title: Apoptotic mode of cell death in substantia nigra following intranigral infusion of the parkinsonian neurotoxin, MPP+ in Sprague-Dawley rats: cellular, molecular and ultrastructural evidences.
abstract: The potent parkinsonian neurotoxin 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) is known to cause dopaminergic neurodegeneration in nigrostriatal system. In the present study we investigated the nuclear morphology of cells in the substantia nigra pars compacta (SNpc) region of rats following unilateral intranigral infusion of the active metabolite, 1-methyl-4-phenyl pyridinium ion (MPP(+)), which resulted in a dose-dependent and prolonged dopamine depletion in the ipsilateral striatum. There appeared a substantial loss of tyrosine hydroxylase immunoreactive neurons in the SNpc that received the neurotoxin. Specific nuclear staining with Hoechst 33342 or acridine orange revealed bright pyknotic, shrunken, distorted nuclei and condensed chromatin with perinuclear nucleolus respectively following visualization with the former and latter dyes in the ipsilateral SNpc, as compared to the round, intact nuclei and centrally positioned nucleolus in the contralateral side. Ultrastructural details of the nucleus under transmission electron microscope confirmed distorted nuclear organization with shrunken or condensed nuclei and disrupted nuclear membrane. These features are typical of nucleus undergoing apoptosis, and suggest that MPP(+) causes dopaminergic neuronal death through an apoptotic mode. Typical laddering pattern of genomic DNA isolated from the ipsilateral SN in agarose gel electrophoresis conclusively established apoptosis following intranigral administration of MPP(+) in rats.
authors.affiliation: Division of Cell Biology and Physiology, Laboratory of Clinical and Experimental Neuroscience, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700 032, India.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Banerjee
authors.forename: Sen
authors.initials: S
authors.lastname: Sreetama
authors.forename: Karuppagounder S
authors.initials: KS
authors.lastname: Saravanan
authors.forename: Sailendra Nath
authors.initials: SN
authors.lastname: Dey
authors.forename: Kochupurackal P
authors.initials: KP
authors.lastname: Mohanakumar
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001562:Benzimidazoles / Q000378:metabolism; D016923:Cell Death / Q000502:physiology*; D003342:Corpus Striatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation; D004298:Dopamine / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009498:Neurotoxins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D001562:Benzimidazoles; D005456:Fluorescent Dyes; D009498:Neurotoxins; C017807:bisbenzimide ethoxide trihydrochloride; D015655:1-Methyl-4-phenylpyridinium; D004298:Dopamine