Cannabinoids as therapeutics for PTSD

Brain region specific regulation of anandamide (down) and sphingosine-1-phosphate (up) in association with anxiety (AEA) and resilience (S1P) in a mouse model of chronic unpredictable mild stress

Chronic unpredictable and unavoidable stress is associated with mental health problems such as depression and anxiety, whereas cycles of stress and stress relief strengthen resilience. It has been suggested that increased breakdown of brain endocannabinoids (eCB) promotes a feeling of adversity. To assess the impact of stress on bioactive lipid homeostasis, we analyzed eCB, sphingolipids, and ceramides in seven brain regions and plasma in a mouse model of chronic unpredictable mild stress. Chronic unpredictable mild stress (CUMS) was associated with low levels of anandamide in hippocampus and prefrontal cortex in association with indicators of anxiety (elevated plus maze). Oppositely, CUMS caused elevated levels of sphingosine-1-phosphate (S1P d18:1) and sphinganine-1-phosphate (S1P d18:0) in the midbrain and thalamus, which was associated with readouts of increased stress resilience, i.e., marble burying and struggling in the tail suspension tests. In the periphery, elevated plasma levels of ceramides revealed similarities with human major depression and suggested unfavorable effects of stress on metabolism, but plasma lipids were not associated with body weight, sucrose consumption, or behavioral features of depression or anxiety. The observed brain site-specific lipid changes suggest that the forebrain succumbs to adverse stress effects while the midbrain takes up defensive adjustments.

New recognition of the heart-brain axis and its implication in the pathogenesis and treatment of PTSD

Post-traumatic stress disorder (PTSD) is a complex psychological disorder provoked by distressing experiences, and it remains without highly effective intervention strategies. The exploration of PTSD's underlying mechanisms is crucial for advancing diagnostic and therapeutic approaches. Current studies primarily explore PTSD through the lens of the central nervous system, investigating concrete molecular alterations in the cerebral area and neural circuit irregularities. However, the body's response to external stressors, particularly the changes in cardiovascular function, is often pronounced, evidenced by notable cardiac dysfunction. Consequently, examining PTSD with a focus on cardiac function is vital for the early prevention and targeted management of the disorder. This review undertakes a comprehensive literature analysis to detail the alterations in brain and heart structures and functions associated with PTSD. It also synthesizes potential mechanisms of heart-brain axis interactions relevant to the development of PTSD. Ultimately, by considering cardiac function, this review proposes novel perspectives for PTSD's prophylaxis and therapy.

Unraveling the molecular basis of cannabidiolic acid methyl Ester's anti-depressive effects in a rat model of treatment-resistant depression

Major depressive disorder (MDD) stands as a significant cause of disability globally. Cannabidiolic Acid-Methyl Ester (CBDA-ME) (EPM-301, HU-580), a derivative of Cannabidiol, demonstrates immediate antidepressant-like effects, yet it has undergone only minimal evaluation in psychopharmacology. Our goal was to investigate the behavioral and potential molecular mechanisms associated with the chronic oral administration of this compound in the Wistar Kyoto (WKY) genetic model of treatment-resistant depression. Male WKY rats were subjected to behavioral assessments before and after receiving chronic (14-day) oral doses of CBDA-ME (0.5 mg/kg), 15 mg/kg of imipramine or vehicle. At the end of the study, plasma corticosterone levels and mRNA expression of various genes in the medial Prefrontal Cortex and Hippocampus were measured. Behavioral outcomes from CBDA-ME treatment indicated an antidepressant-like effect similar to imipramine, as oral ingestion reduced immobility and increased swimming duration in the Forced Swim Test. Neither treatment influenced locomotion in the Open Field Test nor preference in the Saccharin Preference Test. The behavioral impact in WKY rats coincided with reduced corticosterone serum levels, upregulated mRNA expression of Cannabinoid receptor 1, Fatty Acid Amide Hydrolase, and Corticotropin-Releasing Hormone Receptor 1, alongside downregulation of the Serotonin Transporter in the hippocampus. Additionally, there was an upregulation of CB1 mRNA expression and downregulation of Brain-Derived Neurotrophic Factor in the mPFC. These findings contribute to our limited understanding of the antidepressant effects of CBDA-ME and shed light on its potential psychopharmacological mechanisms. This discovery opens up possibilities for utilizing cannabinoids in the treatment of major depressive disorder and related conditions.

Mental and Physical Health-Related Cannabis Motives Mediate the Relationship between Childhood Trauma and Problematic Cannabis Use over Time among Emerging Adult Cannabis Users

BACKGROUND

While growing evidence has identified mental and physical health-related cannabis use motives as significant mechanisms between childhood trauma and problematic cannabis use (PCU) for emerging adults (EA), there is a need to understand the longitudinal stability of these pathways and how they impact PCU as cannabis users age into later adulthood.

METHODS

The current study extends an analysis examining the impact of childhood trauma (e.g., emotional abuse, sexual abuse) on multiple indicators of PCU through a range of cannabis use motives. 339 medical cannabis patient and non-patient EA users from the Los Angeles area were sampled at baseline (mean age = 21.23; SD = 2.48). The present analysis used four waves of follow-up data collected from 2016 to 2018 (W3, W4) and 2019-2020 (W5, W6).

RESULTS

Use of cannabis to cope with nausea, sleep, pain, and emotional distress mediated the relationships between some types of childhood abuse and PCU at W4, though most associations attenuated by later adulthood (W6). Specifically, greater emotional distress and nausea motives were associated with greater PCU in models of emotional abuse and neglect and sexual abuse, with emotional distress continuing to mediate at W6. Conversely, sleep and pain motives were associated with lower PCU in models for emotional neglect.

CONCLUSIONS

Mental and physical health-related motives reflect potential intervenable factors that predict PCU in emerging adulthood among EA cannabis users with histories of childhood trauma. Results highlight the importance of and value for assessing a wide range of motives and PCU outcomes to target and address areas for intervention.

Terahertz Photons Improve Cognitive Functions in Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a serious psychosis leading to cognitive impairment. To restore cognitive functions for patients, the main treatments are based on medication or rehabilitation training but with limited effectiveness and strong side effects. Here, we demonstrate a new treatment approach for PTSD by using terahertz (THz) photons stimulating the hippocampal CA3 subregion. We verified that this method can nonthermally restore cognitive function in PTSD rats in vivo. After THz photon irradiation, the PTSD rats' recognitive index improved by about 10% in a novel object recognition test, the PTSD rats' accuracy improved by about 100% in a shuttler box test, the PTSD rats' numbers to identify target box was about 5 times lower in a Barnes maze test, and the rate of staying in new arm increased by approximately 40% in a Y-maze test. Further experimental studies found that THz photon (34.5 THz) irradiation could improve the expression of NR2B (increased by nearly 40%) and phosphorylated NR2B (increased by about 50%). In addition, molecular dynamics simulations showed that THz photons at a frequency of 34.5 THz are mainly absorbed by the pocket of glutamate receptors rather than by glutamate molecules. Moreover, the binding between glutamate receptors and glutamate molecules was increased by THz photons. This study offers a nondrug, nonthermal approach to regulate the binding between the excitatory neurotransmitter (glutamate) and NR2B. By increasing synaptic plasticity, it effectively improves the cognitive function of animals with PTSD, providing a promising treatment strategy for NR2B-related cognitive disorders.

Corticotropin-releasing factor signaling and its potential role in the prefrontal cortex-dependent regulation of anxiety

A large body of literature has highlighted the significance of the corticotropin-releasing factor (CRF) system in the regulation of neuropsychiatric diseases. Anxiety disorders are among the most common neuropsychiatric disorders. An increasing number of studies have demonstrated that the CRF family mediates and regulates the development and maintenance of anxiety. Thus, the CRF family is considered to be a potential target for the treatment of anxiety disorders. The prefrontal cortex (PFC) plays a role in the occurrence and development of anxiety, and both CRF and CRF-R1 are widely expressed in the PFC. This paper begins by reviewing CRF-related signaling pathways and their different roles in anxiety and related processes. Then, the role of the CRF system in other neuropsychiatric diseases is reviewed and the potential role of PFC CRF signaling in the regulation of anxiety disorders is discussed. Although other signaling pathways are potentially involved in the process of anxiety, CRF in the PFC primarily modulates anxiety disorders through the activation of corticotropin-releasing factor type1 receptors (CRF-R1) and the excitation of the cAMP/PKA signaling pathway. Moreover, the main signaling pathways of CRF involved in sex differentiation in the PFC appear to be different. In summary, this review suggests that the CRF system in the PFC plays a critical role in the occurrence of anxiety. Thus, CRF signaling is of great significance as a potential target for the treatment of stress-related disorders in the future.

Effect of Dexmedetomidine on Posttraumatic Stress Disorder in Patients Undergoing Emergency Trauma Surgery: A Randomized Clinical Trial

Importance

Posttraumatic stress disorder (PTSD) is common in people who have experienced trauma, especially those hospitalized for surgery. Dexmedetomidine may reduce or reverse the early consolidation and formation of conditioned fear memory and prevent the occurrence of postoperative PTSD.

Objective

To evaluate the effects of intraoperative and postoperative low-dose intravenous pumping dexmedetomidine on PTSD among patients with trauma undergoing emergency surgery.

Design, Setting, and Participants

This double-blind, randomized clinical trial was conducted from January 22 to October 20, 2022, with follow-up 1 month postoperatively, in patients with trauma undergoing emergency surgery at 4 hospital centers in Jiangsu Province, China. A total of 477 participants were screened. The observers were blinded to patient groupings, particularly for subjective measurements.

Interventions

Dexmedetomidine or placebo (normal saline) was administered at a maintenance dose of 0.1 μg/kg hourly from the start of anesthesia until the end of surgery and at the same rate after surgery from 9 pm to 7 am on days 1 to 3.

Main Outcomes and Measures

The primary outcome was the difference in the incidence of PTSD 1 month after surgery in the 2 groups. This outcome was assessed with the Clinician-Administered PTSD Scale for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (CAPS-5). The secondary outcomes were the pain score within 48 hours and 1 month postoperatively; incidence of postoperative delirium, nausea, and pruritus; subjective sleep quality; anxiety; and occurrence of adverse events.

Results

A total of 310 patients (154 in the normal saline group and 156 in the dexmedetomidine group) were included in the modified intention-to-treat analysis (mean [SD] age, 40.2 [10.3] years; 179 men [57.7%]). The incidence of PTSD was significantly lower in the dexmedetomidine group than in the control group 1 month postoperatively (14.1% vs 24.0%; P = .03). The participants in the dexmedetomidine group had a significantly lower CAPS-5 score than those in the control group (17.3 [5.3] vs 18.9 [6.6]; mean difference, 1.65; 95% CI, 0.31-2.99; P = .02). After adjusting for potential confounders, the patients in the dexmedetomidine group were less likely to develop PTSD than those in the control group 1 month postoperatively (adjusted odds ratio, 0.51; 95% CI, 0.27-0.94; P = .03).

Conclusions and Relevance

In this randomized clinical trial, the administration of intraoperative and postoperative dexmedetomidine reduced the incidence of PTSD among patients with trauma. The findings of this trial support the use of dexmedetomidine in emergency trauma surgery.

Trial Registration

Chinese Clinical Trial Register Identifier: ChiCTR2200056162.

Regular cannabis use is associated with history of childhood and lifetime trauma in a non-clinical community sample

Higher rate of substance use, including cannabis, has been reported in individuals with a history of childhood trauma, but less is known about the association between cannabis use with lifetime history of trauma and chronic stress, and potential gender differences in this association. This study systematically examined this association in a cross-sectional study of 841 individuals recruited between 2007 and 2012 from the community in New Haven, Connecticut. The Cumulative Adversity Index (CAI) was used to measure cumulative lifetime major life events, life trauma, and recent life events and chronic stress. Childhood Trauma Questionnaire (CTQ) was used to measure childhood trauma. Current and regular use of drugs were assessed using self-report questionnaires and objectively verified with urine drug testing. Higher rates of childhood trauma as well as lifetime trauma, and major life events were found in cannabis users, compared to non-users. The association between cannabis use with childhood trauma (total CTQ scores) was significant after controlling for age, gender, ethnicity and regular use of alcohol or cocaine. In logistic regression analysis, cannabis use had a significant positive association with major life events and lifetime trauma, but not with chronic stress, controlling for confounding factors including age, gender, ethnicity, and regular use of alcohol and cocaine. When analyzed separately, only in women the association between cannabis use and childhood trauma was significant. These associations point to further assessment of the impact of these gender differences on neurobiology of stress and cannabis misuse risk.

Cannabidiol Modulates Alterations in PFC microRNAs in a Rat Model of Depression

Cannabidiol (CBD) is a potential antidepressant agent. We examined the association between the antidepressant effects of CBD and alterations in brain microRNAs in the unpredictable chronic mild stress (UCMS) model for depression. UCMS male rats were injected with vehicle or CBD (10 mg/kg) and tested for immobility time in the forced swim test. Alterations in miRNAs (miR16, miR124, miR135a) and genes that encode for the 5HT1a receptor, the serotonergic transporter SERT, β-catenin, and CB1 were examined. UCMS increased immobility time in a forced swim test (i.e., depressive-like behavior) and altered the expression of miRNAs and mRNA in the ventromedial prefrontal cortex (vmPFC), raphe nucleus, and nucleus accumbens. Importantly, CBD restored UCMS-induced upregulation in miR-16 and miR-135 in the vmPFC as well as the increase in immobility time. CBD also restored the UCMS-induced decrease in htr1a, the gene that encodes for the serotonergic 5HT1a receptor; using a pharmacological approach, we found that the 5HT1a receptor antagonist WAY100135 blocked the antidepressant-like effect of CBD on immobility time. Our findings suggest that the antidepressant effects of CBD in a rat model for depression are associated with alterations in miR-16 and miR-135 in the vmPFC and are mediated by the 5HT1a receptor.

Enhancing Endocannabinoid Signaling via β-Catenin in the Nucleus Accumbens Attenuates PTSD- and Depression-like Behavior of Male Rats

Inhibition of fatty acid amide hydrolase (FAAH), which increases anandamide levels, has been suggested as a potential treatment for stress-related conditions. We examined whether the stress-preventing effects of the FAAH inhibitor URB597 on behavior are mediated via β-catenin in the nucleus accumbens (NAc). Male rats were exposed to the shock and reminders model of PTSD and then treated with URB597 (0.4 mg/kg; i.p.). They were tested for anxiety- (freezing, startle response), depression-like behaviors (despair, social preference, anhedonia), and memory function (T-maze, social recognition). We also tested the involvement of the CB1 receptor (CB1r), β-catenin, and metabotropic glutamate receptor subtype 5 (mGluR5) proteins. URB597 prevented the shock- and reminders-induced increase in anxiety- and depressive-like behaviors, as well as the impaired memory via the CB1r-dependent mechanism. In the NAc, viral-mediated β-catenin overexpression restored the behavior of rats exposed to stress and normalized the alterations in protein levels in the NAc and the prefrontal cortex. Importantly, when NAc β-catenin levels were downregulated by viral-mediated gene transfer, the therapeutic-like effects of URB597 were blocked. We suggest a potentially novel mechanism for the therapeutic-like effects of FAAH inhibition that is dependent on β-catenin activation in the NAc in a PTSD rat model.

Modulation of Endocannabinoid System Components in Depression: Pre-Clinical and Clinical Evidence

Depression is characterized by continuous low mood and loss of interest or pleasure in enjoyable activities. First-line medications for mood disorders mostly target the monoaminergic system; however, many patients do not find relief with these medications, and those who do suffer from negative side effects and a discouragingly low rate of remission. Studies suggest that the endocannabinoid system (ECS) may be involved in the etiology of depression and that targeting the ECS has the potential to alleviate depression. ECS components (such as receptors, endocannabinoid ligands, and degrading enzymes) are key neuromodulators in motivation and cognition as well as in the regulation of stress and emotions. Studies in depressed patients and in animal models for depression have reported deficits in ECS components, which is motivating researchers to identify potential diagnostic and therapeutic biomarkers within the ECS. By understanding the effects of cannabinoids on ECS components in depression, we enhance our understanding of which brain targets they hit, what biological processes they alter, and eventually how to use this information to design better therapeutic options. In this article, we discuss the literature on the effects of cannabinoids on ECS components of specific depression-like behaviors and phenotypes in rodents and then describe the findings in depressed patients. A better understanding of the effects of cannabinoids on ECS components in depression may direct future research efforts to enhance diagnosis and treatment.

The Impact of Electroacupuncture Early Intervention on the Brain Lipidome in a Mouse Model of Post-traumatic Stress Disorder

The neuroprotective effect of electroacupuncture (EA) treatment has been well studied; growing evidence suggests that changes in lipid composition may be involved in the pathogenesis of post-traumatic stress disorder (PTSD) and may be a target for treatment. However, the influence of early EA intervention on brain lipid composition in patients with PTSD has never been investigated. Using a modified single prolonged stress (mSPS) model in mice, we assessed the anti-PTSD-like effects of early intervention using EA and evaluated changes in lipid composition in the hippocampus and prefrontal cortex (PFC) using a mass spectrometry-based lipidomic approach. mSPS induced changes in lipid composition in the hippocampus, notably in the content of sphingolipids, glycerolipids, and fatty acyls. These lipid changes were more robust than those observed in the PFC. Early intervention with EA after mSPS ameliorated PTSD-like behaviors and partly normalized mSPS-induced lipid changes, notably in the hippocampus. Cumulatively, our data suggest that EA may reverse mSPS-induced PTSD-like behaviors due to region-specific regulation of the brain lipidome, providing new insights into the therapeutic mechanism of EA.

Effects of Sevoflurane and Propofol on Posttraumatic Stress Disorder After Emergency Trauma: A Double-Blind Randomized Controlled Trial

OBJECTIVE

Posttraumatic stress disorder (PTSD) is a frequent and disabling consequence of traumatic events. A previous study found that early use of propofol was a potential risk factor for PTSD. This prospective study aimed to investigate the effect of propofol and sevoflurane on PTSD after emergency surgery in trauma patients.

METHODS

A total of 300 trauma patients undergoing emergency surgery were randomly divided into two groups and anesthetized with propofol and/or sevoflurane. Perioperative clinical data were collected. The incidence of PTSD was evaluated with the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) in the two groups 1 month after the operation. The relevance of the injury time and CAPS-5 scores was assessed by Spearman correlation analysis. Logistic regression analysis was used to analyze the risk factors for PTSD.

RESULTS

The incidence of PTSD in the propofol group was higher than that in the sevoflurane group 1 month postoperatively (23.2 vs. 12.2%, P = 0.014). The injury time was negatively correlated with the CAPS-5 score in the propofol group (r = -0.226, P < 0.001). In the logistic regression analysis, the utilization of propofol was an independent risk factor for PTSD (P = 0.017).

CONCLUSION

Early use of propofol general anesthesia in emergency surgery for trauma patients may increase the risk of PTSD.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier: ChiCTR2100050202.

Effects of Marijuana Use in Patients with Orthopaedic Trauma

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The use of cannabis and cannabis-related products has increased dramatically in the last 2 decades. As states continue to legalize cannabis products, it is important for surgeons to understand the effects they may have on patients who have sustained orthopaedic trauma.

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Cannabinoids have been shown to decrease the severity of certain symptoms related to traumatic brain injury as well as posttraumatic stress disorder.

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Cannabinoids can modulate the body's endocannabinoid system, which can play an important role in bone homeostasis. Activation of cannabinoid receptors has been shown to be bone-protective in adults.

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Venous thromboembolism is a major concern for trauma patients. Cannabis use has been linked to overall increased rates of venous thromboembolism events.

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Literature regarding human-based cannabis studies is sparse; however, the growing field is opening new opportunities for research of this topic.

MicroRNAs as biomarker and novel therapeutic target for posttraumatic stress disorder in Veterans

Posttraumatic stress disorder (PTSD) is a common psychiatric disorder for military Veterans, characterized by hyperarousal, intrusive thoughts, flashbacks, hypervigilance, and distress after experiencing traumatic events. Some of the known physiological effects of PTSD include hypothalamic-pituitary-adrenal (HPA)-axis imbalance, a cortical function resulting in neuronal deficit and changes in behavior. Moreover, excessive discharge of inflammatory molecules and a dysregulated immune system are implicated in the pathophysiology of PTSD. Due to complex nature of this disorder, the biological underpinnings of PTSD remain inexplicable. Investigating novel biomarkers to understanding the pathogenesis of PTSD may reflect the underlying molecular network for therapeutic use and treatment. Circulatory microRNAs (miRNAs) and exosomes are evolving biomarkers that have shown a key role in psychiatric and neurological disorders including PTSD. Given the unique nature of combat trauma, as well as evidence that a large portion of Veterans do not benefit from frontline treatments, focus on veterans specifically is warranted. In the present review, we delineate the identification and role of several miRNAs in PTSD among veterans. An association of miRNA with HPA-axis regulation through FKBP5, a key modulator in PTSD is discussed as an emerging molecule in psychiatric diseases. We conclude that miRNAs may be used as circulatory biomarker detection in Veterans with PTSD.

CB1 receptors in corticotropin-releasing factor neurons selectively control the acoustic startle response in male mice

The endocannabinoid system is an important regulator of the hormonal and behavioral stress responses, which critically involve corticotropin-releasing factor (CRF) and its receptors. While it has been shown that CRF and the cannabinoid type 1 (CB1) receptor are co-localized in several brain regions, the physiological relevance of this co-expression remains unclear. Using double in situ hybridization, we confirmed co-localization in the piriform cortex, the lateral hypothalamic area, the paraventricular nucleus, and the Barrington's nucleus, albeit at low levels. To study the behavioral and physiological implications of this co-expression, we generated a conditional knockout mouse line that selectively lacks the expression of CB1 receptors in CRF neurons. We found no effects on fear and anxiety-related behaviors under basal conditions nor after a traumatic experience. Additionally, plasma corticosterone levels were unaffected at baseline and after restraint stress. Only acoustic startle responses were significantly enhanced in male, but not female, knockout mice. Taken together, the consequences of depleting CB1 in CRF-positive neurons caused a confined hyperarousal phenotype in a sex-dependent manner. The current results suggest that the important interplay between the central endocannabinoid and CRF systems in regulating the organism's stress response is predominantly taking place at the level of CRF receptor-expressing neurons.

Long-term molecular differences between resilient and susceptible mice after a single traumatic exposure

BACKGROUND AND PURPOSE

PTSD is a heterogeneous disorder induced by trauma, resulting in severe long-term impairments of an individual's mental health. Interestingly, PTSD does not develop in every individual; thus, some individuals are more resilient than others. However, the underlying molecular mechanisms are poorly understood. Here, we aimed at shedding light on these processes.

EXPERIMENTAL APPROACH

We used a single-trauma PTSD model in mice to induce long-term maladaptive behaviours and profiled the mice four weeks post-trauma into resilient or susceptible individuals. The phenotype's classification was based on their individual responses in different behavioural experiments. We analysed microbiome, circulating endocannabinoids, and long-term changes in brain phospholipid and transcript levels.

KEY RESULTS

We found a plethora of molecular differences between resilient and susceptible individuals across multiple molecular domains, including lipidome, transcriptome, and gut microbiome. Some of these differences were stable even several weeks after the trauma, indicating the long-term impact of traumatic stimuli on the organism's physiology. Furthermore, the integration of these multi-layered molecular data revealed that resilient and susceptible individuals have very distinct molecular signatures across various physiological systems.

CONCLUSIONS AND IMPLICATIONS

We showed that trauma induces individual-specific behavioural responses that, in combination with a longitudinal characterization of mice, can be used to identify distinct sub-phenotypes within the trauma-exposed group. These groups differ significantly not only in their behaviour but also in specific molecular aspects across a variety of tissues and brain regions. This approach may reveal new targets and predictive biomarkers for the pharmacological treatment and prognosis of stress-related disorders.

CB1 Cannabinoid Receptor Signaling and Biased Signaling

The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.

Endocannabinoids, cannabinoids and the regulation of anxiety

Cannabis has been used for hundreds of years, with its ability to dampen feelings of anxiety often reported as a primary reason for use. Only recently has the specific role cannabinoids play in anxiety been thoroughly investigated. Here we discuss the body of evidence describing how endocannabinoids and exogenous cannabinoids are capable of regulating the generation and termination of anxiety states. Disruption of the endogenous cannabinoid (eCB) system following genetic manipulation, pharmacological intervention or stress exposure reliably leads to the generation of an anxiety state. On the other hand, upregulation of eCB signaling is capable of alleviating anxiety-like behaviors in multiple paradigms. When considering exogenous cannabinoid administration, cannabinoid receptor 1 (CB1) agonists have a biphasic, dose-dependent effect on anxiety such that low doses are anxiolytic while high doses are anxiogenic, a phenomenon that is evident in both rodent models and humans. Translational studies investigating a loss of function mutation in the gene for fatty acid amide hydrolase, the enzyme responsible for metabolizing AEA, have also shown that AEA signaling regulates anxiety in humans. Taken together, evidence reviewed here has outlined a convincing argument for cannabinoids being powerful regulators of both the manifestation and amelioration of anxiety symptoms, and highlights the therapeutic potential of targeting the eCB system for the development of novel classes of anxiolytics. This article is part of the special issue on 'Cannabinoids'.

Biomedical Implications of Plant-Based Principles as Antidepressants: Prospects for Novel Drug Development

BACKGROUND

Depression is a most common mental disorder. The symptoms of depression include loss of energy, changes in appetite, more or less sleep, anxiety, low concentration, uncertainty, restlessness, feelings of worthlessness, guilt, or despair, and thoughts of self-harm or suicide. In order to provide safe, efficient and cost-effective medication, the plants based principles in isolation or in combination with traditional antidepressants are attracting increasing attention for depression therapy.

METHOD

The information regarding the present review and its contents such as collected from published literature materials in different international journals. We have used different search engines such as PubMed, Medline, ResearchGate Google Semantic Scholar and ScienceDirect. For this purpose, the data obtained were properly organized and suitably analyzed to include in this article.

RESULTS

Most of the phytomolecules isolated from the medicinal plants display antidepressant effect through the synaptic regulation of levels of neurotransmitters such as dopamine, serotonin, and noradrenaline in different parts of the brain. The mechanism of action of phytomolecules also involves negative regulation of the activities of monoamine oxidase (MAO) and acetylcholinesterase (AChE) and prevention of hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis. In addition, the strong antioxidative and antiinflamatory potential of these phytochemicals offer synergy to their antidepressant as well as antipsychosomatic functions.

CONCLUSION

The application of phytochemicals has proved it to be a safe, cost effective and efficient therapeutic agent to treat the patients suffering from mild to severe state of depression and other psychiatric disorders. The potential phytochemicals may be further optimized using in silico tools to develop better antidepressants and antisychotic agents in future.

Endocannabinoid System as Therapeutic Target of PTSD: A Systematic Review

Post-Traumatic Stress Disorder (PTSD) is a complex disorder involving dysregulation of stress-related hormones and neurotransmitter systems. Research focused on the endocannabinoid system (eCBS) for anxiety and stress regulation, cognitive and emotional responses modulation and aversive memories extinction, leading to the hypothesis that it could represent a possible alternative treatment target for PTSD. In this systematic review, we summarize evidence about the efficacy and safety of medicinal cannabidiol (CBD), Δ⁹-tetrahydrocannabinol (Δ⁹-THC), and nabilone in PTSD treatment. The PRISMA statement guidelines were followed. A systematic literature search was conducted in MEDLINE/PubMed, Scopus and Web of Science by two independent researchers, who also performed data extraction and quality assessment. Among the initial 495 papers, 234 were screened for eligibility and 10 were included. Studies suggested that different medicinal cannabinoids at distinct doses and formulations could represent promising treatment strategies for the improvement of overall PTSD symptomatology as well as specific symptom domains (e.g., sleep disorders, arousal disturbances, suicidal thoughts), also influencing quality of life, pain and social impact. Although there is a robust rationale for treatment with drugs that target the eCBS and the results are promising, further studies are needed to investigate the safety and efficacy profile of their prolonged use.

The endocannabinoid system in the amygdala and modulation of fear

Posttraumatic stress disorder (PTSD) is a persistent, trauma induced psychiatric condition characterized by lifelong complex cognitive, emotional and behavioral phenotype. Although many individuals that experience trauma are able to gradually diminish their emotional responding to trauma-related stimuli over time, known as extinction learning, individuals suffering from PTSD are impaired in this capacity. An inability to decline this initially normal and adaptive fear response, can be confronted with exposure-based therapies, often in combination with pharmacological treatments. Due to the complexity of PTSD, currently available pharmacotherapeutics are inadequate in treating the deficient extinction observed in many PTSD patients. To develop novel therapeutics, researchers have exploited the conserved nature of fear and stress-associated behavioral responses and neurocircuits across species in an attempt to translate knowledge gained from preclinical studies into the clinic. There is growing evidence on the endocannabinoid modulation of fear and stress due to their 'on demand' synthesis and degradation. Involvement of the endocannabinoids in fear extinction makes the endocannabinoid system very attractive for finding effective therapeutics for trauma and stress related disorders. In this review, a brief introduction on neuroanatomy and circuitry of fear extinction will be provided as a model to study PTSD. Then, the endocannabinoid system will be discussed as an important component of extinction modulation. In this regard, anandamide degrading enzyme, fatty acid amide hydrolase (FAAH) will be exemplified as a target identified and validated strongly from preclinical to clinical translational studies of enhancing extinction.

Endocannabinoid system in trauma and psychosis: distant guardian of mental stability

Central endocannabinoid system (eCBS) is a neuromodulatory system that inhibits potentially harmful, excessive synaptic activation. Endocannabinoid receptors are abundant among brain structures pivotal in different mental disorders development (for example, hippocampus, amygdala, medial-prefrontal cortex, hypothalamus). Here, we review eCBS function in etiology of psychosis, emphasizing its role in dealing with environmental pressures such as traumatic life events. Moreover, we explore eCBS as a guard against hypothalamic-pituitary-adrenal axis over-activation, and discuss its possible role in etiology of different psychopathologies. Additionally, we review eCBS function in creating adaptive behavioral patterns, as we explore its involvement in the memory formation process, extinction learning and emotional response. We discuss eCBS in the context of possible biomarkers of trauma, and in preclinical psychiatric conditions, such as at-risk mental states and clinical high risk states for psychosis. Finally, we describe the role of eCBS in the cannabinoid self-medication-theory and extinction learning.

From an Alternative Medicine to a New Treatment for Refractory Epilepsies: Can Cannabidiol Follow the Same Path to Treat Neuropsychiatric Disorders?

Although cannabis has been known for ages as an "alternative medicine" to provide relief from seizures, pain, anxiety, and inflammation, there had always been a limited scientific review to prove and establish its use in clinics. Early studies carried out by Carlini's group in Brazil suggested that cannabidiol (CBD), a non-psychotropic phytocannabinoid present in Cannabis sativa, has anticonvulsant properties in animal models and reduced seizure frequency in limited human trials. Over the past few years, the potential use of cannabis extract in refractory epilepsy, including childhood epilepsies such as Dravet's syndrome and Lennox-Gastaut Syndrome, has opened a new era of treating epileptic patients. Thus, a considerable number of pre-clinical and clinical studies have provided strong evidence that phytocannabinoids has anticonvulsant properties, as well as being promising in the treatment of different neuropsychiatric disorders, such as depression, anxiety, post-traumatic stress disorder (PTSD), addiction, neurodegenerative disorders and autism spectrum disorder (ASD). Given the advances of cannabinoids, especially CBD, in the treatment of epilepsy, would the same expectation regarding the treatment of other neuropsychiatric disorders be possible? The present review highlights some contributions from Brazilian researchers and other studies reported elsewhere on the history, pre-clinical and clinical data underlying the use of cannabinoids for the already widespread treatment of refractory epilepsies and the possibility of use in the treatment of some neuropsychiatric disorders.

Do Adolescent Exposure to Cannabinoids and Early Adverse Experience Interact to Increase the Risk of Psychiatric Disorders: Evidence from Rodent Models

There have been growing concerns about the protracted effects of cannabis use in adolescents on emotion and cognition outcomes, motivated by evidence of growing cannabis use in adolescents, evidence linking cannabis use to various psychiatric disorders, and the increasingly perceived notion that cannabis is harmless. At the same time, studies suggest that cannabinoids may have therapeutic potential against the impacts of stress on the brain and behavior, and that young people sometimes use cannabinoids to alleviate feelings of depression and anxiety (i.e., “self-medication”). Exposure to early adverse life events may predispose individuals to developing psychopathology in adulthood, leading researchers to study the causality between early life factors and cognitive and emotional outcomes in rodent models and to probe the underlying mechanisms. In this review, we aim to better understand the long-term effects of cannabinoids administered in sensitive developmental periods (mainly adolescence) in rodent models of early life stress. We suggest that the effects of cannabinoids on emotional and cognitive function may vary between different sensitive developmental periods. This could potentially affect decisions regarding the use of cannabinoids in clinical settings during the early stages of development and could raise questions regarding educating the public as to potential risks associated with cannabis use.

Meet Your Stress Management Professionals: The Endocannabinoids

The endocannabinoid signaling system (ECSS) is altered by exposure to stress and mediates and modulates the effects of stress on the brain. Considerable preclinical data support critical roles for the endocannabinoids and their target, the CB1 cannabinoid receptor, in the adaptation of the brain to repeated stress exposure. Chronic stress exposure increases vulnerability to mental illness, so the ECSS has attracted attention as a potential therapeutic target for the prevention and treatment of stress-related psychopathology. We discuss human genetic studies indicating that the ECSS contributes to risk for mental illness in those exposed to severe stress and trauma early in life, and we explore the potential difficulties in pharmacological manipulation of the ECSS.

Low brain endocannabinoids associated with persistent non-goal directed nighttime hyperactivity after traumatic brain injury in mice

Traumatic brain injury (TBI) is a frequent cause of chronic headache, fatigue, insomnia, hyperactivity, memory deficits, irritability and posttraumatic stress disorder. Recent evidence suggests beneficial effects of pro-cannabinoid treatments. We assessed in mice levels of endocannabinoids in association with the occurrence and persistence of comparable sequelae after controlled cortical impact in mice using a set of long-term behavioral observations in IntelliCages, motor and nociception tests in two sequential cohorts of TBI/sham mice. TBI mice maintained lower body weights, and they had persistent low levels of brain ethanolamide endocannabinoids (eCBs: AEA, OEA, PEA) in perilesional and subcortical ipsilateral brain tissue (6 months), but rapidly recovered motor functions (within days), and average nociceptive responses were within normal limits, albeit with high variability, ranging from loss of thermal sensation to hypersensitivity. TBI mice showed persistent non-goal directed nighttime hyperactivity, i.e. they visited rewarding and non-rewarding operant corners with high frequency and random success. On successful visits, they made more licks than sham mice resulting in net over-licking. The lower the eCBs the stronger was the hyperactivity. In reward-based learning and reversal learning tasks, TBI mice were not inferior to sham mice, but avoidance memory was less stable. Hence, the major late behavioral TBI phenotype was non-goal directed nighttime hyperactivity and "over-licking" in association with low ipsilateral brain eCBs. The behavioral phenotype would agree with a "post-TBI hyperactivity disorder". The association with persistently low eCBs in perilesional and subcortical regions suggests that eCB deficiency contribute to the post-TBI psychopathology.