Emerging evidence suggest that neuromodulators are the critical factor involved in depression. This study aimed to investigate the effects of unpredictable chronic mild stress (CUMS) and n-3 polyunsaturated fatty acids (n-3 PUFAs) on central nervous system. The depressive-like behaviors induced by CUMS were assessed by sucrose preference test (SPT), open field test (OFT) and forced swimming test (FST). High-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was used to quantify the levels of neurotransmitters and their metabolites involved in serotonergic, dopaminergic, noradrenergic, GABAergic neurotransmitter systems in hippocampus and prefrontal cortex. Repeated CUMS caused depressive-like behaviors of rats, associated with the alteration of neurotransmitters in brain, including the decreasing DA level, the increasing NE and GABA level, and the increasing 5-HT turnover rate in hippocampus, which could be partly alleviated by sufficient n-3 PUFAs supplementation. The influence of stress and diet on neurotransmitters in the prefrontal cortex was slight. However, it was obvious that supplementary of n-3 PUFAs relieved the decreasing DA/NE between-metabolite ratio 1,2 and DA/5-HT between-metabolite ratio 1,2 in the prefrontal cortex caused by CUMS. Altered neurotransmitter turnover rates and between-metabolite ratios in brain may be better predictors in depression and antidepressant treatment compared with monoamine neurotransmitters.
Keywords: Behaviors; Between-metabolite ratio; CUMS; Depression; Turnover rate; n-3 PUFAs.
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