title: Nigrostriatal dopaminergic neurons remain undamaged in rats given high doses of L-DOPA and carbidopa chronically.
abstract: Rats were fed maximally tolerated doses of L-3,4-Dihydroxyphenylalanine (L-DOPA) and carbidopa daily for 120 days in order to achieve a sustained elevation in brain dopamine levels. Some animals were also given buthionine sulfoximine, a gamma-glutamylcysteine synthetase inhibitor, in an unsuccessful effort to reduce brain glutathione contents. L-DOPA- and carbidopa-treated animals displayed no behavioral changes suggestive of nigrostriatal dopaminergic neuronal loss. When sacrificed 60 days after L-DOPA treatment ended, all rats had normal tyrosine hydroxylase activities and dopamine contents in their striata, and cell counts were normal in the substantia nigra. It therefore seems unlikely that a model of Parkinson's disease, suitable for exploring the etiological importance of glutathione deficiency, can be produced in rats merely by administering the largest tolerable doses of L-DOPA.
mesh_terms: D000818:Animals; D019328:Buthionine Sulfoximine; D002230:Carbidopa / Q000494:pharmacology*; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D005978:Glutathione / Q000378:metabolism; D007980:Levodopa / Q000494:pharmacology*; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013378:Substantia Nigra / Q000166:cytology / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D008717:Methionine Sulfoximine; D007980:Levodopa; D019328:Buthionine Sulfoximine; D014446:Tyrosine 3-Monooxygenase; D005978:Glutathione; D002230:Carbidopa; D004298:Dopamine