cDNA was synthesized by using a reverse transcription kit SuperScript III First-Strand Synthesis System for Real Time Polymerase chain reaction (RT-PCR) (Invitrogen) according to the manufacturer's recommendations. Real-time polymerase chain reaction (PCR) was used to quantify the levels of mRNA expression of 10 genes in day 32 dopaminergic populations. PCR reactions were carried out by ABI 900HT instrument according to the manufacturer's instructions. Primer sequences were previously described [5].
