Background: The mechanism of major depressive disorder (MDD) is not fully understood. Consequently, it is currently only possible to diagnose depression at a subjective level and it would thus be of great clinical importance to identify biomarkers of MDD to aid the diagnosis. Recently, it has been shown that the combined miRNA-mRNA profile in human dermal fibroblasts might lead to the discovery of promising peripheral biomarkers in MDD.
Objectives: In selected rat models of depression (stress and genetic), miRNA/mRNA extracted directly from rat-skin and rat dermal fibroblasts will be compared and investigated as peripheral biomarkers of MDD. A list of miRNA/mRNA targets have been compiled from the published human study.
Methods: The methods of this project aim to collect skin tissue and purify RNA from skin/fibroblasts for subsequent real-time qPCR analysis. This includes establishment of fibroblast cultures, high quantity and quality RNA extraction from skin and fibroblast cultures, cDNA synthesis, target election/primer design, real-time qPCR and statistical analysis.
Results: Several miRNAs from the human study are significantly different in the animal models of depression compared to a control, both in skin and fibroblasts. In addition, some miRNAs were not normalized in treatment resistant rats after treatment.
Conclusion: Animal studies are performed under increasingly controlled conditions compared to human studies. Fewer significant miRNAs were found in the animal models which could indicate increased specificity. The loss of normalization in treatment resistant rats further validates these miRNAs’ relationship with depression.