Safranal-promoted differentiation and survival of dopaminergic neurons in an animal model of Parkinson’s disease

Context: Safranal (SAF) is verified to have potential effects in promoting nerve growth. Objectives: This study verifies the role of SAF in promoting dopaminergic neurons growth in vitro and in vivo. Material and methods: Rat neural stem cells (NSC) were treated with 1, 20, or 100 ng/mL of SAF, and the expression levels of tyrosine hydroxylase (TH) and dopamine transporter (DAT) were assayed by flow cytometry and real-time PCR and the secretion of dopamine (DA) was assayed by ELISA. Then, 2 × 10(6) cells of SAF-treated NSC was administrated into PD rat models induced by 6-OHDA. The differentiation and survival of dopaminergic neurons was identified by fluorescence microscope and TH(+) cells by immunostaining and DA secretion by ELISA at week 2 and week 4, respectively. Results: After being treated with SAF at 20 and 100 ng/mL for 1 week, TH and DAT positive rates increased 1.4- and 1.7-fold (p < 0.01, respectively). TH and DAT mRNA also increased 8.05- and 4.41-fold, respectively. And the release of DA statistically increased 1.5-fold (p < 0.01). In vivo, the number of rotations decreased to 4.33 ± 0.97 rpm (p < 0.01) and the survival rates increased to 77.66 ± 7.87% (p < 0.05) at week 4 after transplantation of SAF-treated NSC. Moreover, the transplanted cells increased three-fold, TH fluorescence density increased four-fold and DA releases increased 1.4-fold (p < 0.01) at week 4 after transplantation. Conclusions: SAF promoted the production of functional DA cells and alleviated PD, which may contribute to a new therapy for PD patients.