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(Perhaps some of you missed this posting which contradicts everything we have always been told, but apparently is valid -- nina) ========== Chronic LD not toxic, may promote neural recovery Date: 1/19/99 Chronic levodopa is not toxic for remaining dopamine neurons, but instead promotes their recovery, in rats with moderate nigrostriatal lesions MG Murer, G Dziewczapolski, LB Menalled, MC Garcia, Y Agid, O Gershanik, R Raisman-Vozari Annals of Neurology, 1998, Vol 43, Iss 5, pp 561-575 Six months of oral l-dopa caused no excess loss of dopaminergic neurons versus untreated controls, and may have promoted recovery of surviving neurons, according to this study on OHDA-lesioned rats. Rats were unilaterally injected with either saline or one of two quantities of OHDA (to produce moderate vs. severe lesions). Members of each group were randomly assigned to receive either vehicle or oral l-dopa. Neuronal survival was quantified by immunoautoradiography of tyrosine hydroxylase, vesicular monoamine transporter, and dopamine transporter. Results showed: a) L-dopa treatment caused no loss of dopaminergic neurons in either sham-lesioned or OHDA-lesioned rats compared to sham-lesioned, non-treated controls b) L-dopa treatment caused no reduction in terminal axonal arborization c) In the moderately lesioned group, treated rats showed, "in the denervated regions of the striatum, significantly higher levels of the three dopaminergic markers than their corresponding vehicle-treated control group, and also an increased density of TH-immunoreactive fibers." The authors suggest the recovery is likely to be due to axonal sprouting of surviving dopaminergic neurons. They also note that their study provided no evidence of accompanying functional recovery in this subgroup. In discussing the relevance of these findings to human PD patients, they state "our results cannot be considered as definitive evidence of an absence of toxicity of chronic levodopa in PD patients" but note that other recent findings support the absence of l-dopa toxicity as well. An editorial by Stanley Fahn accompanies the article. ---------------------------------------------------------------------------- ---- Copyright 2000 WE MOVE Editor: Richard Robinson ([log in to unmask]) This service is provided free of charge to the Internet community, courtesy of WEMOVE.org. This document may be freely redistributed by email only in its unedited form. We encourage you to share it with your colleagues. ================== ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn