The expression of TPH2 in median raphe nuclei in depression model rats

Abstract

Objective To explore changes of the content of 5-hydrexytryptamine (5-HT) in hippocampns and the relative expression of tryptophan hydroxylase 2 (TPH2) in raphe nuclei in rats of depression model. Methods Twenty female Sprague-Daw]ey rats were randomly divided into two groups (10 in each), normal group and model group, the later was given living alone in combination with 21 day chronic unexpected mild stress (CUMS). Open-field test was used to evaluate behavioral change, the high performance liquid chromatngram-electrocbemical detection, hemi-qnantitative reverse transcriptionpolymerase chain reaction and immunofluorescence were employed to measure 5-HT in hippocampus, to detect the relative expression of TPH2 mRNA and number of TPH2 immunoreactive neurons in raphe nuclei. Results After 21 days of CUMS, beth crossing and rearing in model rats were significantly lower than that in control rats in Open-field test. Compared with the control group, hippocampal 5-HT content was decreased in rats of depression model, and so were the relative expression of TPH2 mRNA and number of TPH2 immunoreactive neurons in raphe nuclei. Conclusion Living alone in combination with 21 days of CUMS could induce rats into depression model, the decrease of hippocampal 5-HT content might result from the decrease of TPH2 expression in raphe nuclei, which led to lower the synthesis of 5-HT. Key words: Stress; Depression; Serotoanin; Tryptophan hydroxylase