Intranasal oxytocin reduces provoked symptoms in female patients with posttraumatic stress disorder despite exerting sympathomimetic and positive chronotropic effects in a randomized controlled trial

BACKGROUND

Posttraumatic stress disorder (PTSD) is a severe psychiatric disease accompanied by neuroendocrine changes such as adrenergic overdrive and hence an elevated cardiovascular morbidity. Current pharmacotherapeutic options for PTSD are less than suboptimal, necessitating the development of PTSD-specific drugs. Although the neuropeptide oxytocin has been repeatedly suggested to be effective in PTSD treatment, there are, to our knowledge, only three studies that have assessed its efficacy on the intensity of PTSD symptoms in PTSD patients - among them one symptom provocation study in male veterans.

METHODS

To evaluate for the first time how oxytocin influences the intensity of provoked PTSD symptoms and, furthermore, cardiac control in female PTSD patients, we assessed their psychic and cardiac response to trauma-script exposure with and without oxytocin pretreatment in a double-blind randomized placebo-controlled study. We used a within-subject design to study 35 female PTSD patients who received oxytocin and placebo in a 2-week interval. Furthermore, we performed a small pilot study to get an idea of the relation of the stress-modulated endogenous oxytocin levels and heart rate - we correlated oxytocin serum levels with the heart rate of 10 healthy individuals before and after exposure to the Trier Social Stress Test (TSST).

RESULTS

Intranasal oxytocin treatment was followed by a reduction of provoked total PTSD symptoms, in particular of avoidance, and by an elevation in baseline and maximum heart rate together with a drop in the pre-ejection period, a marker for sympathetic cardiac control. Furthermore, we found a positive correlation between endogenous oxytocin levels and heart rate both before and after TSST challenge in healthy control subjects.

CONCLUSIONS

This study provides the first evidence that oxytocin treatment reduces the intensity of provoked PTSD symptoms in female PTSD patients. The small size of both samples and the heterogeneity of the patient sample restrict the generalizability of our findings. Future studies have to explore the gender dependency and the tolerability of the oxytocin-mediated increase in heart rate. This randomized controlled trial was retrospectively registered at the German Trials Register (DRKS00009399) on the 02 October 2015.

Infinite level-dependent QBD processes and matrix-analytic solutions for stochastic chemical kinetics

Systems of stochastic chemical kinetics are modeled as infinite level-dependent quasi-birth-and-death (LDQBD) processes. For these systems, in contrast to many other applications, levels have an increasing number of states as the level number increases and the probability mass may reside arbitrarily far away from lower levels. Ideas from Lyapunov theory are combined with existing matrix-analytic formulations to obtain accurate approximations to the stationary probability distribution when the infinite LDQBD process is ergodic. Results of numerical experiments on a set of problems are provided.

Approximate maximum likelihood estimation for stochastic chemical kinetics

Recent experimental imaging techniques are able to tag and count molecular populations in a living cell. From these data mathematical models are inferred and calibrated. If small populations are present, discrete-state stochastic models are widely-used to describe the discreteness and randomness of molecular interactions. Based on time-series data of the molecular populations, the corresponding stochastic reaction rate constants can be estimated. This procedure is computationally very challenging, since the underlying stochastic process has to be solved for different parameters in order to obtain optimal estimates. Here, we focus on the maximum likelihood method and estimate rate constants, initial populations and parameters representing measurement errors.

In vivo control of CpG and non-CpG DNA methylation by DNA methyltransferases

The enzymatic control of the setting and maintenance of symmetric and non-symmetric DNA methylation patterns in a particular genome context is not well understood. Here, we describe a comprehensive analysis of DNA methylation patterns generated by high resolution sequencing of hairpin-bisulfite amplicons of selected single copy genes and repetitive elements (LINE1, B1, IAP-LTR-retrotransposons, and major satellites). The analysis unambiguously identifies a substantial amount of regional incomplete methylation maintenance, i.e. hemimethylated CpG positions, with variant degrees among cell types. Moreover, non-CpG cytosine methylation is confined to ESCs and exclusively catalysed by Dnmt3a and Dnmt3b. This sequence position-, cell type-, and region-dependent non-CpG methylation is strongly linked to neighboring CpG methylation and requires the presence of Dnmt3L. The generation of a comprehensive data set of 146,000 CpG dyads was used to apply and develop parameter estimated hidden Markov models (HMM) to calculate the relative contribution of DNA methyltransferases (Dnmts) for de novo and maintenance DNA methylation. The comparative modelling included wild-type ESCs and mutant ESCs deficient for Dnmt1, Dnmt3a, Dnmt3b, or Dnmt3a/3b, respectively. The HMM analysis identifies a considerable de novo methylation activity for Dnmt1 at certain repetitive elements and single copy sequences. Dnmt3a and Dnmt3b contribute de novo function. However, both enzymes are also essential to maintain symmetrical CpG methylation at distinct repetitive and single copy sequences in ESCs.

Macroscopic brain architecture changes and white matter pathology in acromegaly: a clinicoradiological study

Although long-term exposure of the brain to increased GH/IGF-1 likely influences cerebral functions, no in vivo studies have been directed towards changes of the brain structure in acromegaly. Here, we used high resolution magnetic resonance images to compare volumes of gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) of forty-four patients with acromegaly to an age and gender matched, healthy control group (n = 44). In addition, white matter lesions (WMLs) were quantified and graded. Patients exhibited larger GM (+3.7% compared with controls, P = 0.018) and WM volumes (+5.1%, P = 0.035) at the expense of CSF. Differences of WML counts between patients and controls were subtle, however, showing more patients in the 21-40 lesions category (P = 0.044). In conclusion, this MRI study provides first evidence that acromegalic patients exhibit disturbances of the macroscopic brain tissue architecture. Furthermore, acromegalic patients may have an increased risk of neurovascular pathology, likely due to secondary metabolic and vascular comorbidities.

Explicitly modeling the effects of aging on response time

Research into the effects of aging on response time has focused on Brinley plots. Brinley plots are constructed by plotting mean response times for older subjects against those for young subjects for a set of experimental conditions. The typical result is a straight line with a slope greater than 1 and a negative intercept. This linear function has been interpreted as showing that aging leads to a general slowing of cognitive processes. In this article, we show that the slope of the Brinley plot is actually a measure of the relative standard deviations of older versus young subjects' response times; it is not a measure of general slowing. We examine current models of the effects of aging on mean response time and show how they might be reinterpreted. We also show how a more comprehensive model, Ratcliff's diffusion model (1978), can account for Brinley plot regularities and, at the same time, provide an account of accuracy rates, the shapes of response time distributions, and the relative speeds of error and correct response times, aspects of the data about which models designed to account for Brinley plots are mute. We conclude by endorsing a research approach that applies explicit models to response time data in aging in order to use the parameters of the model to interpret the effects of aging.