Effects of ipsapirone and cannabidiol on human experimental anxiety

Oxytocin interference in the effects induced by inhalation of 7.5% CO(2) in healthy volunteers

OBJECTIVE

The objective of this study was to assess the acute effect of intranasally administered oxytocin (OT) on subjective states, cardiovascular, and endocrine parameters in healthy volunteers who inhaled 7.5% CO(2) .

METHODS

Forty-five subjects were allocated into three matched groups of subjects who received 24 international units (IU) of OT, 2 mg of lorazepam (LZP), or placebo (PL). The challenge consisted of medical air inhalation for 20 min, 10 min of rest, and CO(2) 7.5% inhalation for 20 min. Subjective effects were evaluated by self-assessment scales; heart rate, blood pressure, skin conductance, and salivary cortisol were also measured. Assessments were performed at four time points: (i) baseline (-15 min); (ii) post-air inhalation (90 min); (iii) post-CO(2) inhalation (120 min), and (iv) post-test (160 min).

RESULTS

CO(2) inhalation significantly increased the anxiety score in the PL group compared with the post-air measurement but not in the OT or LZP groups. The LZP reduced anxiety after medical air inhalation. Other parameters evaluated were not affected by OT.

CONCLUSION

OT, as well as LZP, prevented CO(2) -induced anxiety, suggesting that this hormone has anxiolytic properties.

Cannabidiol in humans-the quest for therapeutic targets

Cannabidiol (CBD), a major phytocannabinoid constituent of cannabis, is attracting growing attention in medicine for its anxiolytic, antipsychotic, antiemetic and anti-inflammatory properties. However, up to this point, a comprehensive literature review of the effects of CBD in humans is lacking. The aim of the present systematic review is to examine the randomized and crossover studies that administered CBD to healthy controls and to clinical patients. A systematic search was performed in the electronic databases PubMed and EMBASE using the key word “cannabidiol”. Both monotherapy and combination studies (e.g., CBD + ∆9-THC) were included. A total of 34 studies were identified: 16 of these were experimental studies, conducted in healthy subjects, and 18 were conducted in clinical populations, including multiple sclerosis (six studies), schizophrenia and bipolar mania (four studies), social anxiety disorder (two studies), neuropathic and cancer pain (two studies), cancer anorexia (one study), Huntington’s disease (one study), insomnia (one study), and epilepsy (one study). Experimental studies indicate that a high-dose of inhaled/intravenous CBD is required to inhibit the effects of a lower dose of ∆9-THC. Moreover, some experimental and clinical studies suggest that oral/oromucosal CBD may prolong and/or intensify ∆9-THC-induced effects, whereas others suggest that it may inhibit ∆9-THC-induced effects. Finally, preliminary clinical trials suggest that high-dose oral CBD (150–600 mg/d) may exert a therapeutic effect for social anxiety disorder, insomnia and epilepsy, but also that it may cause mental sedation. Potential pharmacokinetic and pharmacodynamic explanations for these results are discussed.

Anxiolytic-like effect of oxytocin in the simulated public speaking test

Oxytocin (OT) is known to be involved in anxiety, as well as cardiovascular and hormonal regulation. The objective of this study was to assess the acute effect of intranasally administered OT on subjective states, as well as cardiovascular and endocrine parameters, in healthy volunteers (n = 14) performing a simulated public speaking test. OT or placebo was administered intranasally 50 min before the test. Assessments were made across time during the experimental session: (1) baseline (-30 min); (2) pre-test (-15 min); (3) anticipation of the speech (50 min); (4) during the speech (1:03 h), post-test time 1 (1:26 h), and post-test time 2 (1:46 h). Subjective states were evaluated by self-assessment scales. Cortisol serum and plasma adrenocorticotropic hormone (ACTH) were measured. Additionally, heart rate, blood pressure, skin conductance, and the number of spontaneous fluctuations in skin conductance were measured. Compared with placebo, OT reduced the Visual Analogue Mood Scale (VAMS) anxiety index during the pre-test phase only, while increasing sedation at the pre-test, anticipation, and speech phases. OT also lowered the skin conductance level at the pre-test, anticipation, speech, and post-test 2 phases. Other parameters evaluated were not significantly affected by OT. The present results show that OT reduces anticipatory anxiety, but does not affect public speaking fear, suggesting that this hormone has anxiolytic properties.

Social anxiety and cannabis use: an analysis from ecological momentary assessment

Individuals with elevated social anxiety appear especially vulnerable to cannabis-related problems, yet little is known about the antecedents of cannabis-related behaviors among this high-risk population. The present study used ecological momentary assessment (EMA) to examine the relations among social anxiety, cannabis craving, state anxiety, situational variables, and cannabis use in the natural environment during ad-lib cannabis use episodes. Participants were 49 current cannabis users. During the two-week EMA period, social anxiety significantly interacted with cannabis craving to predict cannabis use both cross-sectionally and prospectively. Specifically, individuals with higher social anxiety and craving were most likely to use cannabis. There was a significant social anxiety x state anxiety x others' use interaction such that when others were using cannabis, those with elevations in both trait social anxiety and state anxiety were the most likely to use cannabis.

Cannabidiol injected into the bed nucleus of the stria terminalis reduces the expression of contextual fear conditioning via 5-HT1A receptors

Systemic administration of cannabidiol (CBD) attenuates cardiovascular and behavioral changes induced by re-exposure to a context that had been previously paired with footshocks. Previous results from our group using cFos immunohistochemistry suggested that the bed nucleus of the stria terminalis (BNST) is involved in this effect. The mechanisms of CBD effects are still poorly understood, but could involve 5-HT(1A) receptor activation. Thus, the present work investigated if CBD administration into the BNST would attenuate the expression of contextual fear conditioning and if this effect would involve the activation of 5-HT(1A) receptors. Male Wistar rats with cannulae bilaterally implanted into the BNST were submitted to a 10 min conditioning session (six footshocks, 1.5 mA/3 s). Twenty-four hours later freezing and cardiovascular responses (mean arterial pressure and heart rate) to the conditioning box were measured for 10 min. CBD (15, 30 or 60 nmol) or vehicle was administered 10 min before the re-exposure to the aversive context. The second experiment was similar to the first one except that animals received microinjections of the 5-HT(1A) receptor antagonist WAY100635 (0.37 nmol) 5 min before CBD (30 nmol) treatment. The results showed that CBD (30 and 60 nmol) treatment significantly reduced the freezing and attenuated the cardiovascular responses induced by re-exposure to the aversive context. Moreover, WAY100635 by itself did not change the cardiovascular and behavioral response to context, but blocked the CBD effects. These results suggest that CBD can act in the BNST to attenuate aversive conditioning responses and this effect seems to involve 5-HT(1A) receptor-mediated neurotransmission.

Neuroanatomical substrates involved in cannabinoid modulation of defensive responses

Administration of Cannabis sativa derivatives causes anxiolytic or anxiogenic effects in humans and laboratory animals, depending on the specific compound and dosage used. In agreement with these findings, several studies in the last decade have indicated that the endocannabinoid system modulates neuronal activity in areas involved in defensive responses. The mechanisms of these effects, however, are still not clear. The present review summarizes recent data suggesting that they involve modulation of glutamate and GABA-mediated neurotransmission in brain sites such as the medial prefrontal cortex, amygdaloid complex, bed nucleus of the stria terminalis, hippocampus and dorsal periaqueductal gray. Moreover, we also discuss results indicating that, in these regions, the endocannabinoid system could be particularly engaged by highly stressful situations.

Anti-aversive effects of cannabidiol on innate fear-induced behaviors evoked by an ethological model of panic attacks based on a prey vs the wild snake Epicrates cenchria crassus confrontation paradigm

Several pharmacological targets have been proposed as modulators of panic-like reactions. However, interest should be given to other potential therapeutic neurochemical agents. Recent attention has been given to the potential anxiolytic properties of cannabidiol, because of its complex actions on the endocannabinoid system together with its effects on other neurotransmitter systems. The aim of this study was to investigate the effects of cannabidiol on innate fear-related behaviors evoked by a prey vs predator paradigm. Male Swiss mice were submitted to habituation in an arena containing a burrow and subsequently pre-treated with intraperitoneal administrations of vehicle or cannabidiol. A constrictor snake was placed inside the arena, and defensive and non-defensive behaviors were recorded. Cannabidiol caused a clear anti-aversive effect, decreasing explosive escape and defensive immobility behaviors outside and inside the burrow. These results show that cannabidiol modulates defensive behaviors evoked by the presence of threatening stimuli, even in a potentially safe environment following a fear response, suggesting a panicolytic effect.

Endocannabinoid system and psychiatry: in search of a neurobiological basis for detrimental and potential therapeutic effects

Public concern on mental health has noticeably increased given the high prevalence of neuropsychiatric disorders. Cognition and emotionality are the most affected functions in neuropsychiatric disorders, i.e., anxiety disorders, depression, and schizophrenia. In this review, most relevant literature on the role of the endocannabinoid (eCB) system in neuropsychiatric disorders will be presented. Evidence from clinical and animal studies is provided for the participation of CB1 and CB2 receptors (CB1R and CB2R) in the above mentioned neuropsychiatric disorders. CBRs are crucial in some of the emotional and cognitive impairments reported, although more research is required to understand the specific role of the eCB system in neuropsychiatric disorders. Cannabidiol (CBD), the main non-psychotropic component of the Cannabis sativa plant, has shown therapeutic potential in several neuropsychiatric disorders. Although further studies are needed, recent studies indicate that CBD therapeutic effects may partially depend on facilitation of eCB-mediated neurotransmission. Last but not least, this review includes recent findings on the role of the eCB system in eating disorders. A deregulation of the eCB system has been proposed to be in the bases of several neuropsychiatric disorders, including eating disorders. Cannabis consumption has been related to the appearance of psychotic symptoms and schizophrenia. In contrast, the pharmacological manipulation of this eCB system has been proposed as a potential strategy for the treatment of anxiety disorders, depression, and anorexia nervosa. In conclusion, the eCB system plays a critical role in psychiatry; however, detrimental consequences of manipulating this endogenous system cannot be underestimated over the potential and promising perspectives of its therapeutic manipulation.

Administration of cannabidiol and imipramine induces antidepressant-like effects in the forced swimming test and increases brain-derived neurotrophic factor levels in the rat amygdala

Réus GZ, Stringari RB, Ribeiro KF, Luft T, Abelaira HM, Fries GR, Aguiar BW, Kapczinski F, Hallak JE, Zuardi AW, Crippa JA, Quevedo J. Administration of cannabidiol and imipramine induces antidepressant-like effects in the forced swimming test and increases brain-derived neurotrophic factor levels in the rat amygdala.

Objective:Cannabidiol is a chemical constituent fromCannabis sativaand it has multiple mechanisms of action, including antidepressant effects. The main objective of the present study was to evaluate behavioural and molecular effects induced by administration of cannabidiol and imipramine in rats.

Methods:In the present study, rats were acutely or chronically treated for 14 days once a day with saline, cannabidiol (15, 30 and 60 mg/kg) or imipramine (30 mg/kg) and the animals behaviour was assessed in forced swimming and open-field tests. Afterwards, the prefrontal cortex, hippocampus and amygdala brain-derived neurotrophic factor (BDNF) levels were assessed by enzyme-linked immunosorbent sandwich assay.

Results:We observed that both acute and chronic treatments with imipramine at the dose of 30 mg/kg and cannabidiol at the dose of 30 mg/kg reduced immobility time and increased swimming time; climbing time was increased only with imipramine at the dose of 30 mg/kg, without affecting locomotor activity. In addition, chronic treatment with cannabidiol at the dose of 15 mg/kg and imipramine at the dose of 30 mg/kg increased BDNF levels in the rat amygdala.

Conclusion:In conclusion, our results indicate that cannabidiol has an antidepressant-like profile and could be a new pharmacological target for the treatment of major depression.

Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naïve social phobia patients

Generalized Social Anxiety Disorder (SAD) is one of the most common anxiety conditions with impairment in social life. Cannabidiol (CBD), one major non-psychotomimetic compound of the cannabis sativa plant, has shown anxiolytic effects both in humans and in animals. This preliminary study aimed to compare the effects of a simulation public speaking test (SPST) on healthy control (HC) patients and treatment-naïve SAD patients who received a single dose of CBD or placebo. A total of 24 never-treated patients with SAD were allocated to receive either CBD (600 mg; n=12) or placebo (placebo; n=12) in a double-blind randomized design 1 h and a half before the test. The same number of HC (n=12) performed the SPST without receiving any medication. Each volunteer participated in only one experimental session in a double-blind procedure. Subjective ratings on the Visual Analogue Mood Scale (VAMS) and Negative Self-Statement scale (SSPS-N) and physiological measures (blood pressure, heart rate, and skin conductance) were measured at six different time points during the SPST. The results were submitted to a repeated-measures analysis of variance. Pretreatment with CBD significantly reduced anxiety, cognitive impairment and discomfort in their speech performance, and significantly decreased alert in their anticipatory speech. The placebo group presented higher anxiety, cognitive impairment, discomfort, and alert levels when compared with the control group as assessed with the VAMS. The SSPS-N scores evidenced significant increases during the testing of placebo group that was almost abolished in the CBD group. No significant differences were observed between CBD and HC in SSPS-N scores or in the cognitive impairment, discomfort, and alert factors of VAMS. The increase in anxiety induced by the SPST on subjects with SAD was reduced with the use of CBD, resulting in a similar response as the HC.

The anxiolytic-like effects of cannabidiol injected into the bed nucleus of the stria terminalis are mediated by 5-HT1A receptors

RATIONALE

Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa that induces anxiolytic-like effects in rodents and humans after systemic administration. Previous results from our group showed that CBD injection into the bed nucleus of the stria terminalis (BNST) attenuates conditioned aversive responses. The aim of this study was to further investigate the role of this region on the anxiolytic effects of the CBD. Moreover, considering that CBD can activate 5-HT1A receptors, we also verified a possible involvement of these receptors in those effects.

METHODS

Male Wistar rats received injections of CBD (15, 30, or 60 nmol) into the BNST and were exposed to the elevated plus-maze (EPM) or to the Vogel conflict test (VCT), two widely used animal models of anxiety.

RESULTS

CBD increased open arms exploration in the EPM as well as the number of punished licks in the VCT, suggesting an anxiolytic-like effect. The drug did not change the number of entries into the enclosed arms of the EPM nor interfered with water consumption or nociceptive threshold, discarding potential confounding factors in the two tests. Moreover, pretreatment with the 5-HT1A receptor antagonist WAY100635 (0.37 nmol) blocked the effects of CBD in both models.

CONCLUSIONS

These results give further support to the proposal that BNST is involved in the anxiolytic-like effects of CBD observed after systemic administration, probably by facilitating local 5-HT1A receptor-mediated neurotransmission.

Effects of cannabidiol on amphetamine-induced oxidative stress generation in an animal model of mania

Cannabidiol (CBD), a Cannabis sativa constituent, may present a pharmacological profile similar to mood stabilizing drugs, in addition to anti-oxidative and neuroprotective properties. The present study aims to directly investigate the effects of CBD in an animal model of mania induced by D-amphetamine (D-AMPH). In the first model (reversal treatment), rats received saline or D-AMPH (2 mg/kg) once daily intraperitoneal (i.p.) for 14 days, and from the 8th to the 14th day, they were treated with saline or CBD (15, 30 or 60 mg/kg) i.p. twice a day. In the second model (prevention treatment), rats were pretreated with saline or CBD (15, 30, or 60 mg/kg) regime i.p. twice a day, and from the 8th to the 14th day, they also received saline or D-AMPH i.p. once daily. In the hippocampus CBD (15 mg/kg) reversed the d-AMPH-induced damage and increased (30 mg/kg) brain-derived neurotrophic factor (BDNF) expression. In the second experiment, CBD (30 or 60 mg/kg) prevented the D-AMPH-induced formation of carbonyl group in the prefrontal cortex. In the hippocampus and striatum the D-AMPH-induced damage was prevented by CBD (15, 30 or 60 mg/kg). At both treatments CBD did not present any effect against d-AMPH-induced hyperactivity. In conclusion, we could not observe effects on locomotion, but CBD protect against d-AMPH-induced oxidative protein damage and increased BDNF levels in the reversal model and these effects vary depending on the brain regions evaluated and doses of CBD administered.

Neural basis of anxiolytic effects of cannabidiol (CBD) in generalized social anxiety disorder: a preliminary report

Animal and human studies indicate that cannabidiol (CBD), a major constituent of cannabis, has anxiolytic properties. However, no study to date has investigated the effects of this compound on human pathological anxiety and its underlying brain mechanisms. The aim of the present study was to investigate this in patients with generalized social anxiety disorder (SAD) using functional neuroimaging. Regional cerebral blood flow (rCBF) at rest was measured twice using (99m)Tc-ECD SPECT in 10 treatment-naïve patients with SAD. In the first session, subjects were given an oral dose of CBD (400 mg) or placebo, in a double-blind procedure. In the second session, the same procedure was performed using the drug that had not been administered in the previous session. Within-subject between-condition rCBF comparisons were performed using statistical parametric mapping. Relative to placebo, CBD was associated with significantly decreased subjective anxiety (p < 0.001), reduced ECD uptake in the left parahippocampal gyrus, hippocampus, and inferior temporal gyrus (p < 0.001, uncorrected), and increased ECD uptake in the right posterior cingulate gyrus (p < 0.001, uncorrected). These results suggest that CBD reduces anxiety in SAD and that this is related to its effects on activity in limbic and paralimbic brain areas.

Intra-dorsal periaqueductal gray administration of cannabidiol blocks panic-like response by activating 5-HT1A receptors

Activation of 5-HT1A receptors in the dorsal periaqueductal gray (dPAG) impairs escape behavior, suggesting a panicolytic-like effect. Cannabidiol (CBD), a major non-psychotomimetic compound present in Cannabis sativa, causes anxiolytic-like effects after intra-dPAG microinjections by activating 5-HT1A receptors. In the present work we tested the hypothesis that CBD could also impair escape responses evoked by two proposed animal models of panic: the elevated T-maze (ETM) and electric stimulation of dPAG. In experiment 1 male Wistar rats with a single cannula implanted in the dPAG received a microinjection of CBD or vehicle and, 10 min later, were submitted to the ETM and open field tests. In experiment 2 escape electrical threshold was measured in rats with chemitrodes implanted in the dPAG before and 10 min after CBD microinjection. In experiment 3 similar to experiment 2 except that the animals received a previous intra-dPAG administration of WAY-100635, a 5-HT1A receptor antagonist, before CBD treatment. In the ETM microinjection of CBD into the dPAG impaired inhibitory avoidance acquisition, an anxiolytic-like effect, and inhibited escape response, a panicolytic-like effect. The drug also increased escape electrical threshold, an effect that was prevented by WAY-100635. Together, the results suggest that CBD causes panicolytic effects in the dPAG by activating 5-HT1A receptors.

Escitalopram prolonged fear induced by simulated public speaking and released hypothalamic-pituitary-adrenal axis activation

Simulated public speaking (SPS) test is sensitive to drugs that interfere with serotonin-mediated neurotransmission and is supposed to recruit neural systems involved in panic disorder. The study was aimed at evaluating the effects of escitalopram, the most selective serotonin-selective reuptake inhibitor available, in SPS. Healthy males received, in a double-blind, randomized design, placebo (n = 12), 10 (n = 17) or 20 (n = 14) mg of escitalopram 2 hours before the test. Behavioural, autonomic and neuroendocrine measures were assessed. Both doses of escitalopram did not produce any effect before or during the speech but prolonged the fear induced by SPS. The test itself did not significantly change cortisol and prolactin levels but under the higher dose of escitalopram, cortisol and prolactin increased immediately after SPS. This fear-enhancing effect of escitalopram agrees with previously reported results with less selective serotonin reuptake inhibitors and the receptor antagonist ritanserin, indicating that serotonin inhibits the fear of speaking in public.

Uso terapêutico dos canabinoides em psiquiatria

OBJETIVO: Revisar os principais avanços no potencial uso terapêutico de alguns compostos canabinoides em psiquiatria. MÉTODO: Foi realizada busca nos bancos de dado PubMed, SciELO e Lilacs e identificados estudos e revisões da literatura sobre o uso terapêutico dos canabinoides em psiquiatria, em particular canabidiol, rimonabanto, Δ9-tetraidrocanabinol e seus análogos. RESULTADOS: O canabidiol demonstrou apresentar potencial terapêutico como antipsicótico, ansiolítico, antidepressivo e em diversas outras condições. O Δ9-tetraidrocanabinol e seus análogos demonstraram efeitos ansiolíticos, na dependência de cannabis, bem como adjuvantes no tratamento de esquizofrenia, apesar de ainda carecerem de mais estudos. O rimonabanto demonstrou eficácia no tratamento de sintomas subjetivos e fisiológicos da intoxicação pela cannabis e como adjuvante no tratamento do tabagismo. Os potenciais efeitos colaterais, de induzir depressão e ansiedade limitaram o uso clínico deste antagonista CB1. CONCLUSÃO: Os canabinoides têm demonstrado que podem ter amplo interesse terapêutico em psiquiatria, porém mais estudos controlados são necessários para confirmar estes achados e determinar a segurança destes compostos.

Involvement of the prelimbic prefrontal cortex on cannabidiol-induced attenuation of contextual conditioned fear in rats

RATIONALE

Systemic administration of cannabidiol (CBD), a non-psychotomimetic component of Cannabis sativa, is able to attenuate cardiovascular and behavioral (freezing) changes induced by re-exposure to a context that had been previously paired with footshocks. The brain sites mediating this effect, however, remain unknown. The medial prefrontal cortex (mPFC) has been related to contextual fear conditioning.

OBJECTIVES

(1) To verify, using c-Fos immunocytochemistry, if the mPFC is involved in the attenuation of contextual fear induced by systemic administration of CBD; (2) to investigate if direct microinjections of CBD into mPFC regions would also attenuate contextual fear.

RESULTS

Confirming previous results systemic administration of CBD (10mg/kg) decreased contextual fear and associated c-Fos expression in the prefrontal cortex (prelimbic and infralimbic regions). The drug also attenuated c-Fos expression in the bed nucleus of the stria terminalis (BNST). Direct CBD (30 nmol) microinjection into the PL prefrontal cortex reduced freezing induced by re-exposure to the aversively conditioned context. In the infralimbic (IL) prefrontal cortex, however, CBD (30 nmol) produced an opposite result, increasing the expression of contextual fear conditioning. This result was confirmed by an additional experiment where the conditioning session was performed under a less aversive protocol.

CONCLUSION

These results suggest that the PL prefrontal cortex may be involved in the attenuation of contextual fear induced by systemic injection of CBD. They also support the proposition that the IL and PL play opposite roles in fear conditioning. A possible involvement of the BNST in CBD effects needs to be further investigated.

Opposite effects of delta-9-tetrahydrocannabinol and cannabidiol on human brain function and psychopathology

Delta-9-tetrahydrocannabinol (Delta-9-THC) and Cannabidiol (CBD), the two main ingredients of the Cannabis sativa plant have distinct symptomatic and behavioral effects. We used functional magnetic resonance imaging (fMRI) in healthy volunteers to examine whether Delta-9-THC and CBD had opposite effects on regional brain function. We then assessed whether pretreatment with CBD can prevent the acute psychotic symptoms induced by Delta-9-THC. Fifteen healthy men with minimal earlier exposure to cannabis were scanned while performing a verbal memory task, a response inhibition task, a sensory processing task, and when viewing fearful faces. Subjects were scanned on three occasions, each preceded by oral administration of Delta-9-THC, CBD, or placebo. BOLD responses were measured using fMRI. In a second experiment, six healthy volunteers were administered Delta-9-THC intravenously on two occasions, after placebo or CBD pretreatment to examine whether CBD could block the psychotic symptoms induced by Delta-9-THC. Delta-9-THC and CBD had opposite effects on activation relative to placebo in the striatum during verbal recall, in the hippocampus during the response inhibition task, in the amygdala when subjects viewed fearful faces, in the superior temporal cortex when subjects listened to speech, and in the occipital cortex during visual processing. In the second experiment, pretreatment with CBD prevented the acute induction of psychotic symptoms by Delta-9-tetrahydrocannabinol. Delta-9-THC and CBD can have opposite effects on regional brain function, which may underlie their different symptomatic and behavioral effects, and CBD's ability to block the psychotogenic effects of Delta-9-THC.

Mood, Anxiety, and Serum IGF-1 in Elderly Men Given 24 Weeks of High Resistance Exercise

As aging advances, changes in mood and anxiety may imply greater risk of mood disorders, particularly anxiety and depression. Resistance exercise reduces anxiety and lessens risk of depression in the elderly, but little is known of the mechanisms involved. It was hypothesized that the human growth factor (IGF-1) may improve mood and anxiety in elderly participants given resistance training. 43 elderly men ages 65 to 75 years were randomly assigned to two groups, Control ( n = 23) and high resistance Exercise ( n = 20). After 24 wk., the Exercise group showed improved muscular strength and higher IGF-1 serum levels than the Control group, as indicated by mean scores on a visual analogue mood scale and the State-Trait Anxiety Inventory. Intensive resistance training was efficacious in improving mood, anxiety, and IGF-1 serum concentration in elderly individuals free of clinical mood disorders.

Cannabis and anxiety: a critical review of the evidence

BACKGROUND

Anxiety reactions and panic attacks are the acute symptoms most frequently associated with cannabis use. Understanding the relationship between cannabis and anxiety may clarify the mechanism of action of cannabis and the pathophysiology of anxiety. Aims of the present study were to review the nature of the relationship between cannabis use and anxiety, as well as the possible clinical, diagnostic and causal implications.

METHOD

Systematic review of the Medline, PsycLIT and EMBASE literature.

RESULTS

Frequent cannabis users consistently have a high prevalence of anxiety disorders and patients with anxiety disorders have relatively high rates of cannabis use. However, it is unclear if cannabis use increases the risk of developing long-lasting anxiety disorders. Many hypotheses have been proposed in an attempt to explain these relationships, including neurobiological, environmental and social influences.

CONCLUSIONS

The precise relationship between cannabis use and anxiety has yet to be established. Research is needed to fully clarify the mechanisms of such the association.

Effects of sex hormonal levels and phases of the menstrual cycle in the processing of emotional faces

Several neuropsychiatry disorders have shown a sexual dimorphism in their incidence, symptom profile and therapeutic response. A better understanding of the impact of sex hormones in emotional processing sexual dimorphism could bring light to this important clinical finding. Some studies have provided evidence of sex differences in the identification of emotional faces, however, results are inconsistent and such inconsistency could be related to the lack of experimental control of the sex hormone status of participants. More recently, a few studies evaluated the modulation of facial emotion recognition by the phase of the menstrual cycle and sex hormones, however, none of them directly compared these results with a group of men. We evaluated the accuracy of facial emotion recognition in 40 healthy volunteers. Eleven women were assigned to early follicular group, nine women to the ovulatory group and 10 women to luteal group, depending on the phase of menstrual cycle, and a group of 10 men were also evaluated. Estrogen, progesterone and testosterone levels were assessed. The performance of the groups in the identification of emotional faces varied depending on the emotion. Early follicular group were more accurate to perceive angry faces than all other groups. Sadness was more accurately recognized by early follicular group than by luteal group and regarding the recognition of fearful faces a trend to a better performance and a significantly higher accuracy was observed, respectively, in the early follicular group and in the ovulatory group, in comparison to men. In women, estrogen negatively correlated to the accuracy in perception of angry male faces. Our results indicate sex hormones to be implicated in a sexual dimorphism in facial emotion recognition, and highlight the importance of estrogen specifically in the recognition of negative emotions such as sadness, anger and fear.

Cannabis and schizophrenia spectrum disorders: a review of clinical studies

Cannabis is the most widely used illegitimate substance in the world, and the number of users has increased by 10% over the last decade worldwide. Therefore, it is important to review the evidence on psychoactive properties of cannabis and its possible association with schizophrenia spectrum disorders (SSD). We searched MEDLINE with the key words cannabis and schizophrenia. The search was limited to articles published in English over the last 10 years (1999-2009). Bibliographies of cited literature were also searched. Data sources included reviews published in core clinical journals, cohort studies, interventional studies, case-control studies, cross-sectional analyses and epidemiological data. Results are discussed under 2 topics. Firstly, evidence related to biochemical functioning of cannabinoids and their relationship to endocannabinoid system is discussed briefly. Secondly, the evidence from clinical studies on cannabis, psychosis proneness and SSD are discussed in detail. The discussion is structured to fit in the evidence from results section to 3 plausible hypotheses on cannabis use and SSD. The evidence for and against each hypothesis is discussed. Despite new evidence, the exact relationship between cannabis and SSD is unclear. There is no firm evidence that cannabis causes SSD. The evidence for the argument that schizophrenic patients are attracted to cannabis is also not strong. The most plausible explanation is that cannabis use and psychosis proneness may have synergistic effects in a vulnerable minority.

Distinct effects of {delta}9-tetrahydrocannabinol and cannabidiol on neural activation during emotional processing

CONTEXT

Cannabis use can both increase and reduce anxiety in humans. The neurophysiological substrates of these effects are unknown.

OBJECTIVE

To investigate the effects of 2 main psychoactive constituents of Cannabis sativa (Delta9-tetrahydrocannabinol [Delta9-THC] and cannabidiol [CBD]) on regional brain function during emotional processing.

DESIGN

Subjects were studied on 3 separate occasions using an event-related functional magnetic resonance imaging paradigm while viewing faces that implicitly elicited different levels of anxiety. Each scanning session was preceded by the ingestion of either 10 mg of Delta9-THC, 600 mg of CBD, or a placebo in a double-blind, randomized, placebo-controlled design.

PARTICIPANTS

Fifteen healthy, English-native, right-handed men who had used cannabis 15 times or less in their life.

MAIN OUTCOME MEASURES

Regional brain activation (blood oxygenation level-dependent response), electrodermal activity (skin conductance response [SCR]), and objective and subjective ratings of anxiety.

RESULTS

Delta9-Tetrahydrocannabinol increased anxiety, as well as levels of intoxication, sedation, and psychotic symptoms, whereas there was a trend for a reduction in anxiety following administration of CBD. The number of SCR fluctuations during the processing of intensely fearful faces increased following administration of Delta9-THC but decreased following administration of CBD. Cannabidiol attenuated the blood oxygenation level-dependent signal in the amygdala and the anterior and posterior cingulate cortex while subjects were processing intensely fearful faces, and its suppression of the amygdalar and anterior cingulate responses was correlated with the concurrent reduction in SCR fluctuations. Delta9-Tetrahydrocannabinol mainly modulated activation in frontal and parietal areas.

CONCLUSIONS

Delta9-Tetrahydrocannabinol and CBD had clearly distinct effects on the neural, electrodermal, and symptomatic response to fearful faces. The effects of CBD on activation in limbic and paralimbic regions may contribute to its ability to reduce autonomic arousal and subjective anxiety, whereas the anxiogenic effects of Delta9-THC may be related to effects in other brain regions.

Antiaversive effects of cannabinoids: is the periaqueductal gray involved?

Cannabinoids play an important role in activity-dependent changes in synaptic activity and can interfere in several brain functions, including responses to aversive stimuli. The regions responsible for their effects, however, are still unclear. Cannabinoid type 1 (CB1) receptors are widely distributed in the central nervous system and are present in the periaqueductal gray (PAG), a midbrain structure closely involved in responses related to aversive states. Accordingly, exposure to stressful stimuli increases endocannabinoid (eCB) levels in the PAG, and local administration of CB1 agonists or drugs that facilitate eCB-mediated neurotransmission produces antinociceptive and antiaversive effects. To investigate if these drugs would also interfere in animal models that are sensitive to anxiolytic drugs, we verified the responses to intra-PAG injection of CB1 agonists in rats submitted to the elevated plus-maze, the Vogel punished licking test, or contextual aversive conditioning model. The drugs induced anxiolytic-like effects in all tests. The same was observed with the transient receptor potential vanilloid type 1 (TRPV1) antagonist capsazepine and with cannabidiol, a nonpsychotomimetic phytocannabinoid that produces anxiolytic-like effects after systemic administration in humans and laboratory animals. These results, therefore, suggest that the PAG could be an important site for the antiaversive effects of cannabinoids.

Cannabidiol: from an inactive cannabinoid to a drug with wide spectrum of action

OBJECTIVE: The aim of this review is to describe the historical development of research on cannabidiol. METHOD: This review was carried out on reports drawn from Medline, Web of Science and SciELO. DISCUSSION: After the elucidation of the chemical structure of cannabidiol in 1963, the initial studies showed that cannabidiol was unable to mimic the effects of Cannabis. In the 1970's the number of publications on cannabidiol reached a first peak, having the research focused mainly on the interaction with delta9-THC and its antiepileptic and sedative effects. The following two decades showed lower degree of interest, and the potential therapeutic properties of cannabidiol investigated were mainly the anxiolytic, antipsychotic and on motor diseases effects. The last five years have shown a remarkable increase in publications on cannabidiol mainly stimulated by the discovery of its anti-inflammatory, anti-oxidative and neuroprotective effects. These studies have suggested a wide range of possible therapeutic effects of cannabidiol on several conditions, including Parkinson's disease, Alzheimer's disease, cerebral ischemia, diabetes, rheumatoid arthritis, other inflammatory diseases, nausea and cancer. CONCLUSION: In the last 45 years it has been possible to demonstrate that CBD has a wide range of pharmacological effects, many of which being of great therapeutic interest, but still waiting to be confirmed by clinical trials.

Cannabis and psychiatric disorders: it is not only addiction

Since the discovery of the endocannabinoid system, a growing body of psychiatric research has emerged focusing on the role of this system in major psychiatric disorders like schizophrenia (SCZ), bipolar disorder (BD), major depression and anxiety disorder. Continuing in the line of earlier epidemiological studies, recent replication studies indicate that frequent cannabis use doubles the risk for psychotic symptoms and SCZ. Further points of clinical research interest are alterations of endocannabinoids and their relation to symptoms as well as postmortem analyses of cannabinoid CB(1) receptor densities in SCZ. A possible neurobiological mechanism for the deleterious influence of cannabis use in SCZ has been suggested, involving the disruption of endogenous cannabinoid signaling and functioning. Even though the number of studies is still limited for affective and anxiety disorders, previous results suggest these diseases to be exciting objectives of cannabinoid-associated research. Therefore, it became apparent that cannabis use is not only frequent in patients suffering from BD, but that it also induces manic symptoms in this group. In addition, prior antipsychotic treatment decreased the numerical density of CB(1) immunoreactive glial cells in bipolar patients. Although the data on the influence of cannabis use on the development of major depression is controversial, cannabinoid compounds could display a new class of medication, as suggested by the antidepressive effects of the fatty acid amino hydrolase inhibitor URB597 in animal models. With numerous open questions and controversial results, further research is required to specify and extend the findings in this area, which provides a promising target for novel pharmacotherapeutic interventions.

Modelling anxiety in humans for drug development

Animal behavioural profiles are commonly employed to investigate new therapeutic agents to treat anxiety disorders as well as to investigate the mechanism of action of anxiolytic drugs. However, many clinically important symptoms of anxiety can not be modelled directly in animals. Human models of anxiety should bridge between animal models and anxiety disorders. Experimental anxiety states in humans can be induced by either pharmacological means such as CO(2) inhalation or psychological means such as aversive conditioning of skin conductance responses to tones. Investigation of these models may contribute to a better understanding of anxiety disorders, both from a biological and behavioural point of view. In a comprehensive review existing models of human experimental anxiety states are summarized and validity is discussed.

Cannabidiol, a Cannabis sativa constituent, as an antipsychotic drug

A high dose of delta9-tetrahydrocannabinol, the main Cannabis sativa (cannabis) component, induces anxiety and psychotic-like symptoms in healthy volunteers. These effects of delta9-tetrahydrocannabinol are significantly reduced by cannabidiol (CBD), a cannabis constituent which is devoid of the typical effects of the plant. This observation led us to suspect that CBD could have anxiolytic and/or antipsychotic actions. Studies in animal models and in healthy volunteers clearly suggest an anxiolytic-like effect of CBD. The antipsychotic-like properties of CBD have been investigated in animal models using behavioral and neurochemical techniques which suggested that CBD has a pharmacological profile similar to that of atypical antipsychotic drugs. The results of two studies on healthy volunteers using perception of binocular depth inversion and ketamine-induced psychotic symptoms supported the proposal of the antipsychotic-like properties of CBD. In addition, open case reports of schizophrenic patients treated with CBD and a preliminary report of a controlled clinical trial comparing CBD with an atypical antipsychotic drug have confirmed that this cannabinoid can be a safe and well-tolerated alternative treatment for schizophrenia. Future studies of CBD in other psychotic conditions such as bipolar disorder and comparative studies of its antipsychotic effects with those produced by clozapine in schizophrenic patients are clearly indicated.

Subjective and neurovegetative changes in healthy volunteers and panic patients performing simulated public speaking

Drug-free symptomatic panic patients, drug-treated nonsymptomatic patients and healthy controls were submitted to simulated public speaking. Subjective anxiety, cognitive impairment and discomfort measured by the visual analog mood scale as well as skin conductance level were higher in symptomatic patients than in controls at the beginning of the experimental session, nonsymptomatic patients lying in between. Subjective sedation, spontaneous fluctuations of skin conductance, heart rate and blood pressure were similar in the three groups. Preparation and performance of speech decreased sedation while increasing anxiety, cognitive impairment, level and fluctuations of skin conductance, heart rate and blood pressure. Anxiety, cognitive impairment and conductance level were less increased in symptomatic patients than in controls. Electrodermal activity, but not cardiovascular measures of sympathetic arousal correlated with anticipatory anxiety. Chronic treatment with serotonin uptake inhibitors attenuated the differences between panic patients and controls, supporting the participation of serotonin in panic disorder.

Reinforcing effects of diazepam under anxiogenic conditions in individuals with social anxiety

Diazepam (DZ) reinforcement was tested under anxiogenic (public speaking) and neutral (computer task) conditions. Individuals with social anxiety disorder (n = 11) and healthy controls (n = 11) participated in two 5-session phases. Each phase used a standard choice procedure (2 sample, 3 choice sessions) comparing 10-mg DZ and placebo. During the public speaking condition, DZ preference was greater among the participants with social anxiety compared with controls (81.8% vs. 36.4%; p < .05). Participants with social anxiety also gave DZ significantly higher crossover values on the multiple choice procedure under the speech condition compared with the computer condition. Subjective effects indicated that DZ reduced anxiety when levels were elevated during the speech in socially anxious participants. These results suggest that DZ reinforcement may occur under conditions of heightened anxiety by bestowing therapeutic efficacy.

Anxiety and salivary cortisol in symptomatic and nonsymptomatic panic patients and healthy volunteers performing simulated public speaking

Anxiety and salivary cortisol were measured in subjects performing simulated public speaking (SPS), a procedure that has been neurobiologically related to panic disorder. The subjects were divided into three groups: 18 symptomatic panic patients, 16 nonsymptomatic, drug-treated panic patients, and 17 healthy controls. In the experimental session, subjective anxiety (Visual Analogue Mood Scale) and the total score of the Bodily Symptom Scale (BSS) were higher in symptomatic patients than in controls, with nonsymptomatic patients in between. Measures of cortisol taken at home showed that the level was higher at 9:00 h than at 23:00 h in every group, indicating a normal circadian regulation of the hypothalamic-pituitary-adrenal (HPA) axis in panic patients. Also in every group, the level of cortisol was high at the beginning of the experimental session and decreased after 70 min. This fall parallels the decrease in anxiety and BSS ratings, and appears to reflect habituation of initial, anticipatory anxiety. Preparation and performance of speech raised anxiety and BSS scores to the initial levels, but failed to increase cortisol measured over 60 min, starting at the end of the speech. Therefore, SPS does not seem to activate the HPA axis, as reported in panic attacks.

Human studies of cannabinoids and medicinal cannabis

Cannabis has been known as a medicine for several thousand years across many cultures. It reached a position of prominence within Western medicine in the nineteenth century but became mired in disrepute and legal controls early in the twentieth century. Despite unremitting world-wide suppression, recreational cannabis exploded into popular culture in the 1960s and has remained easily obtainable on the black market in most countries ever since. This ready availability has allowed many thousands of patients to rediscover the apparent power of the drug to alleviate symptoms of some of the most cruel and refractory diseases known to humankind. Pioneering clinical research in the last quarter of the twentieth century has given some support to these anecdotal reports, but the methodological challenges to human research involving a pariah drug are formidable. Studies have tended to be small, imperfectly controlled, and have often incorporated unsatisfactory synthetic cannabinoid analogues or smoked herbal material of uncertain composition and irregular bioavailability. As a result, the scientific evaluation of medicinal cannabis in humans is still in its infancy. New possibilities in human research have been opened up by the discovery of the endocannabinoid system, a rapidly expanding knowledge of cannabinoid pharmacology, and a more sympathetic political environment in several countries. More and more scientists and clinicians are becoming interested in exploring the potential of cannabis-based medicines. Future targets will extend beyond symptom relief into disease modification, and already cannabinoids seem to offer particular promise in the treatment of certain inflammatory and neurodegenerative conditions. This chapter will begin with an outline of the development and current status of legal controls pertaining to cannabis, following which the existing human research will be reviewed. Some key safety issues will then be considered, and the chapter will conclude with some suggestions as to future directions for human research.

Use of the elevated T-maze to study anxiety in mice

We have recently suggested that the elevated T-maze (ETM) is not a useful test to study different types of anxiety in mice if a procedure similar to that originally validated for rats is employed. The present study investigated whether procedural (five exposures in the enclosed arm instead of three as originally described for rats) and structural (transparent walls instead of opaque walls) changes to the ETM leads to consistent inhibitory avoidance acquisition (IAA) and low escape latencies in mice. Results showed that five exposures to the ETM provoked consistent IAA, an effect that was independent of the ETM used. However, the ETM with transparent walls (ETMt) seemed to be more suitable for the study of conditioned anxiety (i.e. IAA) and unconditioned fear (escape) in mice, since IAA (low baseline latency with a gradual increase over subsequent exposures) and escape (low latency) profiles rendered it sensitive to the effects of anxiolytic and anxiogenic drugs. In addition to evaluation of drug effects on IAA and escape, the number of line crossings in the apparatus were used to control for locomotor changes. Results showed that whereas diazepam (1.0-2.0 mg/kg) and flumazenil (10-30 mg/kg) impaired IAA, FG 7142 (10-30 mg/kg) did not provoke any behavioral change. Significantly, none of these benzodiazepine (BDZ) receptor ligands modified escape latencies. The 5-HT1A partial receptor agonist buspirone (1.0-2.0 mg/kg) and the 5-HT releaser fenfluramine (0.15-0.30 mg/kg) impaired IAA and facilitated escape, while the full 5-HT1A receptor agonist, 8-OH-DPAT (0.05-0.1 mg/kg) and the 5-HT(2B/2C) receptor antagonist, SER 082 (0.5-2.0 mg/kg) failed to modify either response. mCPP (0.5-2.0 mg/kg), a 5-HT(2B/2C) receptor agonist, facilitated IAA but did not alter escape latency. Neither antidepressant utilized in the current study, imipramine (1.0-5.0 mg/kg) and moclobemide (3.0-10 mg/kg) affected IAA or escape performance in mice. The well-known anxiogenic drugs yohimbine (2.0-8.0 mg/kg) and caffeine (10-30 mg/kg) did not selectively affect IAA, although caffeine did impair escape latencies. Present results suggest the ETMt is useful for the study of conditioned anxiety in mice. However, upon proximal threats (e.g. open arm exposure), mice do not exhibit escape behavior as an immediate defensive strategy, suggesting that latency to leave open arm is not a useful parameter to evaluate unconditioned fear in this species.

Effects of cannabidiol (CBD) on regional cerebral blood flow

Animal and human studies have suggested that cannabidiol (CBD) may possess anxiolytic properties, but how these effects are mediated centrally is unknown. The aim of the present study was to investigate this using functional neuroimaging. Regional cerebral blood flow (rCBF) was measured at rest using (99m)Tc-ECD SPECT in 10 healthy male volunteers, randomly divided into two groups of five subjects. Each subject was studied on two occasions, 1 week apart. In the first session, subjects were given an oral dose of CBD (400 mg) or placebo, in a double-blind procedure. SPECT images were acquired 90 min after drug ingestion. The Visual Analogue Mood Scale was applied to assess subjective states. In the second session, the same procedure was performed using the drug that had not been administered in the previous session. Within-subject between-condition rCBF comparisons were performed using statistical parametric mapping (SPM). CBD significantly decreased subjective anxiety and increased mental sedation, while placebo did not induce significant changes. Assessment of brain regions where anxiolytic effects of CBD were predicted a priori revealed two voxel clusters of significantly decreased ECD uptake in the CBD relative to the placebo condition (p<0.001, uncorrected for multiple comparisons). These included a medial temporal cluster encompassing the left amygdala-hippocampal complex, extending into the hypothalamus, and a second cluster in the left posterior cingulate gyrus. There was also a cluster of greater activity with CBD than placebo in the left parahippocampal gyrus (p<0.001). These results suggest that CBD has anxiolytic properties, and that these effects are mediated by an action on limbic and paralimbic brain areas.

Pharmacology of human experimental anxiety

This review covers the effect of drugs affecting anxiety using four psychological procedures for inducing experimental anxiety applied to healthy volunteers and patients with anxiety disorders. The first is aversive conditioning of the skin conductance responses to tones. The second is simulated public speaking, which consists of speaking in front of a video camera, with anxiety being measured with psychometric scales. The third is the Stroop Color-Word test, in which words naming colors are painted in the same or in a different shade, the incongruence generating a cognitive conflict. The last test is a human version of a thoroughly studied animal model of anxiety, fear-potentiated startle, in which the eye-blink reflex to a loud noise is recorded. The evidence reviewed led to the conclusion that the aversive conditioning and potentiated startle tests are based on classical conditioning of anticipatory anxiety. Their sensitivity to benzodiazepine anxiolytics suggests that these models generate an emotional state related to generalized anxiety disorder. On the other hand, the increase in anxiety determined by simulated public speaking is resistant to benzodiazepines and sensitive to drugs affecting serotonergic neurotransmission. This pharmacological profile, together with epidemiological evidence indicating its widespread prevalence, suggests that the emotional state generated by public speaking represents a species-specific response that may be related to social phobia and panic disorder. Because of scant pharmacological data, the status of the Stroop Color-Word test remains uncertain. In spite of ethical and economic constraints, human experimental anxiety constitutes a valuable tool for the study of the pathophysiology of anxiety disorders.

Cannabidiol: an overview of some pharmacological aspects

Over the past few years, considerable attention has focused on cannabidiol (CBD), a major nonpsychotropic constituent of cannabis. The authors present a review on the chemistry of CBD and discuss the anticonvulsive, antianxiety, antipsychotic, antinausea, and antirheumatoid arthritic properties of CBD. CBD does not bind to the known cannabinoid receptors, and its mechanism of action is yet unknown. It is possible that, in part at least, its effects are due to its recently discovered inhibition of anandamide uptake and hydrolysis and to its antioxidative effect.

Die modifizierte Sprechangst-Anordnung

Zusammenfassung. Die Erforschung des Konstrukts Angst erfordert Untersuchungsanordnungen, die Angst induzieren und sie zu messen gestatten. Wie bei anderen Konstrukten existieren keine Anordnungen, die als paradigmatisch angesehen werden könnten. Der Beitrag bezieht sich auf eine in der Angstforschung häufig verwendete Untersuchungsanordnung, bekannt als “Öffentliches Sprechen“ bzw. als “Sprechangst-Paradigma“. Er zeigt Wege und Irrwege auf, die mit dieser Anordnung seit ihrer ersten Erprobung in den 70iger Jahren innerhalb unseres Düsseldorfer Streßlabors (Janke, Debus, Erdmann, Kallus, Bisping) beschritten wurden. “Irrwege“ betreffen die Auswahl und Interpretation der unabhängigen und der abhängigen Variablen als angstinduzierend bzw. angstdeterminiert wegen ihrer Konfundierung mit anderen Konstrukten (mentale Belastung) bzw. der Unspezifität oder “Distalität“ der Messmethoden. “Wege“ beinhalten Modifikationen der Anordnung zur Eliminierung konfundierender Bedingungen und die Ergänzung der Erfassungsmethoden um die im Humanbereich meist vernachlässigte Verhaltensebene. Unter Einbeziehung neuerer pharmakopsychologischer Untersuchungsergebnisse wird diskutiert, inwieweit die Hoffnung, durch diese Modifikationen näher an das Ziel eines Untersuchungsparadigmas der Angst heranzukommen, berechtigt ist.

Do panic patients process unconditioned fear vs. conditioned anxiety differently than normal subjects?

Panic patients were evaluated with two models of experimental anxiety that are believed to generate distinct emotional states: (1) a stimulated public speaking test (SPS), a presumed indicator of unconditioned fear, and (2) conditioning of skin conductance responses (CSCR) to a tone associated with an aversive white noise, an index of conditioned anxiety. Subjective states were evaluated through the visual analogue mood scale (VAMS) and a bodily symptoms scale (BSS). In the SPS test, panic patients showed higher baseline levels of VAMS-measured anxiety than controls. Unlike controls, panic patients failed to show increased anxiety before and during speech. Although baseline levels of arousal were similar in both groups, VAMS mental sedation decreased in controls, but not in panic patients during the SPS. Panic patients showed more discontent than controls throughout the whole experimental session. They also scored higher than controls on several items of the BSS. In the CSCR test, panic patients showed more spontaneous fluctuations of skin conductance than controls. Nevertheless, conditioning of skin conductance responses to the tone was similar in both groups. Therefore, panic patients seemed to process unconditioned fear abnormally.

Effects of tryptophan depletion on anxiety induced by simulated public speaking

Several lines of evidence point to the participation of serotonin (5HT) in anxiety. Its specific role, however, remains obscure. The objective of the present study was to evaluate the effect of reducing 5HT-neurotransmission through an acute tryptophan depletion on anxiety induced by a simulated public speaking (SPS) test. Two groups of 14-15 subjects were submitted to a 24-h diet with a low or normal content of tryptophan and received an amino acid mixture without (TRY-) or with (TRY+) tryptophan under double-blind conditions. Five hours later they were submitted to the SPS test. The state-trait anxiety inventory (STAI) and the visual analogue mood scale (VAMS) were used to measure subjective anxiety. Both scales showed that SPS induced a significant increase in anxiety. Although no overall difference between groups was found, there was a trend (P = 0.078) to an interaction of group x gender x phases of the SPS, and a separate analysis of each gender showed an increase in anxiety measured by the STAI in females of the TRY- group. The results for the female TRY- group also suggested a greater arousing effect of the SPS test. In conclusion, the tryptophan depletion procedure employed in the present study did not induce a significant general change in subjective anxiety, but tended to induce anxiety in females. This suggests a greater sensitivity of the 5HT system to the effects of the procedure in this gender.

The elevated T-maze: a new animal model of anxiety and memory

In an attempt to analyze different types of anxiety, and at the same time assess memory, a new experimental model was developed. The apparatus, named the elevated T-maze, consisted of three arms of equal dimensions (50 x 10 cm) elevated 50 cm from the ground. One arm, enclosed by 40-cm high walls, was perpendicular to two open arms. The first experimental session was conducted 25 min after IP injection of either drug or saline. To assess inhibitory (passive) avoidance, the rat was placed at the end of the enclosed arm and the time taken to withdraw from this arm was recorded three times in succession. Soon afterwards, the rat was placed at the end of one of the open arms and the time taken to withdraw from this arm was measured, thus estimating one-way escape. To assess memory, inhibitory avoidance and escape were measured again 3 days later, without drug. Dose-response curves were determined for the benzodiazepine anxiolytic and amnestic agent diazepam (DZP, 0.5-4 mg/kg), as well as for ipsapirone (IPS, 0.25-2 mg/kg), an azapirone anxiolytic that is devoid of clinically significant amnestic effects. The doses of 1, 2, and 4 mg/kg DZP and of 1 and 2 mg/kg IPS impaired inhibitory avoidance, an effect that may be viewed as anxiolytic. Inhibitory avoidance remained impaired 3 days later in the rats treated with 1-4 mg/kg DZP, indicating anterograde amnesia. This effect was not due to state-dependent learning, because rats injected both at pretraining and pretesting with 2 mg/kg DZP still showed complete amnesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Anxiolytic effect of cannabidiol derivatives in the elevated plus-maze

1. In order to assess the presence of anxiolytic properties in cannabidiol (CBD) derivatives HU-219, HU-252 and HU-261, these drugs were tested in rats submitted to the elevated plus-maze model of anxiety. 2. Additional groups received diazepam or CBD. HU-219 (0.03-1 mg/kg) and CBD (5 mg/kg) significantly increased the percentage of open arm entries without changing the total number of entries, an anxiolytic-like effect. 3. Both HU-252 and HU-261 increased the percentage of time spent in open arms and the total number of entries, but only at the dose of 1 mg/kg. 4. Diazepam (2.5 mg/kg) increased both the percentage of entries and time spent on open arms and the total number of entries. 5. The results confirm previous findings with CBD and indicate that its derivative HU-219 may possess a similar anxiolytic-like profile. 6. Results from HU-252 and HU-261 are less apparent and suggest that the compounds may increase general exploratory activity in a limited range of doses.

Role of the amygdala and periaqueductal gray in anxiety and panic

The amygdala (AM) and the periaqueductal gray (PAG) represent the rostral and the caudal pole, respectively, of a longitudinally organized neural system, that is responsible for the integration of behavioral and physiological manifestations of defensive reactions against innate and learned threats. Microinjection of benzodiazepine (BZD) anxiolytics, GABAA receptor agonists or 5-HT receptor antagonists into the AM has anxiolytic effects in conflict tests and other models of conditioned fear, while similar administration of 5-HT or of a 5-HT1A receptor agonist has anxiogenic effects. On the other hand, in the test of electrical stimulation of the PAG, microinjection of 5-HT, 5-HT mimetics, or of drugs that enhance the action of endogenous 5-HT into the same brain area has an antiaversive effect, like BZD and GABAA agonists. Furthermore, microinjection of midazolam, of the NMDA receptor antagonist AP-7, or of the 5-HT1A/1B receptor blocker propranolol increased the exploration of the open arms of the elevated plus-maze, having therefore an anxiolytic effect. These results point to an inhibitory role of the GABA-BZD system in both the AM and the PAG. In contrast, 5-HT seemingly enhances conditioned fear in the AM, while inhibiting unconditioned fear in the PAG. Thus, 5-HT2/1C antagonists reportedly release punished behavior when injected into the AM, whereas they antagonized the antiaversive effect of 5-HT, zimelidine and 5-HT1A/1B receptor blockers in the PAG. Since reported clinical studies revealed that one of such compounds, ritanserin, relieves generalized anxiety but tends to aggravate panic disorder, a relationship may be established between the AM and anxiety and the PAG and panic.