ABSTRACT
OBJECTIVE: To compare the expressions of miRNAs (microRNAs) in serum exosomes and in hippocampus and to provide insights into the miRNA-mediated relationship between peripheral and central nervous systems in the presence of methamphetamine. METHODS: Published results on conditioned place preference (CPP) in rats conditioned by methamphetamine were replicated. The expressions of miRNAs in serum exosomes and hippocampus were determined by gene-chip sequencing. We then predicted the potential target genes of selected, differentially expressed (DE) miRNAs and then carried out functional analysis of these target genes. We also verified our results by RT-qPCR. RESULTS: Methamphetamine reward could greatly increase the activity time and distance in the intrinsically nonpreferred side of the behavioral apparatus compared with control rats (P < 0.01). Rhynchophylline treatment significantly counteracted these changes (P < 0.01). Methamphetamine-induced CPP upregulated 23 miRNAs (log2 fold change [FC] > 1, P < 0.01) in serum exosomes, whereas rhynchophylline treatment could downregulate these miRNAs (log2 FC < -1, P < 0.01). Analysis of hippocampal miRNAs profiles found 22 DE miRNAs (log2 FC > 1 or <-1, P < 0.01). When methamphetamine induced CPP, 11 of those miRNAs were upregulated, whereas rhynchophylline treatment could downregulate these miRNAs. The other 11 miRNAs behaved in the opposite way. We selected six DE miRNAs from each of serum exosomes and hippocampus for target gene prediction and functional analysis. We found that, in both, the DE miRNAs and their target genes may be related to neuronal information transmission and synaptic transmission. CONCLUSIONS: Rhynchophylline blocked the alteration of behavior and the expression of some DE miRNAs induced by methamphetamine. The biological functions of these DE miRNAs target genes are correlated between serum exosomes and hippocampus. As to these biological processes and pathways which are involved in the development of addiction at multiple stages, we speculate that these DE miRNAs in serum exosomes and hippocampus are closely related to methamphetamine addiction.
ABSTRACT
Drug abuse is a public health and social problem. A number of studies have reported that drug addiction is associated with microRNAs (miRNAs). By comparing the expression of miRNAs in the serum exosomes of methamphetamine-dependent and ketamine-dependent rats, the aim of the present study was to provide insights into the miRNA-mediated associations between the two groups. Published results on conditioned place preference (CPP) in rats conditioned by methamphetamine and ketamine were replicated. The expression of miRNAs in serum exosomes were determined by gene-chip sequencing. The potential target genes of differentially expressed (DE) co-miRNAs were predicted in the methamphetamine and ketamine rats, then functional analysis of their target genes was performed. Methamphetamine and ketamine reward greatly increased the activity time and distance in the intrinsically non-preferred side of the behavioral apparatus when compared with controlled rats (P<0.01). In addition, methamphetamine upregulated the expression of 276 miRNAs and downregulated 25 miRNAs, while ketamine only downregulated the expression of 267 miRNAs. Ten DE co-miRNAs in the two model groups were identified. Functional analysis revealed that DE co-miRNAs are involved in the development of addiction at different stages, and their target genes were enriched in 'vesicular transport', 'amphetamine addiction', 'dopaminergic synapse' and 'GABAergic synapse'. Therefore, it was suggested that these co-miRNAs may have a strong association with drug addiction, and they may be involved in the different addiction processes, which partly explains methamphetamine and ketamine addiction.
