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.

Effects of septal nucleus lesion on dopamine D_2 receptor expression in the prefrontal lobe, striatum, and brainstem in a rat model of schizophrenia

BACKGROUND： It has been demonstrated that the septal nucleus is involved in the pathogenesis of schizophrenia. Based on autopsies of schizophrenia patients, studies have shown a reduced number of septal nucleus neurons and glia. In addition, experimental rat models of schizophrenia have shown increased dopamine receptor D2 binding sites in the basal ganglia, septal nuclei, and substantia nigra. Previous studies have demonstrated that the septal nucleus modulates dopamine metabolic disorder and dopamine D2 receptor balance. OBJECTIVE： Dopamine D2 receptor expression in a rat model of schizophrenia, combined with antipsychotic drugs, was analyzed in the prefrontal lobe, striatum, and brainstem. In situ hybridization was used to observe the effects of stereotactic septal nucleus lesions on dopamine D2 receptor expression in the brains of methylamphetamine-treated rats. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed in the Laboratory of General Institute of Psychosurgery, Third Hospital of Chinese PLA from November 2005 to June 2006. MATERIALS： A total of 120 healthy, adult Sprague Dawley rats, weighing approximately 200 g, were included. Methylamphetamine （Sigma, USA） and an in situ hybridization detection kit for dopamine D2 receptor （Boster, China） were also used for this study. METHODS： All rats were randomly allocated to the following 4 groups, with 30 rats in each group： normal control, simple administration, septal nucleus lesion, and sham-operated groups. In the normal control group, rats were not administered or lesioned. In the remaining 3 groups, rats were intraperitoneally administered 10 mg/kg methylamphetamine, once per day, for 15 successive days to establish a schizophrenia model. Following successful model establishment, rats from the septal nucleus lesion group were subjected to stereotactic septal nucleus lesions. The cranial bone was exposed in rats from the sham-operated group, and the septal nucleus was not lesioned. MAIN OUTCOME MEASURES： At 7 days post-surgery, dopamine D2 receptor expression in the prefrontal lobe, striatum, and brainstem were detected by in situ hybridization. RESULTS： Dopamine D2 receptor expression in the rat prefrontal lobe, striatum, and brainstem was significantly higher in the simple administration group and sham-operated group, compared with the normal control group （P 〈 0.01）. In the septal nucleus lesion group, dopamine D2 receptor expression was significantly less than the simple administration and sham-operated groups, （P 〈 0.01）. There was no significant difference in dopamine D2 receptor expression between the simple administration and sham-operated groups （P 〉 0.05）. CONCLUSION： Septal nucleus lesions reduce dopamine D2 receptor expression in the prefrontal lobe, striatum, and brainstem in a rat model of schizophrenia, indicating that the septal nucleus modulates dopamine D2 receptor expression.

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^＋.

Effects of endogenous dopamine induced by low concentration atropine eye drops on choroidal neovascularization in high myopia mice

AIM:To evaluate effects of endogenous dopamine induced by low concentration atropine eye drops on choroidal neovascularization(CNV)in high myopia mice.METHODS:The C57BL/6J mice were deprived of the right eye for 4wk,and the high myopia was diagnosed by optometry,the diopter was less than-6.00 D,and CNV was induced by 532 nm laser.The changes of dopamine D1 receptor(DRD1),dopamine D2 receptor(DRD2),and vascular endothelial growth factor A(VEGFA)were detected by Western blot technology at 0.5,1,2h,and 7d after 0.01%,0.05%,and 0.1%atropine eye drops,respectively,the area of CNV was measured.RESULTS:Significant increases were observed on the expression of DRD2 in mouse high myopia model at 0.5,1,2h,7d with 0.05%and 0.1%atropine eye drops(P<0.05).Significant decreases were observed on the expression of DRD1 and VEGFA in mouse high myopia model at 0.5,1,2h,7d with 0.05%and 0.1%atropine eye drops(P<0.05).The area of CNV induced by laser in the drug-treated group was significantly smaller than that in the control group,and the higher the concentration,the more significant the inhibitory effect(P<0.05).CONCLUSION:The 0.01%,0.05%,0.1%atropine eye drops can decrease the level of VEGFA and inhibit high myopia CNV indirectly by up-regulating the level of DRD2 and down-regulating the level of DRD1,and the effect of 0.05%and 0.1%atropine eye drops is more significant.

Neuroprotective effects of tadalafil on gerbil dopaminergic neurons following cerebral ischemia

Impairment of dopamine function, which is known to have major effects on behaviors and cognition, is one of the main problems associated with cerebral ischemia. Tadalafil, a long-acting phosphodiesterase type-5 inhibitor, is known to ameliorate neurologic impairment induced by brain injury, but not in dopaminergic regions. We investigated the neuroprotective effects of treatment with tadalafil on cyclic guanosine monophosphate level and dopamine function following cerebral ischemia. Forty adult Mongolian gerbils were randomly and evenly divided into five groups （n = 8 in each group）： Sham-operation group, cerebral ischemia-induced and 0, 0.1, 1, and 10 mg/kg tadalafil-treated groups, respectively. Tadalafil dissolved in distilled water was administered orally for 7 consecutive days, starting 1 day after surgery. Cyclic guanosine monophosphate assay and immunohistochemistry were performed for thyrosine hydroxylase expression and western blot analysis for dopamine D2 receptor expression. A decrease in cyclic guanosine monophosphate level following cerebral ischemia was found with an increase in thyrosine hydroxylase activity and a decrease in dopamine D2 receptor expression in the striatum and substantia nigra region. However, treatment with tadalafil increased cyclic guanosine monophosphate expression, suppressed thyrosine hydroxylase expression and increased dopamine 92 receptor expression in the striatum and substantia nigra region in a dose-dependent manner. Tadalafil might ameliorate cerebral ischemia-induced dopaminergic neuron injury. Therefore, tadalafil has the potential as a new neuroprotective treatment strategy for cerebral ischemic injury.

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.

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.

Activation of Dopamine D2 Receptors Alleviates Neuronal Hyperexcitability in the Lateral Entorhinal Cortex via Inhibition of HCN Current in a Rat Model of Chronic Inflammatory Pain

Functional changes in synaptic transmission from the lateral entorhinal cortex to the dentate gyrus(LEC-DG)are considered responsible for the chronification of pain.However,the underlying alterations in fan cells,which are the predominant neurons in the LEC that project to the DG,remain elusive.Here,we investigated possible mechanisms using a rat model of complete Freund’s adjuvant(CFA)-induced inflammatory pain.We found a substantial increase in hyperpolarization-activated/cyclic nucleotide-gated currents(Ih),which led to the hyperexcitability of LEC fan cells of CFA slices.This phenomenon was attenuated in CFA slices by activating dopamine D2,but not D1,receptors.Chemogenetic activation of the ventral tegmental area-LEC projection had a D2 receptor-dependent analgesic effect.Intra-LEC microinjection of a D2 receptor agonist also suppressed CFA-induced behavioral hypersensitivity,and this effect was attenuated by pre-activation of the Ih.Our findings suggest that down-regulating the excitability of LEC fan cells through activation of the dopamine D2 receptor may be a strategy for treating chronic inflammatory pain.

Parkinson disease drug screening based on the interaction between D2 dopamine receptor and beta-arrestin 2 detected by capillary zone electrophoresis

Parkinson’s disease is the second most common neurodegenerative disease in the world.Beta-arrestin-2 has been reported to be an important protein involved in D2 dopamine receptor desensitization,which is essential to Parkinson’s disease.Moreover,the potential value of pharmacological inactivation of G protein-coupled receptor kinase or arrestin in the treatment of patients with Parkinson’s disease has recently been shown.We studied the interaction between D2 dopamine receptor and beta-arrestin-2 and the pharmacological regulation of chemical compounds on such interaction using capillary zone electrophoresis.The results from screening more than 40 compounds revealed three compounds that remarkably inhibit the beta-arrestin-2/D2 dopamine receptor interaction among them.These compounds are promising therapies for Parkinson’s disease,and the method used in this study has great potential for application in large-scale drug screening and evaluation.

Attenuated inhibition of medium spiny neurons participates in the pathogenesis of childhood depression

Accumulating evidence suggests that the nucleus accumbens, which is involved in mechanisms of reward and addiction, plays a role in the pathogenesis of depression and in the action of anti-depressants. In the current study, intraperitoneal injection of nomifensine, a dopamine reuptake inhibitor, decreased depression-like behaviors in the Wistar Kyoto rat model of depression in the sucrose-preference and forced swim tests. Nomifensine also reduced membrane excitability in medium spiny neurons in the core of the nucleus accumbens in the childhood Wistar Kyoto rats as evaluated by electrophysiological recording. In addition, the expression of dopamine D2-like receptor mRNA was downregulated in the nucleus accumbens, striatum and hippocampus of nomifensine-treated childhood Wistar Kyoto rats. These experimental ifndings indicate that impaired inhibition of medium spiny neurons, mediated by dopamine D2-like receptors, may be involved in the formation of depression-like behavior in childhood Wistar Kyoto rats, and that nomifensine can alleviate depressive behaviors by reducing medium spiny neuron membrane excitability.

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.