Effect of traumatic imagery on cerebrospinal fluid dopamine and serotonin metabolites in posttraumatic stress disorder

Epistasis in neurotransmitter receptors linked to posttraumatic stress disorder and major depressive disorder comorbidity in traumatized Chinese

Background

Posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) comorbidity occurs through exposure to trauma with genetic susceptibility. Neuropeptide-Y (NPY) and dopamine are neurotransmitters associated with anxiety and stress-related psychiatry through receptors. We attempted to explore the genetic association between two neurotransmitter receptor systems and the PTSD-MDD comorbidity.

Methods

Four groups were identified using latent profile analysis (LPA) to examine the patterns of PTSD and MDD comorbidity among survivors exposed to earthquake-related trauma: low symptoms, predominantly depression, predominantly PTSD, and PTSD-MDD comorbidity. NPY2R (rs4425326), NPY5R (rs11724320), DRD2 (rs1079597), and DRD3 (rs6280) were genotyped from 1,140 Chinese participants exposed to earthquake-related trauma. Main, gene-environment interaction (G × E), and gene-gene interaction (G × G) effects for low symptoms, predominantly depression, and predominantly PTSD were tested using a multinomial logistic model with PTSD-MDD comorbidity as a reference.

Results

The results demonstrated that compared to PTSD-MDD comorbidity, epistasis (G × G) NPY2R-DRD2 (rs4425326 × rs1079597) affects low symptoms (β = -0.66, OR = 0.52 [95% CI: 0.32-0.84], p = 0.008, pperm = 0.008) and predominantly PTSD (β = -0.56, OR = 0.57 [95% CI: 0.34-0.97], p = 0.037, pperm = 0.039), while NPY2R-DRD3 (rs4425326 × rs6280) impacts low symptoms (β = 0.82, OR = 2.27 [95% CI: 1.26-4.10], p = 0.006, pperm = 0.005) and predominantly depression (β = 1.08, R = 2.95 [95% CI: 1.55-5.62], p = 0.001, pperm = 0.001). The two G × G effects are independent.

Conclusion

NPY and dopamine receptor genes are related to the genetic etiology of PTSD-MDD comorbidity, whose specific mechanisms can be studied at multiple levels.

Geraniol attenuates behavioral and neurochemical impairments by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to post-traumatic stress disorder

Geraniol is an acyclic isoprenoid monoterpenoid analogue that has been shown to elicit neuroprotective functions, primarily through its ability to stimulate antioxidant and anti-inflammatory systems. An increase in inflammatory cytokines and oxidative stress exacerbate activation hypothalamic-pituitary-adrenal axis (HPA), leading to neurochemical dysfunction, which has important roles in the pathogenesis of post-traumatic disorder (PTSD), a mental health disorder characterized of post-trauma-induced intense fear. The aim of this study was to evaluate the anti-PTSD-like effects and underlying mechanisms of geraniol against single-prolonged-stress (SPS)-induced PTSD in mice. Following concomitant exposure to SPS (triple-paradigm traumatic events) and isolation for 7 days, mice (n = 9) were treated with geraniol (50 and 100 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.) from days 8-21. Mice were assessed for behavioral changes. Neurochemical changes, inflammatory, oxido-nitrergic markers, adrenal weight, serum glucose and corticosterone concentrations were assayed. Geraniol inhibits SPS-induced anxiety- and depressive-like features as well as behavioral despair in the depression paradigms. SPS-induced locomotor and memory impairments were also abated by geraniol treatment similarly to fluoxetine. SPS-induced adrenal hypertrophy and increased blood glucose and corticosterone concentrations, were attenuated by the geraniol treatment. Elevated levels of TNF-α and IL-6, and malondialdehyde, nitrite, acetylcholinesterase enzyme were reduced by geraniol. Geraniol also increased glutathione, superoxide-dismutase, and catalase levels as well as dopamine, serotonin concentrations and GABAergic glutamic acid decarboxylase enzyme activity in the striatum, prefrontal cortex and hippocampus in the PTSD-mice relative to SPS control. In conclusion, geraniol attenuates behavioral impairments and neurochemical dysregulations by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to PTSD.

Sex, Pramipexole and Tiagabine Affect Behavioral and Hormonal Response to Traumatic Stress in a Mouse Model of PTSD

Posttraumatic stress disorder (PTSD) has been associated with abnormal regulation of the hypothalamic-pituitary-adrenal gland axis (HPA). Women demonstrate a more robust HPA response and are twice as likely to develop PTSD than men. The role of sex hormones in PTSD remains unclear. We investigated whether post-trauma chronic treatment with the GABA-ergic agent tiagabine and dopamine-mimetic pramipexole affected the behavioral outcome and plasma levels of corticosterone, testosterone, or 17β-estradiol in female and male mice. These medications were investigated due to their potential capacity to restore GABA-ergic and dopaminergic deficits in PTSD. Animals were exposed to a single prolonged stress procedure (mSPS). Following 13 days treatment with tiagabine (10 mg/kg) or pramipexole (1 mg/kg) once daily, the PTSD-like phenotype was examined in the fear conditioning paradigm. Plasma hormones were measured almost immediately following the conditioned fear assessment. We report that the exposure to mSPS equally enhanced conditioned fear in both sexes. However, while males demonstrated decreased plasma corticosterone, its increase was observed in females. Trauma elevated plasma testosterone in both sexes, but it had no significant effects on 17β-estradiol. Behavioral manifestation of trauma was reduced by pramipexole in both sexes and by tiagabine in females only. While neither compound affected corticosterone in stressed animals, testosterone levels were further enhanced by tiagabine in females. This study shows sex-dependent efficacy of tiagabine but not pramipexole in a mouse model of PTSD-like symptoms and a failure of steroid hormones’ levels to predict PTSD treatment efficacy.

Early life adversity predicts brain-gut alterations associated with increased stress and mood

Alterations in the brain-gut system have been implicated in various disease states, but little is known about how early-life adversity (ELA) impacts development and adult health as mediated by brain-gut interactions. We hypothesize that ELA disrupts components of the brain-gut system, thereby increasing susceptibility to disordered mood. In a sample of 128 healthy adult participants, a history of ELA and current stress, depression, and anxiety were assessed using validated questionnaires. Fecal metabolites were measured using liquid chromatography tandem mass spectrometry-based untargeted metabolomic profiling. Functional brain connectivity was evaluated by magnetic resonance imaging. Sparse partial least squares-discriminant analysis, controlling for sex, body mass index, age, and diet was used to predict brain-gut alterations as a function of ELA. ELA was correlated with four gut-regulated metabolites within the glutamate pathway (5-oxoproline, malate, urate, and glutamate gamma methyl ester) and alterations in functional brain connectivity within primarily sensorimotor, salience, and central executive networks. Integrated analyses revealed significant associations between these metabolites, functional brain connectivity, and scores for perceived stress, anxiety, and depression. This study reveals a novel association between a history of ELA, alterations in the brain-gut axis, and increased vulnerability to negative mood and stress. Results from the study raise the hypothesis that select gut-regulated metabolites may contribute to the adverse effects of critical period stress on neural development via pathways related to glutamatergic excitotoxicity and oxidative stress.

Dopamine, endocannabinoids and their interaction in fear extinction and negative affect in PTSD

There currently exist few frameworks for common neurobiology between reexperiencing and negative cognitions and mood symptoms of PTSD. Adopting a dopaminergic framework for PTSD unites many aspects of unique symptom clusters, and this approach also links PTSD symptomology to common comorbidities with a common neurobiological deficiency. Here we review the dopamine literature and incorporate it with a growing field of research that describes both the contribution of endocannabinoids to fear extinction and PTSD, as well as the interactions between dopaminergic and endocannabinoid systems underlying this disorder. Based on current evidence, we outline an early, preliminary model that links re-experiencing and negative cognitions and mood in PTSD by invoking the interaction between endocannabinoid and dopaminergic signalling in the brain. These interactions between PTSD, dopamine and endocannabinoids may have implications for future therapies for treatment-resistant and comorbid PTSD patients.

Ventral Tegmental Area Dysfunction and Disruption of Dopaminergic Homeostasis: Implications for Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition characterized by intrusive recollections of the traumatic event, avoidance behaviors, hyper-arousal to event-related cues, cognitive disruption, and mood dysregulation. Accumulating preclinical and clinical evidence implicates dysfunction of the ventral tegmental area (VTA) dopaminergic system in PTSD pathogenesis. This article reviews recent advances in our knowledge of the relationship between dopaminergic dyshomeostasis and PTSD, including the contributions of specific dopaminergic gene variants to disease susceptibility, alterations in VTA dopamine neuron activity, dysregulation of dopaminergic transmission, and potential pharmacological and psychological interventions for PTSD targeting the dopaminergic system. An in-depth understanding of PTSD etiology is crucial for the development of innovative risk assessment, diagnostic, and treatment strategies following traumatic events.

L-DOPA and consolidation of fear extinction learning among women with posttraumatic stress disorder

This study tested whether L-DOPA delivered during the consolidation window following fear extinction learning reduces subsequent fear responding among women with PTSD. Adult women diagnosed with PTSD completed a contextual fear acquisition and extinction task during fMRI and then immediately received either placebo (n = 34), 100/25 mg L-DOPA/carbidopa (n = 28), or 200/50 mg L-DOPA/carbidopa (n = 29). Participants completed a resting-state scan before the task and again 45 min following drug ingestion to characterize effects of L-DOPA on extinction memory neural reactivation patterns during consolidation. Twenty-four hours later, participants returned for tests of context renewal, extinction recall, and reinstatement during fMRI with concurrent skin conductance responding (SCR) assessment. Both active drug groups demonstrated increased reactivation of extinction encoding in the amygdala during the post-task resting-state scan. For SCR data, both drug groups exhibited decreased Day 2 reinstatement across all stimuli compared to placebo, and there was some evidence for decreased context renewal to the fear stimulus in the 100 mg group compared to placebo. For imaging data, both drug groups demonstrated decreased Day 2 reinstatement across stimuli in a bilateral insula network compared to placebo. There was no evidence in SCR or neural activity that L-DOPA improved extinction recall. Reactivation of extinction encodings in the amygdala during consolidation on Day 1 predicted Day 2 activation of the insula network. These results support a role for dopamine during the consolidation window in boosting reactivation of amygdala extinction encodings and reducing reinstatement, but not improving extinction recall, in women with PTSD.

Rodent models of post-traumatic stress disorder: behavioral assessment

Although the etiology and expression of psychiatric disorders are complex, mammals show biologically preserved behavioral and neurobiological responses to valent stimuli which underlie the use of rodent models of post-traumatic stress disorder (PTSD). PTSD is a complex phenotype that is difficult to model in rodents because it is diagnosed by patient interview and influenced by both environmental and genetic factors. However, given that PTSD results from traumatic experiences, rodent models can simulate stress induction and disorder development. By manipulating stress type, intensity, duration, and frequency, preclinical models reflect core PTSD phenotypes, measured through various behavioral assays. Paradigms precipitate the disorder by applying physical, social, and psychological stressors individually or in combination. This review discusses the methods used to trigger and evaluate PTSD-like phenotypes. It highlights studies employing each stress model and evaluates their translational efficacies against DSM-5, validity criteria, and criteria proposed by Yehuda and Antelman's commentary in 1993. This is intended to aid in paradigm selection by informing readers about rodent models, their benefits to the clinical community, challenges associated with the translational models, and opportunities for future work. To inform PTSD model validity and relevance to human psychopathology, we propose that models incorporate behavioral test batteries, individual differences, sex differences, strain and stock differences, early life stress effects, biomarkers, stringent success criteria for drug development, Research Domain Criteria, technological advances, and cross-species comparisons. We conclude that, despite the challenges, animal studies will be pivotal to advances in understanding PTSD and the neurobiology of stress.

Rehmannioside A attenuates cognitive deficits in rats with vascular dementia (VD) through suppressing oxidative stress, inflammation and apoptosis

Vascular dementia (VD) is a degenerative cerebrovascular disorder, leading to progressive decline of cognitive abilities and memory. Rehmannioside A (ReA) is isolated from Rehmanniae Radix, which exhibits protective role against various diseases. The present study was performed to calculate the possible neuroprotective effects of ReA on VD. Here, the morris water maze (MWM) test and electrophysiological recordings indicated that ReA reduced cognitive deficits. Additionally, through hematoxylin and eosin (H&E) and Nissl staining, ReA attenuated the histological alterations of hippocampus in rats with VD. ReA group significantly reduced oxidative stress, inflammatory response and apoptosis in the hippocampus of rats with VD, which was linked to the activation of nuclear erythroid related factor-2 (Nrf2), while the inactivation of nuclear factor-κB (NF-κB) and Caspase-3. Further, the anti-oxidative, anti-inflammatory and anti-apoptosis abilities of ReA were confirmed in cells stimulated by hydrogen peroxide. Overall, the results above demonstrated the protective effects of ReA against cognitive deficits and indicated the potential value of ReA in the therapy of VD in future.

Dopamine D2/D3 receptor agonists attenuate PTSD-like symptoms in mice exposed to single prolonged stress

Medications that enhance dopaminergic neurotransmission can be useful in the pharmacotherapy of posttraumatic stress disorder (PTSD), which manifests as fearful memory retrieval, anxiety and depression. We examined the effects of subchronic (15 days) treatment with select dopaminergic medications, including bromocriptine, modafinil, dihydrexidine, rotigotine and pramipexole, in a mouse model of PTSD induced by single prolonged stress (mSPS). The potential antidepressant-like and anxiolytic effects of the medications were measured by the forced swim test (FST) and the elevated plus maze (EPM) test, respectively. In addition, we studied the effects of these medications on memory retrieval in an auditory fear conditioning (FC) test, on ultrasonic vocalizations (USVs) induced by restraint stress, and on spontaneous locomotor activity (SLA). We report that a single exposure to a severe and complex set of stressors several days before testing increased immobility time in the FST and freezing in the FC paradigm and reduced the time spent in the open arms of the EPM. The stressed mice also displayed increased USVs, especially the short type. While none of the tested dopamine-mimetics exhibited anxiolytic-like effects, rotigotine produced antidepressant-like activity specifically in the mSPS-exposed animals. Moreover, both rotigotine and pramipexole shortened the duration of freezing in the fear conditioning test, but only in the mSPS-exposed mice. This study supports the hypothesis that the activation of dopaminergic D2/D3 receptors may be a promising pharmacotherapy for PTSD.

Recent advances in the neurobiology of posttraumatic stress disorder: A review of possible mechanisms underlying an effective pharmacotherapy

Recent progress in the field of neurobiology supported by clinical evidence gradually reveals the mystery of human brain functioning. So far, many psychiatric disorders have been described in great detail, although there are still plenty of cases that are misunderstood. These include posttraumatic stress disorder (PTSD), which is a unique disease that combines a wide range of neurobiological changes, which involve disturbances of the hypothalamic-pituitary-adrenal gland axis, hyperactivation of the amygdala complex, and attenuation of some hippocampal and cortical functions. Such multiplicity results in differential symptomatology, including elevated anxiety, nightmares, fear retrieval episodes that may trigger delusions and hallucinations, sleep disturbances, and many others that strongly interfere with the quality of the patient's life. Because of widespread neurological changes and the disease manifestation, the pharmacotherapy of PTSD remains unclear and requires a multidimensional approach and involvement of polypharmacotherapy. Hopefully, more and more neuroscientists and clinicians will study PTSD, which will provide us with new information that would possibly accelerate establishment of well-tolerated and effective pharmacotherapy. In this review, we have focused on neurobiological changes regarding PTSD, addressing the most disturbed brain structures and neurotransmissions, as well as discussing in detail the recently taken and novel therapeutic paths.

Untangling PTSD and TBI: Challenges and Strategies in Clinical Care and Research

PURPOSE OF REVIEW

Traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) can result from similar injuries and can result in similar symptoms, such as problems with sleep, concentration, memory, and mood. Although PTSD and persistent sequelae due to a TBI (PST) have generally been viewed as pragmatically confounded but conceptually separable entities, we examine emerging evidence emphasizing the breadth of overlap in both clinical presentation and underlying pathophysiology between PST and PTSD.

RECENT FINDINGS

New evidence underscores the poor specificity of symptoms to etiology and emphasizes the potential, after both physical brain injury and traumatic stress, for changes in each of the three interacting systems that coordinate the body's response to the experience or expectation of major injury-the immune, endocrine, and neuromodulatory neurotransmitter systems. A view of PTSD and PST sharing common pathophysiologic elements related to the CNS response to acute injury or threat carries important implications for research and clinical care.

Role of dopamine D3 receptor in alleviating behavioural deficits in animal models of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a complicated psychiatric disorder, which occurs after exposure to a traumatic event. The main clinical manifestation of PTSD includes fear and stress dysregulation. In both animals and humans, dysregulation of dopamine function appears to be related to conditioned fear responses. Previous studies show that the dopamine D3 receptor (D3R) is involved in schizophrenia, autism, and substance use disorders and is related to emotional disorders. However, few studies have investigated the role of the D3R in the pathogenesis and aetiology of PTSD. In the current study, we have reported that D3R knockout (D3R^-/-) mice displayed decreased freezing time of contextual fearing and anxiolytic effects following training sessions consisting of exposure to inescapable electric foot-shocks. Similarly, highly selective blockade of D3Rs by YQA14, a novel D3R antagonist, significantly ameliorated freezing and anxiogenic-like behaviours in the single-prolonged stress (SPS) model of PTSD in rats. And more, YQA14 selectively alleviated the symptoms of PTSD in WT mice but not in D3R^-/- mice. In summary, this study demonstrates the anti-PTSD effects of blockade or knockout of the D3R, suggesting that the D3R might play an important role in the pathogenesis and aetiology of PTSD, and might be a potential target for the clinical management of PTSD.

A DRD2/ANNK1-COMT Interaction, Consisting of Functional Variants, Confers Risk of Post-traumatic Stress Disorder in Traumatized Chinese

Objective: Post-traumatic stress disorder (PTSD) is a trauma- and stress-related psychiatric syndrome that occurs after exposure to extraordinary stressors. The neurotransmitter dopamine (DA) plays important roles in neurobiological processes like reward and stress, and a link between PTSD and the dopaminergic system has been reported. Thus, the investigation of an association between PTSD and gene-gene interaction (epistasis) within dopaminergic genes could uncover the genetic basis of dopamine-related PTSD symptomatology and contribute to precision medicine. Methods: We genotyped seven single nucleotide polymorphisms (SNPs) of three dopaminergic genes DRD2/ANNK1 (rs1800497 and rs1801028), COMT (rs6269, rs4633, rs4818 and rs4680) and DBH (rs1611115), in a Chinese predominantly adult cohort that had been exposed to an earthquake (156 PTSD cases and 978 controls). Results: Statistical genetics analysis identified a DRD2/ANNK1-COMT interaction (rs1800497 × rs6269), which is associated with PTSD diagnosis (P_interaction = 0.0008055 and P_corrected = 0.0169155). Single-variant and haplotype-based subset analyses showed that rs1800497 modulates the association directions of both the rs6269 G allele and the rs6269-rs4633-rs4818-rs4680 haplotype G-C-G-G. The interaction (rs1800497 × rs6269) was replicated in a Chinese young female cohort (32 cases and 581 controls, P_interaction = 0.01329). Conclusions: Rs1800497 is related to the DA receptor D2 density and rs6269-rs4633-rs4818-rs4680 haplotypes affect the catechol O-methyltransferase level and enzyme activity. Thus, the interaction was inferred to be at protein-protein and DA activity level. The genotype combinations of the two SNPs indicate a potential origin of DA homeostasis abnormalities in PTSD development.

Single-Prolonged Stress: A Review of Two Decades of Progress in a Rodent Model of Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a common, costly, and often debilitating psychiatric condition. However, the biological mechanisms underlying this disease are still largely unknown or poorly understood. Considerable evidence indicates that PTSD results from dysfunction in highly-conserved brain systems involved in stress, anxiety, fear, and reward. Pre-clinical models of traumatic stress exposure are critical in defining the neurobiological mechanisms of PTSD, which will ultimately aid in the development of new treatments for PTSD. Single prolonged stress (SPS) is a pre-clinical model that displays behavioral, molecular, and physiological alterations that recapitulate many of the same alterations observed in PTSD, illustrating its validity and giving it utility as a model for investigating post-traumatic adaptations and pre-trauma risk and protective factors. In this manuscript, we review the present state of research using the SPS model, with the goals of (1) describing the utility of the SPS model as a tool for investigating post-trauma adaptations, (2) relating findings using the SPS model to findings in patients with PTSD, and (3) indicating research gaps and strategies to address them in order to improve our understanding of the pathophysiology of PTSD.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Fluoxetine treatment prevents the inflammatory response in a mouse model of posttraumatic stress disorder

Despite intense research efforts the molecular mechanisms affecting stress-vulnerable brain regions in posttraumatic stress disorder (PTSD) remain elusive. In the current study we have applied global transcriptomic profiling to a PTSD mouse model induced by foot shock fear conditioning. We compared the transcriptomes of prelimbic cortex, anterior cingulate cortex (ACC), basolateral amygdala, central nucleus of amygdala, nucleus accumbens (NAc) and CA1 of the dorsal hippocampus between shocked and non-shocked (control) mice, with and without fluoxetine treatment by RNA sequencing. Differentially expressed (DE) genes were identified and clustered for in silico pathway analysis. Findings in relevant brain regions were further validated with immunohistochemistry. DE genes belonging to 11 clusters were identified including increased inflammatory response in ACC in shocked mice. In line with this finding, we noted higher microglial activation in ACC of shocked mice. Chronic fluoxetine treatment initiated in the aftermath of the trauma prevented inflammatory gene expression alterations in ACC and ameliorated PTSD-like symptoms, implying an important role of the immune response in PTSD pathobiology. Our results provide novel insights into molecular mechanisms affected in PTSD and suggest therapeutic applications with anti-inflammatory agents.

A pilot randomized placebo-controlled trial of adjunctive aripiprazole for chronic PTSD in US military Veterans resistant to antidepressant treatment

Many individuals with post-traumatic stress disorder (PTSD) experience persistent symptoms despite pharmacological treatment with antidepressants. Several open-label monotherapy and adjunctive studies have suggested that aripiprazole (a second-generation antipsychotic) may have clinical utility in PTSD. However, there have been no randomized placebo-controlled trials of aripiprazole use for PTSD. We thus conducted a pilot randomized controlled trial of adjunctive aripiprazole versus placebo among Veterans with chronic PTSD serving in the US military since 11 September 2001 to assess the feasibility, safety, tolerability, and therapeutic potential of aripiprazole. Sixteen Veterans were randomized, and 14 completed at least 4 weeks of the study; 12 completed the entire 8-week trial. Outcome measures included the Clinician-Administered PTSD Scale (CAPS), PTSD Checklist, Beck Depression Inventory, Second Edition, and Positive and Negative Syndrome Scale scores. Aripiprazole was well-tolerated in this cohort, and improvements in CAPS, PTSD Checklist, Beck Depression Inventory, Second Edition, and Positive and Negative Syndrome Scale scores were as hypothesized. Although CAPS change scores did not reach statistical significance, aripiprazole outperformed placebo by 9 points on the CAPS in the last observation carried forward analysis compared with the placebo group (n = 7 per group), and by 20 points in the group randomized to aripiprazole that completed the entire study (n = 5) compared with the placebo group (n = 7). Results suggest promise for aripiprazole as an adjunctive strategy for the treatment of PTSD.

Differential effects of sertraline in a predator exposure animal model of post-traumatic stress disorder

Serotonin (5-HT), norepinephrine (NE), and other neurotransmitters are modulated in post-traumatic stress disorder (PTSD). In addition, pro-inflammatory cytokines (PIC) are elevated during the progression of the disorder. Currently, the only approved pharmacologic treatments for PTSD are the selective-serotonin reuptake inhibitors (SSRI) sertraline and paroxetine, but their efficacy in treating PTSD is marginal at best. In combat-related PTSD, SSRIs are of limited effectiveness. Thus, this study sought to analyze the effects of the SSRI sertraline on inflammation and neurotransmitter modulation via a predator exposure/psychosocial stress animal model of PTSD. We hypothesized that sertraline would diminish inflammatory components and increase 5-HT but might also affect levels of other neurotransmitters, particularly NE. PTSD-like effects were induced in male Sprague-Dawley rats (n = 6/group × 4 groups). The rats were secured in Plexiglas cylinders and placed in a cage with a cat for 1 h on days 1 and 11 of a 31-day stress regimen. PTSD rats were also subjected to psychosocial stress via daily cage cohort changes. At the conclusion of the stress regimen, treatment group animals were injected intraperitoneally (i.p.) with sertraline HCl at 10 mg/kg for 7 consecutive days, while controls received i.p. vehicle. The animals were subsequently sacrificed on day 8. Sertraline attenuated inflammatory markers and normalized 5-HT levels in the central nervous system (CNS). In contrast, sertraline produced elevations in NE in the CNS and systemic circulation of SSRI treated PTSD and control groups. This increase in NE suggests SSRIs produce a heightened noradrenergic response, which might elevate anxiety in a clinical setting.

Predator exposure/psychosocial stress animal model of post-traumatic stress disorder modulates neurotransmitters in the rat hippocampus and prefrontal cortex

Post-Traumatic Stress Disorder (PTSD) can develop in response to a traumatic event involving a threat to life. To date, no diagnostic biomarkers have been identified for PTSD. Recent research points toward physiological abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis, sympathoadrenal medullary and immune system that may be implicated in the disorder. The modulation of neurotransmitters is another possible mechanism, but their role in the progression of PTSD is poorly understood. Low serotonin (5-HT) may be a factor, but it may not be the only neurotransmitter affected as modulation affects levels of other neurotransmitters. In this study, we hypothesized the predator exposure/psychosocial stress rodent model of PTSD may alter levels of 5-HT and other neurotransmitters in the rat hippocampus and prefrontal cortex (PFC). Male Sprague-Dawley rats were used in this experiment. We induced PTSD via a predator exposure/psychosocial stress model, whereby rats were placed in a cage with a cat for 1 hour on days 1 and 11 of the 31-day experiment. Rats also received psychosocial stress via daily cage cohort changes. On day 32, the rats were sacrificed and the brains dissected to remove the hippocampus and PFC. Norepinephrine (NE), 5-Hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), dopamine (DA), and 3,4-Dihydroxyphenylacetic acid (DOPAC), and 5-HT levels in the hippocampus and PFC were measured with high-performance liquid chromatography (HPLC). In the hippocampus, 5-HT and HVA were lower, while NE and DOPAC were higher, in the PTSD group vs. controls. In the PFC, only 5-HT was lower, while NE, DA, and DOPAC were higher, in the PTSD group vs. controls. The rate limiting enzymes tyrosine hydroxylase and tryptophan hydroxylase were also examined and confirmed our findings. These results demonstrate that the predator exposure/psychosocial stress model of PTSD produces neurotransmitter changes similar to those seen in human patients and may cause a heightened noradrenergic response.

Multifunctional aspects of allopregnanolone in stress and related disorders

Allopregnanolone (3α-hydroxy-5α-pregnan-20-one) is a major cholesterol-derived neurosteroid in the central nervous system and is synthesized from progesterone by steroidogenic enzymes, 5α-reductase (the rate-limiting enzyme) and 3α-hydroxysteroid dehydrogenase. The pathophysiological role of allopregnanolone in neuropsychiatric disorders has been highlighted in several investigations. The changes in neuroactive steroid levels are detected in stress and stress-related disorders including anxiety, panic and depression. The changes in allopregnanolone in response to acute stressor tend to restore the homeostasis by dampening the hyper-activated HPA axis. However, long standing stressors leading to development of neuropsychiatric disorders including depression and anxiety are associated with decrease in the allopregnanolone levels. GABAA receptor complex has been considered as the primary target of allopregnanolone and majority of its inhibitory actions are mediated through GABA potentiation or direct activation of GABA currents. The role of progesterone receptors in producing the late actions of allopregnanolone particularly in lordosis facilitation has also been described. Moreover, recent studies have also described the involvement of other multiple targets including brain-derived neurotrophic factor (BDNF), glutamate, dopamine, opioids, oxytocin, and calcium channels. The present review discusses the various aspects of allopregnanolone in stress and stress-related disorders including anxiety, depression and panic.

Connecting the pathology of posttraumatic stress and substance use disorders: monoamines and neuropeptides

Posttraumatic stress disorder (PTSD) co-occurs highly with substance use disorders (SUDs), yet the neurobiological basis for this comorbid relationship remains unclear. PTSD and SUDs result in similar pathological states including impulsive behavior, reward deficiency, and heightened stress sensitivity. Hence, PTSD and SUD may depend on overlapping dysfunctional neurocircuitry. Here we provide a short overview of the relationship between comorbid PTSD and SUD, as well as the potential role of select neurotransmitter systems that may underlie enhanced vulnerability to drug abuse in the context of PTSD.