victims. This was not accounted for by gender, age, postmortem interval from death to refrigeration of the body or to autopsy, specimen storage time, or drug effects. The ratio of HVA/5-HIAA was also significantly higher in suicides compared with those who died of physical disease. No differences in cortical 5-HIAA or tryptophan concentrations between the four groups were found. There were no differences in the levels of the three substances in violent and nonviolent suicides. There were no significant correlations between 5-HIAA, HVA and TRP concentrations in all subjects or any of the four subgroups. The implications of these findings for the role of serotonin and dopamine in suicide and violence are discussed.     

Neurochemical effects of vagus nerve stimulation in humans.

An implanted stimulating device chronically stimulated the left cervical vagus nerve in epileptic patients. Cerebrospinal fluid concentrations of free and total gamma-aminobutyric acid, homovanillic acid, 5-hydroxyindoleacetic acid, aspartate, glutamate, asparagine, serine, glutamine, glycine, phosphoethanolamine, taurine, alanine, tyrosine, ethanolamine, valine, phenylalanine, isoleucine, vasoactive intestinal peptide, beta-endorphin, and somatostatin were measured before and after 2 months of chronic stimulation in six patients. Significant increases were seen in homovanillic acid and 5-hydroxyindoleacetic acid in three patients, and significant decreases in aspartate were seen in five patients. These changes were associated with a decrease in seizure frequency.     

Cerebrospinal fluid 5-hydroxyindoleacetic acid and homovanillic acid in the pediatric opsoclonus-myoclonus syndrome

To study the purported role of central monoamine disturbances in the pathophysiology of the opsoclonus-myoclonus syndrome, the serotonin metabolite 5-hydroxyindoleacetic acid and the dopamine metabolite homovanillic acid were measured in cerebrospinal fluid samples from 27 affected children and 47 age- and gender-matched control subjects by high-pressure liquid chromatography with elecrochemical detection. 5-Hydroxyindoleacetic acid and homovanillic acid concentrations in the cerebrospinal fluid were approximately 30 to 40% lower in opsoclonus-myoclonus patients compared to control subjects, and the normal inverse correlation between age and monoamine metabolite concentrations in the cerebrospinal fluid of control subjects was not found in opsoclonus-myoclonus patients. Patients with the lowest values were less than 4 years old, and a subgroup had extremely low levels, but differences in older children were not significant. Cerebrospinal fluid levels of 5-hydroxyindoleacetic acid and homovanillic acid were more positively correlated in control subjects than in opsoclonus-myoclonus patients. None of the patients exhibited high levels of monoamine metabolites. Homovanillic acid levels were slightly lower in the cerebrospinal fluid of patients receiving corticotropin or steroids at the time of lumbar puncture. Clinical variables that could be excluded were paraneoplastic etiology, anesthetic for lumbar puncture, syndrome duration, age at onset, gender, response to steroids, length of time until initiation of corticotropin or steroids, presence of seizures, opsoclonus, and functional impairment. These data suggest a disturbance and possible altered ontogeny of serotonin or dopamine neurotransmission in a subpopulation of children with opsoclonus-myoclonus with low cerebrospinal fluid levels of 5-hydroxyindoleacetic acid and homovanillic acid. Biochemical heterogeneity for this clinical phenotype may have implications for responsiveness to treatment with serotonergic and other drugs.     

Biogenic amines and metabolites in spinal cord of patients with Parkinson's disease and amyotrophic lateral sclerosis

Summary In four human controls, four cases of Parkinson's disease and three cases of amyotrophic lateral sclerosis analysis of dopamine, noradrenaline, serotonin and the metabolites 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid was performed in various segments of postmortem spinal cord. In controls the concentrations of dopamine are about 1/3 to 1/4 that of noradrenaline; the significantly highest content of noradrenaline was found in the lumbar, and dopamine in thoracic, lumbar and sacral segments of the spinal cord. Intersegmental distribution of monoamines was only present in spinal cord of controls, while in the spinal cord of parkinsonian patients such a difference was not found.Otherwise, biogenic amine and metabolite concentrations in spinal cord segments of parkinsonian patients did not differ significantly from those in the control subjects. However, it cannot be excluded that these segments are sensitive to drugs including neuroleptics and combined L-DOPA treatment.In subjects with amyotrophic lateral sclerosis significantly lower concentrations of noradrenaline in the cervical and thoracic, and of dopamine and homovanillic acid in the thoracic and lumbar segments were found in comparison with controls. The concentrations of serotonin and 5-hydroxyindoleacetic acid in the thoracic segments of amyotrophic lateral sclerosis were significantly lower than that of controls. Differences in the inter-segmental distribution of noradrenaline in lumbar, lumbar-sacral, and serotonin in lumbar segments of spinal cord were found in this group.     

Pathogenetic role of monoamine metabolism in complex febrile seizures.

To investigate the pathogenetic role of monoamine metabolism for febrile seizures, concentrations of homovanillic acid and 5-hydroxyindoleacetic acid were evaluated in the lumbar cerebrospinal fluid of affected children. This series included children who underwent lumbar puncture within 4 hours after seizures, at which time the lumbar cerebrospinal fluid is presumed to represent a ventricular source of cerebrospinal fluid, without the consequence of a seizure. The subjects were 21 patients with simple febrile seizures, eight with complex febrile seizures, and eight control patients. The complex febrile seizure group had lower homovanillic acid and 5-hydroxyindoleacetic acid levels than the control group, whereas the simple febrile seizure group and control group did not have a significant difference. Although statistically not significant, the complex febrile seizure group was inclined toward lower homovanillic acid and 5-hydroxyindoleacetic acid levels than the simple febrile seizure group. These results implied that abnormal monoamine metabolism contributes to seizure susceptibility in the complex febrile seizure group. The simple febrile seizure group may be heterogeneous, and abnormal monoamine metabolism can play a role in seizure development for some children of this group.