Figure 6.

Schematic summary of the effects mediated by RA-NPs against MPTP-induced injury in the dopaminergic (DA) nigrostriatal pathway of adult and old mice. The i.p. injection of MPTP induced a decrease in TH DA neurons in SN and TH fibers in the striatum of adult mice (A-red color). This effect was accompanied by a decrease in mRNA expression of transcription factors involved in DA neuronal survival, Nurr1 and Pitx3, in SN and striatum of both age groups (A,B-red color). In the adult mice, the RA released from NPs protects the DA TH neurons in SN as well its neuronal TH fibers/axonal innervations in the striatum against MPTP-induced injury (A-green color). There was also an increase in Nurr1 and Pitx3 mRNA expression levels only in SN of adult mice (A-green color). Under the same conditions there was an increase in Pitx3 and Nurr1 mRNA expression in SN and striatum of old mice, respectively (B-green color).