摘要：

The neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to generate a dose-dependent cell death of dopaminergic nigral neurons in the C57Bl mouse. Mice were injected with a total cumulative dose of 150 mg/kg of MPTP delivered over five days and killed at different time points both during and after the toxin injections. Two independent histological methods were used to determine whether the dopaminergic nigral neurons died via an apoptotic mechanism. <SPAN style="FONT-STYLE: italic">In situ </SPAN>end-labelling with terminal deoxynucleotidyl transferase was used on paraformaldehyde-fixed, serial, frozen sections to identify cells with double-stranded DNA breaks. Apoptotic cell death was found to be initiated within 72 h of the first injection of the neurotoxin and peaked 24 h after the final MPTP injection. The metachromatic fluorochrome, Acridine Orange, was used on alternate sections to provide structural confirmation of the nuclear chromatin "clumping" considered to be representative of apoptosis. Confocal laser imaging combined with deconvolution techniques was used to resolve the fluorescent signal emitted by the <SPAN style="FONT-STYLE: italic">in situ </SPAN>Acridine Orange–DNA complexes. The number of Acridine Orange-stained nuclei demonstrating chromatin clumping was identical to that of the positive <SPAN style="FONT-STYLE: italic">in situ </SPAN>end-labelled nuclei observed over a 25 day period. Based upon these two independent methods of assessing apoptosis <SPAN style="FONT-STYLE: italic">in situ,</SPAN> we conclude that a 150 mg/kg dose of MPTP can elicit apoptotic cell death in nigral dopaminergic neurons of the C57Bl mouse.

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