Metabolites In Central Nervous System Research Articles

An MR spectroscopy study of temporal areas excluding primary auditory cortex and frontal regions in subjective bilateral and unilateral tinnitus

Previous studies indicate changes in neurotransmission along the auditory pathway in subjective tinnitus. Most authors, however, investigated brain regions including the primary auditory cortex, whose physiology can be affected by concurrent hearing deficits. In the present MR spectroscopy study we assumed increased levels of glutamate and glutamine (Glx), and other Central Nervous System metabolites in the temporal lobe outside the primary auditory cortex, in a region involved in conscious auditory perception and memory. We studied 52 participants with unilateral (n = 24) and bilateral (n = 28) tinnitus, and a control group without tinnitus (n = 25), all with no severe hearing losses and a similar hearing profile. None of the metabolite levels in the temporal regions of interest were found related to tinnitus status or laterality. Unexpectedly, we found a tendency of increased concentration of Glx in the control left medial frontal region in bilateral vs unilateral tinnitus. Slightly elevated depressive and anxiety symptoms were also shown in participants with tinnitus, as compared to healthy individuals, with the bilateral tinnitus group marginally more affected. We discuss no apparent effect in the temporal lobes, as well as the role of frontal brain areas, with respect to hearing loss, attention and psychological well-being in chronic tinnitus. We furthermore elaborate on the design-related and technical obstacles of MR spectroscopy.

Effects of a high-caloric diet and physical exercise on brain metabolite levels: a combined proton MRS and histologic study.

Excessive intake of high-caloric diets as well as subsequent development of obesity and diabetes mellitus may exert a wide range of unfavorable effects on the central nervous system (CNS). It has been suggested that one mechanism in this context is the promotion of neuroinflammation. The potentially harmful effects of such diets were suggested to be mitigated by physical exercise. Here, we conducted a study investigating the effects of physical exercise in a cafeteria-diet mouse model on CNS metabolites by means of in vivo proton magnetic resonance spectroscopy ((1)HMRS). In addition postmortem histologic and real-time (RT)-PCR analyses for inflammatory markers were performed. Cafeteria diet induced obesity and hyperglycemia, which was only partially moderated by exercise. It also induced several changes in CNS metabolites such as reduced hippocampal glutamate (Glu), choline-containing compounds (tCho) and N-acetylaspartate (NAA)+N-acetyl-aspartyl-glutamic acid (NAAG) (tNAA) levels, whereas opposite effects were seen for running. No association of these effects with markers of central inflammation could be observed. These findings suggest that while voluntary wheel running alone is insufficient to prevent the unfavorable peripheral sequelae of the diet, it counteracted many changes in brain metabolites. The observed effects seem to be independent of neuroinflammation.

Rapid analysis of neurotransmitters in rat brain using ultra‐fast liquid chromatography and tandem mass spectrometry: application to a comparative study in normal and insomnic rats

Neurotransmitters and their metabolites in central nervous system were known to play a significant role in sedation and hypnosis. A rapid and sensitive UFLC-MS/MS method for simultaneous determination of serotonin, 5-hydroxyindole acetic acid (5-HIAA), tryptophan (Try), dopamine (DA), norepinephrine (NE), γ-aminobutyric acid (GABA), glutamic acid (Glu) and acetylcholine (Ach) in rat brain without derivatization, ion-pairing reagent or pre-concentration was developed. Analytes and IS were separated on a Inertsil ODS-EP column (150 mm × 4.6 mm, 5 µm particles) and analyzed in a single chromatographic run in less than 9.0 min, using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water at a flow rate of 1.2 ml min(-1) . The detection of the analytes was performed on 4000Q UFLC-MS/MS system with turbo ion spray source in positive ion and multiple reaction monitoring mode. The developed method provided excellent linear calibration curves for the assay of analytes (R(2) ≥ 0.9915). Limits of quantification were in the range of 1.0 ng ml(-1) to 1.0 µg ml(-1) for the analytes in rat brain. Intra- and inter-day precision and accuracy of analytes were well within acceptance criteria (15%). Mean extraction recoveries of analytes and IS from rat brain were all more than 80.0%. Furthermore, the validated method was successfully applied to comparing profiles of analytes in normal and insomnic rat brains. Results indicated that there were statistically significant differences for serotonin, 5-HIAA, DA, NE, Glu and Ach, but no significant difference for Try and GABA between two groups.

NEUROLOGIC MANIFESTATION OF ORGANIC ACADEMIA

Inborn errors of organic acid metabolism are relatively recently recognized diseases with a wide spectrum of clinical signs and symptoms: ranging from asymptomatic, normal appearing children to death during first few days of life.In my presentation I will try to explain some of the most common clinical presentation of these disorder with stress on neurologic findings. Organic acidemia usually have three clinical manifestations Severe neonatal form, Intermittent late-onset form and chronic progressive form. Recurrent coma, The main feature of these disorders is due to accumulation of toxic metabolites in Central Nervous system with direct effect on the function, while chronic accumulation of these materials may interfere with CNS development or cerebral metabolism leading to developmental delay.Severe neonatal formsFollowing a symptom free interval of a few days from birth, poor sucking and difficult feeding appears in the newborn, followed by unexplained and progressive coma. Seizures may appear during the course of the disease and EEG may show a burst-suppression pattern. During this stage most infants have axial hypotonia with peripheral dystonia, choreoathetosis, episodic opisthotonus and some repetitive bicycling and boxing movements.Associated biochemical abnormalities including metabolic acidosis, ketonuria and hyperammonemia also is usually present. The overall short-term prognosis with recent advances in medical care is improving. But later in life acute intercurrent episodes triggered by a stress often occur, which can be occasionally fatal.bulging fontanelle and cerebral edema may mimic CNS infection in these babies.Intermittent late-onset formsRecurrent attacks of coma or lethargy with ataxia can occur in childhood or even in adolescence or adulthood. These episodes may be frequent, though in between these the child is entirely normal. These attacks are precipitated by conditions that enhance protein catabolism (trauma, infection etc).Sometimes these episodes can lead to death or severe sequel. Seizure disorder is one of these sequels which is generalized in type with myoclonic seizure in infancy and childhood and later tonic-clonic and atypical absence seizures predominate. Also many of the survivors have acute or progressive extra pyramidal syndrome due to bilateral necrosis of basal ganglia.Chronic progressive formsNon specific Developmental delay, hypotonia, muscular weakness, microcephaly and seizures are rarely the only revealing signs in organic acidemia without any acute presentation.Seizures may become refractory to Anti Epileptic Drugs. In addition many asymptomatic or minimally symptomatic infants have been identified during tandem mass spectrometry newborn screening program. Cognitive deterioration associated with movement disorder such as dystonia or chorea may be caused by any form of organic aciduria.

Flushing Out of Cerebrospinal Fluid as a Therapy for Acute Cerebellar Dysfunction Caused by High Dose of Cytosine Arabinoside: A Case Report

High dose of cytosine arabinoside is usually used in treatment of acute myelogenous leukemia. Here we report 1 case of a child who developed neurologic toxicity and rapidly improved after flushing out of cerebral spinal fluid, suggesting it could be treatment in the acute phase of toxicity. Efficacy of this treatment could be explained by reducing cytosine arabinoside metabolites in central nervous system.

Brain Gamma-Aminobutyric Acid Levels Are Decreased in Patients With Phantageusia and Phantosmia Demonstrated by Magnetic Resonance Spectroscopy

Olfactory and gustatory hallucinations (phantosmias and phantageusias, respectively) are sensory distortions that commonly follow losses of olfactory and gustatory acuity (hyposmia and hypogeusia, respectively). The biochemical basis of these hallucinations is unclear. Functional magnetic resonance imaging has been used previously to demonstrate widespread and robust central nervous system (CNS) activation to memories of these sensory distortions in patients with these symptoms. In this study, possible CNS mechanisms responsible for these distortions were evaluated using magnetic resonance spectroscopy, because this technique has been used to measure various CNS metabolites in patients with neurologic disorders. Forty-seven subjects were studied: 28 normal volunteers (13 men and 15 women) and 19 patients (8 men and 11 women) with persistent oral global phantageusia and/or birhinal phantosmia studied before any treatment. Four patients (1 man and 3 women) were studied before and after pharmacologic treatment that reduced the severity of their sensory distortions. All subjects were studied in a Signa 1.5-T magnetic resonance scanner with a quadrature head coil using a modified standard 2-dimensional J-point resolved excitation in the steady state (PRESS) sequence by which gamma-aminobutyric acid (GABA), glutamic acid, choline, N-acetylaspartate, and creatine (Cre) were measured in various CNS regions. Results were expressed using Cre as a denominator to determine ratios for each measurement. Differences were defined between normal subjects and patients before treatment and in patients before and after successful pharmacologic treatment. Before treatment, GABA levels in several CNS regions were lower in patients than in normal volunteers and were the only biochemical changes found; significantly lowered GABA levels were found in the cingulate, right and left insula, and left amygdala. No differences between patients and normal volunteers were found in any of the metabolites in the posterior occipital region. After treatment that inhibited sensory distortions, CNS GABA levels increased in the cingulate, insula, and amygdala but significantly only in the left insula and in the right and left amygdala. After this successful treatment, no change in any biochemical parameter was found in the posterior occipital region. These results indicate that decreased brain GABA levels can serve as biochemical markers of phantageusia and/or phantosmia in patients with these distortions and are the first biochemical changes in the CNS that reflect these sensory changes. After successful treatment of these distortions, CNS GABA levels increased to levels at or near normal, consistent with functional remission of these symptoms. These results substantiate a role for CNS GABA in the generation and inhibition of these sensory hallucinations. Although the underlying biochemical mechanism(s) for the generation of these decreased GABA levels are complex, because similar types of sensory hallucinations occur as auras or prodromata of epileptic seizure and migraine activity, these results suggest that there may be common biochemical changes among these disorders.

Pressure gradients within the central nervous system

The existence of clinically relevant pressure gradients within the central nervous system (CNS) is the subject of ongoing debate. Such gradients, if they do exist, would have significant implications for intracranial pressure (ICP) monitoring and ICP management in traumatic brain injury. As summarised in this short review, there is considerable experimental and clinical evidence that ICP is not evenly distributed within the central nervous system. Larger clinical trials on the implications of ICP gradients are warranted to address questions on the correct placement of ICP probes and on ICP management. It seems paradoxical to develop and employ ever more sophisticated monitoring devices in traumatic brain injury, such as monitoring of CNS metabolites with microdialysis or near-infrared spectroscopy, while fundamental issues such as the existence of ICP gradients remain unresolved.