γ-Aminobutyric Acid Concentration in Cerebrospinal Fluid in Schizophrenia

Abstract: γ-Aminobutyric acid (GABA) concentration was determined in cerebrospinal fluid (CSF) of acute and chronic schizophrenic patients, in persons with psycho-organic or personality disorders, and in nonpsychiatric controls. The mean CSF GABA level in the chronic schizophrenic patients was found to be significantly higher than in any of the other groups. No other statistically significant differences were found. Statistical analysis revealed that the elevated CSF GABA concentration in the chronic schizophrenic patients was unlikely to be caused by medication. These results are interpreted as evidence for possible primary or secondary GABAergic overactivity in the brain in chronic schizophrenia.     

Cerebrospinal Fluid Parameters in Healthy Volunteers During Serial Lumbar Punctures

Lumbar punctures were performed on four occasions over a 5-day period (8:30 a.m. on days 1, 3, and 5; 2:30 p.m. on day 2) on 10 normal volunteers (five of each sex; mean age, 27.7 years) to assess, with repeated sampling, the day-to-day variation of selected CSF parameters. Two subjects abstained from the lumbar puncture on day 5 due to headache after the third puncture. Lumbar CSF was analyzed for concentrations of free and total gamma-aminobutyric acid (GABA), homocarnosine, homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), total protein, albumin, and immunoglobulin (Ig)G. No significant concentration differences were found between the afternoon and next morning samples. No differences were found in concentrations of free GABA, total GABA, homocarnosine, 5-HIAA, or albumin across the study. In contrast, HVA concentrations significantly increased by day 5, whereas total protein and IgG decreased during the study. The most likely explanation for these changes involves the known concentration gradients in the CSF column.     

Acute Effect of Protein or Carbohydrate Breakfasts on Human Cerebrospinal Fluid Monoamine Precursor and Metabolite Levels

Patients with normal pressure hydrocephalus who had three lumbar punctures during 1 week ingested either water, a protein breakfast, or a carbohydrate breakfast 2.5 h before each of the lumbar punctures. The CSF was analyzed for biogenic amine precursors and metabolites. The protein meal raised CSF tyrosine levels, a finding consistent with animal data, but did not alter those of tryptophan or any of the biogenic amine metabolites. The carbohydrate meal increased CSF 3-methoxy-4-hydroxyphenylethylene glycol, an unexplained finding. The carbohydrate meal did not affect CSF tryptophan, tyrosine, 5-hydroxyindoleacetic acid, or homovanillic acid. Our results support the idea that in humans protein or carbohydrate meals do not alter plasma amino acid levels sufficiently to cause appreciable changes in CNS tryptophan levels or 5-hydroxytryptamine synthesis.     

Low Levels of γ-Aminobutyric Acid in Cerebrospinal Fluid of Dogs with Epilepsy

gamma-Aminobutyric acid (GABA) levels were determined in cisternal cerebrospinal fluid (CSF) of 19 epileptic dogs with generalized tonic-clonic (grand mal) seizures using a radioreceptor assay. Thirty-four healthy age-matched dogs served as controls. The average CSF GABA level in epileptic dogs (40 pmol/ml) was significantly lower than that determined in controls (66 pmol/ml). Treatment with phenobarbital or primidone seemed not to affect CSF GABA levels.     

5-Hydroxytryptophol in Human Cerebrospinal Fluid: Conjugation, Concentration Gradient, Relationship to 5-Hydroxyindoleacetic Acid, and Influence of Hereditary Factors

The serotonin metabolite 5-hydroxytryptophol was studied in human cerebrospinal fluid. A minor fraction (approximately 13%) was found in conjugated form from which it was liberated by treatment with sulphatase containing beta-glucuronidase activity. A concentration gradient of 5-hydroxytryptophol concentration was shown on lumbar tapping and the concentration in ventricular CSF was about 2.5 times higher than that in lumbar CSF. 5-Hydroxytryptophol and 5-hydroxyindoleacetic acid concentrations were significantly correlated in healthy, psychotic, and depressed subjects, but not in alcoholics. 5-Hydroxytryptophol concentrations in CSF of psychotic and depressed subjects were not different from those of healthy controls (4.22 pmol/ml +/- 0.15, SEM). In healthy subjects, hereditary factors seemed to have little influence on the CSF level of 5-hydroxytryptophol.     

Cerebrospinal Fluid Measurements Suggest Precursor Availability and Sex Are Involved in the Control of Biogenic Amine Metabolism in a Primate

Biogenic amine precursors and metabolites were measured in cisternal cerebrospinal fluid from 83 female and 55 male vervet monkeys. The results indicate that mean rates of 5-hydroxytryptamine, dopamine, and noradrenaline metabolism in the brain are higher in females than in males. They also suggest that under physiological circumstances tryptophan availability is involved in the control of brain 5-hydroxytryptamine synthesis while tyrosine availability is involved in control of both dopamine and noradrenaline metabolism. The similarities seen between our results on vervets and those seen with human cerebrospinal fluid suggest that the vervet is a useful primate to study.     

Motor Activity Increases Tryptophan, 5-Hydroxyindoleacetic Acid, and Homovanillic Acid in Ventricular Cerebrospinal Fluid of the Conscious Rat

An investigation was made into the effects of running (1 h at 20 m/min) on central serotonergic and dopaminergic metabolism in trained rats. Methodology involved continuous withdrawal of cerebrospinal fluid (CSF) from the third ventricle of conscious rats and measurements of tryptophan (TRP), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) levels during a 2 h post-exercise period. All three compounds were increased during the hour following exercise and returned to their basal values within an hour later. CSF flow rate was stable when metabolite levels were elevated. Brain determinations indicated that CSF metabolite variations only qualitatively paralleled brain changes. Indeed, post-exercise TRP, 5-HIAA, and HVA levels were increased to a greater extent in brain when compared to CSF. It is suggested that increased serotonergic and dopaminergic metabolism, caused by motor activity, may be involved in the behavioral effects of exercise.     

Determination of N-Acetylaspartic Acid in Human Cerebrospinal Fluid by Gas Chromatography–Mass Spectrometry

N-Acetyl-L-aspartic acid was identified and determined in human cerebrospinal fluid. The concentration in lumbar fluid was about 2 nmol/ml and about 20 nmol/ml in ventricular fluid. There was no difference between healthy subjects and schizophrenic patients.     

Identification of 5-Hydroxy Eicosatetraenoic Acid in Cerebrospinal Fluid After Subarachnoid Hemorrhage

Abstract: To detect and identify lipid peroxides in the CFS following subarachnoid hemorrhage (SAH), CSF samples were obtained sequentially from 10 patients who developed typical vasospasm and were analyzed by HPLC and gas chromatography-mass spectrometry. One of the peaks appearing on the 7th day after SAH was identified as 5-hydroxy eicosatetraenoic acid. On HPLC, an identical peak was detected in samples from other SAH patients. The results gave unequivocal evidence that peroxides of arachidonic acid are present in the CSF following SAH, and a correlation between them and the occurrence of vasospasm seemed likely. The hypothesis that lipid peroxides are involved in the genesis of vasospasm deserves further investigation.     

The Significance of Homovanillic Acid and 3,4-Dihydroxyphenylacetic Acid Concentrations in Human Lumbar Cerebrospinal Fluid

The concentrations of the acidic dopamine (DA) catabolites homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) measured in human CSF are supposed to reflect the "turnover" of DA in the brain. The notion of "turnover" is, however, not synonymous with impulse nerve activity in the dopaminergic systems. Significant amounts of DOPAC and HVA could, indeed, be demonstrated in brain structures wherein dopaminergic innervation has not been documented. It must also be noted that DA is not only a neurotransmitter itself, but also a precursor of norepinephrine and epinephrine. Furthermore, in lumbar CSF, levels of biogenic amine catabolites partially reflect metabolism in the spinal cord and may have limited relevance to neurotransmission in the brain. To elucidate these points further, we determined the concentrations of DOPAC and HVA in 22 areas of six human brains and eight levels of six human spinal cords. The data were correlated with the concentration of DA. Quantitative determinations were done using HPLC with electrochemical detection, after solvent and ion-pair extraction. In this study, significant amounts of both DOPAC and HVA were demonstrated in brain structures not previously associated with dopaminergic innervation. The relatively lower DA concentration in these structures suggests that in these regions, the DOPAC and HVA concentrations are unrelated to dopaminergic neurotransmission. The possible role of capillary walls and glial cells in the catabolism of DA must be further evaluated. The demonstration of DOPAC and HVA in the spinal cord is another argument against the hypothesis that CSF levels of HVA and DOPAC reflect closely the activity of the dopaminergic systems in the brain.     

Relationship Between Plasma and Cerebrospinal Fluid Norepinephrine and Dopamine Metabolites in a Nonhuman Primate

Major and minor pathways of metabolism in the mammalian CNS result in the formation of 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and normetanephrine (NMN) from norepinephrine (NE), and homovanillic acid (HVA) and 3-methoxytyramine (3-MT) from dopamine (DA), respectively. The correlational relationships between HVA and 3-MT and between MHPG and NMN in primate CSF and plasma have not been described. These relationships may help to elucidate the usefulness of CSF and plasma metabolites as indices of CNS NE and DA activity. In addition, because NMN is unlikely to cross the blood-brain barrier. CSF NMN concentrations would not be confounded by contributions from plasma, which is a major issue with CSF MHPG. We have obtained repeated samples of plasma and CSF from drug-naive male squirrel monkeys and have measured the concentrations of MHPG, HVA, NMN, and 3-MT to define their correlational relationships. For the NE metabolites, significant correlations were obtained for CSF MHPG and NMN (r = 0.806, p less than 0.001), plasma MHPG and CSF NMN (r = 0.753, p less than 0.001), and plasma and CSF MHPG (r = 0.776, p less than 0.001). These results suggest that CSF and plasma MHPG and CSF NMN may reflect gross changes in whole brain steady-state noradrenergic metabolism. Only a single significant relationship was demonstrated for the DA metabolites, with CSF 3-MT correlating with plasma HVA (r = 0.301, p less than 0.025). The results for the DA metabolites probably reflect regional differences in steady-state brain dopaminergic metabolism.     

Oxidative Stress in Cerebrospinal Fluid of Patients with Aseptic and Bacterial Meningitis

This study aimed to determine whether patients with aseptic and bacterial meningitis presented alterations in oxidative stress parameters of cerebrospinal fluid (CSF). A total of 30 patients were used in the research. The CSF oxidative stress status has been evaluated through many parameters, such as lipid peroxidation through thiobarbituric acid reactive substances (TBARS) and antioxidant defense systems such as superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and ascorbic acid. TBARS levels, SOD and GST activity increase in aseptic meningitis and in bacterial meningitis. The ascorbic acid concentration increased significantly in patients with both meningitis types. The reduced glutathione levels were reduced in CSF of patients with aseptic and bacterial meningitis. In present study we may conclude that oxidative stress contributes at least in part to the severe neurological dysfunction found in meningitis.     

Administration of Vigabatrin (γ-Vinyl-γ-Aminobutyric Acid) Affects the Levels of Both Inhibitory and Excitatory Amino Acids in Rat Cerebrospinal Fluid

The effect of vigabatrin (gamma-vinyl-gamma-aminobutyric acid), a new anticonvulsant drug, on the transmitter amino acids in rat cisternal CSF was studied. CSF was collected through a permanently implanted polyethylene cannula from freely moving rats at 5, 24, 48, and 96 h after administration of 1,000 mg/kg of vigabatrin. The free gamma-aminobutyric acid (GABA) level was elevated maximally (13.5-fold; p less than 0.01) at 24 h after injection. The homocarnosine (GABA-histidine) level also was increased (123%; p less than 0.01) at 24 h after injection, and its concentration remained at the same level for the next 3 days. Glycine and taurine concentrations had increased [31% (p less than 0.05) and 63% (p less than 0.01), respectively] at 5 h after injection. It is interesting that the levels of glutamate and aspartate increased [330% (p less than 0.05) and 421% (p less than 0.01), respectively] at 96 h after injection, the time when the free GABA level had returned to the baseline concentration and the vigabatrin level was 3% of the maximal concentration. The present study indicates that a single dose of vigabatrin in rats elevates levels of both the inhibitory and excitatory amino acids in CSF. However, the temporal profile of observed changes in relation to vigabatrin injection shows that neither the long-lasting elevation of GABA content nor the increase in glutamate and aspartate levels correlates with the level of vigabatrin in CSF. These findings suggest that the excitatory mechanisms are also augmented following acute administration of vigabatrin, especially when the content of GABA had decreased to the baseline level and the level of vigabatrin was low.     

Increased Cerebrospinal Fluid Dopamine and 3,4-Dihydroxyphenylacetic Acid Levels in Huntington''s Disease: Evidence for an Overactive Dopaminergic Brain Transmission

Levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), 3-methoxy-4-hydroxyphenylglycol (MHPG), and 5-hydroxyindoleacetic acid (5-HIAA) in the CSF of patients with Huntington's disease (HD) were measured by HPLC. CSF DA, DOPAC, and MHPG levels were found to be increased in HD patients. Levels of HVA, 5-HIAA, and NA in the CSF of HD patients did not differ from those of controls. Changes in CSF DA and DOPAC levels were consistent with previous findings of increased DA tissue content in some brain areas of patients with HD. These results suggest that CSF DOPAC levels could be a more reliable index of overactive dopaminergic brain systems in HD than CSF HVA levels.     

Increased Intra- and Extracellular Concentrations of γ-Glutamylglutamate and Related Dipeptides in the Ischemic Rat Striatum: Involvement of γ-Glutamyl Transpeptidase

Abstract: The present work relates to the possibility that the ATP-independent enzyme γ-glutamyl transpeptidase (EC 2.3.2.2), which has been postulated to be part of an amino acid uptake system, is active during cerebral ischemia. This was evaluated in the ischemic rat striatum by determination of intra- and extracellular concentrations of γ-glutamyl dipeptides (the products of the transpeptidation) and glutathione (the physiological γ-glutamyl donor). An ischemic period (0–30 and 31–60 min) resulted in prominent increases in the respective concentration of extracellular γ-glutamylglutamate (24- and 67-fold), γ-glutamyltaurine + γ-glutamylglycine (5.8- and 19-fold), and γ-glutamylglutamine (2.6- and 6.8-fold) as revealed using in vivo microdialysis. The changes coincided with increased respective extracellular concentrations of glutamate (83- and 115-fold), taurine (17- and 25-fold), glycine (4.6- and 6.1-fold), and glutamine (1.7- and 2.1-fold). Furthermore, under anoxic conditions in vitro (0–30 and 0–60 min), respective striatal tissue concentrations were increased for γ-glutamylglutamate (20- and 17-fold), γ-glutamyltaurine (6.7- and 11-fold), γ-glutamylglutamine (1.7- and 1.2-fold), and γ-glutamylglycine (14- and 18-fold), whereas glutathione levels were, on an average, decreased by ∼350 µ M . In summary, γ-glutamyl transpeptidase is involved in de novo dipeptide synthesis in the mammalian brain during anoxic conditions, indicating transport of amino acids such as glutamate.     

Effect of Freezing on γ-Aminobutyric Acid Levels in Human Cerebrospinal Fluid

Abstract Using a radioreceptor assay, the concentration of γ -aminobutyric acid (GABA) in human cerebrospinal fluid (CSF) was found to be elevated significantly following a single deep-freeze to –70°C and thaw. Mean CSF GABA (± SD) in unfrozen CSF was 173 ± 73 pmol/ml ( n = 24). After a single deep-freeze, the mean level was 243 ± 106 pmol/ml ( p < 0.02). Subsequent freeze-thaw cycles resulted in further irregular and unpredictable elevations in CSF GABA. Mean level after two freezes was 379 ± 125 pmol/ml and after three freezes 654 ± 411 pmol/ml. These changes could result in the incorrect interpretation of results in patients suffering from neurological diseases.     

The τ Protein in Human Cerebrospinal Fluid in Alzheimer's Disease Consists of Proteolytically Derived Fragments

Abstract: Previous studies have shown that the levels of the microtubule-associated protein τ in the CSF of patients with Alzheimer's disease (AD) are elevated compared with age-matched controls. In spite of these findings, the nature of τ in CSF has not been well documented. In the present study, τ was immunoprecipitated from CSF of patients with AD or acute stroke, as well as normal elderly controls, followed by immunoblot analysis. In all cases, CSF τ consisted primarily of a band migrating at 26–28 kDa. In AD and stroke patients, several smaller τ fragments were also detected. No intact τ was detected in any of the CSF samples examined. Further immunoprecipitation studies showed that the majority of the τ fragments contained the amino terminus of the molecule. Treatment of CSF τ with alkaline phosphatase did not alter the electrophoretic properties of the fragments. These studies clearly demonstrate that CSF τ is truncated rather than intact.     

3,4-Dihydroxyphenylethylamine and 5-Hydroxytryptamine Metabolism in the Rat: Acidic Metabolites in Cisternal Cerebrospinal Fluid Before and After Giving Probenecid

3,4-Dihydroxyphenylethylamine (DA, dopamine) and 5-hydroxytryptamine (5-HT) turnover values were determined in freely moving male rats by measuring the rates of accumulation of the acidic metabolites of the above transmitters, i.e., 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in cisternal cerebrospinal fluid (CSF) samples after probenecid (200 mg/kg i.p.) administration. Determinations on samples before and after acid hydrolysis showed that the latter procedure was necessary for DA turnover determination. Thus whereas total (DOPAC + HVA) increased linearly with time after probenecid, free (DOPAC + HVA) did not. This was because the percentage of DOPAC + HVA in conjugated form increased with time. Determinations on a group of 28 rats during the dark (red light) period showed that cisternal amine metabolite concentrations before probenecid injection did not parallel turnover values. This was probably because individual differences in metabolite egress strongly affect the pre-probenecid values. The poor correlations between CSF tryptophan and 5-HT turnover suggested that differences of brain tryptophan concentration were not major determinants of differences of brain 5-HT metabolism within this group of normal rats. Considering that the rats were of similar weight and that the turnover values were all determined at approximately the same time of day, the three- to fourfold ranges of the turnover values are remarkable. The positive correlation between the DA and 5-HT turnovers of individual rats suggests the existence of common effects on DA and 5-HT turnover in normal rats.     

Human 14-3-3 Protein: Radioimmunoassay, Tissue Distribution, and Cerebrospinal Fluid Levels in Patients with Neurological Disorders

Abstract: An antiserum to human 14-3-3 protein has been produced in rabbits. The protein was a poor antigen and attempts to improve immunogenicity were unsuccessful. A radioimmunoassay was developed using the antiserum, ¹²⁵I- 14-3-3-2, and unlabelled 14-3-3-2 as standards. The assay had a sensitivity limit of 2.5 ng.m1⁻¹. The minor component of human 14-3-3 protein (14-3-3-1 protein) cross-reacted to approximately 10% in the assay. Human tissues were surveyed for 14-3-3 protein by two-dimensional electrophoresis and by radioimmunoassay. Two-dimensional electrophoresis showed a 14-3-3 protein complex in brain, intestine, and testis, but not in other tissues. Radioimmunoassay showed that although brain had the highest concentration of 14-3-3 (13.3 μg. mg⁻¹ soluble protein), immunoreactivity was present in all tissues, with the concentration in intestine and testis approaching 50% of the brain level. Lower levels (less than 1.0 μg. mg⁻¹ soluble protein) were seen in liver, kidney, skeletal muscle, and erythrocytes. The immunoreactivity present in tissues other than brain showed the same molecular weight and charge characteristics as authentic 14-3-3 protein. The radioimmunoassay also detected 14-3-3 protein in serum (50 ng.m1⁻¹) and in CSF (5-130 ng.ml⁻¹). The immunoreactivity present in CSF appeared to be intact 14-3-3 protein. CSF 14-3-3 levels were measured in 82 patients with various neurological disorders. Measurements of this protein did not appear sufficiently discriminating to be o f diagnostic value.