Changes in dopamine, serotonin and their metabolites in brain microdialysates from rats following exposure to new psychoactive drugs

New psychoactive drugs (NPDs), or so-called "designer drugs" are chemically transformed compounds of traditional drugs of abuse for the purpose of evading crackdown. The abuse of NPDs is a significant social problem and threatens public health; however, few studies on their effects on the central nervous system have been conducted. Microdialysis is a useful in vivo sampling technique in neurochemistry because it enables monitoring of synaptic release of neurotransmitters by drug exposure or other stimuli in real time. Dopamine (DA) and serotonin (5-HT) are important neurotransmitters associated with drug abuse and addiction. In this study, changes of DA, 5-HT and their metabolites in brain microdialysates from rats following exposure to selected 11 NPDs (MPA, 5-APDB, PCA, alpha-PVT, AB-PINACA, QUPIC, 5-fluoropentyl-3-pyridinoylindole, AMT, NMT, 4-OH-DET and desoxy-D2PM, 0.3, 1 and 3 mg/kg, consecutively, intraperitoneally) were investigated using a validated liquid chromatography -tandem mass spectrometry method. Most NPDs affected the extracellular levels of DA, 5-HT and/or their metabolites, showing consistent changes depending on the groups of chemical structures, such as amphetamines, synthetic cannabinoids and tryptamines. Significant DA and/or 5-HT increases were observed for all the amphetamine analogues. Weak fluctuations of DA and/or 5-HT concentrations were observed following exposure to synthetic cannabinoids and more severe fluctuations were shown by the tryptamines. The current results could be used as the preliminary data for further research concerning monoamine neurotransmitter-related mechanisms of NPDs. Moreover, the understanding gained from this research could be helpful to monitor the liability of NPD abuse and addiction.