Objective      To investigate the ascorbic acid (AA)-induced differentiation of neural stem cells (NSCs) to dopaminergic neurons and explore the mechanism preliminarily.       Methods      NSCs derived from 12.5 d rat embryo mesencephalon were maintained and amplified. Cells were divided into a control group and AA-induced groups with AA concentration of 1

10

50

100 μmol/L

and 200 μmol/L. The different

iation results of NSCs to dopaminergic neurons in the groups were compared. Immunocytochemistry was carried out to identify NSCs and cell differentiation. The mRNA expression levels of tyrosine hydroxylase (TH)

dopamine transporter (DAT)

SHH

Nurr1

and Ptx3 were tested by RT-PCR. PD98059

an ERK inhibitor

was added during AA-induced differentiation to study the ERK pathway’s role.       Results      A large number of nestin-positive neurospheres were obtained. Comparing with the control

AA treatment led to a higher degree of dopaminergic differentiation. TH- and DAT-positive cells were increased by about 30-50 folds in the 100 μmol/L AA  group as compared to the control group (

P

0.05). The induction of AA enhanced the mRNA expression of Nurr1

SHH

TH

and DAT. PD98059 could block the mRNA expression of Nurr1

TH

and DAT but not affect the expression of SHH mRNA after AA induction (

P

0.05).       Conclusion      AA can induce differentiation of NSCs into dopaminergic neurons. ERK cascade may be one of the pathways involved in AA-induced dopaminergic differentiation. Nurr1 gene may be the downstream gene of ERK pathway or involved in ERK pathway.