Molecular Signature That Determines the Acute Tolerance of G Protein-Coupled Receptors

Desensitization and acute tolerance are terms used to describe the attenuation of receptor responsiveness by prolonged or intermittent exposure to an agonist. Unlike desensitization of G protein-coupled receptors (GPCRs), which is commonly explained by steric hindrance caused by the β-arrestins that are translocated to the activated receptors, molecular mechanisms involved in the acute tolerance of GPCRs remain unclear. Our studies with several GPCRs and related mutants showed that the acute tolerance of GPCRs could occur independently of agonist-induced β-arrestin translocation. A series of co-immunoprecipitation experiments revealed a correlation between receptor tolerance and interactions among receptors, β-arrestin2, and Gβγ. Gβγ displayed a stable interaction with receptors and β-arrestin2 in cells expressing GPCRs that were prone to undergo tolerance compared to the GPCRs that were resistant to acute tolerance. Strengthening the interaction between Gβγ and β-arrestin rendered the GPCRs to acquire the tendency of acute tolerance. Overall, stable interaction between the receptor and Gβγ complex is required for the formation of a complex with β-arrestin, and determines the potential of a particular GPCR to undergo acute tolerance. Rather than turning off the signal, β-arrestins seem to contribute on continuous signaling when they are in the context of complex with receptor and Gβγ.

Lack of association of DRD3 and CNR1 polymorphisms with premenstrual dysphoric disorders

Premenstrual dysphoric disorder [PMDD] is a mood disorder characterized with physical and affective symptoms during the luteal phase of susceptible women. The aim of this study was to investigate the association of Dopamine D3 receptor [DRD3] polymorphism, and Cannabinoid receptor Type 1 [CNR1] polymorphism with PMDD. Fifty one participants with documented PMDD according to the DSM IV criteria and 51 healthy controls were included in this cross sectional study. Symptom severity was measured with daily self-rating, monthly premenstrual assessment forms and psychiatric interviews. The genotyping of DRD3 receptor and Cannabinoid type 1 receptors were performed using Taqmanfluorogenic assay method. Distribution of DRD3 and CNR1 polymorphism was not different between patients and controls. These findings do not support a major role of DRD3, and CNR1 polymorphisms in contributing to susceptibility to premenstrual dysphoric disorder

Association between Tourette syndrome and the dopamine D3 receptor gene rs6280 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Tourette syndrome (TS) is a complex, heterozygous genetic disorder. The number of molecular genetic studies have investigated several candidate genes, particularly those implicated in the dopamine system. The dopamine D3 receptor (DRD3) gene has been considered as a candidate gene in TS. There was not any report about the association study of TS and DRD3 gene in Han Chinese population. We combined a case-control genetic association analysis and nuclear pedigrees transmission disequilibrium test (TDT) analysis to investigate the association between DRD3 gene rs6280 single nucleotide polymorphisms (SNPs) and TS in a Han Chinese population.</p><p><b>METHODS</b>A total of 160 TS patients was diagnosed by the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The DRD3 gene rs6280 SNPs were genotyped by TaqMan SNP genotyping assay technique in all subjects. We used a case-control genetic association analysis to compare the difference in genotype and allele frequencies between 160 TS patients and 90 healthy controls. At the same time, we used TDT analysis to identify the DRD3 gene rs6280 transmission disequilibrium among 101 nuclear pedigrees.</p><p><b>RESULTS</b>The genotype and allele frequency of DRD3 gene rs6280 SNPs had no statistical difference between control group (90) and TS group (160) (χ2 = 3.647, P = 0.161; χ2 = 0.643, P = 0.423) using Chi-squared test. At the basis of the 101 nuclear pedigrees, TDT analysis showed no transmission disequilibrium of DRD3 gene rs6280 SNPs (χ2 = 0; P = 1).</p><p><b>CONCLUSIONS</b>Our findings provide no evidence for an association between DRD3 gene rs6280 and TS in the Han Chinese population.</p>

Association Study between Treatment Response of Amisulpride and Dopamine D3 Receptor Gene Polymorphisms

OBJECTIVES: The aim of this study is to evaluate the association between rs6280 and rs905568 genetic polymorphism of DRD3 gene and the treatment response of amisulpride. METHODS: After six weeks treatment of amisulpride, 125 schizophrenia patients were interviewed based on the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression-Severity (CGI-S). The genotyping for rs6280 and rs905568 was performed using TaqMan single nucleotide polymorphism (SNP) genotyping assay. RESULTS: There was no significant difference in the frequency of genotype and allele of rs6280 between the responders and non-responders based on the total, positive, and general score of PANSS and CGI-S score. However, there was a significant association between this SNP and treatment response in the negative score of PANSS (chi2 = 5.23, p = 0.022). There was no significant association between rs905568 and the response in positive, negative, general, and total PANSS score and CGI-S score. CONCLUSIONS: This is the first positive association study between DRD3 gene and the treatment response of negative symptoms to amisulpride in Korean schizophrenia patients. A larger scale research on more SNP of the DRD3 gene will make a progress in the study of pharmacogenetics on the treatment response of the amisulpride.

Genetic association analysis of dopamine DRD3 Ser9Gly polymorphism and schizophrenia in Malay population

Molecular components of the dopamine receptor [DRD3] play an important role in the pathophysiology of schizophrenia [SCZ]. Previous studies have demonstrated an association between the DRD3 Ser9Gly polymorphism and SCZ but the results have been inconclusive. In this study, we investigated this controversial association between the Ser9Gly [A/G] polymorphism and SCZ using Malay cases-control [261 cases/157 controls] samples. PCR-RFLP was performed to genotype the distribution of the DRD3 Ser9Gly polymorphism. Both healthy control and SCHZ patient groups were in of Hardy-Weinberg equilibrium for the analyzed genetic variability. There was a significant association between the genotype distribution DRD3 polymorphisms and SCZ [chi[2]= 9.359; df= 2; P= 0.009]. We believe that further studies are required to examine the association between others dopamine-related genes and the behavioral phenotypes of SCZ

DRD1-DRD5 expression profiles in arthritis rheumatoid patients using real time PCR

The cause of rheumatoid arthritis [RA] as a chronic inflammatory autoimmune disease is still unknown. It appears that both genetic and environmental factors play a role in its pathogenesis. Recent studies reveal that in addition to the CNS, immune cells synthesis neurotransmitters so that these catecholamines can regulate immune functions. The aim of this study is to evaluate the dopamine receptor gene expression profiles on peripheral blood mononuclear cells of rheumatoid arthritis patients in comparison with normal individuals. In the present study, we investigated dopamine receptor gene expression in PBMCs of 40 RA patients and 40 healthy individuals using Real Time-PCR. The specificities of the obtained Real time PCR products for the respective dopamine receptors fragments were confirmed by sequenced analysis capillary system. We found that DRD1-DRD5 types of dopamine receptors genes expression profiles of rheumatoid arthritis patients differ compared to healthy individuals. Moreover, a significant difference of DR2 and DR4 gene expression was seen in rheumatoid arthritis patients. This study showed that some types of dopamine receptors genes expression profiles alter in rheumatoid arthritis patients with comparison to healthy individuals Moreover, this alteration possibly could result in dysfunction of dopaminergic system in immune cells and finally lead to rheumatoid arthritis

Association of 14 polymorphisms in the five candidate genes and attention deficit hyperactivity disorder / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Attention deficit hyperactivity disorder (ADHD) is one of the most common behavior disorders in childhood and adolescent. The etiology of ADHD is unknown. The aim of this study was to investigate the relationship between each of the 14 polymorphisms in the five candidate genes and ADHD, and between the combination of some polymorphisms in those genes and ADHD, in attempting to examine whether combinations of genotypes would confer a significant susceptibility to ADHD.</p><p><b>METHODS</b>One hundred and thirty-nine children with ADHD and one hundred and nineteen normal children were enrolled. Eight single nucleotide polymorphisms (SNP) of three candidate genes were examined with PCR and RFLP techniques. 48 bp VNTR in DRD4 gene was examined with PCR, nondenaturing polyacrylamide gel electrophoresis and silver staining. Five microsatellites (MS) of three candidate genes were examined with genotyping. The relationship between the combinations of 12 polymorphisms and ADHD was examined with logistic regression analysis.</p><p><b>RESULTS</b>1.The frequency of 1065T/1065T genotype and the 1065T allele were significantly higher in ADHD children than that in normal controls (P<0.05). The frequency of -48G/-48G genotype of the A-48G polymorphism of DRD1 gene was significantly lower in ADHD children than that in normal controls (P<0.05). 2. A specific combination of three polymorphisms in the two genes showing an association with ADHD gave a prediction level of 77.5%.</p><p><b>CONCLUSIONS</b>The T1065G polymorphism in the SNAP-25 may be associated with ADHD. The 1065T/1065T genotype and the 1065T allele may be a risk factor for ADHD. The A-48G polymorphism of DRDI may be associated with ADHD. The -48G/-48G genotype may be a protective factor for ADHD. The specific combination of three sites of SNP in SNAP-25 gene and DRDI gene is found and shows an association with ADHD in 12 polymorphisms of the five candidate genes on glutamatergic/dopaminergic pathway.</p>

The role of dopamine D3 receptor in the amphetamine-induced conditioned place preference in mice / 法医学杂志

OBJECTIVE@#To study the role of dopamine D3 receptor involved in the amphetamine-induced conditioned place preference (CPP) in mice.@*METHODS@#The CPP was observed in D3 receptor knock-out (D3RKO) mice and C57BL/6 wild-type control mice after administration of amphetamine. The data were analyzed with a two-way ANOVA using the SPSS 13.0 software.@*RESULTS@#D3RKO mice showed a significant amphetamine-induced CPP (P<0.001), compared with the ones administered with saline in C57BL/6 control mice.@*CONCLUSION@#The results indicate that amphetamine can produce significant CPP in dopamine D3 receptor knock-out mice, suggesting that amphetamine-induced addiction can be inhibited by dopamine D3 receptor.

new scaffold for D[3] dopaminergic affinity containing arylpiperazine - fragment: molecular modeling, synthesis, in vitro and in vivo pharmacological evaluation

A new series of N-[6-substitutedbenzo[d]thiazol-2-yl]-2-[4-arylpiperazin-1-yl] acetamides [3a-f] and 2-[3-[4-arylpiprazin-l-yl]propylthio]benzo[d]thiazoles/-oxazoles/-imidazole [6a-f] was synthesized by connecting arylpiperazine through a semi-rigid or flexible spacer to a heterocyclic moiety, respectively. The radioligand binding experiments for the D[1], D[2], D[3] and D[5] subtypes expressed in CHO cells were examined for the target compounds 3a-f, 6a, 6b, 6d and 6f, Compound 6a showed the best binding affinity for dopamine D[3] receptor and is considered as a new scaffold for D[3] dopaminergic affinity. Furthermore, molecular modeling of the best-fitted conformer of target compounds 3a, 6b, 6c, 6d and 6f to alph[1]-adrenoceptor [alph [1]-AR] antagonist hypothesis was performed, using CATALYST software, HipHop modules. Based on the results of simulation studies, these target compounds were evaluated for their in vivo hypotensive activity on blood pressure of normotensive cats

Mediating effect of dopamine D3 receptors on Jak2 and GABAAalpha1 expression in mouse brains induced by cocaine / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cocaine addiction may involve complex neuroadaptations, including many changes of genes expression. Dopamine D3 receptors play an important role in cocaine addiction; however, its role in cocaine induced gene expression change is poorly understood. To identify the changes in gene expression induced by repeated cocaine exposure through D3 dopamine receptors, we compared the expression of four molecules: Janus kinase 2 (Jak2), g-aminobutanoic acid receptor subunit alpha 1 (GABAAalpha1), glutamate receptor AMPA3 alpha 3 (GluR 3) and stromal cell derived factor 1 (SDF1). These four have been implicated in mediating the actions of cocaine in the nucleus accumbens (NAc) and caudoputamen (CPu) in mice after acute and repeated cocaine exposure.</p><p><b>METHODS</b>For the acute and repeated injections, the mice were divided into four groups: 30 mg/kg cocaine, nafadotride 0.5 mg/kg + cocaine 30 mg/kg, nafadotride 0.5 mg/kg, and saline as the basal group. The expression of Jak2, GABAAalpha1, GluR 3 and SDF1 were assayed by Western blot, quantitative real-time RT-PCR and immunohistochemistry.</p><p><b>RESULTS</b>Twenty-four hours after seven consecutive days of repeated cocaine exposure, the expression of GABAAalpha1 decreased in cocaine group compared with basal line and further decreased in the cocaine + nafadotride group and remained at basal level in the nafadotride group. Similarly, the Jak2 expression decreased in cocaine group compared with base line. However, the levels of Jak2 increased in cocaine + nafadotride group compared with cocaine group, while remained at basal level in nafadotride group.</p><p><b>CONCLUSIONS</b>GABAAalpha1 and Jak2 may be involved in chronic cocaine induced neuroadaptations. D3 dopamine receptors play an important role in the expression of these genes.</p>

Dopamine receptors oppositely regulate cocaine-induced transcription factor CREB activation / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the role of dopamine receptors in the regulation of the activity of transcription factor cAMP response element-binding protein (CREB) after cocaine treatment.</p><p><b>METHODS</b>By using dopamine receptor antagonists SCH23390 and nafadotride, the activation of CREB by D1 and D3 dopamine receptors after cocaine treatment and role of extracellular signal-regulated kinase (ERK) in cocaine-induced CREB activation were examined by Western blotting, which was also employed for determination of the effect of SCH23390 and nafadotride on CREB activation.</p><p><b>RESULTS</b>D1 receptor antagonist could inhibit cocaine-induced CREB activation, while D3 receptor antagonist enhanced cocaine-induced CREB activation. Dopamine receptor antagonists SCH23390 and nafadotride did not induce CREB activation. SL327, a MEK inhibitor, inhibited cocaine-induced CREB activation.</p><p><b>CONCLUSION</b>D1 and D3 dopamine receptors can oppositely regulate CREB activation after cocaine treatment and this regulation depends on ERK signaling pathway.</p>

Hypertension in D3 dopamine receptor deficient mice / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the mechanisms by which hypertension occurs in D(3) dopamine receptor null mice (D(3)-/-).</p><p><b>METHODS</b>Several parameters, including blood pressure, renal sodium excretion, D(3) receptor protein and mRNA expression, plasma renin activity, norepinephrine concentration and AT(1) receptor expression were checked in D(3)-/- mice and their littermate wild type mice (D(3)+/+). Moreover, the vasorelaxant effect of D(3) receptor stimulation was measured with ex-vivo mesenteric artery isolated from Wistar-Kyoto rats.</p><p><b>RESULTS</b>Blood pressure was higher in D(3)-/- mice compared with that in D(3)+/+ mice, salt-loading had no effect on blood pressure in both groups, at the last period, sodium excretion was lower in D(3)-/- mice as compared with D(3)+/+ mice, renal renin activity and AT(1) receptor expression were higher in D(3) -/- [corrected] mice than in D(3) +/+ [corrected] mice. In contrast, no difference of renal norepinephrine was found in two groups. When using angiotensin II subtype-1 receptor antagonist, the systolic blood pressure declined for a longer duration in mutant mice than in wild-type mice. Vaso-relaxation was found in ex-vivo isolated mesenteric artery when D(3) receptor was stimulated.</p><p><b>CONCLUSIONS</b>Elevation of blood pressure in D(3)-/- mice might be related with impaired renal sodium excretion and vaso-relaxation in resistance artery.</p>

Pharmacogenetic assessment of antipsychotic-induced tardive dyskinesia: contribution of 5-hydroxytryptamine 2C receptor gene and of a combination of dopamine D3 variant allele (Gly) and MnSOD wild allele (Val) / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To further investigate whether the functional polymorphisms of dopamine D2 receptor (DRD2) and dopamine D3 receptor (DRD3) genes associate with the development of tardive dyskinesia (TD) in schizophrenia, and whether the interactive effects of DRD2, DRD3, 5-hydroxytryptamine 2C receptor (HTR2C) and manganese superoxide dismutase (MnSOD) genes contribute to the severity of TD.</p><p><b>METHODS</b>The patients with schizophrenia were assessed for TD by the Abnormal Involuntary Movement Scale (AIMS). Eventually, 42 schizophrenics with persistent TD were in the TD group, and 59 schizophrenics without TD were in the non-TD group. The polymorphism of each candidate gene was analyzed using a polymerase chain reaction-based restriction fragment length polymorphism analysis.</p><p><b>RESULTS</b>The genotype distributions of the candidate genes in the groups were all consistent with the Hardy-Weinberg equilibrium. Allele frequencies for -759C/T and -697G/C polymorphisms in HTR2C gene showed a significant excess of -697 variant (P<0.05) in the patients with TD, compared against those in patients without TD. There were no differences in the distributions of the allelic frequencies and genotypes of Taq I. A polymorphism in DRD2 gene, of Ser/Gly polymorphism in DRD3 gene, and of Ala-9Val polymorphism in MnSOD gene between the TD group and non-TD group (P>0.05). Interestingly, as compared with the other joint allelic types, a significant excess of carrying both DRD3 variant allele (Gly) and MnSOD wild allele (Val) was found in the TD group (P<0.05). However, neither the allele and genotypes nor the clinical demographic characteristics contributed to the higher total AIMS scores in the patients of the TD group. There were no significant differences in any of the clinical demographic characteristics between the subgroups of any genotype in TD and non-TD groups.</p><p><b>CONCLUSION</b>The excess of -697 variant in the promoter regulation region of the HTR2C gene may be a risk factor for the susceptibility to the occurrence of TD in Chinese male patients with schizophrenia. A combination of DRD3 variant allele (Gly) and MnSOD wild allele (Val) may increase the susceptibility to the development of TD.</p>

The Association between Polymorphism of the Dopamine D3 Receptors and Concentrations of Plasma Homovanillic and 5-hydroxyindoleacetic Acid, and Therapeutic Response of chronic Schizophrenic Patients

OBJECTIVES: Schizophrenia manifests a variety of interindividual differences in therapeutic response to antipsychotics. This might be attributable to dopamine and serotonin receptors that a important target for various antipsychotics, and the D3 receptor(DRD3) alleles they carry. The purpose of our study was to investigate whether the plasma levels of homovanillic acid(HVA) and 5-hydroxyindoleacetic acid(HIAA), and the polymorphism of DRD3 can be held as a predictor of treatment response ni chronic schizophrenic patients. METHODS: Therapeutic response for 16 korean schizophrenia patient treated during 48 weeks were assessed by PANSS used as the clinical symptom rating scales. The levels of concentration of HVA and 5-HIAA were examined by HPLC at baseline and at 48 weeks. We classified the polymorphism of DRD3 receptor using amplifying by polymerase chain reaction(PCR). RESULTS: Neither concentrations of HVA and 5-HIAA nor genotype of dopamine 3 receptor were not significantly associated with the therapeutic response. But, the patients who has A1 alleles of DRD3 gene showed poor therapeutic responses. CONCLUSION: A1 allele of DRD3 gene is associated with poor prognosis of chronic schizophrenia.

D3 Receptor Gene Variant and Tardive Dyskinesia in Schizophrenic Patients / 신경정신의학

Tardive dyskinesia(TD)is one of the serious side effects caused by long-term treatment with neuroleptic medication. It has been known that dopamine D3 receptors are mainly located on the postsynaptic membrane where they display an inhibitory action on locomotor activity. In this study, we investigated the genetic variation of the dopamine D3 receptor gene(DRD3)as a putative risk factor for TD in schizophrenic patients receiving long-term antipsychotic medication. Fifty schizophrenic patients previously treated neuroleptic medication, were assessed for TD severity using Extrapyramidal Symptom Rating Scale(ESRS) Genomic DNA was amplified by PCR and Digestion with MluI yield two bands of 111bp and 47bp in all subjects. Subjects with a 304bp band were classified a1a1, those with 206bp and 98bp bands a2a2, and those with all five bands a1a2. The allelic distributions in TD patients and non-TD patients were not significantly different(x2=.852, df=2, p=.653) The number of each genotype observed in the schizophrenic group, did not differ significantly from the values expected according to Hardy-Weinberg equilibrium(x2=.29, df=2) This result did not support that dopamine D3 receptor gene variant were susceptible to TD in schizophrenic patients. The role of dopamine D3 receptors as a putative risk factors of TD may therefore be less important than previously thought.