精索静脉曲张患者血中儿茶酚胺浓度的变化

目的了解曲张后精索静脉血去甲肾上腺素、肾上腺素及多巴胺浓度的变化，探讨儿茶酚胺在精索静脉曲张病理生理中的作用。方法采用高效液相色谱法测定30例精索静脉曲张患者精索静脉血去甲肾上腺素、肾上腺素及多巴胺浓度，30例无精索静脉曲张的腹股沟斜疝患者作为对照。结果患者精索静脉血的去甲肾上腺素浓度为（597．1±274．3）pg／mL，明显高于对照组（386．2±172．6）pg／mL（P〈0．05）。肾上腺素浓度为（255．0±109．0）pg／mL，亦高于对照组（203．0±67．7）pg／mL（P〈0．05）。多巴胺浓度两组差别无统计学意义。结论精索静脉曲张患者精索静脉血中的去甲肾上腺素、肾上腺素浓度异常，这可能与精索静脉曲张的病理生理有关。     

Blunted renal dopaminergic system activity in puromycin aminonucleoside-induced nephrotic syndrome.

BACKGROUND: A primary tubular sodium handling abnormality has been implicated in the edema formation of nephrotic syndrome. Dopamine synthesized by renal proximal tubules behaves as an endogenous natriuretic hormone by activating D(1)-like receptors as a paracrine/autocrine substance. METHODS: We examined the time courses of the urinary excretion of sodium, protein and dopamine in puromycin aminonucleoside (PAN)-treated and control rats. The rats were sacrificed during greatest sodium retention (day 7) as well as during negative sodium balance (day 14) for the evaluation of renal aromatic l-amino acid decarboxylase (AADC) activity, the enzyme responsible for the synthesis of renal dopamine. Also, the influence of volume expansion (VE) and the effects of the D(1)-like agonist fenoldopam (10 microg/kg bw/min) on natriuresis and on proximal tubular Na(+),K(+)-ATPase activity were examined on day 7. RESULTS: The daily urinary excretion of dopamine was decreased in PAN-treated rats, from day 5 and beyond. This was accompanied by a marked decrease in the renal AADC activity, on days 7 and 14. During VE, the fenoldopam-induced decrease in proximal tubular Na(+),K(+)-ATPase activity was more pronounced in PAN-treated rats than in controls. However, the urinary sodium excretion during fenoldopam infusion was markedly increased in control rats but was not altered in PAN-treated animals. CONCLUSION: PAN nephrosis is associated with a blunted renal dopaminergic system activity which may contribute to enhance the proximal tubular Na(+),K(+)-ATPase activity. However, the lack of renal dopamine appears not to be related with the overall renal sodium retention in a state of proteinuria.     

热应激对大鼠纹状体多巴胺介导的磷脂酰肌醇信号系统的影响

目的探讨热应激对纹状体多巴胺(DA)介导的磷脂酰肌醇(PI)信号转导系统的影响。方法将雄性Wistar大鼠随机分为对照组和热应激组,大鼠在加热小仓中受热,达到设定肛温(Tr)时即刻取出。取纹状体,分别用荧光分光光度法、酸碱滴定法、高压液相法和Fura-2／AM荧光标记法测DA含量、PLA,活性、PI含量和[Ca^2 ]i。结果41．0℃Tr以上时,随Tr升高DA含量有持续增高趋势,并在43．0℃Tr时,比对照显著增加;在41．0℃Tr时,PLA,活性较对照显著增强,热应激组PI含量显著低于对照;在42．0℃Tr时,[Ca^2 ]i比对照显著增高,热应激前1h给予D2R拮抗剂氯氮平,则可减弱热应激引起的[Ca^2 ]i的升高,并延长肛温到达42．0℃的时间。结论热应激可能激动了DA介导的PI信号转导系统,[Ca^2 ]i升高可能经D2R介导,用D2R拮抗剂,可以提高机体耐热性。     

瓜蒌薤白汤对肺纤维化形成阶段的干预作用

目的:观察瓜蒌薤白汤对大鼠肺纤维化形成阶段(造模后14～28 d)肺部病理损害和肺组织去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)含量的影响。方法:普通级雌性Wistar大鼠随机分为正常组、模型组、泼尼松组、瓜蒌薤白汤组。除正常组外,其余各组均采用气管内一次性注入平阳霉素(0.003 g·kg-1体重)复制肺纤维化模型,造模14 d后,泼尼松组以泼尼松0.004 g·kg-1体重ig,瓜蒌薤白汤组以全瓜蒌2.04 g·kg-1体重,薤白1.02 g·kg-1体重ig,第28天处死动物,比较各组肺指数、肺纤维化程度、肺组织DA,NE,5-HT含量。结果:模型组肺纤维化程度重于正常组、泼尼松组与瓜蒌薤白汤组(P<0.05),肺指数高于正常组与各用药组(P<0.05),肺组织DA,NE,5-HT含量高于正常组、泼尼松组(P<0.05);DA:模型组(60.57±8.47)ng·g-1,正常组(20.59±6.68)ng·g-1,泼尼松组(18.44±4.16)ng·g-1;NE:模型组(37.01±4.99)ng·g-1,正常组(26.91±1.90)ng·g-1,泼尼松组(23.06±5.64)ng·g-1;5-HT:模型组(88.87±5.02)ng·g-1,正常组(20.31±4.24)ng·g-1,泼尼松组(69.18±9.00)ng·g-1;瓜蒌薤白汤组NE含量(46.31±4.55)ng·g-1明显高于模型组,DA(27.48±3.20)ng·g-1,5-HT(48.90±8.47)ng·g-1含量低于模型组(P<0.05)。结论:瓜蒌薤白汤具有减轻肺纤维化模型形成阶段肺病理改变的作用;肺纤维化形成阶段肺中DA,NE,5-HT升高;瓜蒌薤白汤能抑制模型肺DA,5-HT含量的升高,增加模型肺中NE含量。     

哌仑西平抑制近视眼机制的研究

目的 观察哌仑西平对实验性近视的抑制作用,初步探讨其作用机制.方法 将出生后48 h内的纯种M99穗麻雄鸡的右眼缝上眼罩进行遮盖,分别在玻璃体内注入500 μg哌仑西平（MD＋P组）及10 μl生理盐水为阴性对照（SS组）,单纯遮盖作为空白对照（MD组）.同时观察单纯注入500 μg哌仑西平（P组）对正常眼（正常组）的影响.4周后进行验光.运用高效液相色谱（HPLC）联合电化学检测（EC）方法分析实验动物视网膜上多巴胺（DA）及其代谢产物多巴克（DOPAC）水平的变化.结果 MD组和正常组屈光度差异有统计学意义（P＜0.01）.MD组与正常组相比,视网膜DA及其代谢产物DOPAC水平明显降低（P＜0.01）,下降率大于40%.MD＋P组视网膜DA和DOPAC水平与正常组相比差异无统计学意义.结论 500 μg哌仑西平能够抑制实验性近视的产生和发展.哌仑西平可能作用于视网膜上毒覃碱受体（M受体）而引起DA改变,进而抑制近视的产生.     

HPLC同时测定附子中盐酸多巴胺和去甲猪毛菜碱

目的:用HPLC同时测定附子中盐酸多巴胺和去甲猪毛菜碱的含量.方法:采用Agilent Eclipse C18柱(4.6 mm×250 mm,5μm),流动相为0.1％磷酸水溶液,流速1 mL·min-1,柱温35℃,检测波长280 nm.结果:盐酸多巴胺和去甲猪毛菜碱色谱峰与其他色谱峰分离良好,样品中盐酸多巴胺和去甲猪毛菜碱色谱峰的DAD光谱与对照品一致,进样量在0.00521 ～0.521 μg和0.005 24 ～0.524 μg线性关系良好,平均回收率分别为100.6％和96.5％,RSD分别为2.0％和1.0％(n=6).结论:实验含量测定方法准确、快速,为附子质量控制提供参考方法.     

Reduced Insulin Sensitivity Is Related to Less Endogenous Dopamine at D2/3 Receptors in the Ventral Striatum of Healthy Nonobese Humans

Background:

Food addiction is a debated topic in neuroscience. Evidence suggests diabetes is related to reduced basal dopamine levels in the nucleus accumbens, similar to persons with drug addiction. It is unknown whether insulin sensitivity is related to endogenous dopamine levels in the ventral striatum of humans. We examined this using the agonist dopamine D_2/3 receptor radiotracer [¹¹C]-(+)-PHNO and an acute dopamine depletion challenge. In a separate sample of healthy persons, we examined whether dopamine depletion could alter insulin sensitivity.

Methods:

Insulin sensitivity was estimated for each subject from fasting plasma glucose and insulin using the Homeostasis Model Assessment II. Eleven healthy nonobese and nondiabetic persons (3 female) provided a baseline [¹¹C]-(+)-PHNO scan, 9 of which provided a scan under dopamine depletion, allowing estimates of endogenous dopamine at dopamine D_2/3 receptor. Dopamine depletion was achieved via alpha-methyl-para-tyrosine (64mg/kg, P.O.). In 25 healthy persons (9 female), fasting plasma and glucose was acquired before and after dopamine depletion.

Results:

Endogenous dopamine at ventral striatum dopamine D_2/3 receptor was positively correlated with insulin sensitivity (r(7)=.84, P=.005) and negatively correlated with insulin levels (r(7)=-.85, P=.004). Glucose levels were not correlated with endogenous dopamine at ventral striatum dopamine D_2/3 receptor (r(7)=-.49, P=.18). Consistently, acute dopamine depletion in healthy persons significantly decreased insulin sensitivity (t(24)=2.82, P=.01), increased insulin levels (t(24)=-2.62, P=.01), and did not change glucose levels (t(24)=-0.93, P=.36).

Conclusion:

In healthy individuals, diminished insulin sensitivity is related to less endogenous dopamine at dopamine D_2/3 receptor in the ventral striatum. Moreover, acute dopamine depletion reduces insulin sensitivity. These findings may have important implications for neuropsychiatric populations with metabolic abnormalities.     

NOX1/NADPH Oxidase Promotes Synaptic Facilitation Induced by Repeated D2 Receptor Stimulation: Involvement in Behavioral Repetition

Repetitive behavior is a widely observed neuropsychiatric symptom. Abnormal dopaminergic signaling in the striatum is one of the factors associated with behavioral repetition; however, the molecular mechanisms underlying the induction of repetitive behavior remain unclear. Here, we demonstrated that the NOX1 isoform of the superoxide-producing enzyme NADPH oxidase regulated repetitive behavior in mice by facilitating excitatory synaptic inputs in the central striatum (CS). In male C57Bl/6J mice, repeated stimulation of D₂ receptors induced abnormal behavioral repetition and perseverative behavior. Nox1 deficiency or acute pharmacological inhibition of NOX1 significantly shortened repeated D₂ receptor stimulation-induced repetitive behavior without affecting motor responses to a single D₂ receptor stimulation. Among brain regions, Nox1 showed enriched expression in the striatum, and repeated dopamine D₂ receptor stimulation further increased Nox1 expression levels in the CS, but not in the dorsal striatum. Electrophysiological analyses revealed that repeated D₂ receptor stimulation facilitated excitatory inputs in the CS indirect pathway medium spiny neurons (iMSNs), and this effect was suppressed by the genetic deletion or pharmacological inhibition of NOX1. Nox1 deficiency potentiated protein tyrosine phosphatase activity and attenuated the accumulation of activated Src kinase, which is required for the synaptic potentiation in CS iMSNs. Inhibition of NOX1 or β-arrestin in the CS was sufficient to ameliorate repetitive behavior. Striatal-specific Nox1 knockdown also ameliorated repetitive and perseverative behavior. Collectively, these results indicate that NOX1 acts as an enhancer of synaptic facilitation in CS iMSNs and plays a key role in the molecular link between abnormal dopamine signaling and behavioral repetition and perseveration.SIGNIFICANCE STATEMENT Behavioral repetition is a form of compulsivity, which is one of the core symptoms of psychiatric disorders, such as obsessive-compulsive disorder. Perseveration is also a hallmark of such disorders. Both clinical and animal studies suggest important roles of abnormal dopaminergic signaling and striatal hyperactivity in compulsivity; however, the precise molecular link between them remains unclear. Here, we demonstrated the contribution of NOX1 to behavioral repetition induced by repeated stimulation of D₂ receptors. Repeated stimulation of D₂ receptors upregulated Nox1 mRNA in a striatal subregion-specific manner. The upregulated NOX1 promoted striatal synaptic facilitation in iMSNs by enhancing phosphorylation signaling. These results provide a novel mechanism for D₂ receptor-mediated excitatory synaptic facilitation and indicate the therapeutic potential of NOX1 inhibition in compulsivity.     

Reduced Motivation in Perinatal Fluoxetine-Treated Mice: A Hypodopaminergic Phenotype

Early life is a sensitive period, in which enhanced neural plasticity allows the developing brain to adapt to its environment. This plasticity can also be a risk factor in which maladaptive development can lead to long-lasting behavioral deficits. Here, we test how early-life exposure to the selective-serotonin-reuptake-inhibitor (SSRI), fluoxetine, affects motivation, and dopaminergic signaling in adulthood. We show for the first time that mice exposed to fluoxetine in the early postnatal period exhibit a reduction in effort-related motivation. These mice also show blunted responses to amphetamine and reduced dopaminergic activation in a sucrose reward task. Interestingly, we find that the reduction in motivation can be rescued in the adult by administering bupropion, a dopamine-norepinephrine reuptake inhibitor used as an antidepressant and a smoke cessation aid but not by fluoxetine. Taken together, our studies highlight the effects of early postnatal exposure of fluoxetine on motivation and demonstrate the involvement of the dopaminergic system in this process.SIGNIFICANCE STATEMENT The developmental period is characterized by enhanced plasticity. During this period, environmental factors have the potential to lead to enduring behavioral changes. Here, we show that exposure to the SSRI fluoxetine during a restricted period in early life leads to a reduction in adult motivation. We further show that this reduction is associated with decreased dopaminergic responsivity. Finally, we show that motivational deficits induced by early-life fluoxetine exposure can be rescued by adult administration of bupropion but not by fluoxetine.     

Mechanism of Pacemaker Activity in Zebrafish DC2/4 Dopaminergic Neurons

Zebrafish models are used increasingly to study the molecular pathogenesis of Parkinson''s disease (PD), owing to the extensive array of techniques available for their experimental manipulation and analysis. The ascending dopaminergic projection from the posterior tuberculum (TPp; diencephalic populations DC2 and DC4) to the subpallium is considered the zebrafish correlate of the mammalian nigrostriatal projection, but little is known about the neurophysiology of zebrafish DC2/4 neurons. This is an important knowledge gap, because autonomous activity in mammalian substantia nigra (SNc) dopaminergic neurons contributes to their vulnerability in PD models. Using a new transgenic zebrafish line to label living dopaminergic neurons, and a novel brain slice preparation, we conducted whole-cell patch clamp recordings of DC2/4 neurons from adult zebrafish of both sexes. Zebrafish DC2/4 neurons share many physiological properties with mammalian dopaminergic neurons, including the cell-autonomous generation of action potentials. However, in contrast to mammalian dopaminergic neurons, the pacemaker driving intrinsic rhythmic activity in zebrafish DC2/4 neurons does not involve calcium conductances, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, or sodium leak currents. Instead, voltage clamp recordings and computational models show that interactions between three components – a small, predominantly potassium, leak conductance, voltage-gated sodium channels, and voltage-gated potassium channels – are sufficient for pacemaker activity in zebrafish DC2/4 neurons. These results contribute to understanding the comparative physiology of the dopaminergic system and provide a conceptual basis for interpreting data derived from zebrafish PD models. The findings further suggest new experimental opportunities to address the role of dopaminergic pacemaker activity in the pathogenesis of PD.SIGNIFICANCE STATEMENT Posterior tuberculum (TPp) DC2/4 dopaminergic neurons are considered the zebrafish correlate of mammalian substantia nigra (SNc) neurons, whose degeneration causes the motor signs of Parkinson''s disease (PD). Our study shows that DC2/4 and SNc neurons share a number of electrophysiological properties, including depolarized membrane potential, high input resistance, and continual, cell-autonomous pacemaker activity, that strengthen the basis for the increasing use of zebrafish models to study the molecular pathogenesis of PD. The mechanisms driving pacemaker activity differ between DC2/4 and SNc neurons, providing: (1) experimental opportunities to dissociate the contributions of intrinsic activity and underlying pacemaker currents to pathogenesis; and (2) essential information for the design and interpretation of studies using zebrafish PD models.