老年大鼠血管平滑肌中多巴胺受体DA1亚型的改变

选用ｆｅｎｏｌｄｏｐａｍ作为ＤＡ１受体的特异性激动剂，利用离体血管环的方法对老年（１８月龄）大鼠与年轻大鼠（３月龄）血管平滑肌中多巴胺受体ＤＡ１亚型的差别进行了观察。结果显示，老年大鼠主动脉、肾动脉、肠系膜动脉由去甲肾上腺素引起的最大收缩反应与年轻大鼠无明显差别，但３种血管由ｆｅｎｏｌｄｏｐａｍ引起的累积浓度－舒张反应曲线均明显右移，提示老年大鼠血管平滑肌中ＤＡ１受体显著下调。

家兔肝动脉平滑肌中多巴胺受体亚型分析

选用ＦＯＤＡ和ＰＢＤＡ分别作为ＤＡ１和ＤＡ２受体的特异性激动剂；以ＳＣＨ２３３９。和ｄｏｍｐｅｒｉｄｏｎｅ分别作为ＤＡ１和ＤＡ２受体的阻断剂，利用离体血管环的方法对家兔肝动脉平滑肌中多巴胺受体的存在情况进行了观察。结果表明：多巴胺受体两亚型（ＤＡ１、ＤＡ２）均在肝动脉平滑肌中存在。

SOX2/DRD2 signaling pathway facilitates astrocytic dedifferentiation in cerebral ischemic mice

Objective:To explore the effects of dopamine receptor D2(DRD2)on astrocytic dedifferentiation based on SOX2-regulated genes in neural stem cells(NSCs)and astrocytes.Methods:Immunofluorescence staining and SOX2-GFP mice were used to examine the lineage differentiation of SOX2-positive cells during the development of cerebral cortex.Primary NSCs/astrocytes culture,ChIP-seq and Western Blot were adopted to analyze and verify the expression of candidate genes.Pharmacological manipulation,neurosphere formation,photochemical ischemia,immunofluorescence staining and behavior tests were adopted to evaluate the effects of activating DRD2 signaling on astrocytic dedifferentiation.Results:Immunofluorescence staining demonstrated the NSC-astrocyte switch of SOX2-expression in the normal development of cerebral cortex.ChIP-seq revealed enrichment of DRD2 signaling by SOX2-bound enhancers in NSCs and SOX2-bound promoters in astrocytes.Western Blot and immunofluorescence staining verified the expression of DRD2 in NSCs and reactive astrocytes.Application of quinagolide hydrocholoride(QH),an agonist of DRD2,significantly promoted astrocytic dedifferentiation both in vitro and in vivo following ischemia.In addition,quinagolide hydrocholoride treatment improved locomotion recovery.Conclusion:Activating DRD2 signaling facilitates astrocytic dedifferentiation and may be used to treat ischemic stroke.

Modeling of Dopamine D2 Receptor and its Agonist DOCK Analyses

A model of transmembrane helices of dopamine D2 receptor was constructed using the X ray coordinates of bacteriorhodopsin (BR) as a template. Based on the results from the model and the site directed mutagenesis experience, the binding pocket, including nine amino acid residues beside indispensable Asp86, Ser141 and Ser144 residues, was defined. In order to testify the 3D structure of dopamine D2 receptor and specially test the binding sites, two sets of D2 receptor agonists (one was rigid and the other flexible) were selected for docking. A good result of correlation between logIC 50 and binding energy E b indicates that the predicted model is reliable for the investigation of the receptor ligand interaction and design of new active molecules.

PSD-95 regulates D1 dopamine receptor resensitization, but not receptor-mediated Gs-protein activation

The present study aims to define the role of postsynaptic density （PSD）-95 in the regulation of dopamine （DA） receptor function. We found that PSD-95 physically associates with either D1 or D2 DA receptors in co-transfected HEK-293 cells. Stimulation of DA receptors altered the association between D1 receptor and PSD-95 in a time-depen- dent manner. Functional assays indicated that PSD-95 co-expression did not affect DI receptor-stimulated cAMP pro- duction, Gs-protein activation or receptor desensitization. However, PSD-95 accelerated the recovery of internalized membrane receptors by promoting receptor recycling, thus resulting in enhanced resensitization of internalized D1 receptors. Our results provide a novel mechanism for regulating DA receptor recycling that may play an important role in postsynaptic DA functional modulation and synaptic neuroplasticity.

Effect of total isoflavones from pueraria lobata on the expressions of preproenkephalin, prodynorphin and D2 dopamine receptor mRNA in PC12 cells induced by MPP^+

Objective： The aim of the study was to observe the effect of total isoflavones from pueraria Iobata （TIP） on D2 dopamine receptor mRNA, preproenkephalin mRNA and prodynorphin mRNA expressions in Parkinson＇s disease （PD） model cells induced by 1-methyl-4-phenylpyridinium ion （MPP^＋）. Methods： TIP was dissolved in 0.1 M NaOH and added to the culture medium at a final concentrations of 50 mg/L, 100 mg/L and 200 mg/L. Some cells （control） were exposed to 0.001 M NaOH. TIP was added to PC12 cells 30 min prior to the administration of MPP^＋. TIP and MPP^＋ remained in the culture medium for 96 h. D2 dopamine receptor mRNA, preproenkephalin mRNA and prodynorphin mRNA expressions were assayed by real-time quantitative reverse transcription-PCR. Results： The D2 dopamine receptor mRNA and preproenkephalin mRNA expressions were up-regulated in MPP^＋ group compared with the control group, and prodynorphin mRNA expression was down-regulated in that. The D2 dopamine receptor mRNA expression being down-regulated and prodynorphin mRNA expression being up-regulated in TIP group compared with the MPP^＋ group. And there was no effect of TIP on preproenkephalin gene expression in PC12 cells induced by MPP^＋. Conclusion： The results suggest that TIP down-regulates the D2 dopamine receptor mRNA expression, up-regulates prodynorphin mRNA expression and not affects preproenkephalin gene expression in PC12 cells induced by MPP^＋.

Differential distributions and trafficking properties of dopamine D1 and D5 receptors in nerve cells

Objective To explore the possible differential trafficking properties of the dopamine D 1-like receptor subtypes, D 1 receptor and D5 receptor. Methods To visualize distributions of dopamine D 1-like receptor subtypes at subcellular level, the yellow and cyan variants of green fluorescent protein （GFP） were used to tag D1 and D5 receptors. After transfection with the tagged dopamine receptors, the neuroblastoma cells NG108-15 were treated with D1 agonist SKF38393 or acetylcholine （ACh）. Then we observed the subcellular distributions of the tagged receptors under the confocal microscopy and tried to determine trafficking properties by comparing their distribution patterns before and after the drug treatment. Results In resting conditions, D 1 receptors located in the plasma membrane of NG108-15 cells, while D5 receptors located in both plasma membrane and cytosol. With the pre-treatment of SKF38393, the subcellular distribution of D1 receptors was changed. The yellow particle-like fluorescence of tagged D 1 receptors appeared in the cytosol, indicating that D 1 receptors were internalized into cytosol from the cell surface. Same situation also occurred in ACh pre-treatment. In contrast, the subcellular distribution of D5 receptors was not changed after SKF38393 or ACh treatment, indicating that D5R was not translocated to cell surface. Interestingly, when D1 and D5 receptors were co-expressed in the same cell, both kept their distinct subcellular distribution patterns and the trafficking properties. Conclusion Our present study reveals that in NG108-15 nerve cells, dopamine D1 and D5 receptors exhibit differential subcellular distribution patterns, and only D1 receptor has a marked trafficking response to the drug stimulation. We further discuss the potential role of the differential trafficking properties of D1-like receptors in complex modulation of DA signaling.

Comparison of dopamine with levodopa in the induction of aryl sulfotransferases and estrogen sulfotransferase in rat liver

Sulfotransferases（SULTs） are one of the most important phase II drug-metabolizing enzymes. Among them, aryl sulfotransferases（SULT1A1） and estrogen sulfotransferase（EST, SULT1E1） belong to the rSULT1 family that catalyzes sulfation of phenolic compounds. Dopamine（DA） acts as a vital neurotransmitter in central nervous system（CNS） and regulates a variety of activities in periphery. In our study, we aim to detect the effects of exogenous DA and levodopa（L-DOPA） on rSULTs（rSULT1A1 and rSULT1E1） in rat liver. In order to achieve this target, varying doses of DA（0, 2, 10 and 100 mg/kg/d） and L-DOPA（0, 5, 25 and 125 mg/kg/d） were provided to male and female rats, respectively. Real-time PCR assay and western blot were used in the determination of the mRNA and protein expression of rSULTs. PNPS assay and radioactivity assay were applied to the detection of enzyme activity of rSULT1A1 and rSULT1E1, respectively. Our results showed that DA induced the expression and activity of rSULT1A1 in the liver of male and female rats and DA had little effect on rSULT1E1. However, L-DOPA caused no evident change of rSULT1A1 in both sex and had no significant effect on rSULT1E1 in female rat liver, but increased rSULT1E1 expression and activity only in male rat liver when administered at high dose. Our results suggest that DA plays different roles in the regulation of rSULT1A1 and rSULT1E1 when it is in periphery or in the CNS.

Dopamine receptor D2 polymorphism is associated with alleviation of obesity after 8-year follow-up: a retrospective cohort study in obese Chinese children and adolescents

Objective： The aim of this study was to explore the association of dopamine receptor D2 （DRD2） polymorphism and alleviation of obesity in children and adolescents after 8-year follow-up. Methods： This retrospective cohort study included obese children and adolescents with a follow-up period of 8 years. Baseline clinical character- istics and DRD2 polymorphisms （including rs1076562, rs2075654, and rs4586205） were extracted from medical records. A follow-up visit was performed in May 2017 to collect related data including height, weight, diet compliance, and exercise compliance. Results： One hundred and nine obese children and adolescents were included in the current study. Among three DRD2 single nucleotide polymorphisms, only rs2075654 had a statistically significant association with alleviation of obesity, as the alleviation rate for minor allele carders （68.6% for TC＋TT） was higher compared to the major allele homozygote （43.3% for CC）. After adjusting for all related factors, the hazard ratio of rs2075654 minor allele carders for the alleviation of obesity was 3.34 （95% confidence interval （CI）： 1.30-8.58）. Conclusions： The rs2075654 ~olvmomhism of DRD2 is related to Ionq-term obesity alleviation in obese Chinese children and adolescents.

Compound C17 inhibits the lung metastasis of breast cancer

Breast cancer is the most common cancer in females with extremely high lethality mainly due to the occurrence of metastasis,which is closely related to cancer stem-like cells(CSCs).It has been reported that CSC frequency in drug-resistant breast cancer and non-small cell lung cancer is reduced by activating dopamine D1 receptor(D1 DR).In the present study,we aimed to investigate the effect of a compound C17 that can be used orally for breast cancer metastasis as well as the underlying mechanism involving the activation of D1 DR.The confocal immunofluorescence analysis demonstrated that D1 DR was up-regulated by C17.The cell survival and colony formation were inhibited by C17 through the detection by Sulforhodamine B colorimetric(SRB)assay and colony formation assay,respectively.Results from both wound healing assay and transwell assay demonstrated that C17 inhibited the migration of 4T1 cells.Flow cytometry analysis indicated that C17 significantly reduced the CSC frequency.In addition,C17 could inhibit the lung metastasis in 4T1 orthotopic mouse model of breast cancer without obvious toxicity,and it could up-regulate the expression of intratumoral E-cadherin and down-regulate the expressions of Snail and N-cadherin in primary breast tumor,which might be related to the activation of D1 DR.Our findings provided a potential candidate compound for the treatment of metastatic breast cancer with good compliance and safety.

Paired related homeobox 1 transactivates dopamine D2 receptor to maintain propagation and tumorigenicity of glioma-initiating cells

GUoblastoma multiforme （GBM） is a highly invasive brain tumor with limited therapeutic means and poor prognosis. Recent stud- ies indicate that glioma-initiating ceUs/gUoma stem ceils （GICs/GSCs） may be responsible for tumor initiation, infiltration, and recurrence. GICs could aberrantly employ molecular machinery balancing self-renewal and differentiation of embryonic neural precursors. Here, we find that paired related homeobox 1 （PRRX1）, a homeodomain transcription factor that was previously reported to control skeletal development, is expressed in cortical neural progenitors and is required for their self-renewal and proper differentiation. Further, PRRX1 is overrepresented in gUoma samples and labels GlCs. Gtioma celts and GlCs depleted with PRRX1 could not propagate in vitro or form tumors in the xenograft mouse model. The GIC self-renewal function regulated by PRRX1 is mediated by dopamine D2 receptor （DRD2）. PRRX1 directly binds to the DRD2 promoter and transactivates its expression in GICs. Blockage of the DRD2 signaling hampers GIC self-renewal, whereas its overexpression restores the propagating and tumorigenic potential of PRRXl-depleted GlCs. Finally, PRRX1 potentiates GICs via DRD2-mediated extracetlutar signal-related kinase （ERK） and AKT activation. Thus, our study suggests that therapeutic targeting the PRRX1-DRD2-ERK/AKT axis in GICs is a promising strategy for treating GBMs.

L-theanine inhibits nicotine-induced dependence via regulation of the nicotine acetylcholine receptor-dopamine reward pathway

In this study, the inhibitory effect of L-theanine, an amino acid derivative of tea, on the rewarding effects of nicotine and its underlying mechanisms of action were studied. We found that L-theanine inhibited the rewarding effects of nicotine in a con- ditioned place preference （CPP） model of the mouse and reduced the excitatory status induced by nicotine in SH-SY5Y cells to the same extent as the nicotine receptor inhibitor dihydro-beta-erythroidine （DHI3E）. Further studies using high performance liquid chromatography, western blotting and immunofluorescence staining analyses showed that L-theanine significantly in- hibited nicotine-induced tyrosine hydroxylase （TH） expression and dopamine production in the midbrain of mice. L-theanine treatment also reduced the upregulation of the ~4,132 and c^7 nicotine acetylcholine receptor （nAChR） subunits induced by nico- tine in mouse brain regions that related to the dopamine reward pathway, thus decreasing the number of cells that could react to nicotine. In addition, L-theanine treatment inhibited nicotine-induced c-Fos expression in the reward circuit related areas of the mouse brain. Knockdown of c-Fos by siRNA inhibited the excitatory status of cells but not the upregulation of TH induced by nicotine in SH-SY5Y cells. Overall, the present study showed that L-theanine reduced the nicotine-induced reward effects via inhibition of the nAChR-dopamine reward pathway. These results may offer new therapeutic strategies for treatment of to- bacco addiction.

Pharmacodynamic model of dopamine D1 receptor agonists in the treatment of breast cancer lung metastasis

Previous study has shown that dopamine D1 receptor(D1DR)agonists,fenoldopam(FEN)and l-stepholidine(l-SPD),have inhibitory effects on breast cancer lung metastasis.To quantitatively describe and predict the pharmacodynamic(PD)properties of FEN and l-SPD and to explore the PD model structure of cancer metastasis treating drugs,we used the data of lung metastasis in 4T1 breast cancer mice under the treatment of either FEN or l-SPD,and established a PD model.The PD model assumed an exponential growth for both primary tumor and metastasis.The primary tumor emitted cells to form metastases,and the cell emitting rate was proportional to power form of the primary tumor weight.The total number of lung metastasis was set as the target value.D1DR agonists inhibited metastasis by inhibiting cell emitting rate instead of the growth rate of primary tumor or metastasis.The model results showed that the decrease in the number of lung metastases was roughly proportional to the square of the drug dose.The values of PD coefficient reflected the inhibitory ability of the drugs,and that of l-SPD(0.274 kg/mg)was greater than that of FEN(0.0393 kg/mg).This PD model can quantitatively describe the effects of FEN and l-SPD on the progression of lung metastasis in 4T1 primary breast cancer mice and can predict the time course of drug efficacy at multiple doses,providing a reference for PD model structure of other drugs for cancer metastasis indication.

QAP21 reduces stemness and mobility of metastatic breast cancer cells involving D1DR activation

Breast cancer is the second leading cause of cancer death in women mainly due to metastasis,which is closely related to cancer stemness.Evidence has shown that cancer stem-like cells(CSCs),which are responsible for cancer stemness,can be decreased by activating dopamine D1 receptor(D1 DR).In the present study,we aimed to explore the pharmacological effects as well as the underlying mechanisms of QAP21,a newly synthesized compound that can be orally administered,in metastatic breast cancer cells.Our results showed that QAP21 dose-dependently inhibited the ability of colony formation in 4 T1 and MDA-MB-231 cells.Cell mobility,including cell migration and invasion,was also remarkably inhibited.Besides,QAP21 significantly inhibited mammosphere formation and decreased CSC proportion,indicating reduced cancer stemness.We further verified that the nuclear factor-kappa B(NF-κB)/Akt/epithelial-mesenchymal transition(EMT)pathway was markedly impacted by QAP21 treatment.Moreover,QAP21 up-regulated the expressions of D1 DR and its second messengers,including cAMP and cGMP,which can be increased when D1 DR is activated.SCH 23390,a specific D1 DR antagonist,partially or completely reversed the above-mentioned effects of QAP21,indicating that D1 DR activation might be involved in the underlying mechanism of QAP21.In summary,QAP21 effectively reduced breast cancer stemness and cell mobility,indicating its potential use for metastatic breast cancer therapy.

Dopaminergic system does not play a major role in the precipitated cannabinoid withdrawal syndrome

AIM:To determine the dopaminergic system involvement in precipitated cannabinoid withdrawal syndrome.METHODS:The dopamine D_(1)receptor antagonist SCH23390 or the dopamine D_(2)receptor antagonist sulphide was administered to rats chronically treated with either△^(9)-tetrahydrocannabinol(THC)or vehicle.Subjects were then injected with either SR141716A or vehicle and behavior was observed for 1 h.RESULTS:Administration of the cannabinoid receptor antagonist SR141716A to animals chronically treated with THC as described by Tsou et al(1995)produced a profound withdrawal syndrome.Treatment with dopamine antagonists did not attenuate cannabinoid precipitated withdrawal syndrome in THC tolerant animals while the agonists increased the syndrome.CONCLUSION:It is unlikely that the dopaminergic system plays a major role in mediating the behavioral aspects of the cannabinoid withdrawal syndrome.

Is there evidence of selection in the dopamine receptor D4 gene in Australian invasive starling populations？

Although population genetic theory is largely based on the premise that loci under study are selectively neutral, it has been acknowledged that the study of DNA sequence data under the influence of selection can be useful. In some circumstances, these loci show increased population differentiation and gene diversity. Highly polymorphic loci may be especially useful when studying populations having low levels of diversity overall, such as is often the case with threatened or newly established inva- sive populations. Using common starlings Sturnus vulgaris sampled from invasive Australian populations, we investigated se- quence data of the dopamine receptor D4 gene （DRD4）, a locus suspected to be under selection for novelty-seeking behaviour in a range of taxa including humans and passerine birds. We hypothesised that such behaviour may be advantageous when species encounter novel environments, such as during invasion. In addition to analyses to detect the presence of selection, we also esti- mated population differentiation and gene diversity using DRD4 data and compared these estimates to those from microsatellite and mitochondrial DNA sequence data, using the same individuals. We found little evidence for selection on DRD4 in starlings. However, we did find elevated levels of within-population gene diversity when compared to microsatellites and mitochondrial DNA sequence, as well as a greater degree of population differentiation. We suggest that sequence data from putatively non- neutral loci are a useful addition to studies of invasive populations, where low genetic variability is expected

Effects of Ningdong granule on DA,DRD2,and HVA in a rat model of Tourette's syndrome

OBJECTIVE:Ningdong granule is a traditional Chinese medicine preparation for the treatment of Tourette's syndrome.METHODS:Sixty-four rats were randomly assigned to a control group and three experimental groups,respectively.Rat models of Tourette's syndrome were established via intraperitoneal injection of apomorphine(Apo).The rats in the experimental groups were subsequently intragastrically injected with haloperidol at 10 mg/kg(haloperidol group),Ningdong granule at 370 mg/kg(NDG group),and normal saline(0.9%) at 10 mL/kg(Apo group),respectively.Rat behaviors were observed and recorded on a daily basis.After 12 w,all rats were sacrificed,and sera and striatal tissues were harvested.Homovanillic acid levels in sera,as well as dopamine and dopamine D2 receptor mRNA expression in the striatum,were measured to determine possible mechanisms of Ningdong granule on the dopamine system in a rat model of Tourette's syndrome.RESULTS:Following intervention,stereotype actions of the Tourette's syndrome rats were significantly inhibited in the haloperidol and NDG groups,respectively(P<0.01).Homovanillic levels were significantly greater in the haloperidol and NDG groups,respectively(P<0.05).In addition,dopamine levels were significantly less in the NDG group(P<0.01),and DRD2 mRNA expression was significantly reduced in the haloperidol and NDG groups,respectively(P<0.05).CONCLUSION:Results demonstrated that Ningdong granule effectively inhibited stereotype actions and Tourette's syndrome symptoms by promoting dopamine metabolism,reducing dopamine levels in the striatum,increasing homovanillic acid content in sera,and reducing mRNA expression of DRD2 in the striatum.