Abstract
Intrastriatal application of 6-hydroxydopamine (6-OHDA) initiates a delayed and progressive loss of nigral dopaminergic neurons and therefore may better resemble the slowly developing neuropathology of Parkinson's disease. We investigated the anatomical, behavioural and biochemical consequences of intrastriatal 6-OHDA after prior labelling of nigral dopaminergic neurons in rats and whether the dihydropyridine L-type calcium channel blocker nimodipine protected from the induced deficits. Adult rats received bilateral intrastriatal injections of the retrograde fluorescence tracer fluorogold and nimodipine (n=12) or placebo (n=9) pellets implanted subcutaneously. One week later all rats were injected unilaterally with 6-OHDA (20 microg) at the same intrastriatal site. Placebo-treated rats displayed relatively few d-amphetamine-induced ipsilateral net rotations (R) (1.3+/-1.4 R/min; mean+/-SEM) 1 week after the lesion with a slight but non-significant decline thereafter (after 2, 3 and 4 weeks). In nimodipine-treated rats the rotation behaviour after 1 week was more prominent (3.5+/-0.8 R/min; mean+/-SEM) with a similar slight decline until week 4. Fluorescent and immunocytochemical analysis of the midbrain after 4 weeks revealed a 35% and 39% loss of tyrosine hydroxylase positive cells and a 62% and 56% (placebo and nimodipine, respectively) loss of fluorogold-labelled cells in the ipsilateral substantia nigra pars compacta. Striatal dopamine levels were reduced to 47% (placebo) and 43% (nimodipine) of the control side and the dopamine metabolites dihydroxyphenylacetic acid and homovanillic acid to about 50%. Pretreatment with nimodipine failed to antagonize or to ameliorate any of the lesion-induced deficits. We conclude that pretreatment with 80 mg nimodipine pellets does not prevent nigrostriatal damage induced by intrastriatal 6-OHDA.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
