microRNA expression and opioid signaling. microRNA expression and opioid signaling

To study the relationship between microRNAs and μ-opioid receptor (MOR) signaling, we examined microRNA expression after chronic morphine or fentanyl treatment in rat primary hippocampal neurons and in mouse hippocampus. Mouse cerebellum region was also tested as a negative control to eliminate microRNA expression changes unrelated to MOR signaling, as the cerebellum is essentially devoid of MOR. We identified a number of microRNAs that altered their expression upon treatment with both morphine and fentanyl in the rat and mouse systems. There were, however, some microRNAs that changed in response to morphine, or fentanyl, but not both. Keywords: Expression profiling Overall design: There are up to three biological replicates (indicated by 1, 2, and 3) of primary hippocampal neurons from new born rats and the cerebellum and hippocampus regions from adult mice treated for three days (control, morphine, and fentanyl). The biological replicates were from experiments performed on different dates. Each biological replicate contained cells or tissues collected from multiple animals so that enough RNA could be extracted for RNA analysis. RNA was labelled with a green dye, mixed with a reference DNA sample labelled with a red dye. The reference DNA contained a number of synthetic DNA oligos with mature microRNA sequences that served to verify microarray hybridization. RNA signals were in ch1, DNA signals ch2.