| Objective: To investigate the relevance between behavioral changes and pathologic degeneration, and further to observe induction of HSP70 in the different encephalic region of rat model of parkinson's disease(PD) induced by proteasome inhibitor, so as to explore neuro-protection of heat shock proteins in parkinson's disease.Methods: (1) Lactacystin (2μl/10μg), 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 in different stages. (3) The spontaneous motor behavioral changes in the open-field were observed in different stages, and behavioral parameters during different stages tested were as follows: total ambulation time, total resting time, total number of rearing, distance covered in frids the number of spontaneous left and right quarter-turns, the number of left and right forelimb use when leanning against the wall in rearing and the number of runs along the walls of the open-field with left or right side of the animals. (4) The pathologic abnormalities of substantia nigra were viewed by HE staining in different stages. (5) The morphological changes of the TH-positive cells in substantia nigral pars compacta were viewed by immunohistochemistry in different stages and TH-positive cells in SNc were counted. (6) The amount and distribution ofα-synuclein proteins in nigral cells were viewed by immunohistochemistry in different stages, and making the measure of the OD of it. (7) The number of TH-positive nerve fibers in striatum was investigated by immunohistochemistry in different stages, and making the measure of the OD of it. (8) The induction of HSP70 in different encephalic region of rat model of parkinson's disease was viewed by immunohistochemistry in different stages, and making the measure of the OD of it. (9) The mRNA induction of HSP70 in different encephalic region of rat model of parkinson's disease was detected by RT-PCR in different stages.Results: (1) The rats with administration of Lactacystin became progressively bradykinetic and displayed contralateral heading tilting, tremor, showing these syndrome till the eighteenth day. The rotation to contralateral after APO-induction was decreasing along with the time, obvious rotation increasing in the seventh day, and the number of rotation up to (213.8±11.2)r/30min and (264.7±9.3)r/30min in the eighteenth and 21-st day respectively. (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 progressively.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 progressively. (3) It was viewed that the number of neurons in the left SNc decreased in Lactacystin group and some nigral cells contained eosinophilic inclusions by the HE staining, compared with the contral SNc and saline groups by obvious significance ( F= 185.443, p < 0.05 ) .(4) The number of TH-positive cells in the left SNc in Lactacystin group decreased significantly, with soma shrinkage and cloudiness structure, the number decreasing by 54.21% and 82.37% till the 14-th and 21-st day respectively by significance p<0.05. (5) The amount ofα-synuclein proteins in the neurons of left SNc increased in Lactacystin group progressively, showing round-helix aggregation with intense immunoreactivity forα-synuclein and thick endochylema, compared with control group with extremely rare and disperse immunoreactivity forα-synuclein, the OD of which in Lactacytin groups was significant by F=47.732, p < 0.05. (6) The number of TH-positive nerve fibers in left striatum was much less than this in right striatum in Lactacystin group progressively, compared with the contral SNc and saline groups by obvious significance p < 0.05.(7) The behavioural changes of rats in Lactacystin groups were driven by the accumulation ofα-synuclein, not by the decreased TH neurons, by statistics. (8) In the Lactacystin lanes, the expressions of HSP70 are more than the control ones by immunohistochemistry, with sequence of HSP70 magnitude of hippocampus > substantia nigra > corpus striatum > frontal lobe > olfactory tract, without expression in corpus callosum, especially with the distribution of HSP70 in CA3>CA2>CA1.(9) The induction of HSP70 in Lactacystin-treated groups was stronger than the contral groups in different encephalic region by means of RT-PCR analysis, the sequence of different encephalic region and the time-dependence of induction were the same as the immunohistochemistry above.Conclusion: The behavioral changes of Parkinson's disease were driven by a -synuclein inclusion formation obviously, but not by decreased TH neurons , in addition, the induction of hsp70 is up-regulated in different encephalic region of rat models induced by proteasome inhibition, demonstrating significant time dependence, the increased heat shock proteins may involved in the role of protecting the neurons from Lactacystin-induced intoxitation by antagonism, and improving retrograde changes of behavior and pathology in Parkinson's disease.
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