槐果碱等苦豆子生物碱对大鼠单胺代谢及多巴胺和5-羟色胺受体的作用

槐果碱(SPC)、拉马宁碱(LM),苦参碱、槐胺碱及槐定碱均能不同程度地升高大鼠纹状体及前脑边缘区的多巴胺代谢物二羟苯乙酸(DOPAC)和高香草酸(HVA)的含量。LM还能降低纹状体中的DA和边缘区中的NA。SPC(40 mg/kg)使纹状体中HVA升高的持续时间长于DOPAC。SPC对DOPAC和HVA的作用,在10～80mg/kg的剂量范围内,有明显的量效关系。SPC还能降低纹状体中的DA含量。受体结合试验表明,上述五种生物碱(LM未测试)对D-2受体、5HT₁和5HT₂受体无亲和力(IC₅₀均大于10^-4mol)。     

L-四氢巴马汀对羟考酮依赖大鼠不同脑区单胺递质水平的影响

目的：观察L-四氢巴马汀（L-THP）对羟考酮依赖大鼠不同脑区单胺递质含量的影响，探讨L—THP对抗羟考酮依赖的机制。方法：以连续递增给药建立羟考酮依赖大鼠模型，L—THP伴随给药，采用HPLC—ECD法测定大鼠前皮层、海马、纹状体和伏隔核内多巴胺（DA）和5-羟色胺（5-HT）含量的变化。结果：与空白对照组相比，羟考酮依赖的大鼠纳络酮催促戒断后前皮层内DA、高香草酸（HVA）和5-HT含量明显降低，伏隔核内DA、3，4-二羟基苯醋酸（DOPAC）、HVA和5-HT含量明显降低，海马内DA、DOPAC、5-HT含量没有明显变化，而5-吲哚乙酸（5-HIAA）明显升高，纹状体内DA及其代谢产物DOPAC、HVA以及5-HT、5-HIAA含量明显降低；L—THP（10，20，30mg·kg^-1，ig）伴随给药，能不同程度抑制上述变化。结论：L—THP可抑制羟考酮依赖引起的不同脑区内单胺类递质含量的变化，提示LTHP对抗羟考酮依赖可能与调节多巴胺和5-HT系统相关。     

螺旋藻多糖对MPTP致多巴胺能神经元损伤的保护

目的探讨螺旋藻多糖(PSP)对MPTP制备的C57BL小鼠帕金森病(PD)模型多巴胺能神经元的保护作用。方法C57BL小鼠分5组:对照组、MPTP组、PSP高、中、低剂量预处理+MPTP组。用免疫组化、RT-PCR和HPLC-ECD方法检测黑质中酪氨酸羟化酶(TH)和多巴胺转运体(DAT)免疫反应阳性表达水平,TH和DAT mRNA表达水平及纹状体中多巴胺(DA)及其代谢产物3,4-二羟苯乙酸(DOPAC)和高香草酸(HVA)的含量。结果模型小鼠黑质中TH和DAT免疫阳性细胞数目减少,TH和DAT mRNA表达水平降低,纹状体中DA、DOPAC和HVA含量降低(P<0.01)。PSP预处理组与模型组相比,TH和DAT免疫阳性细胞数目增加,TH和DAT mRNA表达升高,DA、DOPAC和HVA含量升高(P<0.05)。结论PSP对MPTP所致C57BL小鼠PD模型的多巴胺能神经元有保护作用。     

缺血预适应对沙土鼠脑缺血再灌注后纹状体多巴胺及其代谢产物的影响

目的　研究缺血预适应对沙士鼠脑缺再灌注后纹状体中多巴胺(DA)及其代谢产物的影响,以探讨其神经保护作用的可能机制。方法　应用沙土鼠脑缺血再灌注模型,脑缺血时间为 5min。96只沙土鼠随机分为假手术组 (S)、缺血组(I)、单纯预适应组 (Po)、缺血预适应组 (Ip)。在再灌注 0(即缺血末)、5、30、60min时,断头、分离纹状体,用高效液相-电化学检测器 (HPLC ECD)分别测定各组沙土鼠纹状体DA、3, 4双羟苯乙酸 (DOPAC)和高香草酸 (HVA)的含量。结果　与假手术组相比,短暂缺血组在缺血再灌注期间纹状体中DA、DOPAC和HVA含量均无显著性变化 (P>0 05)。再灌注期间,预适应、缺血再灌注组DA含量均显著低于假手术组,但在再灌注 0min和 30min时,预适应组DA含量及显著高于缺血再灌注组,分别增加了 28% (P<0 01)和 22% (P<0 05)。与假手术组相比,预适应组的DOPAC和HVA含量在再灌注期间均无显著变化 (P>0 05 );缺血再灌注组DOPAC含量在再灌注 5min时有明显增加;HVA含量在再灌注 30min时增加至峰值。结论　缺血预适应能部分抑制沙土鼠脑缺血再灌注期间纹状体DA的降低,显著减少DA氧化代谢产物的产生,从而在脑缺血再灌注损伤中起保护作用。     

地卓西平全身和局部给药对小鼠前皮层多巴胺及其代谢产物和行为学的影响

目的研究地卓西平(MK 801)全身和局部给药对小鼠前皮层(PFC)中多巴胺(DA)及其代谢产物二羟苯乙酸(DOPAC)和高香草酸(HVA)的影响及行为学改变。方法通过微透析结合高效液相色谱电化学法(HPLC ECD)检测DA及其代谢产物,同时监测小鼠的自主活动。结果腹腔注射MK 801(0.6 mg.kg-1)能明显增加小鼠PFC中DA、DOPAC和HVA的水平,并明显增加小鼠自主活动次数;向小鼠PFC中局部灌注MK-801(10、50和250μmol.L-1)可以剂量依赖性地增加PFC中DA的水平和小鼠的自主活动次数,但对DOPAC和HVA没有明显的影响;无论全身给药还是局部灌注给药,小鼠PFC中DA的水平与自主活动呈明显的正性相关。结论MK 801至少部分上是直接作用于PFC的DA能神经元促进DA的释放,DA参与MK 801诱导的行为反应。     

松果菊苷对脑缺血大鼠纹状体细胞外液中单胺类神经递质的影响

目的研究松果菊苷(ECH)对局灶型脑缺血大鼠纹状体细胞外液中单胺类递质的影响,以探讨ECH对脑神经保护作用的可能机制。方法 SD大鼠随机分为对照组、模型组、ECH高、低剂量组和川芎嗪(CXQ)组。各组大鼠给予相应的药物或生理盐水腹腔注射,每天1次,连续7 d。给药第3天,脑纹状体埋置探针套管,末次给药1 h后,制作大鼠局灶性脑缺血模型(MCAO),造模后立刻进行微透析,将透析液注入高效液相-电化学检测器(HPLC-ECD)测定各组纹状体细胞外液中去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)、3,4-二羟苯乙酸(DOPAC)、高香草酸(HVA)、5-羟吲哚乙酸(HIAA)的含量。结果与对照组相比,模型组NE、DA、5-HT水平升高,其酸性代谢产物DOPAC,HVA,HIAA也随之升高。与模型组比较,ECH高、低剂量组(30、15 mg.kg-1.d-1)和CXQ组的6种物质的含量均有所降低。结论 ECH的神经保护作用可能与对抗脑缺血后单胺类神经递质的升高有关。     

钩藤碱对脑缺血大鼠纹状体及海马单胺类递质含量的影响(英文)

目的　探索钩藤碱对大鼠脑缺血损伤的机制。方法　采用大鼠大脑中动脉缺血模型 ,利用微透析方法收集正常及脑缺血后不同时间点纹状体和海马细胞外液 (透析液 )。经反相高效液相电化学法检测其单胺类神经递质含量的变化。结果　大鼠脑缺血后纹状体和海马细胞外液中 5 羟吲哚乙酸 (5 HIAA)、3,4 二羟苯酰乙酸 (DOPAC)和高香草酸(HVA)含量下降 ,去甲肾上腺素 (NE)含量上升 ,钩藤碱能升高脑缺血后细胞外液 5 HIAA ,DOPAC和HVA的含量 ,降低NE的含量。结论　钩藤碱能调节脑缺血大鼠纹状体内和海马单胺类神经递质及代谢物的含量     

神经酸对帕金森病模型小鼠运动障碍的缓解作用及机制研究

目的:研究神经酸对帕金森病(PD)模型小鼠运动障碍的缓解作用及机制。方法:将小鼠随机分为空白对照组(生理盐水)、模型组(生理盐水)、多巴丝肼片组(阳性对照,按左旋多巴计120 mg/kg)和神经酸低、中、高剂量组(20.0、40.0、80.0 mg/kg),每组10只。除空白对照组外,其余各组小鼠均建立PD模型。成模后,每天ig相应药物1次,连续14 d。末次给药后,观察各组小鼠行为学变化,采用高效液相色谱法测定小鼠脑纹状体内多巴胺(DA)及其代谢物二羟苯乙酸(DOPAC)、高香草酸(HVA)的含量。结果:与空白对照组比较,模型组小鼠爬杆时间延长、滚筒时间缩短、自发运动次数减少(P<0.05),脑纹状体内DA、DOPAC、HVA含量均降低(P<0.05)。与模型组比较,多巴丝肼片组和神经酸各剂量组小鼠爬杆时间缩短、滚筒时间延长(P<0.05),脑纹状体内DA、DOPAC、HVA含量均升高(P<0.05);多巴丝肼片组和神经酸高剂量组小鼠自发运动次数增加(P<0.05)。结论:神经酸可有效改善PD模型小鼠的运动障碍症状,其机制可能与增加脑纹状体内DA含量有关。     

吡喹酮对大鼠单胺介质的影响

吡喹酮是一种新型广谱抗寄生虫药。本文报道用高效液相色谱-电化学检测器联用的方法,测定单胺类神经介质及其代谢物的含量,研究吡喹酮对大鼠单胺类介质的影响。结果表明:吡喹酮(250 mg/kg使脑DA的酸性代谢产物DOPAC,HVA和5-HT的代谢物5-HIAA的含量明显升高,而对DA和NA含量无明显影响。DA酸性代谢物和5-HIAA升高表明吡喹酮能增加DA和5-HT的转换率。     

吡喹酮对大鼠单胺介质的影响

吡喹酮是一种新型广谱抗寄生虫药。本文报道用高效液相色谱-电化学检测器联用的方法,测定单胺类神经介质及其代谢物的含量,研究吡喹酮对大鼠单胺类介质的影响。结果表明:吡喹酮(250 mg/kg使脑DA的酸性代谢产物DOPAC,HVA和5-HT的代谢物5-HIAA的含量明显升高,而对DA和NA含量无明显影响。DA酸性代谢物和5-HIAA升高表明吡喹酮能增加DA和5-HT的转换率     

Effect of conditioning with d-amphetamine on the extracellular concentration of dopamine and its metabolites in the striatum of behaving rats

The effect of classical conditioning with d-amphetamine on the extracellular concentrations of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum of awake, freely moving rats was studied using microdialysis. This was done in order to test, whether there occurred alterations in DA release as conditioned responses in the striatum. The first series of experiments studied the acute effects of d-amphetamine on the concentration of DA and its metabolites DOPAC and HVA. d-Amphetamine (2 mg/kg, s.c.) increased extracellular DA and decreased DOPAC and HVA. Behaviorally, it led to stereotyped locomotor activation and sniffing. In principle, these observations confirmed earlier findings. In a second series, conditioned responses to d-amphetamine were studied. Rats were implanted with guide cannulas prior conditioning experiments started. For conditioning experiments, the rats were divided into three groups: conditioned group, pseudoconditioned group and a drug-naive control group. After 7 daily training sessions with d-amphetamine (2 mg/kg), on the 8th day, the test day, rats were injected with saline and exposed to the conditional stimuli, while they were observed for their stereotyped, conditioned response. Additionally, microdialysis was performed in order to observe possible changes in the extracellular transmitter or metabolite concentrations. Conditioning with amphetamine led to conditioned stereotypic behavior. In comparison with the pseudoconditioned rats, there was an increase in DA release as conditioned response to amphetamine. In pseudoconditioned rats. DOPAC and HVA were slightly higher than in both other groups. DOPAC and HVA were lower in rats conditioned to d-amphetamine when compared with the pseudoconditioned ones. The results suggest that with regard to DA release, the conditioned responses to d-amphetamine mimicked the acute pharmacological responses. The same is valid for the DA metabolites, although in the opposite direction — they mimicked decreases. Furthermore, the conditioned DA responses to d-amphetamine might contribute to conditioned behavioral responses observed in these experiments. Correspondence to: K. Kuschinsky at the above address     

Electroconvulsive shock produces large increases in interstitial concentrations of dopamine in the rat striatum: an in vivo microdialysis study.

This study examined the effects of electroconvulsive shock (ECS) on interstitial concentrations of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), and the purine metabolite uric acid, in the striatum using on-line microdialysis in freely moving rats. Interstitial striatal DA increased to 1310% of baseline when the ECS was administered 18 to 24 hours after implantation of the dialysis probe. DOPAC (+ 19%), HVA (+ 30%), 5-HIAA (+10%), and uric acid (+111%) were increased to a smaller extent. The ECS-induced increase in DA was derived from a Ca++ sensitive pool since perfusion of a modified solution in which Ca++ had been replaced with Mg++ blocked this effect.     

Effects of neurotransmitters or drugs on the in vivo release of dopamine and its metabolites

The effects of neurotransmitters or drugs on the release of endogenous dopamine (DA) and extracellular levels of its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were examined in vivo by intracerebral dialysis. A dialysis tube was implanted stereotaxically through bilateral caudate nuclei of rats and perfused with the Ringer solution. Amounts of DA, DOPAC and HVA in the perfusates were measured by high performance liquid chromatography (HPLC) with electrochemical detection. The basal level of DA was 2.76 +/- 0.64 pg/min, whereas the levels of DOPAC and HVA were 218.7 +/- 20.7 and 142.4 +/- 10.6 pg/min, respectively. Apomorphine (4 mg/kg, i.v.) reduced the efflux of DA and its metabolites. Haloperidol (0.4 mg/kg, i.v.) did not change DA release and produced only a minor increase of its metabolites. This increase of metabolites was inhibited by pargyline. Met-enkephalin (10(-4) M), substance P (10(-4) M) and acetylcholine chloride (10(-4) M) added to the perfusing medium increased the release of DA. Met-enkephalin also increased the release of DOPAC. gamma-Amino-n-butyric acid (GABA, 10(-4) M) reduced the release of DOPAC and HVA when added to the perfusing medium. Thyrotropin releasing hormone (TRH, 5 mg/kg, i.v.) increased the release of HVA. These findings indicated that different mechanisms mediated effects of neurotransmitters or drugs on the release and metabolism of DA in the rat striatum.     

Chronic desipramine enhances amphetamine-induced increases in interstitial concentrations of dopamine in the nucleus accumbens

There is accumulating evidence that some antidepressant treatments can increase the functional output of the meso-accumbens dopaminergic system. For example, chronic administration of tricyclic antidepressant drugs such as imipramine and desipramine (DMI) enhances the locomotor stimulant effects of d-amphetamine. Subsensitivity of inhibitory dopamine (DA) autoreceptors and supersensitivity of postsynaptic DA receptor mechanisms are among the mechanisms that have been suggested to underlie these observations. The present experiments investigated the effects of acute and chronic DMI treatment on interstitial DA concentrations in the nucleus accumbens and striatum using in vivo microdialysis in awake freely moving rats (48 h following implantation of a microdialysis probe). Neither acute (5 mg/kg b.i.d. for 2 days followed by 72 h withdrawal) nor chronic (5 mg/kg b.i.d. for 21 days followed by 72 h withdrawal) DMI influenced the ability of apomorphine (25 micrograms/kg s.c.) to decrease extracellular concentrations of DA or its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the nucleus accumbens. In contrast, d-amphetamine (1.5 mg/kg s.c.)-induced increases in extracellular DA were significantly enhanced in the nucleus accumbens of the chronic but not the acute DMI group. This effect was at least partially regionally selective, as significant effects were not observed in the striatum. In accordance with previous reports, the locomotor stimulant effects of d-amphetamine were also enhanced in the chronic DMI groups. DMI itself failed to alter the interstitial concentrations of DA and its metabolites in the nucleus accumbens of the control and chronic DMI groups. These results provide in vivo neurochemical confirmation that chronically administered DMI does not produce DA autoreceptor subsensitivity. They also demonstrate that chronic DMI-induced increases in the locomotor stimulant effects of d-amphetamine are accompanied by a selective potentiation of the effects of this stimulant on interstitial DA concentrations in the nucleus accumbens.     

Acetyl-L-carnitine releases dopamine in rat corpus striatum: an in vivo microdialysis study.

The effect of acetyl-L-carnitine, a compound reported to be beneficial for senile patients, on the release of dopamine (DA) from the striatum was studied by using in vivo brain dialysis in anesthetized rats coupled with HPLC-electrochemical detection. Striatal infusion of acetyl-L-carnitine increased the efflux of DA with no apparent changes in efflux of DA metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxyphenylacetic acid (HVA). The DA-releasing effect of acetyl-L-carnitine was concentration- and Ca(2+)-dependent, and was abolished by omega-conotoxin fraction GVIA and tetrodotoxin, inhibitors of the voltage-dependent Ca2+ and Na+ channels, respectively. Nomifensine, an inhibitor of DA reuptake did not alter the DA-releasing property of acetyl-L-carnitine. DA released from the striatum by acetyl-L-carnitine was decreased by reserpine pretreatment whereas the d-amphetamine-evoked DA outflow was not affected. In contrast to acetyl-L-carnitine, d-amphetamine reduced the extracellular concentrations of DOPAC and HVA. We conclude from the present data that acetyl-L-carnitine evokes DA release from the vesicular pools of the nigrostriatal dopaminergic neurons by a Ca(2+)-dependent, exocytotic process.     

Involvement of opioid mu1-receptors in opioid-induced acceleration of striatal and limbic dopaminergic transmission.

The role of mu1-opioid receptors in the acceleration of cerebral dopaminergic transmission induced by morphine and the putative mu1-opioid agonist, etonitazene, was studied in rats by measuring the tissue levels of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the dorsal striatum and nucleus accumbens. The striatal extracellular concentrations of DA and its metabolites in freely moving rats were estimated as well. Morphine (3 mg/kg) and etonitazene (2.5 microg/kg) increased the striatal and accumbal dopamine metabolism as measured by the tissue ratios of DOPAC/DA and HVA/DA. The mu1-opioid receptor antagonist, naloxonazine (15 mg/kg), significantly antagonized these elevations except the morphine-induced elevation of striatal HVA/DA ratio. Both morphine (3 mg/kg) and etonitazene (1, 2.5, and 5 microg/kg) elevated the striatal extracellular DA, DOPAC, and HVA. Naloxonazine antagonized the effects of morphine and etonitazene on striatal extracellular DA concentration as well as etonitazene's effects on DOPAC and HVA, but not morphine's effects on DOPAC and HVA. As we previously showed concerning morphine, the conditioned place preference induced by etonitazene was inhibited by naloxonazine. These findings emphasize the role of mu1-opioid receptors in opioid reward, in which the mesolimbic dopaminergic system is considered to be importantly involved. Our results clearly show that in addition to the mesolimbic dopaminergic system the mu1-opioid receptors are also involved in the control of nigrostriatal DA release and metabolism. However, the effects of etonitazene on the striatal DA differ from those of morphine, suggesting that the opioid mechanisms regulating these two DA systems differ.     

On the mechanism of d-amphetamine-induced changes in glutamate, ascorbic acid and uric acid release in the striatum of freely moving rats

1. The effects of systemic, intrastriatal or intranigral administration of d-amphetamine on glutamate, aspartate, ascorbic acid (AA), uric acid, dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in dialysates from the striatum of freely-moving rats were evaluated using microdialysis. 2. d-Amphetamine (2 mg kg-1) given subcutaneously (s.c.) increased DA, AA and uric acid and decreased DOPAC + HVA, glutamate and aspartate dialysate concentrations over a 3 h period after d-amphetamine. 5-HIAA concentrations were unaffected. Individual changes in glutamate and AA dialysate concentrations were negatively correlated. 3. d-Amphetamine (0.2 mM), given intrastriatally, increased DA and decreased DOPAC + HVA and aspartate dialysate concentrations, but failed to change those of glutamate, AA uric acid or 5-HIAA, over a 2 h period after d-amphetamine. Haloperidol (0.1 mM), given intrastriatally, increased aspartate concentrations without affecting those of glutamate or AA. 4. d-Amphetamine (0.2 mM), given intranigrally, increased AA and uric acid dialysate concentrations and decreased those of glutamate, aspartate and DA; DOPAC + HVA and 5-HIAA concentrations were unaffected. 5. These results suggest that d-amphetamine-induced increases in AA and uric acid and decreases in glutamate concentrations are triggered at nigral sites. The changes in aspartate levels may be evoked by at least two mechanisms: striatal (mediated by inhibitory dopaminergic receptors) and nigral (activation of amino acid carrier-mediated uptake).     

Effect of low-dose sulpiride on dopamine metabolism in rat nucleus accumbens and locomotor activity: studies with intracerebral dialysis]

Changes in the concentration of dopamine (DA) and its metabolites, 3, 4-dihydroxyphenyl-acetic acid (DOPAC) and homovanillic acid (HVA), were determined sequentially in freely moving rats by using a brain dialysis method. The purpose of this study was to investigate the relationship between changes in the dopamine metabolism in the nucleus accumbens and locomotor activities following low-dose (5 mg/kg) sulpiride administration. The DA content in the dialysis fluid rose significantly 4 to 6 h after sulpiride administration. The DOPAC content rose significantly 6 h after sulpiride administration. The HVA content did not show a significant change. A slight increase of locomotor activity was found, but it was not statistically significant. The elevation of DA release in nucleus accumbens by sulpiride might relate to the clinical efficacy of low-dose administration of this drug for mood disorders.     

Modification of the striatal dopaminergic neuron system by carbon monoxide exposure in free-moving rats,as determined by in vivo brain microdialysis

Acute carbon monoxide (CO) intoxication in humans results in motor deficits, which resemble those in Parkinson's disease, suggesting possible disturbance of the central dopaminergic (DAergic) neuronal system by CO exposure. In the present study, therefore, we explored the effects of CO exposure on the DAergic neuronal system in the striatum of freely moving rats by means of in vivo brain microdialysis. Exposure of rats to CO (up to 0.3%) for 40 min caused an increase in extracellular dopamine (DA) levels and a decrease in extracellular levels of its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the striatum depending on the CO concentration. Reoxygenation following termination of the CO exposure resulted in a decline of DA to the control level and an overshoot in the recovery of DOPAC and HVA to levels higher than the control. A monoamine oxidase type A (MAO-A) inhibitor, clorgyline, significantly potentiated the CO-induced increase in DA and completely abolished the subsequent overshoot in the recovery of DOPAC and HVA. Tetrodotoxin, a Na(+) channel blocker, completely abolished both the CO-induced increase in DA and the overshoot of DOPAC and HVA. A DA uptake inhibitor, nomifensine, strongly potentiated the CO-induced increase in DA without affecting the subsequent overshoot of DOPAC and HVA. Clorgyline further potentiated the effect of nomifensine on the CO-induced increase in DA, although a slight overshoot of DOPAC and HVA appeared. These findings suggest that (1) CO exposure may stimulate Na(+)-dependent DA release in addition to suppressing DA metabolism, resulting in a marked increase in extracellular DA in rat striatum, and (2) CO withdrawal and subsequent reoxygenation may enhance the oxidative metabolism, preferentially mediated by MAO-A, of the increased extracellular DA. In the light of the neurotoxicity of DA per se and reactive substances, such as quinones and activated oxygen species, generated via DA oxidation, the significant modification of the striatal DAergic neuronal system by CO exposure might participate in the neurological outcome following acute CO intoxication.     

Dopamine in the basal ganglia and benzodiazepine-induced sedation

The effects of the anxiolytic benzodiazepine flurazepam on motor activity and the turnover of dopamine were measured in rats. Changes in motor activity were measured using a doppler-shift device; changes in extracellular homovanillic acid (HVA), monitored by linear sweep voltammetry with carbon paste electrodes implanted in the striatum and nucleus accumbens and ex vivo measurements of changes in 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratios in the striatum and nucleus accumbens were used as indices of changes in the turnover of dopamine. Injection of vehicle increased the nocturnal rise in the concentration of HVA and the ex vivo DOPAC/DA ratio in the nucleus accumbens. Injection of flurazepam decreased the nocturnal rise in HVA and DOPAC/DA ratio in the nucleus accumbens below control levels. There was also a decrease in the nocturnal rise in motor activity. Neither injection of vehicle nor injection of flurazepam caused changes in either the concentration of HVA or the DOPAC/DA ratio in the striatum. The correlation coefficient for motor activity compared to concentration of HVA remained high for the nucleus accumbens but was reduced for the striatum after administration of flurazepam. The results suggest that the sedative effect of flurazepam may be due to an action on the mesolimbic but not the nigrostriatal dopaminergic pathway.