Category Archives: Depression

Plastic and Neuroprotective Mechanisms Involved in the Therapeutic Effects of Cannabidiol in Psychiatric Disorders.

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“Beneficial effects of cannabidiol (CBD) have been described for a wide range of psychiatric disorders, including anxiety, psychosis, and depression. The mechanisms responsible for these effects, however, are still poorly understood. Similar to clinical antidepressant or atypical antipsychotic drugs, recent findings clearly indicate that CBD, either acutely or repeatedly administered, induces plastic changes. For example, CBD attenuates the decrease in hippocampal neurogenesis and dendrite spines density induced by chronic stress and prevents microglia activation and the decrease in the number of parvalbumin-positive GABA neurons in a pharmacological model of schizophrenia. More recently, it was found that CBD modulates cell fate regulatory pathways such as autophagy and others critical pathways for neuronal survival in neurodegenerative experimental models, suggesting the potential benefit of CBD treatment for psychiatric/cognitive symptoms associated with neurodegeneration. These changes and their possible association with CBD beneficial effects in psychiatric disorders are reviewed here.”

https://www.ncbi.nlm.nih.gov/pubmed/28588483

http://journal.frontiersin.org/article/10.3389/fphar.2017.00269/full

Cannabis as a substitute for prescription drugs – a cross-sectional study

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“The use of medical cannabis is increasing, most commonly for pain, anxiety and depression. Emerging data suggest that use and abuse of prescription drugs may be decreasing in states where medical cannabis is legal. The aim of this study was to survey cannabis users to determine whether they had intentionally substituted cannabis for prescription drugs.

A total of 1,248 (46%) respondents reported using cannabis as a substitute for prescription drugs. The most common classes of drugs substituted were narcotics/opioids (35.8%), anxiolytics/benzodiazepines (13.6%) and antidepressants (12.7%). A total of 2,473 substitutions were reported or approximately two drug substitutions per affirmative respondent.

These patient-reported outcomes support prior research that individuals are using cannabis as a substitute for prescription drugs, particularly, narcotics/opioids, and independent of whether they identify themselves as medical or non-medical users. This is especially true if they suffer from pain, anxiety and depression. Additionally, this study suggests that state laws allowing access to, and use of, medical cannabis may not be influencing individual decision-making in this area.”

https://www.dovepress.com/cannabis-as-a-substitute-for-prescription-drugs-ndash-a-cross-sectiona-peer-reviewed-article-JPR

[Role of cannabinoid receptor 1-mediated synaptic plasticity in neuropathic pain and associated depression].

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“Neuropathic pain is a class of pain caused by an injury or diseases of the somatosensory system and characterized by spontaneous pain, allodynia, and hyperalgesia. It is well established that central sensitization is one of the key mechanisms underlying the development and maintenance of neuropathic pain. Cannabinoid receptor 1 (CB1R) of endocannabinoid system modulates synaptic transmission, regulates synaptic plasticity, inhibits central sensitization, and thus attenuates neuropathic pain. Recent studies have shown that activation of CB1R also involves in the relief of neuropathic pain-induced depression.” https://www.ncbi.nlm.nih.gov/pubmed/28364110

Changes in the Brain Endocannabinoid System in Rat Models of Depression.

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“A growing body of evidence implicates the endocannabinoid (eCB) system in the pathophysiology of depression.

The aim of this study was to investigate the influence of changes in the eCB system, such as levels of neuromodulators, eCB synthesizing and degrading enzymes, and cannabinoid (CB) receptors, in different brain structures in animal models of depression using behavioral and biochemical analyses.

These findings suggest that dysregulation in the eCB system is implicated in the pathogenesis of depression, although neurochemical changes were linked to the particular brain structure and the factor inducing depression (surgical removal of the olfactory bulbs vs. genetic modulation).”

https://www.ncbi.nlm.nih.gov/pubmed/28247204

FAAH inhibition produces antidepressant-like efforts of mice to acute stress via synaptic long-term depression.

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“Recent studies have shown that inhibition of fatty acid amide hydrolase (FAAH), the major degradative enzyme of the endocannabinoid N-arachidonoylethanolamine (AEA), produced antidepressant behavioral responses, but its underlying mechanism is not clear. Here we find that a systemic administration of the FAAH inhibitor PF3845 or an intra-CA1 application of AEA elicits an in vivo long-term depression (LTD) at excitatory glutamatergic CA3-CA1 synapses of the hippocampus. The PF3845- and/or AEA-elicited LTD are abolished by the LTD-blocking peptide Tat-GluR2. PF3845 significantly decreases passive behavioral coping of naïve mice to acute inescapable stress, which is also abolished by Tat-GluR2 peptide. However, PF3845 does not significantly affect sucrose assumption ratio of mice receiving chronic administration of corticosterone. These results suggest that FAAH inhibitors are able to produce antidepressant effects in naïve animals in response to acute stress through LTD at hippocampal glutamatergic CA3-CA1 synapses.”

https://www.ncbi.nlm.nih.gov/pubmed/28193523

Cannabis use and the course and outcome of major depressive disorder: A population based longitudinal study.

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“Cannabis use has been reported to affect the course of various psychiatric disorders, however its effect on the course of major depressive disorder (MDD) is not yet clear.

After adjusting for baseline confounding factors, no associations were found between cannabis use and suicidality, functionality and quality of life.

We conclude that many of the associations between cannabis use and a more severe course of MDD do not seem to be attributed to cannabis use itself but to associated sociodemographic and clinical factors.”

https://www.ncbi.nlm.nih.gov/pubmed/28214781

Activation of cannabinoid receptors elicits antidepressant-like effects in a mouse model of social isolation stress.

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“Social isolation stress (SIS) paradigm is a chronic stress procedure able to induce profound behavioral and neurochemical changes in rodents and evokes depressive and anxiety-like behaviors.

Recent studies demonstrated that the cannabinoid system plays a key role in behavioral abnormalities such as depression through different pathways; however, there is no evidence showing a relation between SIS and the cannabinoid system.

This study investigated the role of the cannabinoid system in depressive-like behavior and anxiety-like behavior of IC animals.

Our findings suggest that the cannabinoid system is involved in depressive-like behaviors induced by SIS.

We showed that activation of cannabinoid receptors (type 1 and 2) could mitigate depression-like behavior induced by SIS in a mouse model.”

https://www.ncbi.nlm.nih.gov/pubmed/28161196

Targeting the Endocannabinoid System in Psychiatric Illness.

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“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.”

 https://www.ncbi.nlm.nih.gov/pubmed/27811555

Chronic stress leads to epigenetic dysregulation of neuropeptide-Y and cannabinoid CB1 receptor in the mouse cingulate cortex.

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“Persistent stress triggers a variety of mechanisms, which may ultimately lead to the occurrence of anxiety- and depression-related disorders.

Epigenetic modifications represent a mechanism by which chronic stress mediates long-term effects. Here, we analyzed brain tissue from mice exposed to chronic unpredictable stress (CUS), which induced impaired emotional and nociceptive behaviors.

As endocannabinoid (eCB) and neuropeptide-Y (Npy) systems modulate emotional processes, we hypothesized that CUS may affect these systems through epigenetic mechanisms.

We found reduced Npy expression and Npy type 1 receptor (Npy1r) signaling, and decreased expression of the cannabinoid type 1 receptor (CB1) in the cingulate cortex of CUS mice specifically in low CB1-expressing neurons.

Our findings suggest that epigenetic alterations in the Npy and CB1 genes represent one of the potential mechanisms contributing to the emotional imbalance induced by CUS in mice, and that the Npy and eCB systems may represent therapeutic targets for the treatment of psychopathologies associated with or triggered by chronic stress states.”

https://www.ncbi.nlm.nih.gov/pubmed/27737789

The Potential Role of Cannabinoids in Modulating Serotonergic Signaling by Their Influence on Tryptophan Metabolism.

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“Phytocannabinoids present in Cannabis plants are well known to exert potent anti-inflammatory and immunomodulatory effects.

Previously, we have demonstrated that the psychoactive D9-tetrahydrocannabinol (THC) and the non-psychotropic cannabidiol (CBD) modulate mitogen-induced Th1-type immune responses in peripheral blood mononuclear cells (PBMC).

The suppressive effect of both cannabinoids on mitogen-induced tryptophan degradation mediated by indoleamine-2,3-dioxygenase (IDO), suggests an additional mechanism by which antidepressive effects of cannabinoids might be linked to the serotonergic system.

Here, we will review the role of tryptophan metabolism in the course of cell mediated immune responses and the relevance of cannabinoids in serotonergic signaling.

We conclude that in particular the non-psychotropic CBD might be useful for the treatment of mood disorders in patients with inflammatory diseases, since this cannabinoid seems to be safe and its effects on activation-induced tryptophan degradation by CBD were more potent as compared to THC.”

 https://www.ncbi.nlm.nih.gov/pubmed/27713369