BACKGROUND:It has been reported that the conversion of neural stem cells into dopaminergic neurons in vitro can be increased through specific cytokine combinations. Such neural stem cell-derived dopaminergic neurons could be used for the treatment of Parkinson’s disease. However, little is known about the differences in dopaminergic differentiation between neural stem cells derived from adult and embryonic rats. OBJECTIVE: To study the ability of rat adult and embryonic-derived neural stem cells to differentiate into dopaminergic neurons in vitro. DESIGN: Randomized grouping design. SETTING: Department of Neurosurgery in the First Affiliated Hospital of Sun Yat-sen University. MATERIALS: This experiment was performed at the Surgical Laboratory in the First Affiliated Hospital of Sun Yat-sen University (Guangzhou, Guangdong, China) from June to December 2007. Eight, adult, male, Sprague Dawley rats and eight, pregnant, Sprague Dawley rats (embryonic day 14 or 15) were provided by the Experimental Animal Center of Sun Yat-sen University. METHODS: Neural stem cells derived from adult and embryonic rats were respectively cultivated in serum-free culture medium containing epidermal growth factor and basic fibroblast growth factor. After passaging, neural stem cells were differentiated in medium containing interleukin-1α, interleukin-11, human leukemia inhibition factor, and glial cell line-derived neurotrophic factor. Six days later, cells were analyzed by immunocytochemistry and flow cytometry. MAIN OUTCOME MEASURES: Alterations in cellular morphology after differentiation of neural stem cells derived from adult and embryonic rats; and percentage of tyrosine hydroxylase-positive neurons in the differentiated cells. RESULTS: Neural stem cells derived from adult and embryonic rats were cultivated in differentiation medium. Six days later, differentiated cells were immunoreactive for tyrosine hydroxylase. The percentage of tyrosine hydroxylase positive neurons was (5.6 ± 2.8)% and (17.8 ± 4.2)% for adult and embryonic cells, respectively, with a significant difference between the groups (P < 0.01). CONCLUSION: Neural stem cells from embryonic rats have a higher capacity to differentiate into dopaminergic neurons than neural stem cells derived from adult rats. BACKGROUND: It has been reported that the conversion of neural stem cells into dopaminergic neurons in vitro can be increased through specific cytokine combinations. These, neural stem cell-derived dopaminergic neurons could be used for the treatment of Parkinson’s disease. However, little is known about the differences in dopaminergic differentiation between neural stem cells derived from adult and embryonic rats. OBJECTIVE: To study the ability of rat adult and embryonic-derived neural stem cells to differentiate into dopaminergic neurons in vitro. Neurosurgery in the First Affiliated Hospital of Sun Yat-sen University. MATERIALS: This experiment was performed at the Surgical Laboratory in the First Affiliated Hospital of Sun Yat-sen University (Guangzhou, Guangdong, China) from June to December 2007. Eight, adult , male, Sprague Dawley rats and eight, pregnant, Sprague Dawley rats (embryonic day 14 or 15) were provided by the METHODS Animal Neural of Sun Yat-sen University. METHODS: Neural stem cells derived from adult and embryonic rats were cultivated in serum-free culture medium containing epidermal growth factor and basic fibroblast growth factor. After passaging, neural stem cells were differentiated in medium containing interleukin-1α, interleukin-11, human leukemia inhibition factor, and glial cell line-derived neurotrophic factor. Six days later, cells were analyzed by immunocytochemistry and flow cytometry. MAIN OUTCOME MEASURES: Alterations in cellular morphology after differentiation of neural stem cells derived from adult and embryonic rats; and percentage of tyrosine hydroxylase-positive neurons in the differentiated cells. RESULTS: Neural stem cells derived from adult and embryonic rats were cultivated in differentiation medium. Six days later, differentiated cells were immunoreactive for tyrosine hydroxylase. percentage of tyrosine hydroxylase positive neurons was (5.6 ± 2.8)% and (17.8 ± 4.2)% for adult and embryonic cells, respectively, with a significant difference between the groups (P <0.01). CONCLUSION: Neural stem cells from embryonic rats have a higher capacity to differentiate into dopaminergic neurons than neural stem cells derived from adult rats.