Cannabinoid-related agents in the treatment of anxiety disorders: current knowledge and future perspectives.

“Rich evidence has shown that cannabis products exert a broad gamut of effects on emotional regulation. The main psychoactive ingredient of hemp, Δ9-tetrahydrocannabinol (THC), and its synthetic cannabinoid analogs have been reported to either attenuate or exacerbate anxiety and fear-related behaviors in humans and experimental animals. The heterogeneity of cannabis-induced psychological outcomes reflects a complex network of molecular interactions between the key neurobiological substrates of anxiety and fear and the endogenous cannabinoid system, mainly consisting of the arachidonic acid derivatives anandamide and 2-arachidonoylglycerol (2-AG) and two receptors, respectively termed CB1 and CB2. The high degree of interindividual variability in the responses to cannabis is contributed by a wide spectrum of factors, including genetic and environmental determinants, as well as differences in the relative concentrations of THC and other alkaloids (such as cannabidiol) within the plant itself.

The present article reviews the currently available knowledge on the herbal, synthetic and endogenous cannabinoids with respect to the modulation of anxiety responses, and highlights the challenges that should be overcome to harness the therapeutic potential of some of these compounds, all the while limiting the side effects associated with cannabis consumption. In addition the article presents some promising patents on cannabinoid-related agents.”

http://www.ncbi.nlm.nih.gov/pubmed/22280339

Cannabinoid effects on anxiety-related behaviours and hypothalamic neurotransmitters.

“The aim of the present study was to examine the effects of the cannabinoid agonist CP 55,940 and the antagonist SR 141716A, alone and in combination, on rat exploratory and anxiety-like behaviour in the holeboard and elevated plus-maze tests. A further aim was to evaluate the effects of these treatments on hypothalamic neurotransmitters. Animals treated with CP 55,940 doses of 0.125 and 0.1 mg/kg exhibited less exploration and an increase in anxiety-like behaviour accompanied by great motor inhibition. No hypoactivity was seen at 0.075 mg/kg dosage, but anxiety and neophobic responses persisted, indicating independent and specific effects. Motor activity effects induced by CP 55,940 were reversed by pretreatment with SR 141716A (3 mg/kg). Surprisingly, when administered on its own, the antagonist also induced a reduction in exploratory parameters and an increase in anxiety-like responses. These apparently similar effects might be caused by different neural mechanisms. Finally, CP 55,940 increased hypothalamic dopamine and serotonin levels. These increases might be involved in the activation of the hypothalamic-pituitary-adrenal axis described for cannabinoids.”

http://www.ncbi.nlm.nih.gov/pubmed/11566149

Cannabinoid type 1 receptors and transient receptor potential vanilloid type 1 channels in fear and anxiety-two sides of one coin?

“The transient receptor potential vanilloid type 1 channel (TRPV1; originally vanilloid receptor VR1) is activated in peripheral terminals of nociceptive fibers by noxious heat, low pH, and natural products such as capsaicin, the pungent ingredient of red-hot chilli peppers. Evidence has been accumulating that TRPV1 is expressed also in the brain, where it seems to be involved in antinociception, locomotor control, and regulation of affective behaviors. This ion channel might be activated by arachidonoyl ethanolamide (anandamide), the endogenous agonist of the cannabinoid type 1 (CB(1)) receptor. However, while CB(1) activation leads to a decrease in intracellular calcium and attenuation of synaptic transmission, anandamide binding to TRPV1 results in elevated calcium levels and potentiated synaptic transmission. This suggests a tripartite regulatory system with antagonistic effects of CB(1) and TRPV1, which are tied together by the same endogenous ligand. Such a system may have important implication for the modulation of behavioral responses. The present commentary elaborates on this interplay between CB(1) receptors and TRPV1 channels in the context of fear- and anxiety-related behaviors.”

http://www.ncbi.nlm.nih.gov/pubmed/21906661

Impaired action of anxiolytic drugs in mice deficient in cannabinoid CB1 receptors.

“The role of cannabinoid CB(1) receptors in the action of anxiolytics was examined. Deletion of CB(1) receptors resulted in increased anxiety-like behaviours… Our findings reveal that CB(1) receptors are involved in the regulation of emotional responses, and play a pivotal role in the action mechanism of anxiolytics. They suggest that alterations in the functional activity of the CB(1) receptor may be related to the emergence of anxiety disorders, and may affect treatment with anxiolytics.”

http://www.ncbi.nlm.nih.gov/pubmed/15081793

Effects of the cannabinoid receptor ligands on anxiety-related effects of d-amphetamine and nicotine in the mouse elevated plus maze test.

“The purpose of the experiments was to examine the anxiety-related effects of d-amphetamine and nicotine, and the possible involvement of the endocannabinoid system…

These results provide evidence that the endogenous cannabinoid system is involved in the anxiety-related responses to d-amphetamine and/or nicotine.”

http://www.ncbi.nlm.nih.gov/pubmed/19617654

[Benefits of an add-on treatment with the synthetic cannabinomimetic nabilone on patients with chronic pain–a randomized controlled trial].

“The aim of this study was to investigate the efficacy and efficiency of an add-on treatment with the synthetic cannabinomimetic nabilone on patients with chronic pain. Of major interest were the evaluation of the influence the treatment had on pain and on quality of life as well as the subjective assessment of positive effects and side effects by the study participants…

CONCLUSION:

In summary, the study results allow the conclusion that a majority of patients with chronic pain classify nabilone intake in addition to the standard treatment as a measure with a positive individual benefit-riskratio. Thus, this kind of treatment may be an interesting and attractive enrichment of analgetic therapy concepts.”

http://www.ncbi.nlm.nih.gov/pubmed/16855921

Adjunctive nabilone in cancer pain and symptom management: a prospective observational study using propensity scoring.

“A prospective observational study assessed the effectiveness of adjuvant nabilone (Cesamet) therapy in managing pain and symptoms experienced by advanced cancer patients… When compared with those not taking nabilone, patients using this cannabinoid had a lower rate of starting nonsteroidal anti-inflammatory agents, tricyclic antidepressants, gabapentin, dexamethasone, metoclopramide, and ondansetron and a greater tendency to discontinue these drugs.”

http://www.ncbi.nlm.nih.gov/pubmed/18402303

Randomised, double-blind, placebo-controlled trial to assess the potential of cannabinoid receptor stimulation in the treatment of dystonia.

“Cannabis may have medicinal uses in a variety of diseases. The neural mechanisms underlying dystonia involve abnormalities within the basal ganglia-in particular, overactivity of the lateral globus pallidus (GPl). Cannabinoid receptors are located presynaptically on GABA terminals within the GPi, where their activation reduces GABA reuptake. Cannabinoid receptor stimulation may thus reduce overactivity of the GPl and thereby reduce dystonia. A double-blind, randomised, placebo-controlled, crossover study using the synthetic cannabinoid receptor agonist nabilone in patients with generalised and segmental primary dystonia showed no significant reduction in dystonia following treatment with nabilone.”

http://www.ncbi.nlm.nih.gov/pubmed/11835452

The efficacy and safety of nabilone (a synthetic cannabinoid) in the treatment of anxiety.

“The anxiolytic properties of nabilone, a synthetic cannabinoid resembling the natural cannabinoids, were studied in 25 outpatients suffering from anxiety. The drug was compared with a placebo in a double-blind manner over a 28-day treatment period. Patients were seen weekly by the physician and were rated by the Hamilton Rating Scale for Anxiety and the Patient’s Global Evaluation as well as by patient-rated evaluations. The results of the study showed a dramatic improvement in anxiety in the nabilone group when compared with placebo (P less than 0.001). Side effects reported were dry mouth, dry eyes, and drowsiness. Patients did not report any of the subjective “altered state” experience of marihuana.”

http://www.ncbi.nlm.nih.gov/pubmed/6117575

Single-dose study of nabilone in anxious volunteers.

“The effects of single oral doses of nabilone, a synthetic cannabinoid, were studied in eight anxious volunteer subjects. Each subject had two exposures to placebo and three dose levels of nabilone at one-week intervals in a single-blind balanced Latin-square design after the nabilone dose range was determined by each subject’s response to a test dose. Heart rate and blood pressure were monitored. The Profile of Mood States (POMS), a self-rating adjective checklist, was used as the quantitative measure of subjective effects. Four subjects performed a continuous avoidance procedure. High doses (4 or 5 mg) of nabilone produced orthostatic hypotension in these subjects. Mild dose-related increases in heart rate also occurred. Despite the occurrence of highly significant levels of sedation, there were no significant effects of nabilone on the continuous avoidance procedure. Two of these four subjects experienced an antianxiety effect from low (1 or 2 mg) nabilone doses. Four other subjects received comparatively lower doses of nabilone and performed on three behavioral tasks at intervals before and after drug: a recognition memory procedure, a task requiring spaced responding at a controlled rate, and a reaction time task. In these subjects there were no reliable effects on blood pressure or heart rate, no significant subjective effects on the POMS, and no antianxiety effects. Drug effects were also minimal on the three behavioral tasks.”

http://www.ncbi.nlm.nih.gov/pubmed/6117576