New insights into the intracellular distribution pattern of cationic amphiphilic drugs.

Cationic amphiphilic drugs (CADs) comprise a wide variety of different substance classes such as antidepressants, antipsychotics, and antiarrhythmics. It is well recognized that CADs accumulate in certain intracellular compartments leading to specific morphological changes of cells. So far, no adequate technique exists allowing for ultrastructural analysis of CAD in intact cells. Azidobupramine, a recently described multifunctional antidepressant analogue, allows for the first time to perform high-resolution studies of CADs on distribution pattern and morphological changes in intact cells. We showed here that the intracellular distribution pattern of azidobupramine strongly depends on drug concentration and exposure time. The mitochondrial compartment (mDsRed) and the late endo-lysosomal compartment (CD63-GFP) were the preferred localization sites at low to intermediate concentrations (i.e. 1 µM, 5 µM). In contrast, the autophagosomal compartment (LC3-GFP) can only be reached at high concentrations (10 µM) and long exposure times (72 hrs). At the morphological level, LC3-clustering became only prominent at high concentrations (10 µM), while changes in CD63 pattern already occurred at intermediate concentrations (5 µM). To our knowledge, this is the first study that establishes a link between intracellular CAD distribution pattern and morphological changes. Therewith, our results allow for gaining deeper understanding of intracellular effects of CADs.

Identification and characterization of HPA-axis reactivity endophenotypes in a cohort of female PTSD patients.

Analysis of the function of the hypothalamic-pituitary-adrenal (HPA)-axis in patients suffering from posttraumatic stress disorder (PTSD) has hitherto produced inconsistent findings, inter alia in the Trier Social Stress Test (TSST). To address these inconsistencies, we compared a sample of 23 female PTSD patients with either early life trauma (ELT) or adult trauma (AT) or combined ELT and AT to 18 age-matched non-traumatized female healthy controls in the TSST which was preceded by intensive baseline assessments. During the TSST, we determined a variety of clinical, psychological, endocrine and cardiovascular parameters as well as expression levels of four HPA-axis related genes. Using a previously reported definition of HPA-axis responsive versus non-responsive phenotypes, we identified for the first time two clinically and biologically distinct HPA-axis reactivity subgroups of PTSD. One subgroup ("non-responders") showed a blunted HPA-axis response and distinct clinical and biological characteristics such as a higher prevalence of trauma-related dissociative symptoms and of combined AT and ELT as well as alterations in the expression kinetics of the genes encoding for the mineralocorticoid receptor (MR) and for FK506 binding protein 51 (FKBP51). Interestingly, this non-responder subgroup largely drove the relatively diminished HPA axis response of the total cohort of PTSD patients. These findings are limited by the facts that the majority of patients was medicated, by the lack of traumatized controls and by the relatively small sample size. The here for the first time identified and characterized HPA-axis reactivity endophenotypes offer an explanation for the inconsistent reports on HPA-axis function in PTSD and, moreover, suggest that most likely other factors than HPA-axis reactivity play a decisive role in determination of PTSD core symptom severity.