Dysregulation of circadian clock gene expression patterns in a treatment-resistant animal model of depression.

Circadian rhythm (CR) disturbances are among the most commonly observed symptoms during major depressive disorder, mostly in the form of disrupted sleeping patterns. However, several other measurable parameters, such as plasma hormone rhythms and differential expression of circadian clock genes (ccgs), are also present, often referred to as circadian phase markers. In the recent years, CR disturbances have been recognized as an essential aspect of depression; however, most of the known animal models of depression have yet to be evaluated for their eligibility to model CR disturbances. In this study, we investigate the potential of adrenocorticotropic hormone (ACTH)-treated animals as a disease model for research in CR disturbances in treatment-resistant depression. For this purpose, we evaluate the changes in several circadian phase markers, including plasma concentrations of corticosterone, ACTH, and melatonin, as well as gene expression patterns of 13 selected ccgs at 3 different time points, in both peripheral and central tissues. We observed no impact on plasma corticosterone and melatonin concentrations in the ACTH rats compared to vehicle. However, the expression pattern of several ccgs was affected in the ACTH rats compared to vehicle. In the hippocampus, 10 ccgs were affected by ACTH treatment, whereas in the adrenal glands, 5 ccgs were affected and in the prefrontal cortex, hypothalamus and liver 4 ccgs were regulated. In the blood, only 1 gene was affected. Individual tissues showed changes in different ccgs, but the expression of Bmal1, Per1, and Per2 were most generally affected. Collectively, the results presented here indicate that the ACTH animal model displays dysregulation of a number of phase markers suggesting the model may be appropriate for future studies into CR disturbances.

Dysregulation of miR-185, miR-193a, and miR-450a in the skin are linked to the depressive phenotype.

BACKGROUND: Dysregulated microRNAs (miRNAs) in dermal fibroblasts of depressive subjects, indicate biomarker potential and can possibly aid clinical diagnostics. To overcome methodological challenges related to human experiments and fibroblast cultures, we here validate 38 miRNAs previously observed to be dysregulated in human fibroblasts from depressed subjects, in the skin of four distinct rat models of depression. METHODS: In the presented study male rats from the adrenocorticotropic hormone (ACTH) model (n = 10/group), the chronic mild stress model (n = 10/group), Wistar Kyoto/Wistar Hannover rats (n = 10/group), and Flinders Resistant/Flinders Sensitive Line rats (n = 8/group) were included. Real-time qPCR was utilized to investigate miRNA alterations in flash-frozen skin-biopsies from the ear and fibroblast cultures. RESULTS: In the ACTH rat model of depression, we identified nine dysregulated miRNAs in the skin and three in the fibroblasts. As the skin presented three times the amount of dysregulated miRNAs compared to the fibroblasts, skin instead of fibroblasts were continuously used for studies with the other rat models. In the skin from the four rat models of depression, 15 out of 38 miRNAs re-exhibited significant dysregulation in at least one of the rat models of depression and 67% were regulated in the same direction as in the human study. miR-450a and miR-193a presented dysregulation across rat models and miR-193a and miR-185 exhibited very strong dysregulation (30-fold and 50-fold, respectively). Lastly, an Ingenuity Pathway Analysis indicated functional overlap between dysregulated miRNAs, and common regulated pathways. CONCLUSION: Flash-frozen skin is a valid alternative to fibroblast cultures as the skin appear to retain more of the miRNA dysregulation present in vivo. A sub-population of 15 miRNAs appear to be specific for the depressive phenotype, as they are dysregulated in both human depressed patients and distinct rat models of depression. We propose miR-450a, miR-185, and miR-193a as biomarker candidates of particular interest.

No influence of OPG and its ligands, RANKL and TRAIL, on proliferation and regulation of the calcification process in primary human vascular smooth muscle cells.

The aim of this study was to examine the effects of the OPG-RANKL-TRAIL system on proliferation, regulation of calcification-associated genes and calcification of human vascular smooth muscle cells (HVSMCs). Small interfering (si)RNA-mediated knockdown of OPG was followed by treatment of HVSMCs with recombinant RANKL or TRAIL. Regulation of a calcification-associated gene set was assayed by pathway analysis of microarray results. The lack of OPG in HVSMCs or treatment with RANKL or TRAIL did not affect proliferation of HVSMCs. In addition, OPG, RANKL or TRAIL did not modify the regulation of a calcification-associated gene set. Finally, in the long term calcification assay, we found that cells isolated from seven different human donors showed a great variability in the response to RANKL and insulin. However, overall RANKL and/or insulin did not affect the development of calcification of HVSMCs. These studies indicate that OPG knockdown does not alter the calcification process in HVSMCs.