Biochemical basis of circadian rhythms and diseases: With emphasis on post-traumatic stress disorder

Time-course analysis of frontal gene expression profiles in the rat model of posttraumatic stress disorder and a comparison with the conditioned fear model

Posttraumatic stress disorder (PTSD) is a complex disorder that involves physiological, emotional, and cognitive dysregulation that may occur after exposure to a life-threatening event. In contrast with the condition of learned fear with resilience to extinction, abnormal fear with impaired fear extinction and exaggeration are considered crucial factors for the pathological development of PTSD. The prefrontal cortex (mPFC) is considered a critical region of top-down control in fear regulation, which involves the modulation of fear expression and extinction. The pathological course of PTSD is usually chronic and persistent; a number of studies have indicated temporal progression in gene expression and phenotypes may be involved in PTSD pathology. In the current study, we use a well-established modified single-prolonged stress (SPS&FS) rat model to feature PTSD-like phenotypes and compared it with a footshock fear conditioning model (FS model); we collected the frontal tissue after extreme stress exposure or fear conditioning and extracted RNA for transcriptome-level gene sequencing. We compared the genetic profiling of the mPFC at early (<2 h after solely FS or SPS&FS exposure) and late (7 days after solely FS or SPS&FS exposure) stages in these two models. First, we identified temporal differences in the expressional patterns between these two models and found pathways such as protein synthesis factor eukaryotic initiation factor 2 (EIF2), transcription factor NF-E2-related factor 2 (NRF2)-mediated oxidative stress response, and acute phase responding signaling enriched in the early stage in both models with significant p-values. Furthermore, in the late stage, the sirtuin signaling pathway was enriched in both models; other pathways such as STAT3, cAMP, lipid metabolism, Gα signaling, and increased fear were especially enriched in the late stage of the SPS&FS model. However, pathways such as VDR/RXR, GP6, and PPAR signaling were activated significantly in the FS model's late stage. Last, the network analysis revealed the temporal dynamics of psychological disorder, the endocrine system, and also genes related to increased fear in the two models. This study could help elucidate the genetic temporal alteration and stage-specific pathways in these two models, as well as a better understanding of the transcriptome-level differences between them.

Genome to Phenome: A Systems Biology Approach to PTSD Using an Animal Model

Post-traumatic stress disorder (PTSD) is a debilitating illness that imposes significant emotional and financial burdens on military families. The understanding of PTSD etiology remains elusive; nonetheless, it is clear that PTSD is manifested by a cluster of symptoms including hyperarousal, reexperiencing of traumatic events, and avoidance of trauma reminders. With these characteristics in mind, several rodent models have been developed eliciting PTSD-like features. Animal models with social dimensions are of particular interest, since the social context plays a major role in the development and manifestation of PTSD.For civilians, a core trauma that elicits PTSD might be characterized by a singular life-threatening event such as a car accident. In contrast, among war veterans, PTSD might be triggered by repeated threats and a cumulative psychological burden that coalesced in the combat zone. In capturing this fundamental difference, the aggressor-exposed social stress (Agg-E SS) model imposes highly threatening conspecific trauma on naïve mice repeatedly and randomly.There is abundant evidence that suggests the potential role of genetic contributions to risk factors for PTSD. Specific observations include putatively heritable attributes of the disorder, the cited cases of atypical brain morphology, and the observed neuroendocrine shifts away from normative. Taken together, these features underscore the importance of multi-omics investigations to develop a comprehensive picture. More daunting will be the task of downstream analysis with integration of these heterogeneous genotypic and phenotypic data types to deliver putative clinical biomarkers. Researchers are advocating for a systems biology approach, which has demonstrated an increasingly robust potential for integrating multidisciplinary data. By applying a systems biology approach here, we have connected the tissue-specific molecular perturbations to the behaviors displayed by mice subjected to Agg-E SS. A molecular pattern that links the atypical fear plasticity to energy deficiency was thereby identified to be causally associated with many behavioral shifts and transformations.PTSD is a multifactorial illness sensitive to environmental influence. Accordingly, it is essential to employ the optimal animal model approximating the environmental condition that elicits PTSD-like symptoms. Integration of an optimal animal model with a systems biology approach can contribute to a more knowledge-driven and efficient next-generation care management system and, potentially, prevention of PTSD.

The Levels of Cortisol and Oxidative Stress and DNA Damage in Child and Adolescent Victims of Sexual Abuse with or without Post-Traumatic Stress Disorder

OBJECTIVE

The aim of this study was to investigate whether cortisol and oxidative stress levels and DNA damage differ between individuals who developed PTSD or not following a sexual trauma.

METHODS

The study included 61 children aged between 5 and 17 years who sustained sexual abuse (M/F: 18/43). The patients were divided into two groups: patients with PTSD and patients without PTSD based, based on the results of a structured psychiatric interview (K-SADS-PL and CAPS-CA). Cortisol, glutathione peroxidase (GPx), superoxide dismutase (SOD), coenzyme Q, 8-Hydroxy-2-Deoxyguanosine (8-OHdG) were all evaluated by the ELISA method.

RESULTS

Our evaluation revealed a diagnosis of PTSD in 51% (n=31) of victims. There was no significant difference between the groups with or without PTSD in terms of cortisol, GPx, SOD, coenzyme Q, and 8-OHdG levels. There was no correlation between CAPS scores and GPx, SOD, coenzyme Q, and 8-OHdG levels between patients with or without PTSD. In patients with PTSD, both cortisol and 8-OHdG levels decreased with increasing time after trauma, and there was no significant correlation with cortisol and 8-OHdG levels in patients without PTSD.

CONCLUSION

Although the present study did not find any difference between the groups in terms of 8-OHdG concentrations, the decreases in both cortisol and 8-OHdG levels with increasing time after trauma is considered to indicate a relationship between cortisol and DNA damage.

Potential pleiotropic beneficial effects of adjuvant melatonergic treatment in posttraumatic stress disorder

Loss of circadian rhythmicity fundamentally affects the neuroendocrine, immune, and autonomic system, similar to chronic stress and may play a central role in the development of stress-related disorders. Recent articles have focused on the role of sleep and circadian disruption in the pathophysiology of posttraumatic stress disorder (PTSD), suggesting that chronodisruption plays a causal role in PTSD development. Direct and indirect human and animal PTSD research suggests circadian system-linked neuroendocrine, immune, metabolic and autonomic dysregulation, linking circadian misalignment to PTSD pathophysiology. Recent experimental findings also support a specific role of the fundamental synchronizing pineal hormone melatonin in mechanisms of sleep, cognition and memory, metabolism, pain, neuroimmunomodulation, stress endocrinology and physiology, circadian gene expression, oxidative stress and epigenetics, all processes affected in PTSD. In the current paper, we review available literature underpinning a potentially beneficiary role of an add-on melatonergic treatment in PTSD pathophysiology and PTSD-related symptoms. The literature is presented as a narrative review, providing an overview on the most important and clinically relevant publications. We conclude that adjuvant melatonergic treatment could provide a potentially promising treatment strategy in the management of PTSD and especially PTSD-related syndromes and comorbidities. Rigorous preclinical and clinical studies are needed to validate this hypothesis.

Altered lipid peroxidation markers are related to post-traumatic stress disorder (PTSD) and not trauma itself in earthquake survivors

The traumatic life events, including earthquakes, war, and interpersonal conflicts, cause a cascade of psychological and biological changes known as post-traumatic stress disorder (PTSD). Malondialdehyde (MDA) is a reliable marker of lipid peroxidation, and paraoxonase is a known antioxidant enzyme. The aims of this study were to investigate the relationship between earthquake trauma, PTSD effects on oxidative stress and the levels of serum paraoxonase 1 (PON1) enzyme activity, and levels of serum MDA. The study was carried out on three groups called: the PTSD group, the traumatized with earthquake exercise group, and healthy control group, which contained 32, 31, and 38 individuals, respectively. Serum MDA levels and PON1 enzyme activities from all participants were measured, and the results were compared across all groups. There were no significant differences between the PTSD patients and non-PTSD earthquake survivors in terms of the study variables. The mean PON1 enzyme activity from PTSD patients was significantly lower, while the mean MDA level was significantly higher than that of the healthy control group (p < 0.01 for both measurements). Similarly, earthquake survivors who did not develop PTSD showed higher MDA levels and lower PON1 activity when compared to healthy controls. However, the differences between these groups did not reach a statistically significant level. Increased MDA level and decreased PON1 activity measured in PTSD patients after earthquake and may suggest increased oxidative stress in these patients. The nonsignificant trends that are observed in lipid peroxidation markers of earthquake survivors may indicate higher impact of PTSD development on these markers than trauma itself. For example, PTSD diagnosis seems to add to the effect of trauma on serum MDA levels and PON1 enzyme activity. Thus, serum MDA levels and PON1 enzyme activity may serve as biochemical markers of PTSD diagnosis.

Altered one-carbon metabolism in posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with increased morbidity and mortality through somatic conditions, particularly cardiovascular disease. The one-carbon metabolism in connection with the hypothalamic-pituitary-adrenal (HPA)-axis may be an important mediator of this increased cardiovascular risk.

METHODS

In a mixed-gender sample of 49 PTSD patients and 45 healthy controls we therefore investigated: (1) alterations in the one-carbon metabolism as reflected in fasting plasma concentrations of homocysteine, folate, vitamins B6 and B12, and (2) associations of these one-carbon metabolites with the HPA-axis hormones cortisol, dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S).

RESULTS

After correction for confounders, PTSD patients had significantly elevated homocysteine (z = 2.963, p = .003) compared to controls, but normal levels of folate, vitamin B6 and B12. Comorbid depression did not explain the observed higher homocysteine levels. Patients showed increased risk for moderate hyperhomocysteinemia (OR = 7.0, χ(2) = 7.436, p = .006). Additionally, homocysteine was associated with PTSD severity (z = 2.281, p = .005). Moreover, all HPA-axis hormones were associated with folate in both patients and controls (all p's ≤ .011), while DHEA-S influenced folate in patients (z = 2.089, p = .037).

LIMITATIONS

Our clinical sample is relatively small and therefore small-sized effects may have remained undetected.

CONCLUSIONS

Our study indicates that: (1) the one-carbon metabolism is altered in PTSD patients, (2) earlier findings of higher homocysteine in male PTSD patients are generalized to female patients, (3) homocysteine is negatively associated with PTSD severity, and (4) HPA-axis alterations are associated with the one-carbon metabolism. Longitudinal studies are needed to determine whether elevated homocysteine levels reflect preexisting risk factors and/or consequences of psychological trauma.

Serum total oxidant and antioxidant status in earthquake survivors with post-traumatic stress disorder

OBJECTIVE

Oxidative stress has been shown to play an important role in the pathogenesis of post-traumatic stress disorder (PTSD). Although there are some studies on oxidative stress and PTSD, there is no report available on the serum total oxidant and antioxidant status in earthquake survivors with PTSD. Therefore, this study aimed to investigate the serum total oxidant and antioxidant status in earthquake survivors with chronic PTSD.

MATERIAL AND METHODS

The study group included 45 earthquake survivors with PTSD and 40 earthquake survivors without PTSD. The oxidative status was determined using the total antioxidant status and total oxidant status (TOS) measurements and by calculating the oxidative stress index (OSI).

RESULTS

There were no statistically significant differences in the total antioxidant status, TOS, or OSI when comparing individuals with and without PTSD (all, p>0.05). There were no correlations between Clinician-Administered PTSD Scale scores and oxidant and antioxidant stress markers (all, p>0.05).

CONCLUSIONS

Our results suggest that the total oxidant and antioxidant status may not affect earthquake survivors with PTSD. This is the first study to evaluate the oxidative status in earthquake survivors with PTSD. Further studies are necessary to confirm these findings.

The retinoid-related orphan receptor alpha (RORA) gene and fear-related psychopathology

BACKGROUND

This study followed on findings from a recent genome-wide association study of PTSD that implicated the retinoid-related orphan receptor alpha (RORA) gene (Logue et al., 2012) by examining its relationship to broader array of disorders.

METHODS

Using data from the same cohort (N=540), we analyzed patterns of association between 606 single nucleotide polymorphisms (SNPs) spanning the RORA gene and comorbidity factors termed fear, distress (i.e., internalizing factors) and externalizing.

RESULTS

Results showed that rs17303244 was associated with the fear component of internalizing (i.e., defined by symptoms of panic, agoraphobia, specific phobia, and obsessive-compulsive disorder) at a level of significance that withstood correction for gene-wide multiple testing.

LIMITATIONS

The primary limitations were the modest size of the cohort and the absence of a replication sample.

CONCLUSIONS

Results add to a growing literature implicating the RORA gene in a wide range of neuropsychiatric disorders and offer new insight into possible molecular mechanisms of the effects of traumatic stress on the brain and the role of genetic factors in those processes.

Serum bilirubin and lipoprotein-a: how are these associated with whole blood viscosity?

BACKGROUND

It has been demonstrated that oxidative stress can induce red blood cell rigidity and haemolysis, which in turn can cause hyperviscosity and hyperbilirubinaemia, respectively. However, haemolysis may be associated with a low level of haemoglobin, which reduces whole blood viscosity (WBV). Bilirubin can behave as antioxidant or oxidant, and one uncharted course for diagnostic pathology is how or whether bilirubinaemia and viscosity are associated. Further, oxidative stress is now being assessed using lipoprotein-a (Lp(a)), among other things but whether it is associated with blood viscosity has not been established.

AIM

This study investigates the association and correlation of haemoglobin level and WBV with serum Lp(a) and bilirubin levels in a general population of patients.

MATERIALS AND METHODS

Sixty-eight cases that were tested for Lp(a), concomitantly with full blood count and liver function, in our archived clinical pathology database were used in this study. WBV levels were determined using a validated formula. Multivariate and univariate analyses as well as correlation were performed.

RESULTS

WBV was found to be significantly associated with bilirubin (P<0.02), but not with Lp(a). Haemoglobin concentration was inversely correlated with Lp(a) (P<0.04), but not with bilirubinaemia.

CONCLUSION

This pilot study suggests that hyperbilirubinaemia and hyperviscosity are associated and positively correlated. Consideration of whether serum bilirubin (as an indirect index of oxidative stress) can be used in combination with WBV (as index of macrovascular effect of oxidative stress) to assess oxidative damage is recommended.

Physiological consequences of repeated exposures to conditioned fear

Activation of the stress response evokes a cascade of physiological reactions that may be detrimental when repeated or chronic, and when triggered after exposure to psychological/emotional stressors. Investigation of the physiological mechanisms responsible for the health damaging effects requires animal paradigms that repeatedly evoke a response to psychological/emotional stressors. To this end, adult male Sprague Dawley rats were repeatedly exposed (2X per day for 20 days) to a context that they were conditioned to fear (conditioned fear test, CFT). Repeated exposure to CFT produced body weight loss, adrenal hypertrophy, thymic involution, and basal corticosterone elevation. In vivo biotelemetry measures revealed that CFT evokes sympathetic nervous system driven increases in heart rate (HR), mean arterial pressure (MAP), and core body temperature. Extinction of behavioral (freezing) and physiological responses to CFT was prevented using minimal reinstatement footshock. MAP responses to the CFT did not diminish across 20 days of exposure. In contrast, HR and cardiac contractility responses declined by day 15, suggesting a shift toward vascular-dominated MAP (a pre-clinical marker of CV dysfunction). Flattened diurnal rhythms, common to stress-related mood/anxiety disorders, were found for most physiological measures. Thus, repeated CFT produces adaptations indicative of the health damaging effects of psychological/emotional stress.