精神分裂症患者细胞色素P450 2D6酶基因多态性与利培酮治疗效应的关系

目的研究精神分裂症患者细胞色素P450 2D6酶(CYP2D6)多态性是否与利培酮治疗效应有关.方法采用阳性和阴性症状量表(PANSS)、大体评定量表(GAS)、治疗时需处理的副反应量表(TESS)以及锥体外系副反应量表(RSESE)对52例精神分裂症[PANSS基线分(105.59±17.30)分;GAS基线分(31.75±3.32)分]患者,分别在利培酮治疗前及治疗[(5±3)mg/d]第1～8周末各进行一次药物反应评定,采用聚合酶链反应技术对CYP2D6 exon Ⅰ C/T188和CYP2D6 G/A1934两个多态性位点进行检测.根据CYP2D6 exonI C/T188基因型将患者分为三组(C/C组 13例,C/T组20例,T/T组19例);采用治疗前后PANSS 30%减分率为标准 ,将52例患者分为治疗有效组和治疗无效组,比较组间药物治疗效应的差异.结果从利培酮治疗后第5周末开始,三组之间PANSS评分的差异有显著性(P<0.01);两两比较发现,C/C组PANSS分低于T/T组(P<0.01);三组之间GAS评分的差异从第6周开始出现显著性(P<0.01),其中C/C组GAS分明显高于T/T组(P<0.01).多因素方差分析显示,三组的PANSS总分 (F=2.64, P<0.01)及GAS评分(F=1.85,P<0.05)差异有非常显著性;CYP2D6 exon Ⅰ C/T188多态性基因型频率(χ2＝6.56,P<0.05)和等位基因频率(χ2＝5.03,P<0.05,相对风险＝2.54,95%可信区间＝1.40～8.32).利培酮治疗有效组与无效组之间的差异有显著性.样本中未发现CYP2D6 G/A1934多态性.结论中国人群精神分裂症CYP2D6 exon Ⅰ C/T188多态性可能是影响利培酮临床疗效的遗传易感因素.     

利培酮治疗与细胞色素P4502D6/C188T酶基因多态性的关联分析

目的　研究利培酮临床效应的个体差异与其代谢酶细胞色素P4 5 0 2D6 (cytochromeP4 5 02D6 ,CYP2D6 )酶基因多态性的相关性。方法　对 88例符合CCMD 3精神分裂症诊断标准的患者和 96例健康对照者作病例 -对照分析。精神分裂症患者给予利培酮治疗 8周 ,用阳性和阴性症状量表 (posi tiveandnegativesymptomscale ,PANSS)评分评价利培酮疗效。采用聚合酶链反应扩增及限制性片段长度多态性 (PCR RFLP)技术对CYP2D6exonⅠ的C188T位点突变进行检测 ,分析利培酮临床效应与其主要代谢酶CYP2D6 /C188T酶基因多态性的相关性。结果　中国上海地区人群的CYP2D6 /C188T突变率(弱代谢型 )为 36 .3% ,病例组和正常对照组间基因型频率总体分布比较无显著差异 (χ2 =1.15 ,df=2 ,P >0 .0 5 ) ,两组间的等位基因频率之间比较也无显著性差异 (χ2 =0 .78,df=1,P >0 .0 5 )。进行性别及有否家族史分组后分析 ,亦无差异存在 ,且CYP2D6 /C188T突变与利培酮临床效应之间并无相关性 (χ2 =1.12 ,df=2 ;χ2 =0 .0 3,df=1,P >0 .0 5 )。结论　未发现中国人CYP2D6 /C188T多态性与利培酮临床效应的个体差异有相关性。     

细胞色素P4502D6C188T基因多态性与难治性抑郁症的关联

目的:探讨细胞色素P450(CYP)2D6 C188T基因多态性与难治性抑郁症及氟西汀合并小剂量利培酮治疗的疗效、不良反应的关联.方法:应用聚合酶链反应(PCR)扩增技术及限制性片段长度多态性(RFLP)测定92例难治性抑郁症患者及107名正常对照的CYP2D6 C188T基因多态性.其中59例患者接受氟西汀合并小剂量...     

5-羟色胺2A受体基因多态性与利培酮治疗中国首发精神分裂症患者疗效关联

背景5-羟色胺2A受体基因已经证实为精神分裂症的候选易感基因,因为阐明其作为非典型抗精神病药物重要作用靶点减轻阴性症状已引起业界倍加关注.本研究试图探讨(1)5-HT2A受体基因T102C多态性在不同临床亚型之间等位基因和基因型频率的关系,(2)5-HT2A受体基因T102C在利培酮高剂量组和低剂量组之间基因型和等位基因分布频率的关系,(3)5-HT2A受体基因T102C多态性在治疗有效组与无效组之间的基因型和等位基因分布频率的关系,(4)5-羟色胺2A受体T102C基因多态性是否与中国首发精神分裂症患者利培酮疗效有关.方法对201例精神分裂症初发期患者分别进行利培酮治疗[3～5 mg/d,平均(3.2±1.3)mg/d],疗程8周.采用聚合酶链式反应扩增与限制性片段长度多态性(PCR-RFLP)技术检测5-HT2A受体基因T102C多态性.以临床亚型将精神分裂症患者划分为偏执型、瓦解型、未定型和其他型,分析不同临床亚型等位基因和基因型频率的差异;按服用利培酮剂量划分低剂量组(＜4 mg/d)和高剂量组(≥4 mg/d),经比较利培酮高剂量组和低剂量组的5-HT2A受体基因T102C基因型和等位基因分布频率差异性;同时以阴性和阳性症状量表(PANSS)总减分率＞50%有效,≤50%为无效以分析治疗有效组与无效组之间的基因型和等位基因分布频率差异有无显著性;以PANSS评定患者治疗前及治疗后2周、4周、6周和第8周末的精神症状,比较5-HT2A受体T102C各基因亚型与年龄、发病年龄、PANSS总分值、阳性症状基线分、阴性症状基线分、一般病理症状基线分、PANSS总减分率、阳性症状减分率、阴性症状减分率和一般病理症状减分率的差异.结果5-HT2A受体T102C基因型在患者组分布频率均符合H-W平衡定律(P＞0.05);不同临床诊断亚型精神分裂症患者等位基因和基因型频率无显著性差异(χ2=0.415,P=0.937;χ2=1.705,P=0.941);高剂量组与低剂量组之间的基因型和等位基因分布频率差异均无显著性(χ2=2.402,P=0.301;χ2=2.465,P=0.116);治疗有效和无效组的基因型和等位基因分布频率的差异无显著性(χ2=1.995,P=0.369;χ2=1.939,P=0.164);各基因型亚组的年龄、发病年龄及其病程差异均无显著性(P均大于0.05);但基因亚组A1/A1的治疗前PANSS总分(χ2=4.076,P=0.018)和阴性症状分(χ2=3.946,P=0.021)以及治疗结束PANSS总分减分率(χ2=4.036,P=0.019)和阴性症状减分率(χ2=3.876,P=0.022)均显著高于A1/A2及A2/A2基因型.结论(1)首发精神分裂症患者不同临床亚型5-HT2A受体基因T102C基因型和等位基因频率无显著差异.(2)利培酮高剂量组和低剂量组5-HT2A受体基因T102C基因型和等位基因分布频率没有显著性差异.(3)治疗有效组与无效组之间5-HT2A受体基因T102C基因型和等位基因分布频率也无显著性差异.(4)5-HT2A受体T102C Ai/A1基因亚型可能影响中国首发精神分裂症患者对利培酮的治疗效应.     

精神分裂症患者多巴胺D2受体基因多态性与利培酮治疗效应的关联分析

目的:探讨多巴胺D_2受体基因(DRD2)多态性与利培酮治疗精神分裂症临床疗效的关系。方法:纳入汉族精神分裂症患者304例(研究组)和汉族健康对照120名(对照组),研究组服用利培酮8周后以阳性与阴性症状量表(PANSS)评估疗效,同时检测两组DRD2基因rs6275、rs1801028和rs6277位点多态性。结果:rs6277位点在研究组和对照组中的等位基因频率与基因型频率的分布差异有统计学意义(χ~2=8.37,P=0.02)。研究组rs6275(F=15.52,P0.001)、rs1801028(F=19.74,P0.001)和rs6277(F=10.67,P0.001)位点不同基因型在PANSS总分减分率上差异均有统计学意义;同时rs1801028位点不同基因型在阴性症状减分率上差异有统计学意义(F=15.29,P0.001),rs6277位点在阳性症状减分率上差异有统计学意义(F=14.74,P0.001)。结论:DRD2基因rs6277位点多态性与精神分裂症易感性存在关联;不同DRD2基因型患者利培酮疗效可能存在差异。     

多巴胺D2受体基因的TaqI A多态性与迟发性运动障碍的关联分析

目的　研究多巴胺D2受体 (DRD2 )基因TaqIA多态性与精神分裂症伴迟发性运动障碍 (TD)的相关性。方法　使用异常不自主运动量表 (AIMS)评定精神分裂症患者有无TD及TD严重程度 ,并采用简明精神病评定量表 (BPRS)评定患者精神症状 ;应用聚合酶链反应 (PCR)—限制性片段长度多态性 (RFLP)法分析TD组和非TD组的DRD2基因的TaqIA等位基因频率和基因型分布。结果　DRD2基因TaqIA的等位基因频率和基因型分布在TD组与非TD组之间均无显著性差异 ,且不同基因型间的AIMS总分值也无显著性差异。结论　在中国汉族男性精神分裂症患者中DRD2基因的TaqIA多态性可能不是影响TD发生的主要危险因素。     

难治性精神分裂症与细胞色素P4502D6基因多态性相关性研究

目的 探测难治性精神分裂症与细胞色素P4502D6基因多态性关系。方法 用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）技术分析92例难治性精神分裂症患者的CYP2D6基因多态性,并以92例正常人作为对照。结果 在难治性精神分裂症组和对照组中,等位基因C、T及基因型T/T的差异具有非常显著性和显著性（P=0.002;P=0.002;P=0.014）。结论 本组样本中CYP2D6C188T基因多态性与难治性精神分裂症关联。提示CYP2D6C188T突变可能是难治性精神分裂症发病因素之一,本组中国汉族人中22号染色体长臂（22q13.1）可能存在难治性精神分裂症易感性基因。     

精神分裂症患者CYP2D6基因多态性与利培酮疗效的相关性

目的:探讨精神分裂症患者CYP2D6基因多态性与利培酮疗效的相关性。方法:98例精神分裂症患者(研究组)采用利培酮治疗3个月;治疗前后给予阳性和阴性症状量表(PANSS)、个人与社会表现量表(PSP)、数字划消测验、韦氏智能测验和瑞文标准推理测验评估;另选择同期体检健康志愿者85名作为对照组,分别对两组的CYP2D6基因进行基因型和单倍型分析;研究CYP2D6基因多态性与利培酮疗效的关系。结果:两组CYP2D6基因总瑞文标准推理测验在治疗前后的得分差值在rs1135840位点不同基因型患者之间的差异有统计学意义(F=5.21,P=0.01)。数字划消测验2在治疗前后的得分差值在rs16947位点不同基因型患者之间差异有统计学意义(F=3.96,P=0.03)。结论:CYP2D6基因多态性并非精神分裂症的易感因子,但CYP2D6基因的rs16947位点多态性可能影响精神分裂症患者治疗后注意力的改善,rs1135840位点多态性可能影响精神分裂症患者智力损伤和治疗后改善情况。     

多巴胺D2受体基因多态性与脑出血的相关性研究

目的 探讨多巴胺D2受体（DRD2）基因TaqI位点多态性与中国湖南地区汉族人群脑出血发病的相关性.方法 本研究筛选121例脑出血患者,匹配103例正常体检人群为对照,PCR-RFLP检测DRD2 TaqI基因多态性.结果 DRD2 TaqI三种基因型（A1A1,A1 A2,A2A2）频率及两种等位基因（A1,A2）频率在脑出血组和正常对照组分布的差异无统计学意义（P＞0.05）.脑出血组中高血压亚组、非高血压亚组及对照组三者两两比较DRD2 TaqI基因型频率分布的差异无统计学意义（P＞0.05）.Logistic回归调整了脑出血环境因素的影响后,DRD2 TaqI基因多态性仍与脑出血的无相关性（P＞0.05）.结论 DRD2 TaqI基因多态性可能与中国湖南地区汉族人群脑出血无关.     

多巴胺D3受体基因Ser9Gly多态性与阿立哌唑及利培酮治疗效应的关联研究

目的比较阿立哌唑与利培酮治疗女性首发精神分裂症患者的疗效和血浆催乳素水平变化及其与多巴胺D3受体(DRD3)基因Ser9Gly(rs6280)多态性的关联。方法选择完成8周阿立哌唑或利培酮治疗的女性首发精神分裂症患者各60例,于治疗前和治疗8周后分别评测阳性与阴性症状量表(positive and negativesymptom scale,PANSS)。采用放射免疫法检测血浆催乳素水平,DNA测序技术检测DRD3基因Ser9Gly多态性,分析DRD3基因Ser9Gly多态性与两药疗效及血浆催乳素变化的关联。结果治疗8周后,两组PANSS减分率的差异无统计学意义[(59.79±23.48)vs.(63.30±22.66),P>0.05],但利培酮组血浆催乳素的变化值高于阿立哌唑组[(26.92±9.48)vs.(-25.25±8.07),P<0.05]。利培酮组中C等位基因携带者的血浆催乳素的增加明显高于未携带者[(52.48±27.01)ng/mL vs(36.07±17.46),P<0.05];而阿立哌唑组中未见此差异[(-23.27±8.36)vs.TT(-26.05±8.11),P>0.05]。两组8周后PANSS减分率(%)与DRD3基因Ser9Gly的差异均无统计学意义:阿立哌唑组[CC+CT(57.83±19.94)vs.TT(56.84±18.46),P>0.05];利培酮组[CC+CT(53.94±21.08)vs.TT(60.38±19.37),P>0.05]。结论阿立哌唑治疗女性首发精神分裂症疗效与利培酮相当,但引起血浆催乳素水平变化的幅度较小;利培酮引起血浆催乳素水平增加可能与DRD3基因Ser9Gly多态性有关联。     

Attenuation of the locomotor-sensitizing effects of the D2 dopamine agonist bromocriptine by either the D1 antagonist SCH 23390 or the D2 antagonist raclopride

Injections of the selective D₂ dopamine agonist bromocriptine (5.0 mg/kg, IP) produced progressively stronger locomotion over 10 days of repeated testing. Concurrent treatment with either the D₁ antagonist SCH 23390 (0.01 or 0.1 mg/kg, IP) or the D₂ antagonist raclopride (0.1 or 1.0 mg/kg, IP) suppressed bromocriptine-induced locomotion on treatment days and attenuated or blocked the progressive increases in locomotion that accompanied repeated injections of bromocriptine alone. The fact that D₁ and D₂ antagonists each block the acute actions of bromocriptine and attenuate the development of bromocriptine sensitization is suggested to imply a striatal rather than a ventral tegmental mechanism for the sensitization produced by repeated treatments with direct dopamine agonists. © 1994 Wiley-Liss, Inc.     

Dopamine D1 receptors synergize with D2, but not D3 or D4, receptors in the striatum without the involvement of action potentials.

The widespread biological actions of the neurotransmitter dopamine (DA) are mediated by two classes of receptor, the D(1) class (D(1) and D(5)) and the D(2) class (D(2), D(3), and D(4)), which interact synergistically in many paradigms, such as DA agonist-stimulated motor behavior and striatal c-fos expression. Understanding the mechanism(s) of this interaction has been impeded by a controversy regarding the cellular localization of D(1) and D(2) class receptors. To address this issue from a functional point of view, we elicited striatal Fos by combined administration of a D(1) class and a D(2) class agonist either in the presence or absence of the fast sodium channel blocker tetrodotoxin (TTX). Striatal Fos elicited by direct D(1)/D(2) stimulation was not reduced by TTX. By contrast, TTX greatly attenuated the Fos response evoked by cocaine or GBR 12909. In separate experiments using antagonists that distinguish among members of the D(2) class of receptors, amphetamine-stimulated Fos and motor behavior were attenuated dose-dependently by the selective D(2) antagonist L-741,626, but not by the selective D(3) antagonist U99194A or the D(4)-selective antagonist L-745,870. Because Fos expression in the paradigms that were used occurs in enkephalin-negative striatonigral neurons, which show limited coexpression of D(1) and D(2) receptors, the present findings taken together suggest the intriguing possibility that D(1)/D(2) synergism may be mediated by D(1) and D(2) receptors residing on separate striatal neurons and interacting in a manner that is not dependent on action potentials.     

Functional rescue of the inactive splice variant of the dopamine D3 receptor D3nf

We previously found that the dopamine D3 receptor can be split at the third cytoplasmic loop into two fragments (D3trunk and D3tail), and that the mixture of the two fragments retains the binding and functional activity of the wild type receptor. The dopamine D3 receptor gene gives rise to several inactive receptor splice variants, one of which is the D3nf. Since this gene variant very closely resembles our D3trunk fragment, in this study we investigated if the transfection of D3nf with D3tail could result in the rescue of a functional dopamine receptor. Our experiments showed that D3tail can indeed rescue the activity of D3nf, and that the pharmacological profile of this split D3nf/D3tail receptor is identical to that of the wild type D3 receptor.     

Lesions of the nigrostriatal dopamine projection increase the inhibitory effects of D1 and D2 dopamine agonists on caudate-putamen neurons and relieve D2 receptors from the necessity of D1 receptor stimulation

Extracellular single unit recording and microiontophoretic techniques were used to determine the sensitivities and interactions of D1 and D2 dopamine (DA) receptors in the caudate putamen (CPu) of rats that were denervated of DA by intraventricular injections of the catecholamine neurotoxin 6-hydroxydopamine (6-OHDA). Seven to 10 d after the 6-OHDA injection, DA levels in the ipsilateral CPu were reduced to 11.8% of control. Current-response curves revealed that the inhibitory responses of CPu neurons to microiontophoretic administration of both the selective D1 receptor agonist SKF-38393 and the selective D2 receptor agonist quinpirole were significantly increased in 6-OHDA-pretreated rats, suggesting up-regulation of both receptor subtypes. Although our previous studies have established that D1 receptor activation is normally required for (enables) the inhibitory effects of selective D2 agonists in the CPu, this requirement was no longer evident in 6-OHDA-denervated rats. Whereas acute DA depletion [produced by the tyrosine hydroxylase inhibitor alpha-methyl-p-tyrosine (AMPT)] attenuated the inhibitory effects of quinpirole on CPu neurons, long-term DA denervation (produced by 6-OHDA) enhanced the inhibitory effects of the D2 agonist. The enhanced effects of quinpirole in 6-OHDA-lesioned rats were not due to residual DA stimulating supersensitive D1 receptors (i.e., enabling) since further DA depletion (99.7%), produced by acute administration of AMPT in 6-OHDA-lesioned rats, failed to diminish the inhibitory efficacy of quinpirole. In addition to relieving D2 receptors from the need for D1 receptor-mediated enabling, 6-OHDA lesions also abolished the normal synergistic relationship between the receptor subtypes since low (subinhibitory) currents of SKF-38393 (4 nA) failed to potentiate the inhibitory effects of quinpirole on CPu neurons in lesioned rats. Similar findings (i.e., supersensitivity and loss of synergistic effects) were obtained from rats that had received repeated pretreatment with reserpine (2.5 mg/kg) for 4 d, indicating that these effects of 6-OHDA lesions were due to the depletion of synaptic DA rather than to the structural loss of DA terminals. Therefore, both the quantitative (potentiation) and the qualitative (enabling) synergistic effects between D1 and D2 receptors in the rat CPu were abolished when these receptors were functionally supersensitive. The present study provides electrophysiological support for previous behavioral studies indicating that the requirement of D1 receptor stimulation for D2 receptor-mediated functional effects (enabling) is not maintained in rats chronically depleted of DA by either 6-OHDA lesions or repeated reserpine.     

Electrophysiological verification of the presence of D1 and D2 dopamine receptors within the ventral pallidum

The ventral pallidum is a basal forebrain region recently shown to receive dopaminergic projections from the midbrain. Binding sites for the D1 and D2 dopamine receptor families have been identified within the ventral pallidum, yet the consequences of activating these receptors have not been studied. Thus, to characterize the physiological pharmacology of D1 and D2 receptor subtypes for the ventral pallidum, extracellular single-neuron recording and microiontophoretic techniques were used in chloral hydrate-anesthetized rats. Half of the 93 ventral pallidal neurons tested were sensitive to iontophoresis of dopamine (DA), and both rate increases and decreases were observed. Co-iontophoresis of either the D1 antagonist SCH23390, or the D2 antagonist sulpiride, generally attenuated the DA-induced rate changes. Like DA, about half of the ventral pallidal neurons tested were sensitive to the D1 agonist, SKF38393. Yet in contrast to DA, rate suppression was observed almost exclusively, and the magnitude of this decrease was greater than that produced by DA. SKF38393-induced suppressions were antagonized by SCH23390, but not by sulpiride, demonstrating the specificity of the D1 agonist. Most of the neurons tested were not affected by quinpirole, but when responsive to the D2 agonist, rate increases were observed most often. The increases were antagonized by the D2 antagonist sulpiride, but not SCH23390, demonstrating that this response resulted from an activation of D2 receptors. These results support binding studies demonstrating that both D1 and D2 receptors are present in the ventral pallidum, and reveal that the independent activation of each of these is sufficient to alter neuronal activity. © 1994 Wiley-Liss. Inc.     

Regional distribution of dopamine D1 and D2 receptors in the nucleus accumbens of the rat

Dopamine (DA) D1 receptor density was found to be significantly lower in the rostral than in the medial and caudal areas of the nucleus accumbens. This roughly followed the distribution of DA terminals. The distribution of DA D2 receptors did not follow the DA terminal distribution. DA D2 receptor number was lower in the ventrorostral and higher in the dorsomedial area than in any other area of the nucleus accumbens.     

Cyclin D1/D2/D3在大鼠脑胶质瘤组织中的表达

目的 探讨cyclin D1/D2/D3在大鼠脑胶质瘤组织中的表达.方法 将体外培养的大鼠C6胶质瘤细胞(细胞数为3×105个)借助动物立体定向仪接种于Wistar大鼠左侧尾状核区,解剖标本,行组织病理学检查及GFAP、cyclin D1/D2/D3免疫组化检测.结果 cyclinD1/D2/D3均呈阳性表达.cyclin D1/D3主要在细胞胞核表达,cyclin D2主要在胞浆表达,部分在胞核表达,不同存活期荷瘤鼠瘤组织中cyclin D1/D2/D3表达量不同.结论 cyclinD1/D2/D3过分表达参与调节大鼠脑胶质瘤增殖.荷瘤鼠生存期与cyclin D家族蛋白的表达呈负相关关系.     

Phenotypical characterization of the neurons expressing the D1 and D2 dopamine receptors in the monkey striatum

The striatum is regulated by dopaminergic inputs from the substantia nigra. Several anatomical studies using in situ hybridization have demonstrated that in rodents, dopamine D1 and D2 receptors are segregated into distinct striatal efferent populations: dopamine D1 receptor into gamma-aminobutyric acid (GABA)/substance P striatonigral neurons, and dopamine D2 receptor into GABA/enkephalin striatopallidal neurons. The existence of such a segregation has not been investigated in primates. Therefore, to quantify the efferent striatal GABAergic neurons in the adult Cynomolgus monkey, we detected GAD67 mRNA expression while considering that only a minority of the GABAergic population is composed of interneurons. To characterize the peptidergic phenotype of the neurons expressing dopamine D1 or D2 receptors, we examined the mRNA coding for these receptors in the striatum at the cellular level using single- and double in situ hybridization with digoxigenin and 35S ribonucleotide probes. Double in situ hybridization demonstrated a high coexpression of dopamine D1 receptor and substance P mRNAs (91-99%) as well as dopamine D2 receptor and preproenkephalin A mRNAs (96-99%) in medium-sized neurons throughout the nucleus caudatus, putamen, and nucleus accumbens. Only a small subpopulation (2-5%) of the neurons that contained dopamine D1 receptor mRNA also expressed dopamine D2 receptor mRNA in all regions. Large-sized neurons known to be cholinergic expressed D2R mRNA. However, within the nucleus basalis of Meynert, the large cholinergic neurons expressed D2R mRNA, but the neurons producing enkephalin expressed neither D1R nor D2R mRNA. These results demonstrate that the striatal organizational pattern of D1 and D2 receptor segregation in distinct neuronal populations described in rodent also exists in primate.     

Dopamine D2-like receptor agonists induce penile erection in male rats: differential role of D2, D3 and D4 receptors in the paraventricular nucleus of the hypothalamus

Pramipexole, a dopamine D3/D2 receptor agonist, induces penile erection when administered subcutaneously (s.c.) or into the paraventricular nucleus of the hypothalamus of male rats, like apomorphine, a mixed D1/D2 receptor agonist, and PD 168,077, a D4 receptor agonist. A U-inverted dose-response curve was found with pramipexole and apomorphine, but not with PD 168,077 (0.025-0.5 mg/kg s.c.). Pramipexole effect was abolished by L-741,626, a D2 receptor antagonist (2.5 and 5 mg/kg s.c.) and raclopride, a D2/D3 receptor antagonist (0.025 and 0.1 mg/kg s.c.), but not by SB277011A (2.5 and 10 mg/kg s.c.) or FAUC 365 (1 and 2 mg/kg s.c.), two D3 receptor antagonists, or L-745,870 (1 and 5 mg/kg i.p.), a D4 receptor antagonist. Similar results were found with apomorphine (0.08 mg/kg s.c.), although its effect was also partially reduced by L-745,870. In contrast, PD 168,077 effect was abolished by L-745,870, but not L-741,626, SB277011A, FAUC 365 or raclopride. Similar results were found when dopamine agonists (5-200 ng/rat) and antagonists (1-5 μg/rat) were injected into the paraventricular nucleus. However, no U-inverted dose-response curve was found with any of the three dopamine agonists injected into this nucleus. As pramipexole- and apomorphine-induced penile erection was reduced mainly by D2, but not D3 or D4 antagonists, D2 receptors are those that mediate the pro-erectile effect of these dopamine agonists. Although the selective stimulation of paraventricular D4 receptors induces penile erection, D4 receptors seem to play only a modest role in the pro-erectile effect of the above dopamine agonists.     

Differential regulation of the dopamine D1, D2 and D3 receptor gene expression and changes in the phenotype of the striatal neurons in mice lacking the dopamine transporter

Mice with a genetic disruption of the dopamine transporter (DAT-/-) exhibit locomotor hyperactivity and profound alterations in the homeostasis of the nigrostriatal system, e.g. a dramatic increase in the extracellular dopamine level. Here, we investigated the adaptive changes in dopamine D1, D2 and D3 receptor gene expression in the caudate putamen and nucleus accumbens of DAT-/- mice. We used quantitative in situ hybridization and found that the constitutive hyperdopaminergia results in opposite regulations in the gene expression for the dopamine receptors. In DAT-/- mice, we observed increased mRNA levels encoding the D3 receptor (caudate putamen, +60-85%; nucleus accumbens, +40-107%), and decreased mRNA levels for both D1 (caudate putamen, -34%; nucleus accumbens, -45%) and D2 receptors (caudate putamen, -36%; nucleus accumbens, -33%). Furthermore, we assessed the phenotypical organization of the striatal efferent neurons by using double in situ hybridization. Our results show that in DAT+/+ mice, D1 and D2 receptor mRNAs are segregated in two different main populations corresponding to substance P and preproenkephalin A mRNA-containing neurons, respectively. The phenotype of D1 or D2 mRNA-containing neurons was unchanged in both the caudate putamen and nucleus accumbens of DAT-/- mice. Interestingly, we found an increased density of preproenkephalin A-negative neurons that express the D3 receptor mRNA in the nucleus accumbens (core, +35%; shell, +46%) of DAT-/- mice. Our data further support the critical role for the D3 receptor in the regulation of D1-D2 interactions, an action being restricted to neurons coexpressing D1 and D3 receptors in the nucleus accumbens.