Electroacupuncture (EA) has been used in China for many years to treat Parkinson’s disease (PD) with reportedly effective results. However, the physiological and biological mechanism behind its effectiveness is still unknown. In the present study, different frequencies of chronic EA stimulation (0, 2, 100 Hz) were tested in a partially lesioned rat model of PD which was induced by transection of the medial forebrain bundle (MFB). After 24 sessions of EA stimulation (28 days after MFB transection), dopaminergic neurons in the ventral midbrain were examined by immunohistochemical staining, and brain-derived neurotrophic factor (BDNF) mRNA levels in ventral midbrain were measured by in situ hybridization. The results show a marked decrease of dopaminergic neurons on the lesioned side of the substantia nigra (SN) comparing with the unlesioned side. Zero Hz and 2 Hz EA stimulation had no effect on the disappearance of dopaminergic neurons. However, after 100 Hz EA, about 60% of the tyrosine hydroxylase (TH)-positive neurons remained on the lesioned side of the SN. In addition, levels of BDNF mRNA in the SN and ventral tegmental area (VTA) of the lesioned side were significantly increased in the 100 Hz EA group, but unchanged in the 0 and 2 Hz groups. Our results suggest that long-term high-frequency EA is effective in halting the degeneration of dopaminergic neurons in the SN and up-regulating the levels of BDNF mRNA in the subfields of the ventral midbrain. Activation of endogenous neurotrophins by EA may be involved in the regeneration of the injured dopaminergic neurons, which may underlie the effectiveness of EA in the treatment of PD.

Microglia are believed to participate in the mediation of neurodegeneration through producing a variety of cytotoxic factors upon activation. Pharmacological intervention inmicroglial activation may therefore exert a neuroprotective effect. In exploring pharmacological agents that can effect microglial activation, we found in this study that triptolide possesses a powerful inhibitory influence over microglia. Pretreatment with triptolide was able to dose-dependently reduce the lipopolysaccharide (LPS)-induced nitrite accumulation and tumor necrosis factor-a and interleukin-1

Through producing a variety of cytotoxic factors upon activation, microglia are believed to participate in the mediation ofneurodegeneration. Intervention against microglial activation may therefore exert a neuroprotective effect. Our previous study has shown thatthe electro-acupuncture (EA) stimulation at 100Hz can protect axotomized dopaminergic neurons from degeneration. To explore theunderlying mechanism, the effects of 100 Hz EA stimulation on medial forebrain bundle (MFB) axotomy-induced microglial activation wereinvestigated. Complement receptor 3 (CR3) immunohistochemical staining revealed that 24 sessions of 100Hz EA stimulation (28 days afterMFB transection) significantly inhibited the activation of microglia in the substantia nigra pars compacta (SNpc) induced by MFBtransection. Moreover, 100 Hz EA stimulation obviously inhibited the upregulation of the levels of tumor necrosis factor (TNF)-a andinterleukin (IL)-1h mRNA in the ventral midbrains in MFB-transected rats, as revealed by reverse transcriptase polymerase chain reaction(RT-PCR). ED1 immunohistochemical staining showed that a large number of macrophages appeared in the substantia nigra (SN) 14 daysafter MFB transection. The number of macrophages decreased by 47% in the rats that received 12 sessions of EA simulation after MFBtransection. These data indicate that the neuroprotective role of 100Hz EA stimulation on dopaminergic neurons in MFB-transected rats islikely to be mediated by suppressing axotomy-induced inflammatory responses. Taken together with our previous results, this study suggeststhat the neuroprotective effect of EA on the dopaminergic neurons may stem from the collaboration of its anti-inflammatory and neurotrophicactions.D 2004 Elsevier Inc. All rights reserved.

Neural progenitor cells have shown the effectiveness in the treatment of Parkinson's disease, but the therapeutic efficacy remains variable. One of important factors that determine the efficacy is the necessity of pre-differentiation of progenitor cells into dopaminergic neuronsbefore transplantation. This study therefore investigated the therapeutic efficacy of mesencephalon-derived human neural progenitor cellswith or without the pre-differentiation in alleviating a rat model of Parkinson's disease.We found that a combination of 50ng/ml fibroblastgrowth factor 8, 10ng/ml glial cell line-derived neurotrophic factor and 10M forskolin facilitated the differentiation of human fetalmesencephalic progenitor cells into dopaminergic neurons in vitro. More importantly, after transplanted into the striatum of parkinsonianrats, only pre-differentiated grafts resulted in an elevated production of dopamine in the transplanted site and the amelioration of behavioralimpairments of the parkinsonian rats. Unlike pre-differentiated progenitors, grafted intact progenitors rarely differentiated into dopaminergicneurons in vivo and emigrated actively away from the transplanted site.These data demonstrates the importance of pre-differentiation of human progenitor cells before transplantation in enhancing therapeuticpotency for Parkinson's disease.

This study investigated the proliferation and differentiation of adult neural progenitor cells (aNPCs) derived from the striatum and substantianigra (SN) of parkinsonian rats. We found that aNPCs isolated from the two areas of parkinsonian rats readily formed nestin-enrichedneurospheres in vitro and exhibited an ability to differentiate into either neurons or astrocytes. Injection of epidermal growth factor (EGF)and basic fibroblast growth factor (bFGF) into the striatum of parkinsonian rats prior to the harvesting striatal aNPCs significantly increasedthe neurosphere formation rate and multiple differentiation capacity of these aNPCs when cultured in vitro. These data suggest that striataland nigral adult NPCs in parkinsonian rats retain the abilities of proliferation and differentiation in vitro. In addition, exogenously appliedgrowth factors could up-regulate the developmental potential of aNPCs. We conclude that our data supports the notion that endogenous cellreplacement therapies may be useful for the future treatment of Parkinson’s disease (PD).