Editing Substantia nigra (section)

===Levodopa===
{{See also|Levodopa}}
The substantia nigra is the target of chemical therapeutics for the treatment of Parkinson's disease. [[Levodopa]] (commonly referred to as L-DOPA), the dopamine precursor, is the most commonly prescribed medication for Parkinson's disease, despite controversy concerning the [[neurotoxicity]] of dopamine and L-DOPA.<ref name="pmid9017256">{{cite journal | vauthors = Cheng N, Maeda T, Kume T, Kaneko S, Kochiyama H, Akaike A, Goshima Y, Misu Y | title = Differential neurotoxicity induced by L-DOPA and dopamine in cultured striatal neurons | journal = Brain Research | volume = 743 | issue = 1–2 | pages = 278–83 | date = December 1996 | pmid = 9017256 | doi = 10.1016/S0006-8993(96)01056-6 | s2cid = 22529926 }}</ref> The drug is especially effective in treating patients in the early stages of Parkinson's, although it does lose its efficacy over time.<ref>{{cite journal | vauthors = Rascol O, Payoux P, Ory F, Ferreira JJ, Brefel-Courbon C, Montastruc JL | title = Limitations of current Parkinson's disease therapy | journal = Annals of Neurology | volume = 53 | pages = S3–12; discussion S12–5 | year = 2003 | issue = Suppl 3 | pmid = 12666094 | doi = 10.1002/ana.10513 | s2cid = 45078589 }}</ref> Levodopa can cross the [[blood–brain barrier]] and increases dopamine levels in the substantia nigra, thus alleviating the symptoms of Parkinson's disease. The drawback of levodopa treatment is that it treats the symptoms of Parkinson's (low dopamine levels), rather than the cause (the death of dopaminergic neurons in the substantia nigra).