| 1. |
- Lavebratt, C., et al.
(författare)
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The KMO allele encoding Arg(452) is associated with psychotic features in bipolar disorder type 1, and with increased CSF KYNA level and reduced KMO expression
- 2014
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 19:3, s. 334-341
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Tidskriftsartikel (refereegranskat)abstract
- The kynurenine pathway metabolite kynurenic acid (KYNA), modulating glutamatergic and cholinergic neurotransmission, is increased in cerebrospinal fluid (CSF) of patients with schizophrenia or bipolar disorder type 1 with psychotic features. KYNA production is critically dependent on kynurenine 3-monooxygenase (KMO). KMO mRNA levels and activity in prefrontal cortex (PFC) are reduced in schizophrenia. We hypothesized that KMO expression in PFC would be reduced in bipolar disorder with psychotic features and that a functional genetic variant of KMO would associate with this disease, CSF KYNA level and KMO expression. KMO mRNA levels were reduced in PFC of bipolar disorder patients with lifetime psychotic features (P = 0.005, n = 19) or schizophrenia (P = 0.02, n = 36) compared with nonpsychotic patients and controls. KMO genetic association to psychotic features in bipolar disorder type 1 was studied in 493 patients and 1044 controls from Sweden. The KMO Arg(452) allele was associated with psychotic features during manic episodes (P = 0.003). KMO Arg(452) was studied for association to CSF KYNA levels in an independent sample of 55 Swedish patients, and to KMO expression in 717 lymphoblastoid cell lines and 138 hippocampal biopsies. KMO Arg(452) associated with increased levels of CSF KYNA (P = 0.03) and reduced lymphoblastoid and hippocampal KMO expression (P <= 0.05). Thus, findings from five independent cohorts suggest that genetic variation in KMO influences the risk for psychotic features in mania of bipolar disorder patients. This provides a possible mechanism for the previous findings of elevated CSF KYNA levels in those bipolar patients with lifetime psychotic features and positive association between KYNA levels and number of manic episodes.
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| 2. |
- Orhan, F, et al.
(författare)
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CSF GABA is reduced in first-episode psychosis and associates to symptom severity
- 2018
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Ingår i: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 23:5, s. 1244-1250
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia is characterized by a multiplicity of symptoms arising from almost all domains of mental function. γ-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain and is increasingly recognized to have a significant role in the pathophysiology of the disorder. In the present study, cerebrospinal fluid (CSF) concentrations of GABA were analyzed in 41 first-episode psychosis (FEP) patients and 21 age- and sex-matched healthy volunteers by high-performance liquid chromatography. We found lower CSF GABA concentration in FEP patients compared with that in the healthy volunteers, a condition that was unrelated to antipsychotic and/or anxiolytic medication. Moreover, lower CSF GABA levels were associated with total and general score of Positive and Negative Syndrome Scale, illness severity and probably with a poor performance in a test of attention. This study offers clinical in vivo evidence for a potential role of GABA in early-stage schizophrenia.
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| 3. |
- Sellgren, C. M., et al.
(författare)
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A genome-wide association study of kynurenic acid in cerebrospinal fluid: implications for psychosis and cognitive impairment in bipolar disorder
- 2016
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 21:10, s. 1342-1350
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Tidskriftsartikel (refereegranskat)abstract
- Elevated cerebrospinal fluid (CSF) levels of the glia-derived N-methyl-D-aspartic acid receptor antagonist kynurenic acid (KYNA) have consistently been implicated in schizophrenia and bipolar disorder. Here, we conducted a genome-wide association study based on CSF KYNA in bipolar disorder and found support for an association with a common variant within 1p21.3. After replication in an independent cohort, we linked this genetic variant-associated with reduced SNX7 expression-to positive psychotic symptoms and executive function deficits in bipolar disorder. A series of post-mortem brain tissue and in vitro experiments suggested SNX7 downregulation to result in a caspase-8-driven activation of interleukin-1 beta and a subsequent induction of the brain kynurenine pathway. The current study demonstrates the potential of using biomarkers in genetic studies of psychiatric disorders, and may help to identify novel drug targets in bipolar disorder.
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| 4. |
- Sellgren, C. M., et al.
(författare)
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GRK3 deficiency elicits brain immune activation and psychosis
- 2021
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- The G protein-coupled receptor kinase (GRK) family member protein GRK3 has been linked to the pathophysiology of schizophrenia and bipolar disorder. Expression, as well as protein levels, of GRK3 are reduced in post-mortem prefrontal cortex of schizophrenia subjects. Here, we investigate functional behavior and neurotransmission related to immune activation and psychosis using mice lacking functional Grk3 and utilizing a variety of methods, including behavioral, biochemical, electrophysiological, molecular, and imaging methods. Compared to wildtype controls, the Grk3(-/-) mice show a number of aberrations linked to psychosis, including elevated brain levels of IL-1 beta, increased turnover of kynurenic acid (KYNA), hyper-responsiveness to D-amphetamine, elevated spontaneous firing of midbrain dopamine neurons, and disruption in prepulse inhibition. Analyzing human genetic data, we observe a link between psychotic features in bipolar disorder, decreased GRK expression, and increased concentration of CSF KYNA. Taken together, our data suggest that Grk3(-/-) mice show face and construct validity relating to the psychosis phenotype with glial activation and would be suitable for translational studies of novel immunomodulatory agents in psychotic disorders.
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