Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Some amino acids are involved in the biosynthesis of nitric oxide (NO), which has a physiological and pathophysiological role. To study NO biosynthesis, we compared arginine and citrulline levels in the cerebrospinal fluid (CSF) from patients with infectious and/or inflammatory processes within the central nervous system (CNS), with those from patients without those disorders. Arginine concentration was not significantly different between the groups (P = 0.115), whereas citrulline was significantly elevated in the first group (P = 0.020). We propose a simple chromatographic method to estimate NO biosynthesis ex vivo within the CNS, that may be applicable for the study of neurodegenerative and psychiatric diseases such as Parkinson's disease and schizophrenia.
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PMID:Liquid chromatographic-fluorimetric method for the estimation of nitric oxide biosynthesis in the central nervous system. 1517 22

Phospholipids located in the cellular membrane play a critical role in the fluid-mosaic model of membrane structure and membrane function. Evidence is mounting for the role of abnormal phospholipid metabolism in some neuropsychiatric disorders including schizophrenia. As an important essential fatty acid (EFA), omega-3 (omega-3) fatty acid series are found in large amounts in fish oil. The aim of this experimental study was to assess the changes of some of the oxidant and antioxidant parameters in the hypothalamus of rats fed with omega-3 EFA diet (0.4 g/kg/day) for 30 days. Eight control rats and nine rats fed with omega-3 were decapitated under ether anesthesia, and hypothalamus was removed immediately. Malondialdehyde (MDA) and nitric oxide (NO) levels as well as superoxide dismutase (SOD) and xanthine oxidase (XO) enzyme activities in the hypothalamus were measured. SOD activity was significantly decreased in omega-3 EFA treated group compared to control group (p < 0.014). Tissue MDA and NO levels were also decreased in omega-3 EFA treated group compared to control rats (p < 0.0001). Xanthine oxidase activity was found to be increased in omega-3 EFA treated rats when compared to the control group (p < 0.0001). Taken together, this preliminary animal study provides strong support for a therapeutic effect of omega-3 EFA in some neuropsychiatric disorders in which reactive oxygen species (ROS) are recently accused to be an important physiopathogenetic factor.
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PMID:Hypothalamic superoxide dismutase, xanthine oxidase, nitric oxide, and malondialdehyde in rats fed with fish omega-3 fatty acids. 1527 95

The dominant research subject on schizophrenia, mood disorders, autism and other central nervous system diseases has been related to neurotransmitter system abnormalities. For example, the dopamine hypothesis states that schizophrenia is the result of dopaminergic hyperactivity. The therapeutic approach has also been directed towards finding agents which will modulate or regulate these neurotransmitter systems at any step. There is substantial and mounting evidence that subtle abnormalities of reactive oxygen species (ROS) and nitric oxide (NO) may underlie a wide range of neuropsychiatric disorders. NO has chemical properties that make it uniquely suitable as an intracellular and intercellular messenger. It is produced by the activity of nitric oxide synthases which are present in peripheral tissues and in neurons. On the other hand, NO is known to be an oxygen radical in the central and peripheral nervous systems. NO has been implicated in a number of physiological functions such as noradrenaline and dopamine releases, memory and learning and certain pathologies such as schizophrenia, bipolar disorder and major depression. Evidence has been considered here for the proposal that an abnormality of NO metabolism may be a contributory factor in some neuropsychiatric disorders. The direct evidence for NO abnormalities in schizophrenia and other psychiatric disorders remains relatively limited to date, although there are some clinical and experimental studies. The suggestion that NO and other ROS may play a role in some neuropsychiatric disorders clearly has important implications for new treatment possibilities. The primary objective of the present review was to summarize and critically evaluate the current knowledge regarding a potential contribution of NO to the neuropathophysiology of schizophrenia as well as other neuropsychiatric disorders.
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PMID:Nitric oxide as a physiopathological factor in neuropsychiatric disorders. 1534 Nov 94

Nitric oxide (NO) is a diffusible, multifunctional signaling molecule found in many areas of the brain. NO signaling is involved in a wide array of neurophysiological functions including synaptogenesis, modulation of neurotransmitter release, synaptic plasticity, central nervous system blood flow and cell death. NO synthase (NOS) activity regulates the production of NO and the cerebellum expresses high levels of nitric oxide synthase (NOS) in granule, stellate and basket cells. Cerebellar mutant mice provide excellent opportunities to study changes of NO/NOS concentrations and activities to gain a greater understanding of the roles of NO and NOS in cerebellar function. Here, we have reviewed the current understanding of the functional roles of NO and NOS in the cerebellum and present NO/NOS activities that have been described in various cerebellar mutant mice and NOS knockout mice. NO appears to exert neuroprotective effects at low to moderate concentrations, whereas NO becomes neurotoxic as the concentration increases. Excessive NO production can cause oxidative stress to neurons, ultimately impairing neuronal function and result in neuronal cell death. Based on their genetics and cerebellar histopathology, some of cerebellar mutant mice display similarities with human neurological conditions and may prove to be valuable models to study several human neurological disorders, such as autism and schizophrenia.
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PMID:Neuronal nitric oxide synthase expression in cerebellar mutant mice. 1554 2

Angiotensin-II, a product of angiotensin converting enzyme (ACE) action, regulates vascular tone, stimulates the release of pro-inflammatory cytokines, activates NFkappaB, increases oxidant stress, and suppresses nitric oxide synthesis. Thus, angiotensin-II is pro-inflammatory in nature. Hence, increase in ACE activity and the concentrations of angiotensin-II initiate and perpetuate inflammation. Since ACE is present in many tissues including: the uterus, placenta, vascular tissue, heart, brain, adrenal cortex and kidney, leukocytes, alveolar macrophages, peripheral monocytes, neuronal cells and epididymal cells, this suggests that angiotensin-II may have a role in atherosclerosis, congestive cardiac failure, stroke, bipolar disorder, schizophrenia, dementia, Alzheimer's disease, psoriasis, atopic and non-atopic dermatitis, eczema, several acute and chronic inflammatory diseases, and cancer, conditions in which inflammation is known to play a significant role. This suggests that ACE inhibitors and/or angiotensin-II receptor blockers could be of significant benefit in the management of these conditions. Alternatively, structural analogues of presently available ACE inhibitors and angiotensin-II receptor blockers could be developed such that they are not only useful in the treatment of hypertension and CHF but also possess anti-inflammatory actions.
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PMID:Is angiotensin-II an endogenous pro-inflammatory molecule? 1587 6

Alterations in antioxidant status in schizophrenia suggest free radical-mediated neurotoxicity; this finding can be a consequence of increased free radical production. There are multiple pathways to excess free radical generation and subsequent oxidative stress. One such pathway is the formation of peroxynitrite by a reaction of nitric oxide (NO) and superoxide radical. NO is formed from L-arginine by nitric oxide synthase (NOS). A constitutive cytosolic isoform, neuronal NOS (nNOS), appears to be fairly stable in the postmortem brain tissues. Utilizing a sensitive fluorometric assay, NO levels were measured by its stable metabolites, nitrate and nitrite, in the caudate region of postmortem brain tissues from patients and control subjects. In the human brain, NO is metabolized primarily in the form of nitrate. A significantly increased level of NO was found in schizophrenia patients (241 +/- 146 pmol/mg dry weight, n = 18) than was found in those of normal (142 +/- 65 pmol/mg dry weight, n = 20) and psychiatric controls without schizophrenia (125 +/- 83 pmol/mg dry weight, n = 16) (analysis of covariance [ANCOVA], F = 6.446, df = 2,51, p = 0.003). These findings were independent of age, brain weight, postmortem interval (PMI), sample storage time, or cigarette smoking. Elevated NO levels in the brains of schizophrenia patients lend further support for the free radical pathology in schizophrenia.
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PMID:Increased nitric oxide radicals in postmortem brain from patients with schizophrenia. 1595 98

Intense research has been conducted in an effort to identify specific biological markers of schizophrenia. The gas nitric oxide (NO) is one of the most important signaling molecules involved in a plethora of cellular events that take place in the cardiovascular, immune and nervous systems of animals. This survey aims to demonstrate that NO and its metabolites play important roles in schizophrenia and have a significant influence on our understanding of the development, progression and treatment of the disease. Special emphasis is given to the impact of NO metabolism on processes known to be disturbed in schizophrenia (i.e., cell migration, formation of synapses, NMDA receptor mediated neurotransmission, membrane pathology and cognitive abilities). However, when comparing data on the NO metabolism in the brain tissue and body fluids of schizophrenics with those obtained from patients with other neurological and psychiatric diseases, it becomes clear that alterations of NO metabolism are not unique to, or indicative of, schizophrenia. Thus, NO and its metabolites are not suitable diagnostic tools to distinguish schizophrenia from psychically healthy control cases or from other brain disorders.
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PMID:The many faces of nitric oxide in schizophrenia. A review. 1600 89

Angiotensin-II regulates vascular tone, stimulates the release of pro-inflammatory cytokines, activates NF-kappaB, increases oxidant stress, and suppresses nitric oxide synthesis, and thus, it functions as an inflammatory molecule. Since ACE is present in many tissues, this suggests that angiotensin-II may play a significant role in atherosclerosis, congestive cardiac failure, stroke, bipolar disorder, schizophrenia, dementia, Alzheimer's disease, psoriasis, atopic and non-atopic dermatitis, eczema, several acute and chronic inflammatory diseases, and cancer, conditions in which inflammation is an aetiopathogenic factor. Thus, ACE inhibitors and/or angiotensin-II receptor blockers could be of benefit in these conditions. Furthermore, structural analogues of ACE inhibitors and angiotensin-II receptor blockers could be developed that possess anti-inflammatory actions without significant action on the cardiovascular system.
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PMID:Angiotensin-II behaves as an endogenous pro-inflammatory molecule. 1612 58

Depression is frequently associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which leads to repeated episodes of hypercortisolemia. Hypothalamic paraventricular neurons are believed to trigger these processes by aberrant generation and/or release of corticotropin releasing hormone, oxytocin, vasopressin, and nitric oxide (NO). Recent findings from two independent laboratories have demonstrated that the suprachiasmatic nucleus, which in part controls the cellular activity of paraventricular neurons (PVN), is also involved in affective disorder. The aim of the present study was to elucidate by stereological analysis, whether suprachiasmatic nucleus (SCN) nitric oxide synthase and neurophysin generating neurons are affected in neuropsychiatric disorders. We show that compared to controls the number of nitric oxide synthase immunoreactive neurons is greatly reduced both in depression and in schizophrenia. In subjects with affective disorder there was a correlation between the number of NOS-expressing cells and duration of treatment with antidepressants. The number of neurophysin-expressing SCN neurons was also fewer in cases with mood disorder. It is concluded that SCN-derived NO may be a relevant pathophysiological factor in neuropsychiatric disorders.
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PMID:Hypothalamic nitric oxide synthase in affective disorder: focus on the suprachiasmatic nucleus. 1619 95

Tetrahydrobiopterin (BH(4)) is a vital cofactor maintaining availability of the amine neurotransmitters [dopamine (DA), noradrenaline (NA), and serotonin (5-HT)], regulating the synthesis of nitric oxide (NO) by nitric oxide synthase (NOS), and stimulating and modulating the glutamatergic system (directly and indirectly). These BH(4) properties and their potential relevance to schizophrenia led us to investigate the hypothesis of a study group (healthy controls, n=37; schizophrenics, n=154) effect on fasting plasma total biopterin levels (a measure of BH(4)). Study analysis showed a highly significant deficit of total biopterins for the schizophrenic sample after partialling out the effects of potential confounds of gender, age, ethnicity, neuroleptic use history and dose of current use, 24-hour dietary phenylalanine/protein ratio (a dietary variable relevant to BH(4) synthesis), and plasma phenylalanine (which stimulates BH(4) synthesis). A mean decrement of 34% in plasma total biopterins for schizophrenics from control values supports clinical relevance for the finding. In a subsample (21 controls and 23 schizophrenics), sequence analysis was done of the GTP cyclohydrolase I feedback regulatory gene and no mutations were found in the coding region of the gene. A deficiency of BH(4) could lead to hypofunction of the systems of DA, NA, 5-HT, NOS/NO, and glutamate, all of which have been independently implicated in schizophrenia psychopathology. Further, evidence has been accumulating which implicates the critical interdependence of these neurotransmitter systems in schizophrenia; this concept, along with the present study finding of a biopterin deficit, suggests that further study of the BH(4) system in schizophrenia is warranted and desirable.
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PMID:Evidence for a tetrahydrobiopterin deficit in schizophrenia. 1624


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