Therapeutic applications of cannabinoids.

Chemico-Biological Interactions

“The psychoactive properties of cannabinoids are well known and there has been a continuous controversy regarding the usage of these compounds for therapeutic purposes all over the world. Their use for medical and research purposes are restricted in various countries. However, their utility as medications should not be overshadowed by their negative physiological activities.

This review article is focused on the therapeutic potential and applications of phytocannabinoids and endocannabinoids. It highlights their mode of action, overall effects on physiology, various in vitro and in vivo studies that have been done so far and the extent to which these compounds can be useful in different disease conditions such as cancer, Alzheimer’s disease, multiple sclerosis, pain, inflammation, glaucoma and many others.

Thus, this work is an attempt to make the readers understand the positive implications of these compounds and indicates the significant developments that can occur upon utilizing cannabinoids as therapeutic agents.”  https://www.ncbi.nlm.nih.gov/pubmed/30040916

“Cannabinoids can be used as therapeutic agents.”   https://www.sciencedirect.com/science/article/pii/S0009279718307373?via%3Dihub

Endocannabinoid system, Stress and HPA axis.

European Journal of Pharmacology

“The endocannabinoid system (ECS), which is composed of the cannabinoid receptors types 1 and 2 (CB1 and CB2) for marijuana’s psychoactive ingredient ∆9-tetrahydrocannabinol (∆9-THC), the endogenous ligands (AEA and 2-AG) and the enzymatic systems involved in their biosynthesis and degradation, recently emerged as important modulator of emotional and non-emotional behaviors. In addition to its recreational actions, some of the earliest reports regarding the effects of Cannabis use on humans were related to endocrine system changes. Accordingly, the ∆9-THC and later on, the ECS signaling have long been known to regulate the hypothalamic-pituitary-adrenocortical (HPA) axis, which is the major neuroendocrine stress response system of mammals. However, how the ECS could modify the stress hormone secretion is not fully understood. Thus, the present article reviews current available knowledge on the role of the ECS signaling as important mediator of interaction between HPA axis activity and stressful conditions, which, in turn could be involved in the development of psychiatric disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/30036537

https://www.sciencedirect.com/science/article/pii/S0014299918304138?via%3Dihub

Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues.

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“Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes.

In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55.

Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.”

Cannabinoid type 2 receptors mediate a cell type-specific self-inhibition in cortical neurons.

 Neuropharmacology

“Endogenous cannabinoids are diffusible lipid ligands of the main cannabinoid receptors type 1 and 2 (CB1R and CB2R). In the central nervous system endocannabinoids are produced in an activity-dependent manner and have been identified as retrograde modulators of synaptic transmission.

Additionally, some neurons display a cell-autonomous slow self-inhibition (SSI) mediated by endocannabinoids. In these neurons, repetitive action potential firing triggers the production of endocannabinoids, which induce a long-lasting hyperpolarization of the membrane potential, rendering the cells less excitable. Different endocannabinoid receptors and effector mechanisms have been described underlying SSI in different cell types and brain areas.

Here, we investigate SSI in neurons of layer 2/3 in the somatosensory cortex. High-frequency bursts of action potentials induced SSI in pyramidal cells (PC) and regular spiking non-pyramidal cells (RSNPC), but not in fast-spiking interneurons (FS). In RSNPCs the hyperpolarization was accompanied by a change in input resistance due to the activation of G protein-coupled inward-rectifying K+ (GIRK) channels. A CB2R-specific agonist induced the long-lasting hyperpolarization, whereas preincubation with a CB2R-specific inverse agonist suppressed SSI. Additionally, using cannabinoid receptor knockout mice, we found that SSI was still intact in CB1R-deficient but abolished in CB2R-deficient mice.

Taken together, we describe an additional SSI mechanism in which the activity-induced release of endocannabinoids activates GIRK channels via CB2Rs. These findings expand our knowledge about cell type-specific differential neuronal cannabinoid receptor signaling and suggest CB2R-selective compounds as potential therapeutic approaches.”

https://www.ncbi.nlm.nih.gov/pubmed/30025920

https://www.sciencedirect.com/science/article/pii/S0028390818303885?via%3Dihub

The endocannabinoid system in mental disorders: Evidence from human brain studies.

Biochemical Pharmacology

“Mental disorders have a high prevalence compared with many other health conditions and are the leading cause of disability worldwide. Several studies performed in the last years support the involvement of the endocannabinoid system in the etiopathogenesis of different mental disorders.

The present review will summarize the latest information on the role of the endocannabinoid system in psychiatric disorders, specifically depression, anxiety, and schizophrenia. We will focus on the findings from human brain studies regarding alterations in endocannabinoid levels, cannabinoid receptors and endocannabinoid metabolizing enzymes in patients suffering mental disorders.

Studies carried out in humans have consistently demonstrated that the endocannabinoid system is fundamental for emotional homeostasis and cognitive function. Thus, deregulation of the different elements that are part of the endocannabinoid system may contribute to the pathophysiology of several mental disorders. However, the results reported are controversial. In this sense, different alterations in gene and/or protein expression of CB1 receptors have been shown depending on the technical approach used or the brain region studied.

Despite the current discrepancies regarding cannabinoid receptors changes in depression and schizophrenia, present findings point to the endocannabinoid system as a pivotal neuromodulatory pathway relevant in the pathophysiology of mental disorders.

Role of the Endocannabinoid System in the Pathophysiology of Schizophrenia: Implications for Pharmacological Intervention.

 

“The term schizophrenia describes a group of multifaceted psychiatric conditions causing significant impairment of the quality of life of affected patients. Although multiple pharmacological treatment options exist, e.g. first- or second-generation antipsychotics, these therapeutics often cause disturbing side effects, such as extrapyramidal symptoms, prolactin increase, sexual dysfunction and/or metabolic syndrome. Furthermore, cognitive impairments and negative symptoms, two factors significantly influencing the course and outcome, are not sufficiently addressed by the available antipsychotics.

Since its discovery, multiple clinical and preclinical studies have linked the endocannabinoid system to schizophrenia.

Both the endocannabinoid anandamide and the cannabinoid CB1 receptor are deeply linked to underlying disease processes. Based hereon, clinical trials in schizophrenia have explored cannabidiol, a primary component of Cannabis sativa, and rimonabant, a partial antagonist to the CB1 receptor.

While the latter did not reveal positive results, cannabidiol significantly ameliorated psychotic symptoms, which was associated with an increase in anandamide serum levels. However, the exact mechanisms of the antipsychotic effects of cannabidiol are not fully understood, and, furthermore, only a limited number of clinical trials in humans have been concluded to date.

Thus, the level of proof of safety and efficacy required to approve the therapeutic use of cannabidiol in schizophrenia is currently lacking. However, cannabidiol is a promising candidate as an effective and mechanistically different antipsychotic treatment with a favourable side-effect profile. We therefore conclude that further studies are urgently needed to clarify the antipsychotic effects and safety profile of cannabidiol, and to fully explore its potential antipsychotic mechanism.”

https://www.ncbi.nlm.nih.gov/pubmed/30022465

https://link.springer.com/article/10.1007%2Fs40263-018-0539-z

Modulation of the endocannabinoid system by sex hormones: Implications for Posttraumatic Stress Disorder.

Neuroscience & Biobehavioral Reviews

“The endocannabinoid system is an increasingly recognised pharmacological target for treating stress and anxiety disorders, including post-traumatic stress disorder (PTSD). Recent preclinical developments have implicated the endocannabinoid system in stress responses, emotional memories and fear extinction, all critical to PTSD aetiology. However, preclinical research in endocannabinoid biology has neglected the influential role of sex hormone differences on PTSD symptomology, which is particularly important given that PTSD is twice as common in women as in men. In this review, we compile and consider the evidence that the endocannabinoid system is influenced by ovarian hormones, with application to stress disorders such as PTSD. It is clear that therapeutic modulation of the endocannabinoid system needs to be approached with awareness of ovarian hormonal influences, and knowledge of these influences may enhance treatment outcomes for female PTSD populations.”

Integrating endocannabinoid signaling in the regulation of anxiety and depression

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“Brain endogenous cannabinoid (eCB) signaling seems to harmonize appropriate behavioral responses, which are essential for the organism’s long-term viability and homeostasis. Dysregulation of eCB signaling contributes to negative emotional states and increased stress responses. An understanding of the underlying neural cell populations and neural circuit regulation will enable the development of therapeutic strategies to mitigate behavioral maladaptation and provide insight into the influence of eCB on the neural circuits involved in anxiety and depression. This review focuses on recent evidence that has added a new layer of complexity to the idea of targeting the eCB system for therapeutic benefits in neuropsychiatric disease and on the future research direction of neural circuit modulation.” 

https://www.nature.com/articles/s41401-018-0051-5

Role of endocannabinoids in the hippocampus and amygdala in emotional memory and plasticity.

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“Posttraumatic stress disorder (PTSD) is characterized by the reexperiencing of a traumatic event and is associated with slower extinction of fear responses.

Impaired extinction of fearful associations to trauma-related cues may interfere with treatment response, and extinction deficits may be premorbid risk factors for the development of PTSD.

We examined the effects of exposure to a severe footshock followed by situational reminders (SRs) on extinction, plasticity, and endocannabinoid (eCB) content and activity in the hippocampal CA1 area and basolateral amygdala (BLA).

The findings suggest that targeting the eCB system before extinction may be beneficial in fear memory attenuation and these effects may involve metaplasticity in the CA1 and BLA.”

https://www.ncbi.nlm.nih.gov/pubmed/29977073

https://www.nature.com/articles/s41386-018-0135-4

Brain endocannabinoid signaling exhibits remarkable complexity.

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“The endocannabinoid (eCB) signaling system is one of the most extensive of the mammalian brain. Despite the involvement of only few specific ligands and receptors, the system encompasses a vast diversity of triggered mechanisms and driven effects. It mediates a wide range of phenomena, including the regulation of transmitter release, neural excitability, synaptic plasticity, impulse spread, long-term neuronal potentiation, neurogenesis, cell death, lineage segregation, cell migration, inflammation, oxidative stress, nociception and the sleep cycle. It is also known to be involved in the processes of learning and memory formation. This extensive scope of action is attained by combining numerous variables. In a properly functioning brain, the correlations of these variables are kept in a strictly controlled balance; however, this balance is disrupted in many pathological conditions. However, while this balance is known to be disrupted by drugs in the case of addicts, the stimuli and mechanisms influencing the neurodegenerating brain remain elusive. This review examines the multiple factors and phenomena affecting the eCB signaling system in the brain. It evaluates techniques of controlling the eCB system to identify the obstacles in their applications and highlights the crucial interdependent variables that may influence biomedical research outcomes.”

https://www.ncbi.nlm.nih.gov/pubmed/29953913