CSF miR-16 expression and its association with miR-16 and serotonin transporter in the raphe of a rat model of depression

Background: Depression is a common mental disorder with unknown mechanism. Emerging evidence shows that miRNAs play a critical role in the process of depression. Here we reported the cerebrospinal fluid (CSF) miR-16 expression and its association with miR-16 and serotonin transporter (SERT) in the raphe of a rat model of depression. Methods: 20 rats were randomized to the control or CUMS (chronic unpredictable mild stress) group. The rats in the CUMS group underwent CUMS for 21 days, while those in the control group received no treatment. After anesthetization, CSF was collected for the measurement of miR-16. Then raphes from all rats were separated for determination of miR-16 and SERT protein. Results: The expression levels of miR-16 in CSF and raphe of the CUMS group were significantly lower than those of the control group (P=0.007 and 0.031). However, SERT protein in raphe of the CUMS group was obviously increased as compared that of the control group (P=0.005). There was a positive correlation between CSF miR-16 and raphe miR-16 (r=0.95, P=0.000). Meanwhile, negative correlations between miR-16 and SERT protein in raphe (r=-0.70 P=0.02), between CSF miR-16 and raphe SERT protein (r=-0.86, P=0.002) were observed in the CUMS group. Limitations: We have not explored the reason why CSF miR-16 was decreased in the rat model of depression and only tested the association of miR-16 between CSF and raphe. Conclusions: CSF miR-16 was involved in the pathogenesis of depression via reflecting raphe miR-16 level, and thus affecting raphe SERT expression.