Cannabinoid CB1 receptors in the amygdalar cholecystokinin glutamatergic afferents to nucleus accumbens modulate depressive-like behavior.

 Image result for nature medicine“Major depressive disorder is a devastating psychiatric disease that afflicts up to 17% of the world’s population. Postmortem brain analyses and imaging studies of patients with depression have implicated basal lateral amygdala (BLA) dysfunction in the pathophysiology of depression. However, the circuit and molecular mechanisms through which BLA neurons modulate depressive behavior are largely uncharacterized. Here, in mice, we identified that BLA cholecystokinin (CCK) glutamatergic neurons mediated negative reinforcement via D2 medium spiny neurons (MSNs) in the nucleus accumbens (NAc) and that chronic social defeat selectively potentiated excitatory transmission of the CCKBLA-D2NAc circuit in susceptible mice via reduction of presynaptic cannabinoid type-1 receptor (CB1R). Knockdown of CB1R in the CCKBLA-D2NAc circuit elevated synaptic activity and promoted stress susceptibility. Notably, selective inhibition of the CCKBLA-D2NAc circuit or administration of synthetic cannabinoids in the NAc was sufficient to produce antidepressant-like effects. Overall, our studies reveal the circuit and molecular mechanisms of depression.”

https://www.ncbi.nlm.nih.gov/pubmed/30643290

https://www.nature.com/articles/s41591-018-0299-9

“Antidepressant-like effect of delta9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L. Results of this study show that Delta(9)-THC and other cannabinoids exert antidepressant-like actions, and thus may contribute to the overall mood-elevating properties of cannabis.”  https://www.ncbi.nlm.nih.gov/pubmed/20332000

Structure of a Signaling Cannabinoid Receptor 1-G Protein Complex.

Image result for cell journal

“Cannabis elicits its mood-enhancing and analgesic effects through the cannabinoid receptor 1 (CB1), a G protein-coupled receptor (GPCR) that signals primarily through the adenylyl cyclase-inhibiting heterotrimeric G protein Gi. Activation of CB1-Gi signaling pathways holds potential for treating a number of neurological disorders and is thus crucial to understand the mechanism of Giactivation by CB1.

Here, we present the structure of the CB1-Gi signaling complex bound to the highly potent agonist MDMB-Fubinaca (FUB), a recently emerged illicit synthetic cannabinoid infused in street drugs that have been associated with numerous overdoses and fatalities.”

https://www.ncbi.nlm.nih.gov/pubmed/30639101

https://linkinghub.elsevier.com/retrieve/pii/S0092867418315654

“Antidepressant-like effect of delta9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L. Results of this study show that Delta(9)-THC and other cannabinoids exert antidepressant-like actions, and thus may contribute to the overall mood-elevating properties of cannabis.”   https://www.ncbi.nlm.nih.gov/pubmed/20332000

Cannabis and Mood Disorders.

 “The present review will provide an overview of the neurobiology, epidemiology, clinical impact, and treatment of cannabis use disorder (CUD) in mood disorders.

Patients with mood disorders including major depressive disorder (MDD) and bipolar disorder (BD) have higher rates of cannabis use, and CUD compared to the general population. Reasons for this association are not clear, nor are the putative therapeutic effects of cannabis use, or its components delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), in these illnesses.

Cannabis use may be associated mood disorders, but more research is needed to increase our understanding of the mechanisms for this association, and to develop more effective treatments for this comorbidity.”

https://www.ncbi.nlm.nih.gov/pubmed/30643708

https://link.springer.com/article/10.1007%2Fs40429-018-0214-y

“Antidepressant-like effect of delta9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L. Results of this study show that Delta(9)-THC and other cannabinoids exert antidepressant-like actions, and thus may contribute to the overall mood-elevating properties of cannabis.”   https://www.ncbi.nlm.nih.gov/pubmed/20332000

Culture and cannabinoid receptor gene polymorphism interact to influence the perception of happiness.

 Image result for plos one“Previous studies have shown that a cytosine (C) to thymine (T) single nucleotide polymorphism (SNP) of the human cannabinoid receptor 1 (CNR1) gene is associated with positive emotional processing.

C allele carriers are more sensitive to positive emotional stimuli including happiness. The effects of several gene polymorphisms related to sensitivity to emotional stimuli, such as that in the serotonin transporter gene-linked polymorphic region (5HTTLPR), on emotional processing have been reported to differ among cultures-e.g., between those that are independent and interdependent. Thus, we postulated that the effects of the CNR1 genotype on happiness might differ among different cultures because the concept of happiness varies by culture.

We recruited healthy male and female young adults in Japan, where favorable external circumstances determine the concept of happiness, and Canada, where the concept of happiness centers on positive inner feelings, and compared the effects of the CNR1 genotype on both subjective happiness levels (self-evaluation as being a happy person) and situation-specific happiness (happy feelings accompanying various positive events) by using a questionnaire.

We found that the effect of CNR1 on subjective happiness was different between the Japanese and Canadian groups. The subjective happiness level was the highest in Japanese individuals with the CC genotype, whereas in Canadian participants, it was the highest in individuals with the TT genotype. Furthermore, the effects of CNR1 genotype on situation-specific happiness were also different between the groups. Happiness accompanied with being surrounded by happy people was the highest among Japanese individuals with the CC genotype, whereas among Canadian individuals, it was the highest in TT genotype carriers.

These findings suggest that culture and CNR1 polymorphism interact to influence the perception of happiness.”

https://www.ncbi.nlm.nih.gov/pubmed/30576341

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209552

“Genetic Variations in the Human Cannabinoid Receptor Gene Are Associated with Happiness” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3972248/

Effects of cannabidiol in males and females in two different rat models of depression.

Physiology & Behavior

“The current study explores the therapeutic potential of Cannabidiol (CBD), a compound in the Cannabis plant, using both sexes of 2 “depressive-like” genetic models, Wistar Kyoto (WKY) and Flinders Sensitive Line (FSL) rats. Rats ingested CBD (30 mg/kg) orally. In the saccharin preference test, following a previous report of a pro-hedonic effect of CBD in male WKY, we now found similar results in female WKY. CBD also decreased immobility in the forced swim test in males (both strains) and in female WKY. These findings suggest a role for CBD in treating mental disorders with prominent symptoms of helplessness and anhedonia.”

https://www.ncbi.nlm.nih.gov/pubmed/30571957

https://www.sciencedirect.com/science/article/abs/pii/S0031938418307509?via%3Dihub

An Analysis of Endocannabinoid Concentrations and Mood Following Singing and Exercise in Healthy Volunteers.

Image result for frontiers in behavioral neuroscience “The euphoric feeling described after running is, at least in part, due to increased circulating endocannabinoids (eCBs). eCBs are lipid signaling molecules involved in reward, appetite, mood, memory and neuroprotection.

The aim of this study was to investigate whether activities other than running can increase circulating eCBs.

Nine healthy female volunteers (mean 61 years) were recruited from a local choir. Circulating eCBs, haemodynamics, mood and hunger ratings were measured before and immediately after 30 min of dance, reading, singing or cycling in a fasted state.

Singing increased plasma levels of anandamide (AEA) by 42% (P < 0.05), palmitoylethanolamine (PEA) by 53% (P < 0.01) and oleoylethanolamine (OEA) by 34% (P < 0.05) and improved positive mood and emotions (P < 0.01), without affecting hunger scores.

Dancing did not affect eCB levels or hunger ratings, but decreased negative mood and emotions (P < 0.01).

Cycling increased OEA levels by 26% (P < 0.05) and tended to decrease how hungry volunteers felt, without affecting mood.

Reading increased OEA levels by 28% (P < 0.01) and increased the desire to eat.

Plasma AEA levels were positively correlated with how full participants felt (P < 0.05). Plasma OEA levels were positively correlated with positive mood and emotions (P < 0.01). All three ethanolamines were positively correlated with heart rate (HR; P < 0.0001).

These data suggest that activities other than running can increase plasma eCBs associated with changes in mood or appetite. Increases in eCBs may underlie the rewarding and pleasurable effects of singing and exercise and ultimately some of the long-term beneficial effects on mental health, cognition and memory.”

https://www.ncbi.nlm.nih.gov/pubmed/30534062

https://www.frontiersin.org/articles/10.3389/fnbeh.2018.00269/full

Exploiting the Multifaceted Effects of Cannabinoids on Mood to Boost Their Therapeutic Use Against Anxiety and Depression.

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“The endocannabinoid system (ECS) has been recently recognized as a prominent promoter of the emotional homeostasis, mediating the effects of different environmental signals including rewarding and stressing stimuli. The complex influences of the ECS on both the environmental and internal stimuli processing, make the cannabinoid-based drugs an appealing option to treat different psychiatric conditions. In particular, better knowledge of the multifaceted effects of cannabinoids could help to understand how to boost their therapeutic use in anxiety and depression treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/30515077

https://www.frontiersin.org/articles/10.3389/fnmol.2018.00424/full

Activation of GPR55 induces neuroprotection of hippocampal neurogenesis and immune responses of neural stem cells following chronic, systemic inflammation.

Brain, Behavior, and Immunity

“New neurons are continuously produced by neural stem cells (NSCs) within the adult hippocampus. Numerous diseases, including major depressive disorder and HIV-1 associated neurocognitive disorder, are associated with decreased rates of adult neurogenesis. A hallmark of these conditions is a chronic release of neuroinflammatory mediators by activated resident glia.

Recent studies have shown a neuroprotective role on NSCs of cannabinoid receptor activation. Yet, little is known about the effects of GPR55, a candidate cannabinoid receptor, activation on reductions of neurogenesis in response to inflammatory insult.

In the present study, we examined NSCs exposed to IL-1β in vitro to assess inflammation-caused effects on NSC differentiation and the ability of GPR55 agonists to attenuate NSC injury.

Taken together, these results suggest a neuroprotective role of GPR55 activation on NSCs in vitro and in vivo and that GPR55 provides a novel therapeutic target against negative regulation of hippocampal neurogenesis by inflammatory insult.”

Pain and Depression: A Systematic Review.

 Image result for harv rev psychiatry

“Pain comorbid with depression is frequently encountered in clinical settings and often leads to significant impaired functioning. Given the complexity of comorbidities, it is important to address both pain and depressive symptoms when evaluating treatment options.

Overall, studies suggested that pain and depression are highly intertwined and may co-exacerbate physical and psychological symptoms. These symptoms could lead to poor physical functional outcomes and longer duration of symptoms. An important biochemical basis for pain and depression focuses on serotonergic and norepinephrine systems, which is evident in the pain-ameliorating properties of serotonergic and norepinephrine antidepressants.

Alternative pharmacotherapies such as ketamine and cannabinoids appear to be safe and effective options for improving depressive symptoms and ameliorating pain. In addition, cognitive-behavioral therapy may be a promising tool in the management of chronic pain and depression.

CONCLUSION:

The majority of the literature indicates that patients with pain and depression experience reduced physical, mental, and social functioning as opposed to patients with only depression or only pain. In addition, ketamine, psychotropic, and cognitive-behavioral therapies present promising options for treating both pain and depression.”

https://www.ncbi.nlm.nih.gov/pubmed/30407234

https://insights.ovid.com/crossref?an=00023727-201811000-00005

Cannabidiol regulates the expression of hypothalamus-pituitary-adrenal axis-related genes in response to acute restraint stress.

SAGE Journals

“Research interest has grown around the potential therapeutic use of cannabidiol in mood-related disorders, due to its anxiolytic and antidepressant-like effects.

These have been partially attributed to its action as an allosteric modulator of 5-HTR1A. However, the exact mechanism supporting cannabidiol properties remains unclear.

Taken together, these data suggest the ability of cannabidiol to regulate acute stress hypothalamus-pituitary-adrenal axis activation might be explained, at least in part, by its action on 5-HTR1A receptors.”

https://www.ncbi.nlm.nih.gov/pubmed/30324842