Assessment of noradrenergic functioning in patients with non-combat-related posttraumatic stress disorder: a study with desmethylimipramine and orthostatic challenges

Catecholamines in Post-traumatic Stress Disorder: A Systematic Review and Meta-Analysis

Studies on the association between post-traumatic stress disorder (PTSD) and levels of catecholamines have yielded inconsistent results. The aim of this study was to conduct a systematic review and meta-analysis to assess whether concentrations of the catecholamines dopamine, norepinephrine, and epinephrine are associated with PTSD. This study searched relevant articles in the following databases: PubMed, Embase, Web of Science, and Psyc-ARTICLES. Each database was searched from its inception to September, 2018. Data related to catecholamine concentrations were extracted for patients with PTSD and the controls to calculate standardized mean differences and to evaluate effect sizes. A meta-analysis was then performed to compare the concentration of each catecholamine between the two groups in blood and/or urine samples. Heterogeneity was quantified using I² and its significance was tested using the Q statistics. Subgroup analyses of the types of controls, PTSD assessment tools, and assayed methods used in the studies were performed to explore sources of heterogeneity among studies. Random-effects models were used to combine results from selected studies. A total of 1,388 articles were identified, of which 27 were included in the final analysis. Heterogeneity was high; hence random-effects models were used to combine results of selected studies. Results revealed significantly higher norepinephrine levels in people with PTSD than in the controls [standardized mean difference (SMD) = 0.35, 95% confidence interval (CI): 0.13 to 0.57, p = 0.002]. No difference was found in dopamine and epinephrine concentrations between the two groups. Elevated norepinephrine levels may be an important indicator for PTSD.

Neuroendocrine and immune responses to a cognitive stress challenge in veterans with and without PTSD

BACKGROUND

PTSD has been associated with altered hypothalamus-pituitary-adrenal-axis (HPA-axis), immune and sympathetic nervous system (SNS) regulation. The purpose of this study was to evaluate the effect of cognitive stress on these systems in PTSD patients and controls.

METHODS

The subjective units of distress score (SUDS), NK-cell response, plasma levels of noradrenalin and ACTH in response to cognitive stress were assessed in male veterans with PTSD (n=15) and age, region and year of deployment matched veterans without psychopathology (n=15).

RESULTS

The challenge induced an increase in SUDS, noradrenalin, ACTH and NK-cell response in both groups. Baseline levels of ACTH were lower in PTSD patients. The test was experienced as more stressful by PTSD patients and resulted in an augmented ACTH response in patients. The noradrenalin and NK-cell responses showed no group differences. The ACTH response correlated with the severity of symptoms in patients, and the noradrenalin response correlated with the ACTH and NK-cell response in controls, but not in patients.

DISCUSSION

PTSD patients experience more distress and present with an exaggerated pituitary response to this stressor. In addition, our results suggest an altered interaction between the HPA-axis, SNS and immune system in PTSD.

Exaggerated platelet reactivity to physiological agonists in war veterans with posttraumatic stress disorder

An association between traumatic stress and cardiovascular disease (CVD) is supported by various epidemiological studies. Platelet activation and binding of activated platelets to leukocytes contributes to the pathophysiology of CVD. Evidence of hyperactive sympathetic nervous system, altered expression of platelet α(2)-adrenoreceptors (α(2)AR), and altered platelet adenylate cyclase activity in patients with posttraumatic stress disorder (PTSD) suggest that platelet reactivity in PTSD may be altered as well. We tested whether platelet reactivity to increasing doses of adenosine-diphosphate (ADP), epinephrine (EPI), or their combination differs between war veterans with PTSD (n=15) and healthy controls (n=12). For this purpose, citrated whole blood was incubated with increasing concentrations of ADP (0.1, 1, 10 μM), EPI alone (10 nM, 100 nM, 1000 nM), or EPI (10 nM, 100 nM, 1000 nM) in combination with 0.1 μM ADP. A subset of samples was also incubated with 10 μM yohimbine (YOH), α(2)AR antagonist, to distinguish receptor-specific effects. Platelet CD62P expression and formation of platelet-leukocyte aggregates (PLA) [platelet-monocyte (P-Mo), -lymphocyte (P-Ly), and -neutrophil (P-Ne) aggregates] were measured using three-color flow cytometry. Platelet reactivity was higher in war veterans with PTSD when compared to controls, as determined by greater CD62P expression and formation of PLA in response to ADP alone or in combination with EPI. Platelet reactivity also correlated with the severity of PTSD symptoms. Preliminary experiments with YOH indicate that stress-associated EPI elevations may contribute to platelet activation through a α(2)AR-dependent mechanism. The enhanced platelet reactivity observed in our study may be the underlying mechanism contributing to the development of CVD in PTSD patients.

Increased serum cortisol and growth hormone levels in earthquake survivors with PTSD or subclinical PTSD

Alteration of neuroendocrine systems has been demonstrated to be involved in the pathology of posttraumatic stress disorder (PTSD). Three months after an earthquake in Northern China, cortisol, growth hormone (GH) and prolactin (PRL) levels were assessed in 34 earthquake survivors with PTSD (according to DSM-IV criteria), 30 earthquake survivors with subclinical PTSD and 34 normal controls. Only earthquake survivors diagnosed with PTSD had significantly higher serum GH levels. Also, we found that earthquake survivors (either with PTSD or subclinical PTSD) had significantly higher serum cortisol levels. We concluded that PTSD might be associated with an increased level of serum GH and traumatic survivors might be associated with a higher level of serum cortisol.

Noradrenergic dysfunction and the psychopharmacology of posttraumatic stress disorder

The catecholamine norepinephrine is a critical effector of the mammalian stress response and has been implicated in the pathophysiology of posttraumatic stress disorder (PTSD)-a syndrome intrinsically related to the experience of extraordinary stress. Symptom-linked hypernoradrenergic derangements have been observed in PTSD and several studies have examined the potential therapeutic effects of agents that dampen the centrally hyperactive noradrenergic state. These agents include compounds that decrease norepinephrine release (e.g. centrally acting alpha(2) agonists such as clonidine) and those which block post-synaptic norepinephrine receptors (e.g. centrally acting alpha(1) or beta receptor antagonists such as prazosin or propranolol). In this article, we review studies of central noreadrenergic hyperactivity under both basal and challenge conditions and explore the evidence for these derangements as potential psychopharmacologic targets in patients with PTSD. Given the significant involvement of CNS norepinephrine hyperactivity in PTSD, and its link to intrusive and hyperarousal symptoms, it is not surprising that interventions directed at this system have therapeutic potential in PTSD. The utility of these anti-adrenergics in the clinical treatment of PTSD remains to be determined, though it is possible that they may prove to have primary roles in a disorder that is only modestly responsive to antidepressant treatment.

Stress hormones and post-traumatic stress disorder in civilian trauma victims: a longitudinal study. Part II: the adrenergic response

The aim of the study was to prospectively evaluate the association between the occurrence of post-traumatic stress disorder (PTSD) and the adrenergic response to the traumatic event, and additionally, to explore the link between PTSD and the initial norepinephrine:cortisol ratio. Plasma levels and urinary excretion of norepinephrine (NE) were measured in 155 survivors of traumatic events during their admission to a general hospital emergency room (ER) and at 10 d, 1 month and 5 months later. Symptoms of peri-traumatic dissociation, PTSD and depression were assessed in each follow-up session. The Clinician-Administered PTSD Scale (CAPS) conferred a diagnosis of PTSD at 5 months. Trauma survivors with (n=31) and without (n=124) PTSD had similar levels of plasma NE, urinary NE excretion, and NE:cortisol ratio in the ER. Plasma NE levels were lower in subjects with PTSD at 10 d, 1 month, and 5 months. There was a weak but significant positive correlation between plasma levels of NE in the ER and concurrent heart rate, and a negative correlation between NE in the ER and dissociation symptoms. Peripheral levels of NE, shortly after traumatic events, are poor risk indicators of subsequent PTSD among civilian trauma victims. Simplified biological models may not properly capture the complex aetiology of PTSD.

Molecular cloning and functional expression of the murine noradrenaline transporter

The cDNA of the murine noradrenaline transporter (mNAT) was cloned from the RNA of the placenta of a C57BL/6 mouse. The cloned mNAT differs from a previously published sequence in two amino acids within the C-terminal region. A cDNA obtained from an inbred mouse strain showed a further amino acid exchange (Ile(505)Val) within the fifth intracellular loop. The pharmacological properties of both, the wild-type mNAT and the variant (mNAT-I(505)V), were studied in human embryonic kidney HEK293 cells transfected with the corresponding cDNA. The kinetic constants for transport (K (m), V (max)) of [(3)H]noradrenaline ([(3)H]-NA) and binding (K (D), B (max)) of the selective NAT inhibitor [(3)H]nisoxetine were not different between the two isoforms; the mean kinetic constants amounted to about 4 microM and 120pmol/mg protein for K (m) and V (max) and 6nM and 18pmol/mg protein for K (D) and B (max), respectively. [(3)H]-NA transport by both isoforms showed the typical properties of an NAT because it was dependent on sodium and chloride and inhibited with almost identical K (i) values by various NAT substrates and inhibitors. The only significant pharmacological difference identified between the two mNAT isoforms was an about threefold higher affinity for cocaine of the very rare mNAT-I(505)V variant.

PTSD and stress sensitisation: a tale of brain and body Part 1: human studies

Post-traumatic stress disorder (PTSD) is a chronic, debilitating psychiatric disorder that can follow exposure to extreme stressful experiences. It is characterised by hyperarousal and increased startle responses, re-experiencing of the traumatic event, withdrawal or avoidance behaviour and emotional numbing. The focus of this review is on aspects that have received less attention. PTSD develops only in a substantial minority of people exposed to traumatic stress, and possible individual traits that increase vulnerability are discussed. An overview is given of the wide variety of physiological disturbances that accompany PTSD and may contribute to disability, including neuroendocrine, cardiovascular, gastrointestinal and immune function and pain sensitivity. Brain imaging and pharmacological studies have generated some insight into the circuitry that may be involved in the generation of PTSD symptoms. Major limitations of human studies so far are the issue of causality and our lack of understanding of the underlying molecular substrates in the brain, which are easier to address in relevant animal models and will be discussed in a companion paper.

Endocrine and inflammatory alterations in post-traumatic stress disorder

Post-traumatic stress disorder has frequently been found associated with alterations in endogenous stress hormone systems, for example the hypothalamus-pituitary-adrenal axis and sympatho-adrenal-medullary system. Hormonal alterations are observed at the central and peripheral level of the central nervous system, and in the periphery for inflammatory disinhibition. Both consequences bear significant hazards for the individual, the former by sustaining or exacerbating the psychiatric condition, the latter by its detrimental effects on somatic health. However, the role of hormonal modifications in the development and maintenance of post-traumatic stress disorder symptoms and in the accompanying cognitive and emotional impairments still remains quite unclear.

Noradrenergic mechanisms in the pathophysiology of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a serious psychiatric illness that may develop in individuals after exposure to a traumatic event. Recent data suggest that trauma and/or long-term stressors can cause alterations in the functioning of neuroanatomical structures and neural networks throughout the central nervous system. Specifically, dysregulation in central and perhaps, peripheral noradrenergic neural networks has been implicated as the cause of specific symptom clusters in the pathophysiology of PTSD. In this review, both clinical and preclinical data are presented to highlight types of noradrenergic dysfunction observed in individuals with PTSD. Additionally, the role of noradrenaline dysregulation in the acquisition/initiation, and maintenance of hyperarousal and reexperiencing symptom clusters in PTSD will be addressed.

Hypothalamic-pituitary-adrenal activity among Armenian adolescents with PTSD symptoms

This study evaluated basal levels and responsiveness to exercise of plasma adrenocorticotropic hormone (ACTH), and serum thyroid stimulating hormone (TSH), growth hormone (GH) and cortisol among adolescents from two differentially exposed groups 6 1/2 years after the 1988 earthquake in Armenia. Severity of total PTSD and Category C and D symptoms were negatively correlated with baseline cortisol. Preexercise ACTH was significantly lower, and preexercise TSH higher, among adolescents with more exposure. Depressive symptoms were negatively correlated with baseline cortisol and positively with TSH. Mean GH, TSH, and cortisol levels in both groups fell within normal limits. The pre- to postexercise increase in GH, TSH, and cortisol suggests that exercise challenge may be useful in the field investigation of neurohormonal activity among traumatized individuals.

Pharmacological properties of naturally occurring variants of the human norepinephrine transporter

The human norepinephrine transporter (hNET) gene has five sequence polymorphisms that predict amino acid substitutions in the transporter protein: Val69Ile, Thr99Ile, Val245Ile, Val449Ile, and Gly478Ser. In order to functionally characterize the naturally occurring transporter variants, we used site-directed mutagenesis to establish the hNET variants and compared some basic pharmacological properties (uptake of norepinephrine and its inhibition by the tricyclic antidepressant desipramine) in COS-7 cells transiently expressing variant hNETs and wild-type hNET. None of the hNET variants displayed changes in the potency (Ki) of desipramine for inhibition of norepinephrine uptake. Furthermore, variants Val69Ile, Thr99Ile, ValZ45Ile, and Val449Ile did not affect kinetic constants (Km, Vmax) of norepinephrine uptake. However, COS-7 cells expressing the hNET variant Gly478Ser displayed an approximately four-fold increase in the Km for norepinephrine, while the Vmax was unaffected. The increase in the Km, which is equivalent to a four-fold reduction in the affinity of the variant hNET for its natural substrate norepinephrine, indicates that the glycine in position 478 is part of a substrate recognition domain. The reduced clearance of released norepinephrine by reuptake through the Gly478Ser variant might cause an increase in the synaptic and the circulating concentration of norepinephrine. Elevated norepinephrine concentrations have been associated with human diseases and it will be interesting to explore a possible contribution by the Gly478Ser variant to certain disease states.

Predictors of cortisol and 3-methoxy-4-hydroxyphenylglycol responses in the acute aftermath of rape

BACKGROUND

Prospective studies of trauma survivors can provide information about the relationship between rape characteristics and the development of subsequent symptoms.

METHODS

The present study examined the relationship of prior assault, rape severity, posttraumatic stress disorder (PTSD) symptoms following rape, and subsequent PTSD diagnosis, to the acute cortisol and 3-methoxy-4-hydroxyphenylglycol (MHPG) response to this traumatic event in 20 women.

RESULTS

Women with a history of prior physical or sexual assault showed a significantly attenuated cortisol response to the acute stress of rape compared to women without such a history. MHPG appeared to be associated with injury-related rape characteristics, and symptoms of active avoidance, but not prior history. PTSD status at the 3-month follow-up was predicted by both a prior history of assault and high injury rape, but was not directly predicted by either cortisol or MHPG levels. MHPG and cortisol were not correlated in the sample as a whole, but were correlated among individuals who did not subsequently develop PTSD (p = .04)

CONCLUSIONS

The results suggest that different neuroendocrine systems may mediate different components of the response to traumatic stress.

The long term effects of childhood sexual abuse: rationale for and experience of pharmacotherapy with nefazodone

Studies estimate that 1 in 6 women and 1 in 10 men experience childhood sexual abuse (CSA). Whilst ill-health is not an inevitable consequence, approximately 20% of victims go on to have serious long-term pathology. This is reflected in an excess incidence of CSA survivors in problem populations, be they medical, forensic or psychiatric. Four groups of research studies suggest that PTSD-related mechanisms might be a major mediating factor in the development of symptoms: 1. There is high incidence of PTSD following sexual trauma; 2. Psychometric studies show evidence of impaired limbic functions; 3. There is evidence of neuroendocrine disturbances similar to those seen in war veterans with PTSD; 4. MRI studies show evidence of hippocampal atrophy. There is a growing database of studies showing that drugs that act as seroionergic modulators are effective in the treatment of PTSD. Drugs such as nefazodone which block 5HT2 receptors and inhibit the uptake of serotonin may be of particular value. Studies suggest that trauma-related issues are not always addressed in patients with a history of abuse. Given the problems posed, there is a need to review their treatment in the light of emergent knowledge. Further research is needed to validate these findings.