Effects Of Glial Derived Neurotrophic Factor By Continuous Microperfusion On Parkinsonian Rats

Objective:To study the effects of GDNF in rotational behavior and dopamine neuron of the substantia nigra in 6-OHDA induced parkinsonian rats. Meanwhile, to investigate the effects of GDNF on gene expression of magnesium transporters SLC41A1 and Mag T1, and the density and function of DAT in the striatum of PD rats.Methods: A hemiparkinsonium rat PD model was established by a unilateral injection of 6-hydroxydopamine(6-OHDA) into the right medial forebrain bundle(MFB). For assessment of the severity of 6-OHDA-induced dopaminergic degeneration, apomorphine(APO)-induced contralateral rotational behavior was monitored after a single injection of APO(0.5 mg/kg, i.p.) at 2 and 6 weeks post 6-OHDA infusion respectively. Alzet pump was inserted in the right lateral ventricle(LV), and microperfusion GDNF continuously for 4 weeks after 2 weeks 6-OHDA lesioning. At the same time, Mg SO4(3.6 g/L Mg SO4 ? 7 H2O) was added to daily drinking water and raise for 4 weeks. The striatal DAT 99mTc-TRODAT-1 bindings were performed with a small-animal SPECT system at 6 weeks post lesion. The degree of dopaminergic neuron degeneration in substantia nigra was assessed by immunohistochemical analysis. The m RNA expressions of magnesium transporters(SLC41A1 and Mag T1) in striatum were detected by q-PCR.Results: 1. APO-induced rotation behavior there were no significant differences between the PD and PD treated groups at 2 weeks post lesion. However, the rotational behavior in both groups were significant higher than those in control(P<0.001). After 6 weeks, the rotational behavior in PD/Mg, PD/GDNF and PD/GDNF+Mg groups were significant decreased when compared with PD group(p< 0.05), especially in the PD/GDNF and PD/GDNF+Mg groups( p< 0.01). 2. The degree of dopaminergic neuron degeneration in substantia nigra on the unlesioned side of every group, the numbers of TH positive neurons were no statistical difference compared with the control. However, the numbers of TH positive neurons on the lesioned side in both PD and PD/ NS groups were significantly decreased comparing with the control(p<0.01). When compared with the PD group, the numbers of TH positive neuron in PD/Mg group were a rising trend, but there was no significant difference, and both the PD/GDNF and PD/GDNF+Mg groups were significantly increased(p<0.05). There were no significant differences between the PD/GDNF and PD/GDNF+Mg groups on the both sides. 3. The striatal DAT radioactivity after 6 weeks post-surgery there were no significant difference in the striatal DAT radioactivity between the unlesioned and lesioned sides in control. The striatal DAT radioactivity in PD group on both sides were significantly lower than those in control(the unesioned side p<0.05, and the lesioned side p< 0.01). The PD/Mg group was a slightly upward trend when compared with PD group, but there was no significant difference. The striatal DAT radioactivity in PD/GDNF group was significant higher than those in PD group on both sides(p<0.01).The DAT radioactivity in PD/GDNF+Mg was significantly increased compared with PD group on the lesioned side(p<0.05). 4. The m RNA expressions of SLC41A1 and Mag T1 the m RNA expressions of SLC41A1 and Mag T1 in PD group were significant higher than those in control on both sides at 6 weeks post-sugery(p<0.01).There were no significant differences between the lesioned and unlesioned sides in the control. The m RNA expression of SLC41A1 in PD/Mg group was significantly lower than those in the PD group on both sides(p<0.01). Both the PD/GDNF and PD/GDNF+Mg groups were significantly lower than those in the PD group on both sides as well(p<0.01). The m RNA expression of Mag T1 in the PD/GDNF and PD/GDNF+Mg groups were significantly lower than those in the PD group on both sides(p<0.01).Conclusion: 1. GDNF may improve the rotational behavior and protect dopaminergic neurons in 6-OHDA induced PD rat. 2. Continuous minipump can deliver drug into target directly. It is a relatively safe, simple operation and convenient methods for clinical. 3. There may be relevant between GDNF and the expression of magnesium transporters.