Effects of ipsapirone and cannabidiol on human experimental anxiety

Cannabidiolic acid methyl ester, a stable synthetic analogue of cannabidiolic acid, can produce 5-HT1A receptor-mediated suppression of nausea and anxiety in rats

BACKGROUND AND PURPOSE

The aim of this study was to compare the abilities of cannabidiolic acid methyl ester (HU-580) and cannabidiolic acid (CBDA) to enhance 5-HT_1A receptor activation in vitro and produce 5-HT_1A -mediated reductions in nausea and anxiety in vivo.

EXPERIMENTAL APPROACH

We investigated the effects of HU-580 and CBDA on (i) activation by 8-hydroxy-2-(di-n-propylamino)tetralin of human 5-HT_1A receptors in CHO cell membranes, using [³⁵ S]-GTPγS binding assays, (ii) gaping by rats in acute and anticipatory nausea models, and (iii) stress-induced anxiety-like behaviour, as indicated by exit time from the light compartment of a light-dark box of rats subjected 24 h earlier to six tone-paired foot shocks.

KEY RESULTS

HU-580 and CBDA increased the E_max of 8-hydroxy-2-(di-n-propylamino) tetralin in vitro at 0.01-10 and 0.1-10 nM, respectively, and reduced signs of (i) acute nausea at 0.1 and 1 μg·kg^-1 i.p. and at 1 μg·kg^-1 i.p., respectively, and (ii) anticipatory nausea at 0.01 and 0.1 μg·kg^-1 , and at 0.1 μg·kg^-1 i.p. respectively. At 0.01 μg·kg^-1 , HU-580, but not CBDA, increased the time foot-shocked rats spent in the light compartment of a light-dark box. The anti-nausea and anti-anxiety effects of 0.01 or 0.1 μg·kg^-1 HU-580 were opposed by the 5-HT_1A antagonist, WAY100635 (0.1 mg·kg^-1 i.p.).

CONCLUSIONS AND IMPLICATIONS

HU-580 is more potent than CBDA at enhancing 5-HT_1A receptor activation, and inhibiting signs of acute and anticipatory nausea, and anxiety. Consequently, HU-580 is a potential medicine for treating some nausea and anxiety disorders and possibly other disorders ameliorated by enhancement of 5-HT_1A receptor activation.

Pharmacological challenge studies with acute psychosocial stress

Chronic stress is known to affect many psychiatric disorders, and studies of responses to acute stress may reveal processes that ultimately lead to maladaptive responses to chronic stress. Many studies have used simulated public speaking tasks to induce stress in the laboratory and, of interest to this review, the tasks have been used to assess the effects of both therapeutic and nonmedical drugs on stress reactivity. Here we review 38 studies that examined effects of single doses of drugs on subjective, cardiovascular and hormonal responses to an acute social stressor in healthy volunteers. Most studies have used the Trier Social Stress Test (TSST), or variations on it involving public speaking or mental arithmetic. Pharmacological studies with the TSST (ph-TSST) have been conducted for three main reasons: i) to determine the clinical effectiveness of psychiatric medications to reduce stress responses, ii) to investigate the neurochemical mechanisms involved in the stress response, and iii) to determine whether drugs of abuse relieve, or occasionally worsen, responses to acute stress. The review indicates that standard anxiolytic medications consistently reduce subjective responses to the TSST, whereas single doses of antidepressants produce mixed effects. Mechanistic studies indicate that several neurotransmitter systems are involved in the stress response, including serotonin, norepinephrine, GABA, glutamate, opioids, and endocannabinoids. Among drugs of abuse, alcohol and cannabinoids exert some stress-dampening effects, whereas caffeine, nicotine, and amphetamines tend to increase stress responses. Comparing outcome measures of the responses to stress, subjective ratings of anxiety are among the most sensitive indices of the stress response, with cortisol levels second and cardiovascular responses least sensitive. We conclude that the TSST is a valuable tool to study the clinical effectiveness of medications for stress-related disorders, and that it is important to use standardized procedures to enable comparisons across studies.

Is cannabis treatment for anxiety, mood, and related disorders ready for prime time?

Anxiety and related disorders are the most common mental conditions affecting the North American population. Despite their established efficacy, first-line antidepressant treatments are associated with significant side effects, leading many afflicted individuals to seek alternative treatments. Cannabis is commonly viewed as a natural alternative for a variety of medical and mental health conditions. Currently, anxiety ranks among the top five medical symptoms for which North Americans report using medical marijuana. However, upon careful review of the extant treatment literature, the anxiolytic effects of cannabis in clinical populations are surprisingly not well-documented. The effects of cannabis on anxiety and mood symptoms have been examined in healthy populations and in several small studies of synthetic cannabinoid agents but there are currently no studies which have examined the effects of the cannabis plant on anxiety and related disorders. In light of the rapidly shifting landscape regarding the legalization of cannabis for medical and recreational purposes, it is important to highlight the significant disconnect between the scientific literature, public opinion, and related policies. The aim of this article is to provide a comprehensive review of the current cannabis treatment literature, and to identify the potential for cannabis to be used as a therapeutic intervention for anxiety, mood, and related disorders. Searches of five electronic databases were conducted (PubMed, MEDLINE, Web of Science, PsychINFO, and Google Scholar), with the most recent in February 2017. The effects of cannabis on healthy populations and clinical psychiatric samples will be discussed, focusing primarily on anxiety and mood disorders.

Cannabidiol regulation of emotion and emotional memory processing: relevance for treating anxiety-related and substance abuse disorders

Learning to associate cues or contexts with potential threats or rewards is adaptive and enhances survival. Both aversive and appetitive memories are therefore powerful drivers of behaviour, but the inappropriate expression of conditioned responding to fear- and drug-related stimuli can develop into anxiety-related and substance abuse disorders respectively. These disorders are associated with abnormally persistent emotional memories and inadequate treatment, often leading to symptom relapse. Studies show that cannabidiol, the main non-psychotomimetic phytocannabinoid found in Cannabis sativa, reduces anxiety via 5-HT1A and (indirect) cannabinoid receptor activation in paradigms assessing innate responses to threat. There is also accumulating evidence from animal studies investigating the effects of cannabidiol on fear memory processing indicating that it reduces learned fear in paradigms that are translationally relevant to phobias and post-traumatic stress disorder. Cannabidiol does so by reducing fear expression acutely and by disrupting fear memory reconsolidation and enhancing fear extinction, both of which can result in a lasting reduction of learned fear. Recent studies have also begun to elucidate the effects of cannabidiol on drug memory expression using paradigms with translational relevance to addiction. The findings suggest that cannabidiol reduces the expression of drug memories acutely and by disrupting their reconsolidation. Here, we review the literature demonstrating the anxiolytic effects of cannabidiol before focusing on studies investigating its effects on various fear and drug memory processes. Understanding how cannabidiol regulates emotion and emotional memory processing may eventually lead to its use as a treatment for anxiety-related and substance abuse disorders. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

Dose-related effects of delta-9-THC on emotional responses to acute psychosocial stress

OBJECTIVES

Cannabis smokers often report that they use the drug to relax or to relieve emotional stress. However, few clinical studies have shown evidence of the stress-relieving effects of cannabis or cannabinoid agonists. In this study, we sought to assess the influence of delta-9-tetrahydrocannabinol (THC), a main active ingredient of cannabis, upon emotional responses to an acute psychosocial stressor among healthy young adults.

METHODS

Healthy volunteers (N=42) participated in two experimental sessions, one with psychosocial stress (Trier Social Stress Test, TSST) and another with a non-stressful task, after receiving 0 (N=13), 7.5mg (N=14) or 12.5mg (N=15) oral THC. Capsules were administered under randomized, double blind conditions, 2.5h before the tasks began. We measured subjective mood and drug effects, vital signs and salivary cortisol before and at repeated times after the capsule and tasks. Subjects also appraised the tasks, before and after completion.

RESULTS

In comparison to placebo, 7.5mg THC significantly reduced self-reported subjective distress after the TSST and attenuated post-task appraisals of the TSST as threatening and challenging. By contrast, 12.5mg THC increased negative mood overall i.e., both before and throughout the tasks, and pre-task ratings of the TSST as threatening and challenging. It also impaired TSST performance and attenuated blood pressure reactivity to the stressor.

CONCLUSIONS

Our findings suggest that a low dose of THC produces subjective stress-relieving effects in line with those commonly reported among cannabis users, but that higher doses may non-specifically increase negative mood.

Effect of prior foot shock stress and Δ9-tetrahydrocannabinol, cannabidiolic acid, and cannabidiol on anxiety-like responding in the light-dark emergence test in rats

RATIONALE

Cannabis is commonly used by humans to relieve stress.

OBJECTIVES AND METHODS

Here, we evaluate the potential of intraperitoneally (i.p.) administered Δ⁹-tetrahydrocannabiol (THC) and cannabidiolic acid (CBDA, the precursor of cannabidiol [CBD]) to produce dose-dependent effects on anxiety-like responding in the light-dark (LD) emergence test of anxiety-like responding in rats, when administered acutely or chronically (21 days). As well, we evaluate the potential of THC, CBDA, and CBD to reduce anxiogenic responding produced by foot shock (FS) stress 24 h prior to the LD test.

RESULTS

In the absence of the explicit FS stressor, THC (1 and 10 mg/kg) produced anxiogenic-like responding when administered acutely or chronically, but CBDA produced neither anxiogenic- nor anxiolytic-like responding. Administration of FS stress 24 h prior to the LD test enhanced anxiogenic-like responding (reduced time spent and increased latency to enter the light compartment) in rats pretreated with either vehicle (VEH) or THC (1 mg/kg); however, administration of CBDA (0.1-100 μg/kg) or CBD (5 mg/kg) prevented the FS-induced anxiogenic-like responding (an anxiolytic-like effect). The 5-hydroxytryptamine 1A (5-HT_1A) receptor antagonist, WAY100635, reversed CBDA's anxiolytic effect (1 μg/kg). Combining an anxiolytic dose of CBDA (1 μg/kg) or CBD (5 mg/kg) with an anxiogenic dose of THC (1 mg/kg) did not modify THC's anxiogenic effect.

CONCLUSION

These results suggest the anxiolytic effects of CBDA and CBD may require the presence of a specific stressor.

Cannabidiol Does Not Dampen Responses to Emotional Stimuli in Healthy Adults

Introduction: Cannabidiol (CBD) is a nonpsychoactive constituent of whole plant cannabis that has been reported to reduce anxiety-like behaviors in both pre-clinical and human laboratory studies. Yet, no controlled clinical studies have demonstrated its ability to reduce negative mood or dampen responses to negative emotional stimuli in humans. The objective of this study was to investigate the effects of CBD on responses to negative emotional stimuli, as a model for its potential anxiety-reducing effects. Materials and Methods: The study used a double-blind, placebo (PLB)-controlled, within-subjects design in which 38 healthy, drug-free participants consumed oral CBD (300, 600, and 900 mg) or PLB before completing several behavioral tasks selected to assess reactivity to negative stimuli. Dependent measures included emotional arousal to negative and positive visual stimuli, perceptual sensitivity to emotional facial expressions, attentional bias toward emotional facial expressions, and feelings of social rejection. In addition, subjective drug effects and physiological data were also gathered during each experimental session to assess drug effects. Discussion: CBD did not dampen responses to negative emotional stimuli and did not affect feelings of social rejection. The high dose of CBD (900 mg) marginally reduced attentional bias toward happy and sad facial expressions, and produced a slight increase in late-session heart rate. CBD did not produce detectable subjective effects or alterations in mood or anxiety. Conclusion: These findings indicate that CBD has minimal behavioral and subjective effects in healthy volunteers, even when they are presented with emotional stimuli. Further research into the behavioral and neural mechanisms of CBD and other phytocannabinoids is needed to ascertain the clinical function of this drug.

Inverted U-Shaped Dose-Response Curve of the Anxiolytic Effect of Cannabidiol during Public Speaking in Real Life

The purpose of this study was to investigate whether the anxiolytic effect of cannabidiol (CBD) in humans follows the same pattern of an inverted U-shaped dose-effect curve observed in many animal studies. Sixty healthy subjects of both sexes aged between 18 and 35 years were randomly assigned to five groups that received placebo, clonazepam (1 mg), and CBD (100, 300, and 900 mg). The subjects were underwent a test of public speaking in a real situation (TPSRS) where each subject had to speak in front of a group formed by the remaining participants. Each subject completed the anxiety and sedation factors of the Visual Analog Mood Scale and had their blood pressure and heart rate recorded. These measures were obtained in five experimental sessions with 12 volunteers each. Each session had four steps at the following times (minutes) after administration of the drug/placebo, as time 0: -5 (baseline), 80 (pre-test), 153 (speech), and 216 (post-speech). Repeated-measures analyses of variance showed that the TPSRS increased the subjective measures of anxiety, heart rate, and blood pressure. Student-Newman-Keuls test comparisons among the groups in each phase showed significant attenuation in anxiety scores relative to the placebo group in the group treated with clonazepam during the speech phase, and in the clonazepam and CBD 300 mg groups in the post-speech phase. Clonazepam was more sedative than CBD 300 and 900 mg and induced a smaller increase in systolic and diastolic blood pressure than CBD 300 mg. The results confirmed that the acute administration of CBD induced anxiolytic effects with a dose-dependent inverted U-shaped curve in healthy subjects, since the subjective anxiety measures were reduced with CBD 300 mg, but not with CBD 100 and 900 mg, in the post-speech phase.

The endocannabinoid system as a target for novel anxiolytic drugs

The endocannabinoid (eCB) system has attracted attention for its role in various behavioral and brain functions, and as a therapeutic target in neuropsychiatric disease states, including anxiety disorders and other conditions resulting from dysfunctional responses to stress. In this mini-review, we highlight components of the eCB system that offer potential 'druggable' targets for new anxiolytic medications, emphasizing some of the less well-discussed options. We discuss how selectively amplifying eCBs recruitment by interfering with eCB-degradation, via fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), has been linked to reductions in anxiety-like behaviors in rodents and variation in human anxiety symptoms. We also discuss a non-canonical route to regulate eCB degradation that involves interfering with cyclooxygenase-2 (COX-2). Next, we discuss approaches to targeting eCB receptor-signaling in ways that do not involve the cannabinoid receptor subtype 1 (CB1R); by targeting the CB2R subtype and the transient receptor potential vanilloid type 1 (TRPV1). Finally, we review evidence that cannabidiol (CBD), while representing a less specific pharmacological approach, may be another way to modulate eCBs and interacting neurotransmitter systems to alleviate anxiety. Taken together, these various approaches provide a range of plausible paths to developing novel compounds that could prove useful for treating trauma-related and anxiety disorders.

Does Cannabis Composition Matter? Differential Effects of Delta-9-tetrahydrocannabinol and Cannabidiol on Human Cognition

Purpose of Review

The lack of clarity about the effect of cannabis use on cognition may be attributable to the considerable heterogeneity among studies in terms of cannabis composition. This article selectively reviews studies examining the distinctive effects of cannabinoids on human cognition, particularly those of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD).

Recent Findings

Research indicates that ∆9-THC administration acutely impairs cognition, particularly memory and emotional processing. Limited evidence suggests that CBD administration might improve cognition in cannabis users but not in individuals with neuropsychiatric disorders. Moreover, studies indicate that some acute Δ9-THC-induced cognitive impairments may be prevented if Δ9-THC is administered in combination or following CBD treatment. Δ9-THC and CBD have also shown opposite effects on cognition-related brain activation, possibly reflecting their antagonistic behavioral effects.

Summary

Research suggests greater cognitive impairments in individuals when exposed to high ∆9-THC or low CBD cannabis. It is unclear whether at specific concentrations CBD might outweigh any harmful effects of Δ9-THC on cognition.

Oral cannabidiol does not produce a signal for abuse liability in frequent marijuana smokers

BACKGROUND

Cannabidiol (CBD) is a naturally occurring constituent of the marijuana plant. In the past few years, there has been great interest in the therapeutic effects of isolated CBD and it is currently being explored for numerous disease conditions (e.g., pain, epilepsy, cancer, various drug dependencies). However, CBD remains a Schedule I drug on the U.S. Controlled Substances Act (CSA). Despite its status, there are no well-controlled data available regarding its abuse liability.

METHODS

Healthy, frequent marijuana users (n=31) were enrolled in this within subject, randomized, placebo-controlled, double-blind, multisite study that administered oral cannabidiol (0, 200, 400, 800mg) alone and in combination with smoked marijuana (0.01%, 5.3-5.8% THC). Participants received one dose combination across 8 once-weekly outpatient sessions (7.5h). The primary findings on the drug interaction effects were previously reported (Haney et al., 2016). The present study is a secondary analysis of the data to examine the abuse liability profile of oral cannabidiol (200, 400, 800mg) in comparison to oral placebo and active smoked marijuana (5.3-5.8% THC).

RESULTS

Active marijuana reliably produced abuse-related subjective effects (e.g., high) (p<0.05). However, CBD was placebo-like on all measures collected (p>0.05).

CONCLUSIONS

Overall, CBD did not display any signals of abuse liability at the doses tested and these data may help inform U.S. regulatory decisions regarding CBD schedule on the CSA.

A Systematic Review and Meta-Analysis of the Haemodynamic Effects of Cannabidiol

Despite cannabidiol (CBD) having numerous cardiovascular effects in vitro, its haemodynamic effects in vivo are unclear. Nonetheless, the clinical use of CBD (Epidiolex) is becoming more widespread. The aim of this systematic review was to establish whether CBD is associated with changes in haemodynamics in vivo. Twenty-five studies that assessed the haemodynamic effects of CBD (from PubMed, Medline and EMBASE) were systematically reviewed and meta-analyzed. Data on blood pressure (BP), heart rate (HR), and blood flow (BF) were extracted and analyzed using random effects models. Twenty-two publications assessed BP and HR among 6 species (BP n = 344 and HR n = 395), and 5 publications assessed BF in 3 species (n = 56) after acute dosing of CBD. Chronic dosing was assessed in 4 publications in 3 species (total subjects BP, n = 6; HR, n = 27; BF, n = 3). Acute CBD dosing had no effect on BP or HR under control conditions. Similarly, chronic dosing with CBD had no effect on HR. In models of stress, acute CBD administration significantly reduced the increase in BP and HR induced by stress (BP, mean difference (MD) −3.54, 95% CI −5.19, −1.9, p < 0.0001; HR, MD −16.23, 95% CI −26.44, −6.02, p = 0.002). In mouse models of stroke, CBD significantly increased cerebral blood flow (CBF, standardized mean difference (SMD) 1.62, 95% CI 0.41, 2.83, p = 0.009). Heterogeneity among the studies was present, there was no publication bias except in HR of control and stressful conditions after acute CBD dosing, and median study quality was 5 out of 9 (ranging from 1 to 8). From the limited data available, we conclude that acute and chronic administration of CBD had no effect on BP or HR under control conditions, but reduces BP and HR in stressful conditions, and increases cerebral blood flow (CBF) in mouse models of stroke. Further studies are required to fully understand the potential haemodynamic effects of CBD in humans under normal and pathological conditions.

Evidences for the Anti-panic Actions of Cannabidiol

BACKGROUND

Panic disorder (PD) is a disabling psychiatry condition that affects approximately 5% of the worldwide population. Currently, long-term selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for PD; however, the common side-effect profiles and drug interactions may provoke patients to abandon the treatment, leading to PD symptoms relapse. Cannabidiol (CBD) is the major non-psychotomimetic constituent of the Cannabis sativa plant with anti-anxiety properties that has been suggested as an alternative for treating anxiety disorders. The aim of the present review was to discuss the effects and mechanisms involved in the putative anti-panic effects of CBD.

METHODS

electronic database was used as source of the studies selected selected based on the studies found by crossing the following keywords: cannabidiol and panic disorder; canabidiol and anxiety, cannabidiol and 5-HT1A receptor).

RESULTS

In the present review, we included both experimental laboratory animal and human studies that have investigated the putative anti-panic properties of CBD. Taken together, the studies assessed clearly suggest an anxiolytic-like effect of CBD in both animal models and healthy volunteers.

CONCLUSION

CBD seems to be a promising drug for the treatment of PD. However, novel clinical trials involving patients with the PD diagnosis are clearly needed to clarify the specific mechanism of action of CBD and the safe and ideal therapeutic doses of this compound.

Targeting the Endocannabinoid System in Psychiatric Illness

Prevalence of psychiatric disorders continues to rise globally, yet remission rates and patient outcome remain less than ideal. As a result, novel treatment approaches for these disorders are necessary to decrease societal economic burden, as well as increase individual functioning. The recent discovery of the endocannabinoid system has provided an outlet for further research into its role in psychiatric disorders, because efficacy of targeted treatments have been demonstrated in medical illnesses, including cancers, neuropathic pain, and multiple sclerosis. The present review will investigate the role of the endocannabinoid system in psychiatric disorders, specifically schizophrenia, depressive, anxiety, and posttraumatic stress disorders, as well as attention-deficit hyperactivity disorder. Controversy remains in prescribing medicinal cannabinoid treatments due to the fear of adverse effects. However, one must consider all potential limitations when determining the safety and tolerability of cannabinoid products, specifically cannabinoid content (ie, Δ-tetrahydrocannabinol vs cannabidiol) as well as study design. The potential efficacy of cannabinoid treatments in the psychiatric population is an emerging topic of interest that provides potential value going forward in medicine.

Oral Cannabidiol does not Alter the Subjective, Reinforcing or Cardiovascular Effects of Smoked Cannabis

Cannabidiol (CBD), a constituent of cannabis with few psychoactive effects, has been reported in some studies to attenuate certain aspects of Δ(9)-tetrahydrocannabinol (THC) intoxication. However, most studies have tested only one dose of CBD in combination with one dose of oral THC, making it difficult to assess the nature of this interaction. Further, the effect of oral CBD on smoked cannabis administration is unknown. The objective of this multi-site, randomized, double-blind, within-subject laboratory study was to assess the influence of CBD (0, 200, 400, 800 mg, p.o.) pretreatment on the reinforcing, subjective, cognitive, and physiological effects of smoked cannabis (0.01 (inactive), 5.30-5.80% THC). Non-treatment-seeking, healthy cannabis smokers (n=31; 17M, 14 F) completed eight outpatient sessions. CBD was administered 90 min prior to cannabis administration. The behavioral and cardiovascular effects of cannabis were measured at baseline and repeatedly throughout the session. A subset of participants (n=8) completed an additional session to measure plasma CBD concentrations after administration of the highest CBD dose (800 mg). Under placebo CBD conditions, active cannabis (1) was self-administered by significantly more participants than placebo cannabis and (2) produced significant, time-dependent increases in ratings of 'High', 'Good Effect', ratings of the cannabis cigarette (eg, strength, liking), and heart rate relative to inactive cannabis. CBD, which alone produced no significant psychoactive or cardiovascular effects, did not significantly alter any of these outcomes. Cannabis self-administration, subjective effects, and cannabis ratings did not vary as a function of CBD dose relative to placebo capsules. These findings suggest that oral CBD does not reduce the reinforcing, physiological, or positive subjective effects of smoked cannabis.

Drug effects on responses to emotional facial expressions: recent findings

Many psychoactive drugs increase social behavior and enhance social interactions, which may, in turn, increase their attractiveness to users. Although the psychological mechanisms by which drugs affect social behavior are not fully understood, there is some evidence that drugs alter the perception of emotions in others. Drugs can affect the ability to detect, attend to, and respond to emotional facial expressions, which in turn may influence their use in social settings. Either increased reactivity to positive expressions or decreased response to negative expressions may facilitate social interaction. This article reviews evidence that psychoactive drugs alter the processing of emotional facial expressions using subjective, behavioral, and physiological measures. The findings lay the groundwork for better understanding how drugs alter social processing and social behavior more generally.

Targeting the endocannabinoid system to treat anxiety-related disorders

The endocannabinoid system plays an important role in the control of emotions, and its dysregulation has been implicated in several psychiatric disorders. The most common self-reported reason for using cannabis is rooted in its ability to reduce feelings of stress, tension, and anxiety. Nevertheless, there are only few studies in controlled clinical settings that confirm that administration of cannabinoids can benefit patients with a post-traumatic stress disorder (PTSD). There are considerable encouraging preclinical data to suggest that endocannabinoid-targeted therapeutics for anxiety disorders should continue. In this review, we will describe data supporting a role for the endocannabinoid system in preventing and treating anxiety-like behavior in animal models and PTSD patients. Cannabinoids have shown beneficial outcomes in rat and mouse models of anxiety and PTSD, but they also may have untoward effects that discourage their chronic usage, including anxiogenic effects. Hence, clinical and preclinical research on the endocannabinoid system should further study the effects of cannabinoids on anxiety and help determine whether the benefits of using exogenous cannabinoids outweigh the risks. In general, this review suggests that targeting the endocannabinoid system represents an attractive and novel approach to the treatment of anxiety-related disorders and, in particular, PTSD.

Cannabis craving in response to laboratory-induced social stress among racially diverse cannabis users: The impact of social anxiety disorder

Social anxiety disorder appears to be a risk factor for cannabis-related problems. Although it is presumed that increases in cannabis craving during elevated social anxiety reflect an intent to cope with greater negative affectivity, it is unclear whether increases in physiological arousal during social stress are related to cannabis craving, especially among those with social anxiety disorder. Similarly, no studies have assessed motivational reasons for cannabis use during elevated social stress. Thus, the current study tested whether increases in state social anxiety (measured subjectively and via physiological arousal) were related to greater cannabis craving among 126 current cannabis users (88.9% with cannabis use disorder, 31.7% with social anxiety disorder, 54.0% non-Hispanic Caucasian) randomly assigned to either a social interaction or reading task. As predicted, cannabis users in the social interaction condition reported greater cannabis craving than those in the reading condition. This effect was particularly evident among those with social anxiety disorder. Although physiological arousal did not moderate the relationship between condition and craving, coping motives were the most common reasons cited for wanting to use cannabis and were reported more among those in the social interaction task. These experimental results uniquely add to a growing literature suggesting the importance of elevated state social anxiety (especially among those with social anxiety disorder) in cannabis use vulnerability processes.

Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation?

The Cannabis sativa plant has been used to treat various physiological and psychiatric conditions for millennia. Current research is focused on isolating potentially therapeutic chemical constituents from the plant for use in the treatment of many central nervous system disorders. Of particular interest is the primary nonpsychoactive constituent cannabidiol (CBD). Unlike Δ(9)-tetrahydrocannabinol (THC), CBD does not act through the cannabinoid type 1 (CB1) receptor but has many other receptor targets that may play a role in psychiatric disorders. Here we review preclinical and clinical data outlining the therapeutic efficacy of CBD for the treatment of motivational disorders such as drug addiction, anxiety, and depression. Across studies, findings suggest promising treatment effects and potentially overlapping mechanisms of action for CBD in these disorders and indicate the need for further systematic investigation of the viability of CBD as a psychiatric pharmacotherapy.

Cannabidiol, neuroprotection and neuropsychiatric disorders

Cannabidiol (CBD) is a non-psychotomimetic phytocannabinoid derived from Cannabis sativa. It has possible therapeutic effects over a broad range of neuropsychiatric disorders. CBD attenuates brain damage associated with neurodegenerative and/or ischemic conditions. It also has positive effects on attenuating psychotic-, anxiety- and depressive-like behaviors. Moreover, CBD affects synaptic plasticity and facilitates neurogenesis. The mechanisms of these effects are still not entirely clear but seem to involve multiple pharmacological targets. In the present review, we summarized the main biochemical and molecular mechanisms that have been associated with the therapeutic effects of CBD, focusing on their relevance to brain function, neuroprotection and neuropsychiatric disorders.

Influence of single and repeated cannabidiol administration on emotional behavior and markers of cell proliferation and neurogenesis in non-stressed mice

Therapeutic effects of antidepressants and atypical antipsychotics may arise partially from their ability to stimulate neurogenesis. Cannabidiol (CBD), a phytocannabinoid present in Cannabis sativa, presents anxiolytic- and antipsychotic-like effects in preclinical and clinical settings. Anxiolytic-like effects of repeated CBD were shown in chronically stressed animals and these effects were parallel with increased hippocampal neurogenesis. However, antidepressant-like effects of repeated CBD administration in non-stressed animals have been scarcely reported. Here we investigated the behavioral consequences of single or repeated CBD administration in non-stressed animals. We also determined the effects of CBD on cell proliferation and neurogenesis in the dentate gyrus (DG) and subventricular zone (SVZ). Single CBD 3mg/kg administration resulted in anxiolytic-like effect in mice submitted to the elevated plus maze (EPM). In the tail suspension test (TST), single or repeated CBD administration reduced immobility time, an effect that was comparable to those of imipramine (20 mg/kg). Moreover, repeated CBD administration at a lower dose (3 mg/kg) increased cell proliferation and neurogenesis, as seen by an increased number of Ki-67-, BrdU- and doublecortin (DCX)-positive cells in both in DG and SVZ. Despite its antidepressant-like effects in the TST, repeated CBD administration at a higher dose (30 mg/kg) decreased cell proliferation and neurogenesis in the hippocampal DG and SVZ. Our findings show a dissociation between behavioral and proliferative effects of repeated CBD and suggest that the antidepressant-like effects of CBD may occur independently of adult neurogenesis in non-stressed Swiss mice.

Cannabidiol as a Potential Treatment for Anxiety Disorders

Cannabidiol (CBD), a Cannabis sativa constituent, is a pharmacologically broad-spectrum drug that in recent years has drawn increasing interest as a treatment for a range of neuropsychiatric disorders. The purpose of the current review is to determine CBD's potential as a treatment for anxiety-related disorders, by assessing evidence from preclinical, human experimental, clinical, and epidemiological studies. We found that existing preclinical evidence strongly supports CBD as a treatment for generalized anxiety disorder, panic disorder, social anxiety disorder, obsessive-compulsive disorder, and post-traumatic stress disorder when administered acutely; however, few studies have investigated chronic CBD dosing. Likewise, evidence from human studies supports an anxiolytic role of CBD, but is currently limited to acute dosing, also with few studies in clinical populations. Overall, current evidence indicates CBD has considerable potential as a treatment for multiple anxiety disorders, with need for further study of chronic and therapeutic effects in relevant clinical populations.

Marijuana use is associated with worse outcomes in symptom severity and violent behavior in patients with posttraumatic stress disorder

OBJECTIVE

An increasing number of states have approved posttraumatic stress disorder (PTSD) as a qualifying condition for medical marijuana, although little evidence exists evaluating the effect of marijuana use in PTSD. We examined the association between marijuana use and PTSD symptom severity in a longitudinal, observational study.

METHOD

From 1992 to 2011, veterans with DSM-III/-IV PTSD (N = 2,276) were admitted to specialized Veterans Affairs treatment programs, with assessments conducted at intake and 4 months after discharge. Subjects were classified into 4 groups according to marijuana use: those with no use at admission or after discharge ("never-users"), those who used at admission but not after discharge ("stoppers"), those who used at admission and after discharge ("continuing users"), and those using after discharge but not at admission ("starters"). Analyses of variance compared baseline characteristics and identified relevant covariates. Analyses of covariance then compared groups on follow-up measures of PTSD symptoms, drug and alcohol use, violent behavior, and employment.

RESULTS

After we adjusted for relevant baseline covariates, marijuana use was significantly associated with worse outcomes in PTSD symptom severity (P < .01), violent behavior (P < .01), and measures of alcohol and drug use (P < .01) when compared with stoppers and never-users. At follow-up, stoppers and never-users had the lowest levels of PTSD symptoms (P < .0001), and starters had the highest levels of violent behavior (P < .0001). After adjusting for covariates and using never-users as a reference, starting marijuana use had an effect size on PTSD symptoms of +0.34 (Cohen d = change/SD), and stopping marijuana use had an effect size of -0.18.

CONCLUSIONS

In this observational study, initiating marijuana use after treatment was associated with worse PTSD symptoms, more violent behavior, and alcohol use. Marijuana may actually worsen PTSD symptoms or nullify the benefits of specialized, intensive treatment. Cessation or prevention of use may be an important goal of treatment.

Dissociation between the panicolytic effect of cannabidiol microinjected into the substantia nigra, pars reticulata, and fear-induced antinociception elicited by bicuculline administration in deep layers of the superior colliculus: The role of CB1-cannabinoid receptor in the ventral mesencephalon

Many studies suggest that the substantia nigra, pars reticulata (SNpr), a tegmental mesencephalic structure rich in γ-aminobutyric acid (GABA)- and cannabinoid receptor-containing neurons, is involved in the complex control of defensive responses through the neostriatum-nigral disinhibitory and nigro-tectal inhibitory GABAergic pathways during imminently dangerous situations. The aim of the present work was to investigate the role played by CB1-cannabinoid receptor of GABAergic pathways terminal boutons in the SNpr or of SNpr-endocannabinoid receptor-containing interneurons on the effect of intra-nigral microinjections of cannabidiol in the activity of nigro-tectal inhibitory pathways. GABAA receptor blockade in the deep layers of the superior colliculus (dlSC) elicited vigorous defensive behaviour. This explosive escape behaviour was followed by significant antinociception. Cannabidiol microinjection into the SNpr had a clear anti-aversive effect, decreasing the duration of defensive alertness, the frequency and duration of defensive immobility, and the frequency and duration of explosive escape behaviour, expressed by running and jumps, elicited by transitory GABAergic dysfunction in dlSC. However, the innate fear induced-antinociception was not significantly changed. The blockade of CB1 endocannabinoid receptor in the SNpr decreased the anti-aversive effect of canabidiol based on the frequency and duration of defensive immobility, the frequency of escape expressed by running, and both the frequency and duration of escape expressed by jumps. These findings suggest a CB1 mediated endocannabinoid signalling in cannabidiol modulation of panic-like defensive behaviour, but not of innate fear-induced antinociception evoked by GABAA receptor blockade with bicuculline microinjection into the superior colliculus, with a putative activity in nigro-collicular GABAergic pathways.

Medicinal plants with potential anti-arthritic activity

ETHNO PHARMACOLOGICAL RELEVANCE

Traditional medicinal plants are practiced worldwide for treatment of arthritis especially in developing countries where resources are meager. This review presents the plants profiles inhabiting throughout the world regarding their traditional usage by various tribes/ethnic groups for treatment of arthritis.

MATERIALS AND METHODS

Bibliographic investigation was carried out by analyzing classical text books and peer reviewed papers, consulting worldwide accepted scientific databases from the last six decades. Plants/their parts/extracts/polyherbal formulations, toxicity studies for arthritis have been included in the review article. The profiles presented also include information about the scientific name, family, dose, methodology along with mechanism of action and toxicity profile. Research status of 20 potential plant species has been discussed. Further, geographical distribution of research, plants distribution according to families has been given in graphical form.

RESULTS

485 plant species belonging to 100 families, traditionally used in arthritis are used. Among 100 plant families, malvaceae constitute 16, leguminasae 7, fabaceae 13, euphorbiaceae 7, compositae 20, araceae 7, solanaceae 12, liliaceae 9, apocynaceae, lauraceae, and rubiaceae 10, and remaining in lesser proportion. It was observed in our study that majority of researches are carried mainly in developing countries like India, China, Korea and Nigeria.

CONCLUSION

This review clearly indicates that list of medicinal plants presented in this review might be useful to researchers as well as practioners. This review can be useful for preliminary screening of potential anti-arthritis plants. Further toxicity profile given in the review can be useful for the researchers for finding the safe dose.

Cannabinoid modulation of fear extinction brain circuits: a novel target to advance anxiety treatment

Anxiety disorders, such as post-traumatic stress (PTSD), panic, and phobic disorders, can be conceptualized as a failure to inhibit inappropriate fear responses. A common, effective treatment strategy involves repeated presentations to the feared cue without any danger (extinction). However, extinction learning has a number of important limitations, and enhancing its effects, generalizability and durability via cognitive enhancers may improve its therapeutic impact. In this review we focus specifically on the role of the cannabinoid system in fear extinction learning and its retention. We address the following questions: What are the neural circuits mediating fear extinction?; Can we make fear extinction more effective?; Can cannabinoids facilitate fear extinction in humans?; How might the cannabinoid system effect fear extinction? Collectively, translational evidence suggest that enhancing cannabinoid transmission may facilitate extinction learning and its recall, and that the cannabinoid system is a potential pharmacological target for improving the active learning that occurs during exposure-based behavioral treatments prompting future research in terms of mechanisms research, novel treatment approaches ('cognitive enhancers'), and pharmacotherapeutic drug discovery.

Cannabidiol increases survival and promotes rescue of cognitive function in a murine model of cerebral malaria

Cerebral malaria (CM) is a severe complication resulting from Plasmodium falciparum infection that might cause permanent neurological deficits. Cannabidiol (CBD) is a nonpsychotomimetic compound of Cannabis sativa with neuroprotective properties. In the present work, we evaluated the effects of CBD in a murine model of CM. Female mice were infected with Plasmodium berghei ANKA (PbA) and treated with CBD (30mg/kg/day - 3 or 7days i.p.) or vehicle. On 5th day-post-infection (dpi), at the peak of the disease), animals were treated with single or repeated doses of Artesunate, an antimalarial drug. All groups were tested for memory impairment (Novel Object Recognition or Morris Water Maze) and anxiety-like behaviors (Open field or elevated plus maze test) in different stages of the disease (at the peak or after the complete clearance of the disease). Th1/Th2 cytokines and neurotrophins (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) were measured in the prefrontal cortex and hippocampus of experimental groups. PbA-infected mice displayed memory deficits and exhibited increase in anxiety-like behaviors on the 5dpi or after the clearance of the parasitemia, effects prevented by CBD treatment. On 5dpi, TNF-α and IL-6 increased in the hippocampus, while only IL-6 increased in the prefrontal cortex. CBD treatment resulted in an increase in BDNF expression in the hippocampus and decreased levels of proinflammatory cytokines in the hippocampus (TNF-α) and prefrontal cortex (IL-6). Our results indicate that CBD exhibits neuroprotective effects in CM model and might be useful as an adjunctive therapy to prevent neurological symptoms following this disease.

Cannabis and adolescent brain development

Heavy cannabis use has been frequently associated with increased rates of mental illness and cognitive impairment, particularly amongst adolescent users. However, the neurobiological processes that underlie these associations are still not well understood. In this review, we discuss the findings of studies examining the acute and chronic effects of cannabis use on the brain, with a particular focus on the impact of commencing use during adolescence. Accumulating evidence from both animal and human studies suggests that regular heavy use during this period is associated with more severe and persistent negative outcomes than use during adulthood, suggesting that the adolescent brain may be particularly vulnerable to the effects of cannabis exposure. As the endocannabinoid system plays an important role in brain development, it is plausible that prolonged use during adolescence results in a disruption in the normative neuromaturational processes that occur during this period. We identify synaptic pruning and white matter development as two processes that may be adversely impacted by cannabis exposure during adolescence. Potentially, alterations in these processes may underlie the cognitive and emotional deficits that have been associated with regular use commencing during adolescence.

Just say 'know': how do cannabinoid concentrations influence users' estimates of cannabis potency and the amount they roll in joints?

AIMS

(1) To determine whether measured concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in individuals' own cannabis predict their estimates of drug potency and actual titration; and (2) to ascertain if these effects are influenced by frequency of use and cannabis type.

DESIGN

Cross-sectional, naturalistic.

SETTING

Participants' own homes.

PARTICIPANTS

A total of 247 cannabis users in the United Kingdom: 152 'recreational' (1-24 days/month) and 95 'daily' (≥25 days/month).

METHODS

Participants rated their own cannabis for its potency (1-10) and type ('resin', 'herbal', 'skunk') before smoking it in front of the researcher. The amount of cannabis (g) used in their joints was recorded and an additional sample was analysed for THC and CBD concentrations (%).

FINDINGS

THC concentrations were related negatively to the amount of cannabis used [unstandardized regression coefficient: b = -0.009, 95% confidence interval (CI) = -0.017, -0.002]. Potency estimates were predicted by increasing THC (b = 0.055, 95% CI = 0.020, 0.090) and decreasing CBD (b = -0.160, 95% CI = -0.284, -0.062), and both of these associations were mediated by cannabis type (THC: b = 0.018, 95% CI = 0.006, 0.037; CBD: b = -0.105, 95% CI = -0.198, -0.028). Potency estimates were more reflective of THC as frequency of use increased (b = 0.004, 95% CI = 0.001, 0.007) and were 7.3 times more so in daily (partial r = 0.381) than recreational users (r = 0.052).

CONCLUSIONS

When using their own cannabis in a naturalistic setting, people titrate the amount they roll in joints according to concentrations of delta-9-tetrahydrocannabinol (THC) but not cannabidiol (CBD). Recreational users thus show poor understanding of cannabis potency.

Experimental public speaking: contributions to the understanding of the serotonergic modulation of fear

Public speaking is widely used as a model of experimental fear and anxiety. This review aimed to evaluate the effects of pharmacological challenges on public speaking responses and their implications for the understanding of the neurobiology of normal and pathological anxiety, specifically panic disorder. We also describe methodological features of experimental paradigms using public speaking as an inducer of fear and stress. Public speaking is a potent stressor that can provoke significant subjective and physiological responses. However, variations in the manners in which public speaking is modelled can lead to different responses that need to be considered when interpreting the results. Results from pharmacological studies with healthy volunteers submitted to simulated public speaking tests have similarities with the pharmacological responses of panic patients observed in clinical practice and panic patients differ from controls in the response to the public speaking test. These data are compatible with the Deakin and Graeff hypothesis that serotonin inhibits fear, as accessed by public speaking tasks, and that this inhibition is likely related to the actions of serotonin in the dorsal periaqueductal grey matter.

A comparison of cannabidiolic acid with other treatments for anticipatory nausea using a rat model of contextually elicited conditioned gaping

RATIONALE

The effectiveness of cannabidiolic acid (CBDA) was compared with other potential treatments for anticipatory nausea (AN), using a rat model of contextually elicited conditioned gaping reactions.

OBJECTIVE

The potential of ondansetron (OND), Δ(9)-tetrahydrocannabinol (THC), chlordiazepoxide (CDP), CBDA, and co-administration of CBDA and tetrahydrocannabinolic acid (THCA) to reduce AN and modify locomotor activity was evaluated.

MATERIALS AND METHODS

Following four pairings of a novel context with lithium chloride (LiCl), the rats were given a test for AN. On the test trial, they received pretreatment injections of the following: vehicle, OND (0.1 or 1.0 mg/kg), THC (0.5 mg/kg), CBDA (0.0001, 0.001, 0.01, 0.1 mg/kg or 1.0 mg/kg), CDP (1, 5, or 10 mg/kg) or co-administration of subthreshold doses of CBDA (0.1 μg/kg), and THCA (5 μg/kg). Immediately following the AN test trial in all experiments, rats were given a 15 min locomotor activity test. Finally, the potential of CBDA (0.001, 0.01, 0.1, and 1 mg/kg) to attenuate conditioned freezing to a shock-paired tone was assessed.

RESULTS

THC, CBDA, and CDP, but not OND, reduced contextually elicited gaping reactions. Co-administration of subthreshold doses of CBDA and THCA also suppressed AN, and this effect was blocked by pretreatment with either a cannabinoid receptor 1 (CB1) receptor antagonist or a 5-hydroxytryptamine 1A (5-HT1A) receptor antagonist. CDP (but not CBDA, THC or CBDA and THCA) also suppressed locomotor activity at effective doses. CBDA did not modify the expression of conditioned fear.

CONCLUSIONS

CBDA has therapeutic potential as a highly potent and selective treatment for AN without psychoactive or locomotor effects.

Human experimental anxiety: actual public speaking induces more intense physiological responses than simulated public speaking

OBJECTIVES

a) To perform a systematic and meta-analytic review to verify whether the Simulated Public Speaking Task (SPST) leads to a greater increase in self-rated anxiety than in physiological correlates of anxiety; and b) to compare the results obtained with the SPST with an actual public speaking task involving healthy volunteers.

METHODS

a) The PubMed and ISI Web of Knowledge databases were searched for studies involving the SPST prior to 2012. Eleven publications were eligible and provided data from 143 healthy volunteers for meta-analysis; b) 48 university students without somatic or psychiatric disorders were divided into three experimental groups of 16 subjects to undergo one of the following: SPST, real-world public speaking task (real-world), and control situation (control).

RESULTS

The meta-analysis showed that the SPST induced a significant increase in the Visual Analogue Mood Scale (VAMS) anxiety factor, but no significant increases in systolic blood pressure or heart rate. The empirical study showed that the real-world public speaking task increased heart rate, systolic blood pressure and diastolic blood pressure significantly more than the control and SPST conditions.

CONCLUSIONS

These results suggest that real public speaking might be better than SPST in inducing experimental anxiety.

Effects of intra-prelimbic prefrontal cortex injection of cannabidiol on anxiety-like behavior: involvement of 5HT1A receptors and previous stressful experience

The prelimbic medial prefrontal cortex (PL) is an important encephalic structure involved in the expression of emotional states. In a previous study, intra-PL injection of cannabidiol (CBD), a major non-psychotomimetic cannabinoid present in the Cannabis sativa plant, reduced the expression of fear conditioning response. Although its mechanism remains unclear, CBD can facilitate 5HT1A receptor-mediated neurotransmission when injected into several brain structures. This study was aimed at verifying if intra-PL CBD could also induce anxiolytic-like effect in a conceptually distinct animal model, the elevated plus maze (EPM). We also verified if CBD effects in the EPM and contextual fear conditioning test (CFC) depend on 5HT1A receptors and previous stressful experience. CBD induced opposite effects in the CFC and EPM, being anxiolytic and anxiogenic, respectively. Both responses were prevented by WAY100,635, a 5HT1A receptor antagonist. In animals that had been previously (24h) submitted to a stressful event (2h-restraint) CBD caused an anxiolytic, rather than anxiogenic, effect in the EPM. This anxiolytic response was abolished by previous injection of metyrapone, a glucocorticoid synthesis blocker. Moreover, restraint stress increased 5HT1A receptors expression in the dorsal raphe nucleus, an effect that was attenuated by injection of metyrapone before the restraint procedure. Taken together, these results suggest that CBD modulation of anxiety in the PL depend on 5HT1A-mediated neurotransmission and previous stressful experience.

Oxytocin's role in anxiety: a critical appraisal

A growing literature suggests that the oxytocin (OT) system may play a role in human anxiety states, anxiety-related traits, and moreover, that this system may be a target for the development of novel anxiolytic treatments. However, studies of OT's acute and chronic effects on various aspects of anxiety have produced mixed results. In this forward-looking review, we discuss the myriad phenomena to which the term "anxiety" is applied in the OT literature and the problem this presents developing a coherent picture of OT's role in anxiety. We then survey several different fields of research that support the role of the OT system in human anxiety, including evolutionary perspectives, translational and neuroimaging research, genetic studies, and clinical trials of intranasal OT. As an outgrowth of this data, we propose a "bowtie" model of OT's role at the interface of social attachment and anxiety. We next direct attention to understudied brain regions and neural circuits which may be important to study in OT experiments in humans anxiety disorders. Finally, we conclude by proposing questions and priorities for studying both the clinical potential of OT in anxiety, as well as mechanisms that may underlie this potential. Crucially, these priorities include targeted proof-of-concept clinical trials of IN OT in certain anxiety disorders, including investigations of individual moderators of OT's anxiolytic effects (i.e. sex, genetic factors, and early experience). This article is part of a Special Issue entitled Oxytocin and Social Behav.

Does Cannabidiol Protect Against Adverse Psychological Effects of THC?

The recreational use of cannabis can have persistent adverse effects on mental health. Delta-9-tetrahydrocannabinol (THC) is the main psychoactive constituent of cannabis, and most, if not all, of the effects associated with the use of cannabis are caused by THC. Recent studies have suggested a possible protective effect of another cannabinoid, cannabidiol (CBD). A literature search was performed in the bibliographic databases PubMed, PsycINFO, and Web of Science using the keyword "cannabidiol." After removing duplicate entries, 1295 unique titles remained. Based on the titles and abstracts, an initial selection was made. The reference lists of the publications identified in this manner were examined for additional references. Cannabis is not a safe drug. Depending on how often someone uses, the age of onset, the potency of the cannabis that is used and someone's individual sensitivity, the recreational use of cannabis may cause permanent psychological disorders. Most recreational users will never be faced with such persistent mental illness, but in some individuals cannabis use leads to undesirable effects: cognitive impairment, anxiety, paranoia, and increased risks of developing chronic psychosis or drug addiction. Studies examining the protective effects of CBD have shown that CBD can counteract the negative effects of THC. However, the question remains of how the laboratory results translate to the types of cannabis that are encountered by real-world recreational users.

Cannabidiol administration into the bed nucleus of the stria terminalis alters cardiovascular responses induced by acute restraint stress through 5-HT₁A receptor

Systemic administration of cannabidiol (CBD) is able to attenuate cardiovascular responses to acute restraint stress through activation of 5-HT1A receptors. Previous results from our group suggest that the bed nucleus of the stria terminalis (BNST) is involved in the antiaversive effects of the CBD. Moreover, it has been proposed that synapses within the BNST influence restraint-evoked cardiovascular changes, in particular by an inhibitory influence on the tachycardiac response associated to restraint stress. Thus, the present work investigated the effects of CBD injected into the BNST on cardiovascular changes induced by acute restraint stress and if these effects would involve the local activation of 5-HT1A receptors. The exposition to restraint stress increased both blood pressure and heart rate (HR). The microinjection of CBD (30 and 60 nmol) into the BNST enhanced the restraint-evoked HR increase, in a dose-dependent manner, without affecting the pressor response. The selective 5-HT1A receptor antagonist WAY100635 by itself did not change the cardiovascular responses to restraint stress, but blocked the effects of CBD. These results showed that CBD microinjected into the BNST enhanced the HR increase associated with acute restraint stress without affecting the blood pressure response. Although these results are not in agreement with those observed after systemic administration of CBD, they are similar to effects observed after reversible inactivation of the BNST. Moreover, similar to the effects observed after systemic administration, CBD effects in the BNST seem to depend on activation of 5-HT1A receptors.

Multiple mechanisms involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders

Cannabidiol (CBD) is a major phytocannabinoid present in the Cannabis sativa plant. It lacks the psychotomimetic and other psychotropic effects that the main plant compound Δ(9)-tetrahydrocannabinol (THC) being able, on the contrary, to antagonize these effects. This property, together with its safety profile, was an initial stimulus for the investigation of CBD pharmacological properties. It is now clear that CBD has therapeutic potential over a wide range of non-psychiatric and psychiatric disorders such as anxiety, depression and psychosis. Although the pharmacological effects of CBD in different biological systems have been extensively investigated by in vitro studies, the mechanisms responsible for its therapeutic potential are still not clear. Here, we review recent in vivo studies indicating that these mechanisms are not unitary but rather depend on the behavioural response being measured. Acute anxiolytic and antidepressant-like effects seem to rely mainly on facilitation of 5-HT1A-mediated neurotransmission in key brain areas related to defensive responses, including the dorsal periaqueductal grey, bed nucleus of the stria terminalis and medial prefrontal cortex. Other effects, such as anti-compulsive, increased extinction and impaired reconsolidation of aversive memories, and facilitation of adult hippocampal neurogenesis could depend on potentiation of anandamide-mediated neurotransmission. Finally, activation of TRPV1 channels may help us to explain the antipsychotic effect and the bell-shaped dose-response curves commonly observed with CBD. Considering its safety profile and wide range of therapeutic potential, however, further studies are needed to investigate the involvement of other possible mechanisms (e.g. inhibition of adenosine uptake, inverse agonism at CB2 receptor, CB1 receptor antagonism, GPR55 antagonism, PPARγ receptors agonism, intracellular (Ca(2+)) increase, etc.), on CBD behavioural effects.

Plant-based medicines for anxiety disorders, part 2: a review of clinical studies with supporting preclinical evidence

Research in the area of herbal psychopharmacology has revealed a variety of promising medicines that may provide benefit in the treatment of general anxiety and specific anxiety disorders. However, a comprehensive review of plant-based anxiolytics has been absent to date. Thus, our aim was to provide a comprehensive narrative review of plant-based medicines that have clinical and/or preclinical evidence of anxiolytic activity. We present the article in two parts. In part one, we reviewed herbal medicines for which only preclinical investigations for anxiolytic activity have been performed. In this current article (part two), we review herbal medicines for which there have been both preclinical and clinical investigations of anxiolytic activity. A search of MEDLINE (PubMed), CINAHL, Scopus and the Cochrane Library databases was conducted (up to 28 October 2012) for English language papers using the search terms 'anxiety' OR 'anxiety disorder' OR 'generalized anxiety disorder' OR 'social phobia' OR 'post-traumatic stress disorder' OR 'panic disorder' OR 'agoraphobia' OR 'obsessive compulsive disorder' in combination with the search terms 'Herb*' OR 'Medicinal Plants' OR 'Botanical Medicine' OR 'Chinese herb*', in addition to individual herbal medicines. This search of the literature revealed 1,525 papers, of which 53 plants were included in the review (having at least one study using the whole plant extract). Of these plants, 21 had human clinical trial evidence (reviewed here in part two), with the other 32 having solely preclinical evidence (reviewed in part one). Support for efficacy was found for chronic use (i.e. greater than one day) of the following herbs in treating a range of anxiety disorders in human clinical trials: Piper methysticum, Matricaria recutita, Ginkgo biloba, Scutellaria lateriflora, Silybum marianum, Passiflora incarnata, Withania somniferum, Galphimia glauca, Centella asiatica, Rhodiola rosea, Echinacea spp., Melissa officinalis and Echium amoenum. For several of the plants studied, conclusions need to be tempered due to methodological issues such as small sample sizes, brief intervention durations and non-replication. Current evidence does not support Hypericum perforatum or Valeriana spp. for any anxiety disorder. Acute anxiolytic activity was found for Centella asiatica, Salvia spp., Melissa officinalis, Passiflora incarnata and Citrus aurantium. Bacopa monnieri has shown anxiolytic effects in people with cognitive decline. The therapeutic application of psychotropic plant-based treatments for anxiety disorders is also discussed, specifically Psychotria viridis and Banisteriopsis caarti (ayahuasca), Psilocybe spp. and cannabidiol-enriched (low tetrahydrocannabinol (Δ(9)-THC)) Cannabis spp.

Cannabidiol exhibits anxiolytic but not antipsychotic property evaluated in the social interaction test

Cannabidiol (CBD), a non-psychotomimetic compound of the Cannabis sativa, has been reported to have central therapeutic actions, such as antipsychotic and anxiolytic effects. We have recently reported that Spontaneously Hypertensive Rats (SHRs) present a deficit in social interaction that is ameliorated by atypical antipsychotics. In addition, SHRs present a hyperlocomotion that is reverted by typical and atypical antipsychotics, suggesting that this strain could be useful to study negative symptoms (modeled by a decrease in social interaction) and positive symptoms (modeled by hyperlocomotion) of schizophrenia as well as the effects of potential antipsychotics drugs. At the same time, an increase in social interaction in control animals similar to that induced by benzodiazepines is used to screen potential anxiolytic drugs. The aim of this study was to investigate the effects of CBD on social interaction presented by control animals (Wistar) and SHRs. The lowest dose of CBD (1mg/kg) increased passive and total social interaction of Wistar rats. However, the hyperlocomotion and the deficit in social interaction displayed by SHRs were not altered by any dose of CBD. Our results do not support an antipsychotic property of cannabidiol on symptoms-like behaviors in SHRs but reinforce the anxiolytic profile of this compound in control rats.

A biopsychosocial model of social anxiety and substance use

Emerging prospective work suggests that individuals with social anxiety disorder (SAD) may be at particular risk for developing substance use disorders (SUD). Yet, little is known about why this may be so. Most research has utilized existing theories of substance use (e.g. tension reduction-based theories) to understand SAD-SUD relations. However, these theories do not address why individuals with social anxiety, in particular, experience such high rates of substance-related problems. A possible explanation may lie in the nature of social anxiety itself, which is characterized not only by chronically elevated negative affective states, but by low positive affect, fear of scrutiny, and social avoidance. These aspects of social anxiety may work in concert to place these especially vulnerable individuals at risk for SUD. The current paper presents a biopsychosocial model of SAD-SUD comorbidity that focuses on several specific facets of social anxiety that may be especially related to SUD risk. The utility of this model is evaluated via a review of the literature on the relations between SAD and substance-related behaviors.

Ethopharmacological evaluation of the rat exposure test: a prey-predator interaction test

The rat exposure test (RET) is a prey (mouse)-predator (rat) situation that activates brain defensive areas and elicits hormonal and defensive behavior in the mouse. Here, we investigated possible correlations between the spatiotemporal [time spent in protected (home chamber and tunnel) and unprotected (surface) compartments and frequency of entries into the three compartments] and ethological [e.g., duration of protected and unprotected stretched-attend postures (SAP), duration of contact with the rat's compartment] measures (Experiment 1). Secondly, we investigated the effects of systemic treatment with pro- or anti-aversive drugs on the behavior that emerged from the factor analysis (Experiment 2). The effects of chronic (21 days) imipramine and fluoxetine on defensive behavior were also investigated (Experiment 3). Exp. 1 revealed that the time in the protected compartment, protected SAP and rat contacts loaded on factor 1 (defensive behavior), while the total entries and unprotected SAP loaded on factor 2 (locomotor activity). Exp. 2 showed that alprazolam (but not diazepam) selectively changed the defensive factor. Caffeine produced a mild proaversive-like effect, whereas yohimbine only decreased locomotor activity (total entries). Fluoxetine (but not imipramine) produced a weak proaversive-like effect. 5-HT(1A)/5-HT(2) receptor ligands did not change any behavioral measure. In Exp. 3, chronic fluoxetine (but not imipramine) attenuated the defensive behavior factor without changing locomotion. Given that the defensive factor was sensitive to drugs known to attenuate (alprazolam and chronic fluoxetine) and induce (caffeine) panic attack, we suggest the RET as a useful test to assess the effects of panicolytic and panicogenic drugs.

Cannabidiol blocks long-lasting behavioral consequences of predator threat stress: possible involvement of 5HT1A receptors

Posttraumatic stress disorder (PTSD) is an incapacitating syndrome that follows a traumatic experience. Predator exposure promotes long-lasting anxiogenic effect in rodents, an effect related to symptoms found in PTSD patients. Cannabidiol (CBD) is a non-psychotomimetic component of Cannabis sativa with anxiolytic effects. The present study investigated the anti-anxiety actions of CBD administration in a model of PTSD. Male Wistar rats exposed to a predator (cat) received, 1 h later, singled or repeated i.p. administration of vehicle or CBD. Seven days after the stress animals were submitted to the elevated plus maze. To investigate the involvement of 5HT1A receptors in CBD effects animals were pre-treated with WAY100635, a 5HT1A receptor antagonist. To explore possible neurobiological mechanisms involved in these effects, 5HT1A receptor mRNA and BDNF protein expression were measured in the hippocampus, frontal cortex, amygdaloid complex and dorsal periaqueductal gray. Repeated administration of CBD prevented long-lasting anxiogenic effects promoted by a single predator exposure. Pretreatment with WAY100635 attenuated CBD effects. Seven days after predator exposure 5HT1A mRNA expression was up regulated in the frontal cortex and hippocampus. CBD and paroxetine failed to prevent this effect. No change in BDNF expression was found. In conclusion, predator exposure promotes long-lasting up-regulation of 5HT1A receptor gene expression in the hippocampus and frontal cortex. Repeated CBD administration prevents the long-lasting anxiogenic effects observed after predator exposure probably by facilitating 5HT1A receptors neurotransmission. Our results suggest that CBD has beneficial potential for PTSD treatment and that 5HT1A receptors could be a therapeutic target in this disorder.