Lymphocyte glucocorticoid receptor expression level and hormone-binding properties differ between war trauma-exposed men with and without PTSD

<p>Objective: Posttraumatic stress disorder (PTSD) has been shown to be associated with altered glucocorticoid receptor (GR) activity. We studied the expression and functional properties of the receptor in peripheral blood mononuclear cells (PBMCs) from non-traumatized healthy individuals (healthy controls; n = 85), and war trauma-exposed individuals with current PTSD (n = 113), with life-time PTSD (n = 61) and without PTSD (trauma controls; n = 88). The aim of the study was to distinguish the receptor alterations related to PTSD from those related to trauma itself or to resilience to PTSD.</p><p>Methods: Functional status of the receptor was assessed by radioligand binding and lysozyme synthesis inhibition assays. The level of GR gene expression was measured by quantitative PCR and immunoblotting.</p><p>Results: Current PTSD patients had the lowest, while trauma controls had the highest number of glucocorticoid binding sites (B-max) in PBMCs. Hormone-binding potential (B-max/K-D ratio) of the receptor was diminished in the current PTSD group in comparison to all other study groups. Correlation between B-max and K-D that normally exists in healthy individuals was decreased in the current PTSD group. Contrasting B-max data, GR protein level was lower in trauma controls than in participants with current or life-time PTSD.</p><p>Conclusions: Current PTSD is characterized by reduced lymphocyte GR hormone-binding potential and by disturbed compensation between B-max and hormone-binding affinity. Resilience to PTSD is associated with enlarged fraction of the receptor molecules capable of hormone binding, within the total receptor molecule population in PBMCs. (C) 2013 Elsevier Inc. All rights reserved.</p>

Phenotypic diversity, population structure and stress protein-based capacitoring in populations of Xeropicta derbentina, a heat-tolerant land snail species

The shell colour of many pulmonate land snail species is highly diverse. Besides a genetic basis, environmentally triggered epigenetic mechanisms including stress proteins as evolutionary capacitors are thought to influence such phenotypic diversity. In this study, we investigated the relationship of stress protein (Hsp70) levels with temperature stress tolerance, population structure and phenotypic diversity within and among different populations of a xerophilic Mediterranean snail species (Xeropicta derbentina). Hsp70 levels varied considerably among populations, and were significantly associated with shell colour diversity: individuals in populations exhibiting low diversity expressed higher Hsp70 levels both constitutively and under heat stress than those of phenotypically diverse populations. In contrast, population structure (cytochrome c oxidase subunit I gene) did not correlate with phenotypic diversity. However, genetic parameters (both within and among population differences) were able to explain variation in Hsp70 induction at elevated but non-pathologic temperatures. Our observation that (1) population structure had a high explanatory potential for Hsp70 induction and that (2) Hsp70 levels, in turn, correlated with phenotypic diversity while (3) population structure and phenotypic diversity failed to correlate provides empirical evidence for Hsp70 to act as a mediator between genotypic variation and phenotype and thus for chaperone-driven evolutionary capacitance in natural populations