The L-Dopa Story: Translational Neuroscience Ante Verbum
Total Page：16
File Type：pdf, Size：1020Kb
Article Clinical & Translational Neuroscience January-June 2018: 1–5 ª The Author(s) 2018 The L-dopa story: Translational Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/2514183X18765401 neuroscience ante verbum journals.sagepub.com/home/ctn Hans-Peter Ludin Abstract Since almost 50 years L-Dopa is the gold standard for the treatment of patients with Parkinson’s disease (PD). For the first time, a specific chemical abnormality was found in a specific brain disorder. It has been shown that the striatal dopamine (DA) content is greatly reduced in PD patients. The substitution of DA by its precursor L-dopa greatly enhanced the quality of life of PD patients. Keywords Parkinson’s disease, dopamine, L-dopa, history In the late 60s and the early 70s of the 20th century, the metabolized to dopamine (DA) by dopa decarboxylase.4 introduction of levodopa (L-dopa) in treatments markedly It is not surprising that his contribution, published in Ger- changed the fate of patients suffering from Parkinson’s man, received little attention at the time. Holtz and Cred- disease (PD) in Western countries. It was preceded by a ner5 have injected 50 mg of L-dopa intravenously to a series of antecedents during several decades. Nowadays, volunteer, resulting merely in an increase in the pulse rate. L-dopa combined with a decarboxylase inhibitor is the gold For a long time, DA was considered as a mere meta- standard treatment for PD. This conclusion has been bolic intermediate in the formation of the catecholamines reached along a long and winding path. adrenaline and noradrenaline. Only Carlsson et al.6,7 demonstrated that it is a neurotransmitter occurring on its own]. In animal experiments, ‘catalepsy’ induced by L-dopa and dopamine reserpine was completely abolished by L-dopa. It replen- ished brain DA depleted by reserpine. Sano et al.8 in Japan Dihydroxyphenylalanine (D,L-dopa) was first synthesized discovered that DA is normally highly concentrated in by Funk.1 Casimir Funk (1884–1967) was a Polish bioche- human brains. Bertler and Rosengren,9 working at Carls- mist. He worked in Berlin, Berne (where he wrote his son’s lab in Lund (Sweden), found the same in dog brains. doctoral thesis), London and the United States. He coined They showed that about 80% of the total brain DA was the term ‘vitamine’. The young Swiss chemist Markus concentrated in the striatum, especially in the caudate Guggenheim (1884–1967; Figure 1) at Hoffmann-La nucleus and the putamen. Roche isolated L-dopa from broad bean seeds (Vicia faba), Carlsson (Figure 2) was born in 1926 at Uppsala characterized it chemically and developed a simplified (Sweden), and he became a professor of pharmacology method for its synthesis.2 The substance was licensed by at the University of Gothenburg in 1959. In 2000, the Hoffmann-La Roche. In animal experiments, he could not detectanyobviouseffect.Onself-ingestingupto2.5gof Nobel Prize was awarded jointly to Arvid Carlsson, Paul L-dopa, Guggenheim developed minimal nausea and Greengard and Eric R. Kandel for their discoveries con- vomiting, and he observed no clinical use for it and the cerning signal transduction in the nervous system. Many substance disappeared in his drawer for many years. Later, neurologists and neuroscientists regretted that Oleh in his comprehensive textbook Die biogenen Amine,Gug- 3 genheim dedicated not more than two pages to L-dopa. Corresponding author: In 1939, just at the start of World War II, Peter Holtz Hans-Peter Ludin, Kra¨yigenweg 85, 3074 Muri b. Bern, Switzerland. (1902–1970) showed in Germany that L-dopa is Email: [email protected] Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). 2 Clinical & Translational Neuroscience Figure 3. Oleh Hornykiewicz (*1926). no appropriate project for him, he was recommended to Hugh (Hermann) Blaschko, another Germanemigr´ ´ e. Under Figure 1. Markus Guggenheim (1884–1967). his auspices, Hornykiewicz worked on the role of DA in peripheral tissues. Blaschko10 had argued that DA in addi- tion to being a metabolic intermediate may have ‘some regulatory functions of its own which are not yet known’. Back to Vienna, encouraged by Kathleen Montagu’s11 finding of DA in the brains of different animals and the above-mentioned papers by Sano et al.8 and by Bertler and Rosengren,9 Hornykiewicz decided to investigate DA in human brains. Together with his assistant Herbert Ehringer, he examined post-mortem brain material, 3–20 h after death, from 20 controls, 2 patients with Huntington’s chorea, 6 with other extrapyramidal diseases and 6 with PD (4 postencephalitic and 2 PD) with a rather insensitive colorimetric method. In the basal ganglia of controls as well as in the Huntington cases, they found high concentra- tions of DA, whereas it was diminished by a factor of approximately 10 only in the Parkinsonian patients.12 In 2007, Hornykiewcz stated, ‘For the first time, a specific chemical abnormality was found in a specific brain region in specific brain disorder ...’. A few months later, Barbeau et al.13 published that DA Figure 2. Arvid Carlsson (*1926). excretion in the urine of PD patients is reduced. Later, with a more sensitive spectrofluorometric Hornykiewicz was not awarded at the same time for his method, Hornykiewcz14 demonstrated DA depletion in the crucial contributions to the L-dopa treatment of patients pars compacta of substantia nigra. He concluded that the with PD. striatal DA deficiency is a consequence of the nigral cell Oleh Hornykiewicz (Figure 3) was born 1926 in Galicia, loss and that there must exist an anatomical connection at the time part of Poland, now in Ukraine. His father, an originating in the melanin-containing substantia nigra and orthodox priest, moved with his family to Vienna to escape terminating in the striatum. the Stalinist terror. After having learned German, he stud- ied medicine in Vienna after World War II. He graduated in 1953 and started to work at the Department of Pharmacol- Treating PD patients with L-dopa ogy, at the time chaired by Franz von Bru¨cke. He obtained Hornykiewicz was determined to replace the missing DA in a scholarship from the British Council with the intention to PD patients by L-dopa. He chose the intravenous route, work with the German-born physician, biochemist and which had been used successfully and without severe side Nobel Laureate Sir Hans Krebs in Oxford. As Krebs had effects by Degkwitz et al.15 in their attempt to overcome the Ludin 3 Figure 5. George Cotzias (1918–1977). Figure 4. Walther Birkmayer (1910–1996). George Cotzias (1918–1977; Figure 5) was born in the side effects of reserpine, and because he disposed only a Isle of Crete and started his medical studies at the Univer- very limited amount of L-dopa delivered by Hoffmann-La sity of Athens. Because he had served in the Greek army, he Roche in Basle. had to leave Greece in 1941 when the German army He contacted Walther Birkmayer (1910–1996; Figure 4), invaded Greece. He immigrated to the United States, and at the time head of the neurological ward of the Municipal despite initially speaking hardly a word of English, he was, Home for the aged in Lainz-Vienna that permanently eventually, able to continue his medical education at Har- housed PD patients, for collaboration. In the beginning, vard Medical School, where he graduated summa cum Birkmayer was not very enthusiastic and he delayed the laude in 1943. He came in contact with Parkinsonism when start of the project by 6 months. Later, he confessed that he was studying toxicity of manganese. Miners from Chile he was taking revenge because 2 years earlier Hornykie- excavating manganese suffered from Parkinsonism.29 wicz had refused to collaborate in a project which was not Cotzias was aware of the publications from Lund and appealing to him.16 Vienna; nevertheless, he started dopa treatment with They injected intravenously 50–150 mg of L-dopa in another goal than increasing striatal DA level. He suspected saline to 21 patients with PD or with postencephalitic Par- that melanin depletion was the major problem in PD. By kinsonism. The effect of a single injection was spectacular: giving precursors of melanin, such as melanocyte- Patients who had been almost completely immobilized were stimulating hormone, phenylalanine and dopa, he able to move almost freely. The effect on bradykinesia lasted attempted to increase nigral melanin concentration. Only from 3 to 24 h after a single injection. Intravenous injections dopa shows clinical improvement. Nowadays, it is gener- with chemically related substances (i.e. D-dopa, DA, 3-O- ally accepted that this concept was wrong. Cotzias et al.30 methyldopa, dihydroxyphenylalanine [DOPS], 5-hydroxy- later spoke of an ‘erroneous but fruitful hypothesis’. tryptophane [5-HTP]) resulted in no similar effect.17,18 Cotzias et al.27,28 first used D,L-dopa and later L-dopa in Subsequently, several authors reported similar effect daily doses up to 16 and 8 g, respectively. They started at with intravenous L-dopa (cited by Calne19). Two controlled low doses and gradually increased the daily dosage divided double-blind studies did not provide any therapeutic benefit in several small amounts. The highest level that could be from 1.5 mg/kg of intravenous L-dopa.20,21 Oral L-dopa in achieved in an individual patient was maintained over sev- PD patients gave rather controversial results (Greer and eral weeks.