An immunohistochemical and stereological analysis of PSI-induced nigral neuronal degeneration in the rat
Version of Record online: 2 FEB 2009
© 2009 The Authors. Journal Compilation © 2009 International Society for Neurochemistry
Journal of Neurochemistry
Volume 109, Issue 1, pages 52–59, April 2009
How to Cite
Bukhatwa, S., Iravani, M. M., Zeng, B.-Y., Cooper, J. D., Rose, S. and Jenner, P. (2009), An immunohistochemical and stereological analysis of PSI-induced nigral neuronal degeneration in the rat. Journal of Neurochemistry, 109: 52–59. doi: 10.1111/j.1471-4159.2009.05956.x
- Issue online: 9 MAR 2009
- Version of Record online: 2 FEB 2009
- Received October 28, 2008; revised manuscript received December 17, 2008; accepted December 22, 2008.
- dopaminergic neurones;
- Parkinson’s disease;
- proteasomal inhibitor I;
- substantia nigra
Systemic administration of the proteasomal inhibitor I (PSI) to rats was reported to cause progressive nigral dopaminergic neuronal loss but this is disputed. A major controversy centres over the use of manual counting of tyrosine hydroxylase (TH) positive neurons at the level of third cranial nerve as opposed to employing systematic stereological analysis of cell loss in the entire substantia nigra (SN). To provide a method of marking SN neurones independent of protein expression, fluorogold™ (FG) was stereotaxically injected bilaterally into the striatum of male Wistar rats to retrogradely label nigral dopaminergic neurons. After 1 week, animals were treated with six doses of PSI (8 mg/kg, s.c.) or its vehicle (dimethyl sulphoxide) on alternate days over a 2-week period. Five weeks after the last treatment, PSI-treated animals showed decreased spontaneous locomotor activity and reduced TH positive SN cell number at the level of the third cranial nerve compared to control rats. Manual cell counting showed loss of FG-labelled SN neurones at this level, with a subpopulation of surviving neurons displaying abnormal morphology. Manual counting of all FG-labelled cells in the entire SN also showed regional PSI-induced loss of neurones with both normal and compromised morphology. Stereological optical fractionator estimates of total FG-labelled cell number confirmed the manual cell counting data both at the level of the third cranial nerve and throughout the entire SN. These findings confirm that PSI does cause a persistent nigral dopaminergic neuronal loss. The reason for the lack of reproducibility between laboratories requires further investigation. We suggest that a failure to distinguish between TH-positive neurones with normal and abnormal morphology following PSI administration contributes to equivocal results.