Accumulation of alpha-synuclein (A-SYN) in dopaminergic neurons plays an important role in the development of both genetic and sporadic Parkinson’s disease (PD). The missense mutation A30P in the A-SYN gene causes abnormal A-SYN metabolism and accumulation in familial PD. A single stereotaxic injection into rat substantia nigra (pars compacta, SNpc) of the A30P mutated form of A-SYN, fused to a TAT protein transduction domain, mimicks the early stages of the human PD, characterized by a loss of dopaminergic neurons in the SNpc, a decrease in striatal tissue dopamine (DA) and behavior impairment . Adult male Sprague–Dawley rats (250-310 g) were uses in this study. Rats were housed under controlled conditions of temperature and illumination until a single stereotaxic injection of A30P-A-SYN-TAT (5 µg/5 µL/10 min) was performed in the right SNpc under chloral hydrate anesthesia. Control rats received the same volume of vehicle at the same coordinates (sham). A second stereotaxyc surgery was performed in different groups of animals 6, 13 and 20 days after A30P-A-SYN-TAT/vehicle injection and a microdialysis probe was inserted in the right striatum. Microdialysis experiments were carried out 24h after surgery (on days 7, 14 and 21 after A30P-A-SYN-TAT/vehicle injections) and microdialysis samples were collected and analyzed using high performance liquid chromatography (HPLC). Baseline values of DA were recorded and a DA-releasing agent (nicotine) was added to the microdialytic perfusion fluid in order to study the amount of DA released from the striatal dopaminergic endings under pharmacological stimulation. On day 7, baseline levels of DA (2 ± 0.6 nM) decreased in the extracellular striatal compartment of A-SYN-treated rats (-75 ± 8% compared to vehicle groups; P<0.01) and maintained the same levels in the following two weeks (day 14 and 21). After local infusion of nicotine (5mM /60 min), extracellular DA increased of about. 85/95 times in sham animals, compared to basal levels, while in A-SYN-treated rats this overflow was limited to 50/60 times the baseline (-45/55%; P<0.01). Rats behavioral changes were similar to those previously described . The stable reduction both in DA baseline and the nicotine-induced increases in dialysate DA levels, suggests of a stable nigro-striatal lesion with a lack in dopaminergic neurochemical recovery, which, however, has been demonstrated in MPTP or 6-OH-DA models of PD . The described A-SYN model of PD may be useful for the study and characterization of the therapeutic effects of both drugs and neural stem cells  on both striatal extracellular DA levels and animals’ behavior.
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|Titolo:||MICRODIALYSIS STUDY OF STRIATAL DOPAMINE CHANGES IN A A-SYNUCLEIN-GENERATED RAT MODEL OF PARKINSON’S DISEASE|
|Data di pubblicazione:||2009|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|