The Degeneration Of Dopaminergic Neurons And Changes Of Inducible Nitric Oxide Synthase Induced By The Inhibitor Of Proteasome

Objective:To observe the motor behavior changes and the degeneration of dopaminergic neurons and changes of inducible nitricoxide synthase induced by the inhibitor of proteasome,and to investigate the role of proteasomal dysfunction in the pathogenesis of Parkinson's Disease as well as whether the changes of inducible nitric oxide synthase are involved in the degeneration of DA neurons induced by proteasome dysfunction.Methods:(1)10μg/2μlLactacystin,a selective proteasome inhibitor,was unilaterally injected stereotaxically into the left substantia nigral pars compacta of rats.Equal volume of saline were injected in control group.(2)The spontaneous behavioral abnormalities and apomorphine-induced contralateral rotations of rats were observed. (3)The spontaneous motor behavioral changes in the open-field were observed,and behavioral parameters tested were as follows:total ambulation time,total resting time, total number of rearings,distance covered in grids,the number of spontaneous left and right quarter-turns,the number of left and right forelimb use when leaning against the wall in rearing and the number of runs along the walls of the open-field with left of right side of the animals.(4)The degeneration of dopaminergic neurons and changes of inducible nitric oxide synthase at different time points(1d,3d,1w,3w ) in the substantia nigra were detected by immunohistochemistry. Results:(1)The rats became progressively bradykinetic and displayed contralateral head tilting,tremor and apomorphine-induced contralateral rotation 7 days after Lactacystin injection.On the 21st day after the injection of Lactacystin,the number of apomorphine-induced contralateral rotations in 30 minutes was 258.90±11.56.(2) Total ambulation time,total resting time,total number of rearings and distance covered in grids were less in the Lactacystin group compared with saline group.The numbers of spontaneous left quarter-turns,left forelimb use when leaning against the wall in rearing and runs along the walls of the open-field with left side of the animals were significantly more than those of right side.(3) The number of TH-positive cells in the left SNc significantly decreased in the 3ws group.The numbers of iNOS positive cells in the left SNc increased dramatically after 1 d with Lactacystin injection and peaked in the 3rd day,since the 7th day it began to decrease and disappeared nearly at the 21th day after the administration of Lactacystin.Conclusion:10μg /2μl Lactacystin,a selective proteasome inhibitor,unilaterally injected stereotaxically into the left substantia nigral pars compacta of rats,can induce motor behavioral changes just like the clinical symptoms of PD.The dysfunction of Proteasome may play a triggered role in the pathogenesis of PD.Up-regulation of iNOS may be one of the crucial mechanisms in Lactacystin-induced degeneration of DA neurons.