Archive for the ‘Dopaminergic Medicine’ Category

[A review of the effects of prolactin hormone and cytokine on the development and pathogenesis of autoimmune diseases]

Wednesday, June 30th, 2010

Prolactin (PRL) is not only a pituitary hormone with important role in the reproduction but it also acts as a cytokine involved in the immune response. Prolactin is produced by many immune system cells that express the prolactin receptor (PRL-R). PRL is then able to affect local microenvironment of the immune system organs and contribute to maturation as well as functioning of the immune system cells. The role of PRL in the immune reactions is stimulating; its presence significantly increases the ability of the immune cells to proliferate and produce cytokines such as TNF-alpha, IFN-gamma, IL-12, IL-1 beta. This effect results from activation of a number of intracellular pathways (Jak2/STAT, Ras/Raf/MAPK etc.) and activation of the genes linked to apoptosis and proliferation (Bcl-XL, Bcl-2, pim, XIAP) or transcription factors (IRF-1). Interestingly, PRL itself is unable to initiate an immune reaction; it is more a factor maintaining balance within immune reactions, contra-regulatory to glucocorticoids, which effect is manifested under critical circumstances of physical or psychological stress. Intensified immunosuppression during stress, combined with a lack of prolactin, has surprisingly been identified during experiments on mice and is also found in human medicine. On the other hand, increased prolactin serum levels were described in several systemic as well as organ-specific autoimmune diseases. PRL levels elevation in these diseases might result from several factors: an increased release of prolactin from the anterior pituitary due to inflammatory cytokines or reduced production of suppressive dopamine, or, alternatively, an increased production of prolactin in immune system cells. In some of these diseases, such as celiac disease and systemic lupus erythematosus (SLE), the PRL level correlates with the disease activity. This supports the hypothesis that PRL oversupply shifts the balance in the immune response towards higher activity of the immune system cells and initiation of the immune reaction. For example, in SLE, prolactin prolongs the life cycle of autoreactive B-lymphocytes and their ability to produce pathogenic autoantibodies. Further research into the effects of PRL and monitoring of patients with hyperprolactinaemia and autoimmune diseases will provide guidance on how to best utilize the possibly so far hidden prolactin potential. It is questionable whether pharmacotherapy could be used to decrease serum PRL levels in the treatment ofautoimmune diseases. However, the currently running studies suggest it might be possible to use PRL level detection as a marker of a disease activity.

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The ALDH2 and DRD2/ANKK1 genes interacted in bipolar II but not bipolar I disorder.

Sunday, June 27th, 2010

AIM: Clarifying the association between bipolar I and bipolar II, the two most common subtypes of bipolar disorder, at the genetic level is essential for improving our understanding of these disorders. The dopaminergic system has been implicated in the pathogenesis of bipolar disorder. It may be important to investigate genes involved in metabolizing dopamine and encoding dopamine receptors, such as the aldehyde dehydrogenase 2 (ALDH2) and dopamine D2 receptor/ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1) genes. We examined the association of the ALDH2 and DRD2/ANKK1 Taq IA polymorphisms with bipolar I and II disorders and possible interactions between these genes. METHODS: Seven hundred and fifty participants were recruited: 207 with bipolar I disorder, 277 with bipolar II disorder, and 266 healthy controls. The genotypes of the ALDH2 and DRD2/ANKK1 TaqIA polymorphisms were determined using polymerase chain reactions plus restriction fragment length polymorphism analysis. RESULTS: Logistic regression analysis showed a statistically significant interaction for the A1/A1 genotype of the DRD2/ANKK1 TaqIA, and the ALDH2*1*1 genotypes (P=0.009) could predict bipolar II patients compared with individuals without bipolar disorder. However, there was no association between the ALDH2 or DRD2/ANKK1 gene with neither bipolar I nor bipolar II disorder. CONCLUSION: Our findings may provide initial evidence that the ALDH2 and DRD2/ANKK1 genes interact in specific subtypes of bipolar disorders. Our findings also suggest a unique genetic distinction between bipolar I and bipolar II disorders.

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Neurotrophin-3 gene, intelligence, and selective attention deficit in a Korean sample with attention-deficit/hyperactivity disorder.

Sunday, June 27th, 2010

OBJECTIVE: Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder with a strong genetic component. Neurotrophin-3 (NTF3), which participates in the differentiation and survival of dopaminergic and noradrenergic neurons, has been identified as a factor in the development of ADHD. We investigated the relationships between ADHD and NTF3 gene polymorphism. METHODS: We conducted a case-control analysis of 202 ADHD subjects and 159 controls, performed a transmission disequilibrium test (TDT) on 151 trios, and compared the intelligence quotient (IQ) and a continuous performance test (CPT) according to the genotype of two single-nucleotide polymorphisms (SNPs) (rs6332 and rs6489630) in the NTF3 gene. RESULTS: In the case-control and family-based analyses, NTF3 was not significantly associated with ADHD. However, in the ADHD probands, the subjects with AA genotype in the rs6332 SNP had significantly higher mean T-scores for commission errors on the CPT than did those with the AG genotypes (p=0.045). The mean IQ of the ADHD probands who had the CC genotype of the rs6489630 SNP were higher compared with those who had the CT or TT genotype (p=0.035). The mean T-score for response time on the CPT was higher in the subjects with TT genotype in the rs6489630 SNP compared to those with the CC or CT genotype, even after adjusting for the effect of IQ (p=0.021). CONCLUSIONS: These results provide preliminary evidence of an association between NTF3 and the intelligence and selective attention deficit in the Korean population. Copyright © 2010. Published by Elsevier Inc.

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HPC-1/syntaxin 1A gene knockout mice show abnormal behavior possibly related to a disruption in 5-HTergic systems.

Sunday, June 27th, 2010

Abstract HPC-1/syntaxin 1A (STX1A) is thought to regulate the exocytosis of synaptic vesicles in neurons. In recent human genetic studies, STX1A has been implicated in neuropsychological disorders. To examine whether STX1A gene ablation is responsible for abnormal neuropsychological profiles observed in human psychiatric patients, we analysed the behavioral phenotype of STX1A knockout mice. Abnormal behavior was observed in both homozygotes (STX1A(-/-)) and heterozygotes (STX1A(+/-)) in a social interaction test, a novel object exploring test and a latent inhibition (LI) test, but not in a pre-pulse inhibition test. Interestingly, attenuation of LI, which is closely related to human schizotypic symptoms, was restored by administration of the selective serotonin reuptake inhibitor, fluoxetine, but not by the dopamine reuptake inhibitor, GBR12935, or the noradrenalin reuptake inhibitor, desipramine. We also observed that LI attenuation was restored by DOI (a 5-HT(2A) receptor agonist), but not by 8-OH-DPAT (a 5-HT(1A) receptor agonist), mCPP (a 5-HT(2C) receptor agonist), SKF 38393 (a D(1) receptor agonist), quinpirole (a D(2)/D(3) receptor agonist) or haloperidol (a D(2)/D(3) receptor antagonist). Thus, attenuation of LI is mainly caused by disruption of 5-HT-ergic systems via 5-HT(2A) receptors. In addition, 5-HT release from hippocampal and hypothalamic slices was significantly reduced. Therefore, ablation of STX1A may cause disruption of 5-HT-ergic transmission and induce abnormal behavior.

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Cariprazine, an orally active D2/D3 receptor antagonist, for the potential treatment of schizophrenia, bipolar mania and depression.

Sunday, June 27th, 2010

Cariprazine (RGH-188), which is being codeveloped by Gedeon Richter Ltd, Forest Laboratories Inc and Mitsubishi Tanabe Pharma Corp, is a novel putative antipsychotic drug that exerts partial agonism at dopamine D2/D3 receptors, with preferential binding to D3 receptors, and partial agonism at serotonin 5-HT1A receptors. Its activity at D2/D3 receptors may be lower than that of the prototype partial agonist aripiprazole. The antipsychotic activity of cariprazine was demonstrated in animal models, and data also suggest that the propensity for extrapyramidal side effects is low and that the drug may have procognitive properties. Cariprazine is rapidly absorbed, with high oral bioavailability and a long plasma elimination t1/2. Cariprazine is in phase III clinical trials in patients with schizophrenia and in patients with bipolar disorder. Data from phase II trials in patients with schizophrenia and bipolar mania indicate that the drug has antipsychotic and antimanic properties that are superior to placebo. With its unique receptor affinity profile, cariprazine may represent a potential enrichment of the therapeutic armamentarium for schizophrenia and affective disorders. Its activity against the cognitive deficits associated with schizophrenia has to be carefully investigated.

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Cooperativity between the phosphorylation of Thr95 and Ser77 of NHERF-1 in the hormonal regulation of renal phosphate transport.

Sunday, June 27th, 2010

The phosphorylation of the Sodium-Hydrogen Exchanger Regulatory Factor-1 (NHERF-1) plays a key role in the regulation of renal phosphate transport by parathyroid hormone (PTH) and dopamine. Ser77 in the first PDZ domain of NHERF-1 is a downstream target of both hormones. The current experiments explore the role of Thr95, another phosphate acceptor site in the PDZ I domain, on hormone-mediated regulation of phosphate transport in the proximal tubule of the kidney. The substitution of alanine for threonine at position 95 (T95A) significantly decreased the rate and extent of in vitro phosphorylation of Ser77 by PKC. In NHERF-1 null proximal tubule cells, neither PTH nor dopamine inhibited sodium-dependent phosphate transport. Infection of the cells with adenovirus expressing full length wild-type green fluorescent protein (GFP)-NHERF-1 increased basal phosphate transport and restored the inhibitory effect of both PTH and dopamine. Infection with full-length NHERF-1 containing a T95A mutation, however, increased basal phosphate transport but not the responsiveness to either hormone. As determined by surface plasmon resonance (SPR), the substitution of serine for aspartic acid (S77D) in the PDZ I domain decreased the binding affinity to the sodium-dependent phosphate transporter2a (Npt2a) as compared to wild-type PDZ I but a T95D mutation had no effect on binding. Finally, cellular studies indicated that both PTH and dopamine treatment increased the phosphorylation of Thr95. These studies indicate a remarkable cooperativity between the phosphorylation of Thr95 and Ser77 of NHERF-1 in the hormonal regulation of renal phosphate transport. The phosphorylation of Thr95 facilitates the phosphorylation of Ser77. This, in turn, results in the dissociation of NHERF-1 from Npt2a and a decrease in phosphate transport in renal proximal tubule cells.

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A water extract of Mucuna pruriens provides long-term amelioration of parkinsonism with reduced risk for dyskinesias.

Sunday, June 27th, 2010

Dopaminergic anti-parkinsonian medications, such as levodopa (LD) cause drug-induced dyskinesias (DID) in majority of patients with Parkinson’s disease (PD). Mucuna pruriens, a legume extensively used in Ayurveda to treat PD, is reputed to provide anti-parkinsonian benefits without inducing DID. We compared the behavioral effects of chronic parenteral administration of a water extract of M. pruriens seed powder (MPE) alone without any additives, MPE combined with the peripheral dopa-decarboxylase inhibitor (DDCI) benserazide (MPE+BZ), LD+BZ and LD alone without BZ in the hemiparkinsonian rat model of PD. A battery of behavioral tests assessed by blinded investigators served as outcome measures in these randomized trials. In experiment 1, animals that received LD+BZ or MPE+BZ at high (6mg/kg) and medium (4mg/kg) equivalent doses demonstrated significant alleviation of parkinsonism, but, developed severe dose-dependent DID. LD+BZ at low doses (2mg/kg) did not provide significant alleviation of parkinsonism. In contrast, MPE+BZ at an equivalent low dose significantly ameliorated parkinsonism. In experiment 2, MPE without any additives (12mg/kg and 20mg/kg LD equivalent dose) alleviated parkinsonism with significantly less DID compared to LD+BZ or MPE+BZ. In experiment 3, MPE without additives administered chronically provided long-term anti-parkinsonian benefits without causing DID. In experiment 4, MPE alone provided significantly more behavioral benefit when compared to the equivalent dose of synthetic LD alone without BZ. In experiment 5, MPE alone reduced the severity of DID in animals initially primed with LD+BZ. These findings suggest that M. pruriens contains water-soluble ingredients that either have an intrinsic DDCI-like activity or mitigate the need for an add-on DDCI to ameliorate parkinsonism. These unique long-term anti-parkinsonian effects of a parenterally administered water extract of M. pruriens seed powder may provide a platform for future drug discoveries and novel treatment strategies in PD. Copyright © 2010 Elsevier Ltd. All rights reserved.

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Immediate Serum Growth Hormone Decrease as a Potential Index of Dopamine-Related Response to Electroconvulsive Therapy in Schizophrenic Patients.

Tuesday, June 22nd, 2010

OBJECTIVES:: The objective of this study was to investigate the immediate response of the dopamine-regulated growth hormone (GH) to electroconvulsive therapy (ECT) in schizophrenic patients and the changes in the serum GH levels throughout the consecutive sessions of the therapeutic ECT course. METHODS:: Serum GH levels were measured in a sample of 11 men with schizophrenia according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, who were administered a course of 8 bilateral ECT treatments. Measurements were performed 5 minutes before ECT, during ECT, 15 minutes after an ECT session, and 30 minutes after an ECT session during the first, fourth, and eighth ECT sessions. RESULTS:: At both the fourth and the eighth ECT sessions, a significant decrease in GH levels 15 and 30 minutes after ECT was observed compared with the baseline values. No change in baseline serum GH levels was observed either during or at the end of the treatment. Clinical improvement was indicated by a significant reduction in the total score, negative subscale score, and positive subscale score of the Positive and Negative Syndrome Scale. CONCLUSIONS:: The results are consistent with the potential role of immediate serum GH changes as an index of potential dopamine-mediated response to ECT. It can be assumed that GH reduction may be partially related to an antidopaminergic action of ECT, but further research is still needed to better evaluate the correlation of the dopamine system instability during the course of the illness with the previously mentioned immediate treatment response. Also, the role of other neurotransmitters in the regulation of GH production and ECT response must be taken into account for the purpose of an overall evaluation of the results and of their potential clinical implications.

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Parent-child concordance of Taq1 A1 allele predicts similarity of parent-child weight loss in behavioral family-based treatment programs.

Tuesday, June 22nd, 2010

Family-based treatments show positive relationships between parent and child weight losses. One mechanism for similar parent-child changes may be a common genetic predisposition to respond similarly to a structured weight loss program. We examined whether concordance of the Taq1 A1 allele of the dopamine D2 receptor (DRD2) predicts similarities in zBMI change in 26 families with obese parents and overweight/obese 8-12 year-old children. Results showed a relationship between parent and child zBMI change over 6 and 12 months (r's=.69, .77, p's<0.001), and concordance for the number of Taq1 A1 alleles predicted the similarity in parent and child weight loss at 6 (p=0.003) and 12 (p=0.025) months. These results show concordance of the Taq1 A1 allele of the DRD2 between parents and children may be one mechanism for the similar response to family-based treatments within families. Copyright © 2010. Published by Elsevier Ltd.

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[A case report : Severe anaphylactic shock followed by positive skin-prick-test to multiple vasoconstrictors]

Tuesday, June 22nd, 2010

A 71-year-old woman was scheduled for revision of total hip replacement under general anesthesia. Twenty minutes before entering the operating room, slight urticaria was caused by drop infusion of cefotiam. It was stopped immediately and the patient entered the operating room without any symptoms. Anesthesia was induced and maintained with sevoflurane and remifentanil. After 3 hours, systolic arterial pressure (SAS) dropped to 80 mmHg. Injecting of ephedrine 8 mg was not effective, and we injected a total of 3 mg of methoxamine. Then SAS dropped to 50 mmHg. We injected epinephrine 0.2 mg twice and also started continuous infusion of norepinephrine. Severe skin rash indicated that anaphylactic reaction had occurred. About 20 minutes after starting norepinephrine, the SAS was stabilized. We decided to stop the operation, and the patient was moved to the intensive care unit (ICU). A few hours after entering the ICU, she was extubated and moved to the general ward next day. Skin-prick-tests performed 14 days later indicated that she was allergic to ephedrine, methoxamine, epinephrine, dopamine and a few more drugs.

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