Post-traumatic stress avoidance is attenuated by corticosterone and associated with brain levels of steroid receptor co-activator-1 in rats

Modulating glucocorticoid receptor actions in physiology and pathology: Insights from coregulators

Glucocorticoids (GCs) are a class of steroid hormones that regulate key physiological processes such as metabolism, immune function, and stress responses. The effects of GCs are mediated by the glucocorticoid receptor (GR), a ligand-dependent transcription factor that activates or represses the expression of hundreds to thousands of genes in a tissue- and physiological state-specific manner. The activity of GR is modulated by numerous coregulator proteins that interact with GR in response to different stimuli assembling into a multitude of DNA-protein complexes and facilitate the integration of these signals, helping GR to communicate with basal transcriptional machinery and chromatin. Here, we provide a brief overview of the physiological and molecular functions of GR, and discuss the roles of GR coregulators in the immune system, key metabolic tissues and the central nervous system. We also present an analysis of the GR interactome in different cells and tissues, which suggests tissue-specific utilization of GR coregulators, despite widespread functions shared by some of them.

The role of the dorsal hippocampus in resistance to the development of posttraumatic stress disorder-like behaviours

This study aimed to determine the activity of the dorsal hippocampus (dHIP) in resistance to the development of posttraumatic stress disorder (PTSD)-like behaviours. Rats were divided into resistant, PTSD(-), and susceptible, PTSD(+) groups based on the time spent in the central area in an open field test and freezing duration during exposure to an aversive context one week after stress experience (electric foot shock). The PTSD(-) rats, compared to the PTSD(+) group, had an increased concentration of corticosterone in plasma and changes in the activity of the dHIP, specifically, increased c-Fos expression in the dentate gyrus (DG) and increased Neuroligin-2 (marker of GABAergic neurotransmission) expression in the DG and CA3 area of the dHIP. Moreover, in the hippocampus, the PTSD(-) group showed decreased mRNA expression for corticotropin-releasing factor receptors type 1 and 2, increased mRNA expression for orexin receptor type 1, and decreased miR-9 and miR-34c levels compared with the PTSD(+) group. This study may suggest that the increase in GABA signalling in the hippocampus attenuates the activity of the CRF system and enhances the function of the orexin system. Moreover, decreased expression of miR-34c and miR-9 could facilitate fear extinction and diminishes the anxiety response. These effects may lead to an anxiolytic-like effect and improve resistance to developing PTSD-like behaviours.

Comorbidity of Post-Traumatic Stress Disorder and Alcohol Use Disorder: Animal Models and Associated Neurocircuitry

Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are prevalent neuropsychiatric disorders and frequently co-occur concomitantly. Individuals suffering from this dual diagnosis often exhibit increased symptom severity and poorer treatment outcomes than those with only one of these diseases. Lacking standard preclinical models limited the exploration of neurobiological mechanisms underlying PTSD and AUD comorbidity. In this review, we summarize well-accepted preclinical model paradigms and criteria for developing successful models of comorbidity. We also outline how PTSD and AUD affect each other bidirectionally in the nervous nuclei have been heatedly discussed recently. We hope to provide potential recommendations for future research.

The effects of stress on avoidance in rodents: An unresolved matter

In the face of a possible threat, a range of physiological (e.g., increased heart rate) and behavioral (e.g., avoidance or escape) responses are recruited. Here, we will focus on avoidance, in its persistent form one of the core symptoms of anxiety disorders and obsessive-compulsive disorder. The initial goal of fear and avoidance responses is to increase survival, but if they become persistent or overgeneralize, they can disrupt normal daily functioning, and ultimately even result in anxiety-related disorders. Relatedly, acute stress responses promote adaptation and survival, while chronic stress has been found to aggravate pathophysiology. Thus, stress might trigger the transition from adaptive to maladaptive responses, e.g., from goal-directed to persistent avoidance. Animal models are prime tools to unravel if and how stress influences avoidance. This is typically done by performing stress inductions prior to the assessment of (passive or active) avoidance behavior. Despite its clinical relevance, the current literature on this topic is fragmented, and an overall conclusion is lacking. In this Review, we first recapitulate the state of the art regarding stress and active as well as passive avoidance procedures. We then summarize the behavioral effects of acute and chronic stress on active and passive avoidance, and discuss the main neurobiological findings of the field. Finally, we highlight possible reasons for the largely contradictory findings in the literature and we propose strategies to further unravel the effect of stress on avoidance behavior. A deeper understanding of this currently unresolved matter may provide further insights in the etiology and treatment of anxiety-related disorders.

Immune receptor toll-like receptor 4 contributes to stress-induced affective responses in a sex-specific manner

Stress activates innate immune Toll-like receptors (TLRs) and enhances susceptibility to depression, a condition that is more prevalent in females. The TLR4 receptor type is involved in inflammatory responses and its expression levels associate with depressive symptoms and their successful treatment. Yet, little preclinical research has examined the role of TLR4 in stress-induced affective responses to determine if these are sex-specific. One group per genotype of male and female Tlr4 knockout (KO) and wild type (WT) rats were exposed to predator odor in a place conditioning apparatus with others exposed to saline. Affective behaviors evaluated included distance traveled and center time in an open-field apparatus, sucrose preference and fluid intake in a two-bottle test, and conditioned place aversion to the odor-paired compartment. Predator odor exposed rats showed conditioned place aversion to the odor-paired compartment, demonstrating predator odor was aversive. Such exposure led to anhedonia (decreased sucrose preference) across genotypes and sex. Predator odor exposure decreased distance traveled, an effect that was greater in KO rats, especially in females. Tlr4 deletion also resulted in sex-specific effects on anxiety-like behavior. Compared to WTs, female KO rats showed lower center time after predator odor exposure whereas genotype did not affect this response in male rats. Across litters, fewer male KO and heterozygous rats and more WT rats were born whereas female rats showed the typical genotype distribution. Results suggest predator odor alters affective behaviors, consistent with the preclinical literature, and deletion of Tlr4 enhances some stress-induced affective responses, often in a sex-specific manner.

Is PTSD-Phenotype Associated with HPA-Axis Sensitivity? Feedback Inhibition and Other Modulating Factors of Glucocorticoid Signaling Dynamics

Previously, we found that basal corticosterone pulsatility significantly impacts the vulnerability for developing post-traumatic stress disorder (PTSD). Rats that exhibited PTSD-phenotype were characterized by blunted basal corticosterone pulsatility amplitude and a blunted corticosterone response to a stressor. This study sought to identify the mechanisms underlining both the loss of pulsatility and differences in downstream responses. Serial blood samples were collected manually via jugular vein cannula at 10-min intervals to evaluate suppression of corticosterone following methylprednisolone administration. The rats were exposed to predator scent stress (PSS) after 24 h, and behavioral responses were assessed 7 days post-exposure for retrospective classification into behavioral response groups. Brains were harvested for measurements of the glucocorticoid receptor, mineralocorticoid receptor, FK506-binding protein-51 and arginine vasopressin in specific brain regions to assess changes in hypothalamus–pituitary–adrenal axis (HPA) regulating factors. Methylprednisolone produced greater suppression of corticosterone in the PTSD-phenotype group. During the suppression, the PTSD-phenotype rats showed a significantly more pronounced pulsatile activity. In addition, the PTSD-phenotype group showed distinct changes in the ventral and dorsal CA1, dentate gyrus as well as in the paraventricular nucleus and supra-optic nucleus. These results demonstrate a pre-trauma vulnerability state that is characterized by an over-reactivity of the HPA and changes in its regulating factors.

Chronic early trauma impairs emotion recognition and executive functions in youth; specifying biobehavioral precursors of risk and resilience

Exposure to chronic early trauma carries lasting effects on children's well-being and adaptation. Guided by models on resilience, we assessed the interplay of biological, emotional, cognitive, and relational factors in shaping two regulatory outcomes in trauma-exposed youth: emotion recognition (ER) and executive functions (EF). A unique war-exposed cohort was followed from early childhood to early adolescence. At preadolescence (11-13 years), ER and EF were assessed and respiratory sinus arrhythmia (RSA), biomarker of parasympathetic regulation, was quantified. Mother-child dyadic reciprocity, child's avoidance symptoms, and cortisol (CT) were measured in early childhood. Trauma-exposed youth displayed impaired ER and EF abilities. Conditional process analysis described two differential indirect paths leading from early trauma to regulatory outcomes. ER was mediated by avoidance symptoms in early childhood and modulated by cortisol, such that this path was evident only for preadolescents with high, but not low, CT. In comparison, EF was mediated by the degree of dyadic reciprocity experienced in early childhood and modulated by RSA, observed only among youth with lower RSA. Findings pinpoint trauma-related disruptions to key regulatory support systems in preadolescence as mediated by early-childhood relational, clinical, and physiological factors and highlight the need to specify biobehavioral precursors of resilience toward targeted early interventions.

Low glucocorticoids in stress-related disorders: the role of inflammation

There is evidence that plasma cortisol concentration can be either increased or decreased in patients with depression and related anxiety and stress-related disorders; the exact pathophysiological mechanisms of this state are not almost clear. Several distinct theories were proposed and mechanisms, which could lead to decreased glucocorticoid signaling and/or levels, were described. However, there is a possible drawback in almost all the theories proposed: insufficient attention to the inflammatory process, which is undoubtedly present in several stress-related disorders, including post-traumatic stress disorder (PTSD). Previous studies only briefly mentioned the presence of an inflammatory reaction's signs in PTSD, without giving it due importance, although recognizing that it can affect the course of the disease. With that, the state of biochemical changes, characterized by the low glucocorticoids, glucocorticoid receptor's resistance and the signs of the persistent inflammation (with the high levels of circulating cytokines) might be observed not only in PTSD but in coronary heart diseases and systemic chronic inflammatory diseases (rheumatoid arthritis) as well. That is why the present review aims to depict the pathophysiological mechanisms, which lead to a decrease in glucocorticoids in PTSD due to the action of inflammatory stimuli. We described changes in the glucocorticoid system and inflammatory reaction as parts of an integral system, where glucocorticoids and the glucocorticoid receptor reside at the apex of a regulatory network that blocks several inflammatory pathways, while decreased glucocorticoid signaling and/or level leads to unchecked inflammatory reactions to promote pathologies such as PTSD. LAY SUMMARY This review emphasizes the importance of inflammatory reaction in the development of puzzling conditions sometimes observed in severe diseases including post-traumatic stress disorder - the decreased levels of glucocorticoids in the blood. Following the classical concepts, one would expect an increase in glucocorticoid hormones, since they are part of the feedback mechanism in the immune system, which reduces stress and inflammation. However, low levels of glucocorticoid hormones are also observed. Thus, this review describes potential mechanisms, which can lead to the development of such a state.

Effects of RU486 treatment after single prolonged stress depend on the post-stress interval

The Single Prolonged Stress protocol is considered a model for PTSD, as it induces long lasting changes in rat behaviour and endocrine regulation. Previous work demonstrated that some of these changes can be prevented by treatment with the glucocorticoid receptor antagonist RU486, administered a week after the stressor. The current study evaluated the effects of an earlier intervention with RU486, as evaluated 1 week after SPS-exposure. Most RU486 effects occurred independent of prior stress, except for the reversal of a stress-induced increase in locomotor behaviour. The accompanying changes in gene expression depended on gene, brain region, and time. DNA methylation of the robustly down-regulated Fkbp5 gene was dissociated of changes in mRNA expression. The findings reinforce the long term effects of GR antagonist treatment, but also emphasize the need to evaluate changes over time to allow the identification of robust correlates between gene expression and behavioural/endocrine outcome of stressful experiences.

Nuclear Receptor Coactivators (NCOAs) and Corepressors (NCORs) in the Brain

Nuclear receptor coactivators (NCOAs) and corepressors (NCORs) bind to nuclear hormone receptors in a ligand-dependent manner and mediate the transcriptional activation or repression of the downstream target genes in response to hormones, metabolites, xenobiotics, and drugs. NCOAs and NCORs are widely expressed in the mammalian brain. Studies using genetic animal models started to reveal pivotal roles of NCOAs/NCORs in the brain in regulating hormonal signaling, sexual behaviors, consummatory behaviors, exploratory and locomotor behaviors, moods, learning, and memory. Genetic variants of NCOAs or NCORs have begun to emerge from human patients with obesity, hormonal disruption, intellectual disability, or autism spectrum disorders. Here we review recent studies that shed light on the function of NCOAs and NCORs in the central nervous system.

Individual susceptibility or resistance to posttraumatic stress disorder-like behaviours

The aim of this study was to explore the neurobiological background of individual susceptibility and resistance to the development of posttraumatic stress disorder (PTSD)-like behaviours. Rats were divided into susceptible, PTSD(+), and resistant, PTSD(-), groups based on freezing duration during exposure to aversive context and the time spent in the central area in open field test one week after threefold stress experience (modified single prolonged stress). PTSD(-) rats showed increased concentrations of corticosterone in plasma and changes in GAD67 expression: decreased in the infralimbic cortex (IL) and increased in the lateral amygdala (LA), dentate gyrus (DG), and CA1 area of the hippocampus. Moreover, in this group, we found an increase in the number of CRF-positive nuclei in the parvocellular neurons of the paraventricular hypothalamic nucleus (pPVN). The PTSD(+) group, compared to PTSD(-) rats, had decreased concentrations of corticosterone in plasma and reduced CRF expression in the pPVN, higher CRF expression in the CA1, increased expression of CRF-positive nuclei and GR receptors in the CA3 area of the hippocampus, and increased expression of GR receptors in the DG and the central amygdala (CeA). Biochemical analysis showed higher concentrations of noradrenaline, glutamic acid in the dorsal hippocampus and amygdala and lower levels of dopamine and its metabolites in the amygdala of the PTSD(+) group than in the PTSD(-) group. The study revealed different behavioural and biochemical profiles of PTSD(+) and PTSD(-) rats and suggested that individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity may determine hippocampal- and amygdala-dependent memory and fear processing.

Inhibition of steroid receptor coactivator-1 in the hippocampus impairs the consolidation and reconsolidation of contextual fear memory in mice

AIMS

Steroid receptor coactivator-1 (SRC-1) is a key coactivator for the efficient transcriptional activity of steroids in the regulation of hippocampal functions. However, the effect of SRC-1 on hippocampal memory processes remains unknown. Our aim was to investigate the roles of hippocampal SRC-1 in the consolidation and reconsolidation of contextual fear memory in mice.

MAIN METHODS

Contextual fear conditioning paradigm was constructed in adult male C57BL/6 mice to examine the fear learning and memory processes. Adeno-associated virus (AAV) vector-mediated RNA interference (RNAi) was infused into hippocampus to block hippocampal SRC-1 level. Immunofluorescent staining was used to detect the efficiency of transfection. High plus maze and open field test were used to determine anxiety and locomotor activity. Western blot analyses were used to detect the expression of SRC-1 and synaptic proteins in the hippocampus.

KEY FINDINGS

We first showed that the expression of SRC-1 was regulated by fear conditioning training in a time-dependent manner, and knockdown of SRC-1 impaired contextual fear memory consolidation without affecting innate anxiety or locomotor activity. In addition, hippocampal SRC-1 was also regulated by the retrieval of contextual fear memory, and downregulation of SRC-1 disrupted fear memory reconsolidation. Moreover, knockdown of SRC-1 reversed the increased GluR1 and PSD-95 levels induced by contextual fear memory retrieval.

SIGNIFICANCE

Our data indicate that hippocampal SRC-1 is required for the consolidation and reconsolidation of contextual fear memory, and SRC-1 may be a potential therapeutic target for mental disorders that are involved in hippocampal memory dysfunction.

Accelerated development of cocaine-associated dopamine transients and cocaine use vulnerability following traumatic stress

Post-traumatic stress disorder and cocaine use disorder are highly co-morbid psychiatric conditions. The onset of post-traumatic stress disorder generally occurs prior to the development of cocaine use disorder, and thus it appears that the development of post-traumatic stress disorder drives cocaine use vulnerability. We recently characterized a rat model of post-traumatic stress disorder with segregation of rats as susceptible and resilient based on anxiety-like behavior in the elevated plus maze and context avoidance. We paired this model with in vivo fast scan cyclic voltammetry in freely moving rats to test for differences in dopamine signaling in the nucleus accumbens core at baseline, in response to a single dose of cocaine, and in response to cocaine-paired cues. Further, we examined differences in the acquisition of cocaine self-administration across groups. Results indicate that susceptibility to traumatic stress is associated with alterations in phasic dopamine signaling architecture that increase the rate at which dopamine signals entrain to cocaine-associated cues and increase the magnitude of persistent cue-evoked dopamine signals following training. These changes in phasic dopamine signaling correspond with increases in the rate at which susceptible rats develop excessive cocaine-taking behavior. Together, our studies demonstrate that susceptibility to traumatic stress is associated with a cocaine use-vulnerable phenotype and suggests that differences in phasic dopamine signaling architecture may contribute to the process by which this vulnerability occurs.

The role of central amygdala corticotropin-releasing factor in predator odor stress-induced avoidance behavior and escalated alcohol drinking in rats

Post-traumatic stress disorder (PTSD) is characterized by avoidance of trauma-associated stimuli and amygdala hyperreactivity, and is highly co-morbid with alcohol use disorder (AUD). Our lab uses a predator odor (bobcat urine) stress model that produces conditioned avoidance of an odor-paired context in a subset of rats, mirroring avoidance symptoms that manifest in some but not all humans exposed to trauma. We previously showed that after predator odor stress, Avoiders exhibit escalated operant alcohol self-administration (SA), higher aversion-resistant operant alcohol responding, hyperalgesia, and greater anxiety-like behavior compared to unstressed Controls. We also showed previously that systemic antagonism of corticotropin-releasing factor-1 receptors (CRFR1) reduced escalation of operant alcohol SA in rats not indexed for avoidance, that corticotropin-releasing factor (CRF) infusions into the central amygdala (CeA) produced conditioned place avoidance in stress-naïve rats, and that intra-CeA infusion of a CRFR1 antagonist reduced hyperalgesia in Avoiders. Here, we show that avoidance behavior is persistent after repeated predator odor exposure. In addition, Avoiders showed lower weight gain than Controls after predator odor re-exposure. In the brain, higher avoidance was correlated with higher number of c-Fos + cells and CRF immunoreactivity in the CeA. Finally, we show that intra-CeA CRFR1 antagonism reversed post-stress escalation of alcohol SA and reduced avoidance behavior in Avoiders. Collectively, these findings suggest that elucidation of the mechanisms by which CRFR1-gated CeA circuits regulate avoidance behavior and alcohol SA may lead to better understanding of the neural mechanisms underlying co-morbid PTSD and AUD.

The predator odor avoidance model of post-traumatic stress disorder in rats

Individuals with post-traumatic stress disorder avoid trauma-related stimuli and exhibit blunted hypothalamic-pituitary-adrenal axis response at the time of trauma. Our laboratory uses predator odor (i.e. bobcat urine) stress to divide adult Wistar rats into groups that exhibit high (avoiders) or low (nonavoiders) avoidance of a predator odor-paired context, modeling the fact that not all humans exposed to traumatic events develop psychiatric conditions. Male avoiders exhibit lower body weight gain after stress, as well as extinction-resistant avoidance that persists after a second stress exposure. These animals also show attenuated hypothalamic-pituitary-adrenal axis response to predator odor that predicts subsequent avoidance of the odor-paired context. Avoiders exhibit unique brain activation profiles relative to nonavoiders and controls (as measured by Fos immunoreactivity), and higher corticotropin-releasing factor levels in multiple brain regions. Furthermore, avoider rats exhibit escalated and compulsive-like alcohol self-administration after traumatic stress. Here, we review the predator odor avoidance model of post-traumatic stress disorder and its utility for tracking behavior and measuring biological outcomes predicted by avoidance. The major strengths of this model are (i) etiological validity with exposure to a single intense stressor, (ii) established approach distinguishing individual differences in stress reactivity, and (iii) robust behavioral and biological phenotypes during and after trauma.

Bilateral amygdala stimulation reduces avoidance behavior in a predator scent posttraumatic stress disorder model

OBJECTIVE The predator scent model of posttraumatic stress disorder (PTSD) produces prolonged abnormal anxiety and avoidance-like behaviors. Increased basolateral amygdala activity has been shown to correlate with severity of PTSD symptoms in human studies. Modulation of this increased amygdala activity by deep brain stimulation led to improved symptoms in prior studies that used a foot shock model of inducing PTSD. The predator scent model is a different technique that induces long-lasting avoidance behavioral responses by exposing the animal to an inescapable scent of one of its predators. The authors hypothesize that high-frequency stimulation of the bilateral basolateral amygdala will decrease avoidance and anxiety-like behaviors in a predator scent rodent model of PTSD. METHODS Rodents underwent cat urine exposure in a place preference protocol. Avoidance in the place preference paradigm and anxiety-like behavior in the elevated plus maze were measured before and after high-frequency stimulation. RESULTS Predator scent exposure resulted in long-term significant avoidance behavior in rodents. Bilateral stimulation significantly decreased avoidance behavior in rodents compared to no stimulation following predator scent exposure. There were no significant differences in anxiety behaviors on the elevated plus maze between stimulated and unstimulated cohorts. CONCLUSIONS Bilateral stimulation of the basolateral amygdala leads to decreased avoidance behavior compared to controls in a predator scent model of PTSD.

Medullary Respiratory Circuit Is Reorganized by a Seasonally-Induced Program in Preparation for Hibernation

Deep hibernators go through several cycles of profound drops in body temperature during the winter season, with core temperatures sometimes reaching near freezing. Yet unlike non-hibernating mammals, they can sustain breathing rhythms. The physiological processes that make this possible are still not understood. In this study, we focused on the medullary Ventral Respiratory Column of a facultative hibernator, the Syrian hamster. Using shortened day-lengths, we induced a "winter-adapted" physiological state, which is a prerequisite for hibernation. When recording electrophysiological signals from acute slices in the winter-adapted pre-Bötzinger complex (preBötC), spike trains showed higher spike rates, amplitudes, complexity, as well as higher temperature sensitivity, suggesting an increase in connectivity and/or synaptic strength during the winter season. We further examined action potential waveforms and found that the depolarization integral, as measured by the area under the curve, is selectively enhanced in winter-adapted animals. This suggests that a shift in the ion handling kinetics is also being induced by the winter-adaptation program. RNA sequencing of respiratory pre-motor neurons, followed by gene set enrichment analysis, revealed differential regulation and splicing in structural, synaptic, and ion handling genes. Splice junction analysis suggested that differential exon usage is occurring in a select subset of ion handling subunits (ATP1A3, KCNC3, SCN1B), and synaptic structure genes (SNCB, SNCG, RAB3A). Our findings show that the hamster respiratory center undergoes a seasonally-cued alteration in electrophysiological properties, likely protecting against respiratory failure at low temperatures.

A Rodent Model of Exposure Therapy: The Use of Fear Extinction as a Therapeutic Intervention for PTSD

The symptoms of post-traumatic stress disorder (PTSD) include cognitive impairment related to medial prefrontal cortical dysfunction. Indeed, a deficit of cognitive flexibility, i.e., an inability to modify previously learned thoughts and behaviors based on changes in the environment, may underlie many of the other symptoms of PTSD, such as changes in mood, hyper-arousal, intrusive thoughts, exaggerated and over-generalized fear, and avoidance behavior. Cognitive-behavioral therapies target the cognitive dysfunction observed in PTSD patients, training them to recalibrate stress-related perceptions, interpretations and responses. Preclinically, the extinction of conditioned fear bears resemblance to one form of cognitive therapy, exposure therapy, whereby an individual learns, through repeated exposure to a fear-provoking stimulus in a safe environment, that the stimulus no longer signals imminent threat, and their fear response is suppressed. In this review article, we highlight recent findings from our lab using fear extinction as a preclinical model of exposure therapy in rodents exposed to chronic unpredictable stress (CUS). We specifically focus on the therapeutic effects of extinction on stress-compromised set-shifting as a measure of cognitive flexibility, and active vs. passive coping behavior as a measure of avoidance. Finally, we discuss mechanisms involving activity and plasticity in the medial prefrontal cortex (mPFC) necessary for the therapeutic effects of extinction on cognitive flexibility and active coping.

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.

Biobehavioral Interactions Between Stress and Alcohol

In this review, the effects of stress on alcohol drinking are discussed. The interactions between biological stress systems and alcohol drinking are examined, with a focus on the hypothalamic pituitary adrenal axis, corticotropin releasing factor, dynorphin, neuropeptide Y, and norepinephrine systems. Findings from animal models suggest that these biological stress systems may be useful targets for medications development for alcohol use disorder and co-occurring stress-related disorders in humans.

Integrating Endocannabinoid Signaling and Cannabinoids into the Biology and Treatment of Posttraumatic Stress Disorder

Exposure to stress is an undeniable, but in most cases surmountable, part of life. However, in certain individuals, exposure to severe or cumulative stressors can lead to an array of pathological conditions including posttraumatic stress disorder (PTSD), characterized by debilitating trauma-related intrusive thoughts, avoidance behaviors, hyperarousal, as well as depressed mood and anxiety. In the context of the rapidly changing political and legal landscape surrounding use of cannabis products in the USA, there has been a surge of public and research interest in the role of cannabinoids in the regulation of stress-related biological processes and in their potential therapeutic application for stress-related psychopathology. Here we review the current state of knowledge regarding the effects of cannabis and cannabinoids in PTSD and the preclinical and clinical literature on the effects of cannabinoids and endogenous cannabinoid signaling systems in the regulation of biological processes related to the pathogenesis of PTSD. Potential therapeutic implications of the reviewed literature are also discussed. Finally, we propose that a state of endocannabinoid deficiency could represent a stress susceptibility endophenotype predisposing to the development of trauma-related psychopathology and provide biologically plausible support for the self-medication hypotheses used to explain high rates of cannabis use in patients with trauma-related disorders.

Neurobiology of comorbid post-traumatic stress disorder and alcohol-use disorder

Post-traumatic stress disorder (PTSD) and alcohol-use disorder (AUD) are highly comorbid in humans. Although we have some understanding of the structural and functional brain changes that define each of these disorders, and how those changes contribute to the behavioral symptoms that define them, little is known about the neurobiology of comorbid PTSD and AUD, which may be due in part to a scarcity of adequate animal models for examining this research question. The goal of this review is to summarize the current state-of-the-science on comorbid PTSD and AUD. We summarize epidemiological data documenting the prevalence of this comorbidity, review what is known about the potential neurobiological basis for the frequent co-occurrence of PTSD and AUD and discuss successes and failures of past and current treatment strategies. We also review animal models that aim to examine comorbid PTSD and AUD, highlighting where the models parallel the human condition, and we discuss the strengths and weaknesses of each model. We conclude by discussing key gaps in our knowledge and strategies for addressing them: in particular, we (1) highlight the need for better animal models of the comorbid condition and better clinical trial design, (2) emphasize the need for examination of subpopulation effects and individual differences and (3) urge cross-talk between basic and clinical researchers that is reflected in collaborative work with forward and reverse translational impact.