Effects of serotonin 5-HT1A agonist in advanced Parkinson's disease.
Intermittent stimulation of striatal dopaminergic receptors seems to contribute to motor dysfunction in advanced Parkinson's disease (PD). With severe dopaminergic denervation, exogenous levodopa is largely decarboxylated to dopamine in serotonergic terminals. If 5-HT1A autoreceptors regulate dopamine as well as serotonin release, in parkinsonian patients inhibition of striatal serotonergic neuron firing might help maintain more physiological intrasynaptic dopamine concentrations and thus ameliorate motor fluctuations and dyskinesias. To evaluate this hypothesis, effects of a selective 5-HT1A agonist, sarizotan, given orally at 2 and 5 mg twice daily to 18 relatively advanced parkinsonian patients, were compared with baseline placebo function during a 3-week, double-blind, placebo-controlled, proof-of-concept study. Sarizotan alone or with intravenous levodopa had no effect on parkinsonian severity. But at safe and tolerable doses, sarizotan coadministration reduced levodopa-induced dyskinesias and prolonged its antiparkinsonian response (P < or = 0.05). Under the conditions of this study, our findings suggest that 5-HT1A receptor stimulation in levodopa-treated parkinsonian patients can modulate striatal dopaminergic function and that 5-HT1A agonists may be useful as levodopa adjuvants in the treatment of PD.
Bara-Jimenez
William
W
Experimental Therapeutics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA. baraw@ninds.nih.gov
Bibbiani
Francesco
F
Morris
Michael J
MJ
Dimitrova
Tzvetelina
T
Sherzai
Abdullah
A
Mouradian
Maral M
MM
Chase
Thomas N
TN
D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004341:Drug Evaluation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009930:Organic Chemicals; D010300:Parkinson Disease / Q000188:drug therapy*; D058825:Serotonin 5-HT1 Receptor Agonists; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000978:Antiparkinson Agents; D009930:Organic Chemicals; D058825:Serotonin 5-HT1 Receptor Agonists; C443959:sarizotan