Effect of baicalein on brain injury induced by 6-hydroxydopamine at different sites in rats / 中国药理学通报

ABSTRACT

Aim To explore the therapeutical effect and mechanism of baicalein on two 6-hydroxydopamine (6-OHDA ) induced Parkinson′s disease (PD ) rat models,which received unilateral lesions of the left medial forebrain bundle (MFB ) or caudate putamen (CPu ) made by stereotaxic injection of 6-OHDA (MFB-M,CPu-M).Methods PD rat models were established by microinjection of 6-OHDA into MFB or CPu.The anti-tremor effect of baicalein on PD rat models was examined.Spontaneous activity was recor-ded. Dopamine (DA ), dihydroxyphenylacetic acid (DOPAC)and homovanilic acid (HVA)in striatum were quantified by HPLC-ECD.The tyrosine hydroxy-lase (TH)and OX-42 positive cells were detected by immunohistochemical method.The morphological vari-ation of the neurons was confirmed by analysis at an ul-trastructural level.Results Baicalein significantly in-creased the spontaneous activity in CPu-M.The elec-tromyography (EMG ) recordings revealed that com-pared with 6-OHDA group,the tremor frequency in ba-icalein group was decreased by 55% in MFB-M,and by 60% in CPu-M.6-OHDA treatment decreased DA levels in the striatum,while treatment with baicalein attenuated the DA decreases in CPu-M.Moreover,ba-icalein treatment could increase TH-positive neurons and decrease OX-42-postive microglia compared with 6-OHDA group in both MFB-M and CPu-M.Conclu-sions In the present study,it is illustrated that ①microinjection of 6-OHDA into the MFB and the CPu could cause different pathological changes of PD, which is important for efficacy evaluation;②baicalein showed the ability to alleviate the behavior symptoms in PD-rats at different stages by improving motor function and attenuating muscle tremor;③therapeutic effect of baicalein was produced by inhibiting the inflammatory medium production and release,anti-apoptosis,chan-ging dopamine catabolism, and inhibiting dopamine turnover.