RESUMO
Objective To investigate dynamic changes in extracellular striatal 5-hydroxy indole acetic acid (5-HIAA) and melatonin (MLT) concentrations in the 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease (PD) rat models.Methods A hemiparkinsonium rat model was established by a unilateral injection of 6-OHDA into the right substantia nigra pars compacta (SNc) and the right medial forebrain bundle (MFB).Dialysate samples were collected at 10:00 in the lesioned striatum by microdialysis at 1,2,3 and 4 weeks post-lesion,respectively.The levels of dopamine (DA) and 5-HIAA,as well as MLT in dialysate sanples were measured by high performance liquid chromotorgraphy (HPLC).Results One week after surgery,the level of DA in PD group was (1.19±0.22) ng/ml,which was distinctly lower than those in the vehicle group ((8.62 ± 0.73) ng/ml) and the sham group ((8.73 ± 0.78) ng/ml) (P ＜ 0.01).The levels of 5-HIAA in PD group had a downward trend,but there were no significant differences.The level of MLT in PD group was (43.31 ± 11.37) pg/ml at 4 weeks post-lesion,and significantly higher than those in the vehicle group ((19.13 ± 5.38)pg/ml) and the sham group ((19.80 ± 6.96) pg/ml) (P＜ 0.05).The striatal dialysate DA and 5-HIAA concentrations had a good positive correlation in the PD group (r =0.867,P ＜ 0.01).Conclusion Decreased DA level concomitantly with changes of 5-HIAA and MLT in the ipsilateral striatum of 6-OHDA-induced PD rats,and these changes may be related to PD progression.