A Comparison of Oral and Rectal Absorption of L-Dopa Esters in Rats and Mice

Short-chain alkyl esters of L-dopa were administered to rats and mice via oral and rectal routes. Plasma L-dopa esters and L-dopa were determined in the systemic and portal circulation by HPLC. A comparison of isopropyl, butyl, and 4-hydroxybutyl esters of L-dopa demonstrated significantly higher levels of the esters in both systemic and portal blood samples following rectal administration than following oral administration. In most cases, oral administration resulted in nondetectable (<0.01 µg/ml) levels of the esters in plasma. Correspondingly, the plasma levels of L-dopa itself were consistently higher following rectal administration. At very high oral doses (500 mg L-dopa equivalents/kg body weight), systemic plasma levels of the butyl ester could be detected (1.25 µg/ml at 10 min), which might indicate saturation of the esterase activity of the small intestine. These studies indicate that the systemic availability of L-dopa from short-chain alkyl esters of L-dopa may be best optimized by rectal administration, which avoids the relatively high esterase activity characteristic of the small intestine.     

Cytochemical manifestations of short- and long-term activation of the rat brain dopaminergic system

Laboratory of Cytochemistry, Brain Research Institute, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR O. S. Adrianov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 7, pp. 41–42, July, 1991.     

Potentiation of central effects of L-dopa by an inhibitor of catechol-O-methyltransferase

Summary The effects of a COMT-inhibitor, U-0521, and a MAO-B-inhibitor, l-deprenyl, on L-dopa-induced circling behaviour were compared in 6-OHDA-lesioned rats. The actions of U-0521 and l-deprenyl on the anticataleptic effect of L-dopa were also studied. Both U-0521 and l-deprenyl were found to potentiate L-dopa-induced circling behaviour and anticataleptic effect of L-dopa. In both test systems the L-dopa potentiation of l-deprenyl was longer-lasting than that caused by U-0521. Thus inhibition of COMT, like inhibition of MAO, is able to enhance the central effects of L-dopa. This principle might be beneficial in the treatment of Parkinson's disease especially if COMT-inhibitors with greater performance can be developed.     

对左旋多巴长期治疗帕金森病的评价

很多研究证明长期应用左旋多巴(L-dopa)治疗帕金森病(PD),可明显改善PD患者的症状,而且应该在PD的早期应用适量的左旋多巴进行治疗,以改善患者的早期症状。长期应用左旋多巴治疗PD与长期应用多巴胺受体激动剂对疾病导致的病死率相同。长期应用多巴胺受体激动剂治疗PD的疗效与长期应用左旋多巴相同,前者并未显示出优越性。     

A Rat Model of Striatonigral Degeneration Generated by Simultaneous Injection of 6-Hydroxydopamine into the Medial Forebrain Bundle and Quinolinic Acid into the Striatum

A double toxin-double lesion strategy is well-known to generate a rat model of striatonigral degeneration (SND) such as multiple system atrophy-parkinsonian type. However, with this model it is difficult to distinguish SND from Parkinson''s disease (PD). In this study, we propose a new rat model of SND, which is generated by simultaneous injection of 6-hydroxydopamine into the medial forebrain bundle and quinolinic acid into the striatum. Stepping tests performed 30 min after intraperitoneal L-dopa administration at 6 weeks post-surgery revealed an L-dopa response in the PD group but not the SND group. Apomorphine-induced rotation tests revealed no rotational bias in the SND group, which persisted for 2 months, but contralateral rotations in the PD group. MicroPET scans revealed glucose hypometabolism and dopamine transporter impairment on the lesioned striatum in the SND group. Tyrosine hydroxylase immunostaining in the SND group revealed that 74.7% of nigral cells on the lesioned side were lost after lesion surgery. These results suggest that the proposed simultaneous double toxin-double lesion method successfully created a rat model of SND that had behavioral outcomes, multitracer microPET evaluation, and histological aspects consistent with SND pathology. This model will be useful for future study of SND.     

小剂量左旋多巴上调pCREB及CD39蛋白表达发挥抗氧化应激损伤作用的研究

目的明确左旋多巴对PC12细胞生长及应激状态下存活的影响,探讨其抗氧化应激损伤的机制。方法不同浓度左旋多巴处理PC12细胞,用MTT法检测PC12细胞增长率及加入过氧化氢后细胞存活率;免疫荧光、Western blot方法测定磷酸化环单磷酸腺苷反应元件结合蛋白(pCREB)及CD39蛋白表达。结果低浓度左旋多巴(20μmol·L-1)促进PC12细胞生长,且可抗氧化应激损伤,而蛋白激酶抑制剂减弱此保护作用。免疫荧光及Western blot结果显示CD39及pCREB表达升高。结论低浓度左旋多巴可通过上调CD39及pCREB表达发挥抗氧化应激神经保护作用。     

左旋多巴激发试验在生长发育迟缓儿童中的临床价值

目的探讨左旋多巴激发试验在生长发育迟缓儿童中的临床价值。方法对生长发育迟缓儿童采用左旋多巴激发试验,生长激素测定采用化学发光法。结果(1)生长激素的峰值在左旋多巴激发后30和60 m in出现最多(P<0.01);(2)生长激素完全缺乏者占29.8%,部分缺乏占55.3%,而完全不缺乏者仅占14.9%。结论儿童生长发育迟缓大多数是由于生长激素缺乏或部分缺乏所致。左旋多巴激发试验可作为临床诊断侏儒症的方法之一。     

成年人的多巴反应性肌张力失常

目的 加强对多巴反应性肌张力失常的认识和重视。方法 回顾近2年我们诊治的3例成年人DRD患者之临床表现、辅助检查与治疗。结果 3例均为女性,无家族史。发病年龄14～29岁,平均20±7.94岁,平均误诊时间29.33±15.95年。表现为缓慢起病,四肢发僵,活动困难或伴有肢体震颤,足趾屈曲、内翻畸形;症状呈晨轻暮重。查体发现四肢肌张力强直性或齿轮样增高,双下肢腱反射活跃至亢进,1例病理征可疑阳性和脊柱前屈。辅助检查:血清学检查、CSF、头颅CT或MRI和神经电生理检查均正常。用小剂量复方左旋多巴有显著改善,平均剂量为98.21±49.17mg/d,使用最长者已达14年,无需增加剂量。结论 本病为少见的运动障碍疾病,在诊断中应与帕金森病鉴別。小剂量复方左旋多巴有显著、持久的疗效,早期应用安坦、金刚烷胺也有效。     

Repeated administration of the monoamine reuptake inhibitor BTS 74 398 induces ipsilateral circling in the 6-hydroxydopamine lesioned rat without sensitizing motor behaviours

BTS 74 398 (1-[1-(3,4-dichlorophenyl)cyclobutyl]-2-(3-diaminethylaminopropylthio)ethanone monocitrate) is a monoamine reuptake inhibitor that reverses motor deficits in MPTP-treated (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) common marmosets without provoking established dyskinesia. However, it is not known whether BTS 74 398 primes the basal ganglia for dyskinesia induction. In this study, the ability of BTS 74 398 to sensitize 6-hydroxydopamine (6-OHDA)-lesioned rats for the production of abnormal motor behaviours and the induction of striatal DeltaFosB were determined in comparison with l-3,4-dihydroxyphenylalanine methyl ester (L-dopa). Acute administration of BTS 74 398 induced a dose-dependent ipsilateral circling response in unilaterally 6-OHDA-lesioned rats whereas L-dopa produced dose-dependent contraversive rotation. The ipsilateral circling response to BTS 74 398 did not alter during 21 days of administration. In contrast, L-dopa treatment for 21 days caused a marked increase in rotational response. Repeated administration of both L-dopa and BTS 74 398 increased general motor activity and stereotypic behaviour. In L-dopa-treated rats, orolingual, locomotive, forelimb and axial abnormal movements developed whereas BTS 74 398 produced only locomotion with a side bias but no other abnormal movements. Sensitization of circling responses and the development of abnormal movements in 6-OHDA-lesioned rats have been associated with the potential of dopaminergic drugs to induce dyskinesia. Furthermore, striatal DeltaFosB immunoreactivity, shown to correlate with dyskinesia induction, was increased by L-dopa but was unaffected by repeated BTS 74 398 administration. The lack of such changes following repeated BTS 74 398 treatment suggests that it may be an effective antiparkinsonian therapy that is unlikely to produce involuntary movements.