“Cannabinoids participate in the modulation of numerous functions in the human organism, increasing the sense of hunger, affecting carbohydrate and lipid metabolism, and controlling systemic energy balance mechanisms. Moreover, they influence the endocrine system functions, acting via two types of receptors, CB1 and CB2. The aim of the present study was to examine the number, distribution and activity of ghrelin and somatostatin producing endocrine cells in the pancreas of rats after a single administration of selective CP 55,940 agonist of CB1 receptor. The study was performed on 20 rats. Neuroendocrine cells were identified by immunohistochemical reactions, involving specific antibodies against ghrelin and somatostatin. The distribution and number of ghrelin- and somatostatin-immunoreactive cells were separately studied in five pancreas islets of each section. A performed analysis showed a decreased number of somatostatin-immunoreactive cells and a weak immunoreactivity of ghrelin and somatostatin containing neuroendocrine cells in the pancreatic islets of experimental rats, compared to control animals. The obtained results suggest that a single administration of a selective CP 55,940 agonist of CB1 receptor influences the immunoreactivity of endocrine cells with ghrelin and somatostatin expression in the pancreas islets.”
Tag Archives: CB(1) and CB(2) receptors
The endocannabinoid system and the treatment of mood and anxiety disorders.
“The central endocannabinoid system is a neuroactive lipid signalling system in the brain which acts to control neurotransmitter release. The expression patterns of this system throughout limbic regions of the brain ideally situate it to exert regulatory control over emotional behaviour, mood and stress responsivity. A growing body of evidence unequivocally demonstrates that deficits in endocannabinoid signalling may result in depressive and anxiogenic behavioral responses, while pharmacological augmentation of endocannabinoid signalling can produce both antidepressive and anxiolytic behavioral responses. The aim of this review is to summarize current knowledge of the role of the endocannabinoid system in the etiology and treatment of mood and anxiety disorders, such as depression, anxiety and post-traumatic stress disorder.
Collectively, both clinical and preclinical data argue that cannabinoid receptor signalling may be a realistic target in the development of a novel class of agent for the pharmacotherapy of mood and anxiety disorders.”
The endocannabinoid system in the regulation of emotions throughout lifespan: a discussion on therapeutic perspectives.
“Alterations in emotion regulation processes may form the basis of psychopathologies. The endocannabinoid (eCB) system, composed of endogenous ligands, the enzymatic machinery in charge of their metabolism and the specific metabotropic receptors, has emerged as a major neuromodulatory system critically involved in the control of emotional homeostasis and stress responsiveness. Data from animal models indicate that the eCB system plays a key role in brain development, and is probably involved in the control of emotional states from early developmental stages.
The present review summarizes the latest information on the role of the eCB system in emotionality and anxiety-related disorders throughout the lifespan. Putative therapeutic strategies based on the pharmacological modulation of this system will be discussed.
Given the fact that the pharmacological modulation of the eCB system has recently arisen as a promising strategy in the management of anxiety and mood disorders, the potential efficacy of this pharmacological approach (i.e. blockers of the catabolic pathway) will be discussed, as well as pharmacological alternatives such as modulators of cannabinoid receptors other than the classical CB1 receptor, or administration of other plant-derived compounds (e.g. cannabidiol).”
Pharmacological exploitation of the endocannabinoid system: new perspectives for the treatment of depression and anxiety disorders?
“Animal experiments suggest that drugs promoting endocannabinoid action may represent a novel strategy for the treatment of depression and anxiety disorders.
Because of its analgesic, antiemetic and tranquilizing effects, the herb Cannabis sativa has been used for medical purposes for centuries. In addition, preparations of cannabis, such as marijuana, hashish or skunk, have a long history as drugs of abuse.1 Typical effects of cannabis abuse are amnesia, sedation and a feeling of well-being described as “bliss”.2 In the middle of the last century, Raphael Mechoulam and colleagues identified Δ9-tetrahydrocannabinol (Δ9-THC) as the main psychoactive ingredient of this herb. Today, it is known that Cannabis sativa contains more than 60 substances, such as cannabidiol, cannabinol and cannabicromene, which are referred to as phytocannabinoids.3 Their lipid nature posed a significant obstacle to chemical experiments, which might explain why the discovery of phytocannabinoids occurred late compared to other natural compounds (e.g. morphine was isolated from opium in the XIX century). The molecular structure rendered it likely that Δ9-THC exerts its effects primarily by changing physico-chemical characteristics of cell membranes. Therefore it came as a surprise that specific binding sites could be identified within the mammalian brain,4 followed by isolation and characterization of endogenous binding substances, named endocannabinoids.5 The development of novel pharmacological compounds targeting receptors or ligand synthesis and degradation revealed a number of complex brain functions, which are tightly controlled by the endocannabinoid system. The aim of the present review is to briefly introduce this system and its pharmacology, to discuss its involvement in psychopathology and to illustrate its therapeutic potential.
Conclusion
Malfunctions in the endocannabinoid system may promote the development and maintenance of psychiatric disorders such as depression, phobias and panic disorder. Thus, CB1 agonists or inhibitors of anandamide hydrolysis are expected to exert antidepressant and anxiolytic effects. Future studies should consider 1) the development of CB1 antagonists that cannot readily cross the blood-brain barrier, 2) shifts in the balance of CB1 vs. TRPV1 signalling, 3) the allosteric site of CB1 receptor and 4) the potential involvement of CB2 receptor in mood regulation. Striking similarities in (endo)cannabinoid action in animals and men render it likely that the new pharmacological principle outlined in the present article may find their way into clinical practice.”
Discovery and development of endocannabinoid-hydrolyzing enzyme inhibitors.
“Fatty acid amide hydrolase (FAAH) and monoglyceride lipase (MGL) are hydrolytic enzymes which degrade the endogenous cannabinoids (endocannabinoids) N-arachidonoylethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), respectively. Endocannabinoids are an important class of lipid messenger molecules that are produced on demand in response to elevated intracellular calcium levels. They recognize and activate the cannabinoid CB(1) and CB(2) receptors, the molecular targets for Delta(9)-tetrahydrocannabinol (Delta(9)-THC) in marijuana evoking several beneficial therapeutic effects. However, in vivo the cannabimimetic effects of AEA and 2-AG remain weak owing to their rapid inactivation by FAAH and MGL, respectively. The inactivation of FAAH and MGL by specific enzyme inhibitors increases the levels of AEA and 2-AG, respectively, producing therapeutic effects such as pain relief and depression of anxiety.”
The cannabinoid receptor CB₁ inverse agonist AM251 potentiates the anxiogenic activity of urocortin I in the basolateral amygdala.
The basolateral amygdala is reported to play an important role in the neural bases of emotional processing… Based on these findings, we propose that urocortin and endocannabinoid signaling are part of an integrated neural axis modulating anxiety states within the basolateral amygdala. This article is part of a Special Issue entitled ‘Anxiety and Depression’.”
Pharmacological and pharmacokinetic characterization of the cannabinoid receptor 2 agonist, GW405833, utilizing rodent models of acute and chronic pain, anxiety, ataxia and catalepsy.
“To date, two cannabinoid receptors have been identified, CB1 and CB2. Activation of these receptors with non-selective cannabinoid receptor agonists reduces pain sensitivity in animals and humans. However, activation of CB1 receptors is also associated with central side effects… More recently, a role for selective CB2 agonists in pain modification has been demonstrated…a selective CB2 agonist, was recently reported to partially reverse the inflammation and hyperalgesia in a rat model of acute inflammation. In the current report, we extend the characterization and therapeutic potential of this compound…
These data support the tenet that selective CB2 receptor agonists have the potential to treat pain without eliciting the centrally-mediated side effects associated with non-selective cannabinoid agonists…”
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.”
Expression pattern of the cannabinoid receptor genes in the frontal cortex of mood disorder patients and mice selectively bred for high and low fear.
“Although the endocannabinoid system (ECS) has been implicated in brain development and various psychiatric disorders, precise mechanisms of the ECS on mood and anxiety disorders remain unclear. Here, we have investigated developmental and disease-related expression pattern of the cannabinoid receptor 1 (CB1) and the cannabinoid receptor 2 (CB2) genes in the dorsolateral prefrontal cortex (PFC) of humans. Using mice selectively bred for high and low fear, we further investigated potential association between fear memory and the cannabinoid receptor expression in the brain…
These results suggest that the CB1 in the PFC may play a significant role in regulating mood and anxiety symptoms. Our study demonstrates the advantage of utilizing data from postmortem brain tissue and a mouse model of fear to enhance our understanding of the role of the cannabinoid receptors in mood and anxiety disorders.”
Endocannabinoid system and mood disorders: Priming a target for new therapies.
“The endocannabinoid system (ECS), comprising two G protein-coupled receptors (the cannabinoid receptors 1 and 2 [CB1 and CB2] for marijuana’s psychoactive principle ∆(9)-tetrahydrocannabinol [∆(9)-THC]), their endogenous small lipid ligands (namely anandamide [AEA] and 2-arachidonoylglycerol [2-AG], also known as endocannabinoids), and the proteins for endocannabinoid biosynthesis and degradation, has been suggested as a pro-homeostatic and pleiotropic signaling system activated in a time- and tissue-specific way during physiopathological conditions. In the brain activation of this system modulates the release of excitatory and inhibitory neurotransmitters and of cytokines from glial cells. As such, the ECS is strongly involved in neuropsychiatric disorders, particularly in affective disturbances such as anxiety and depression. It has been proposed that synthetic molecules that inhibit endocannabinoid degradation can exploit the selectivity of endocannabinoid action, thus activating cannabinoid receptors only in those tissues where there is perturbed endocannabinoid turnover due to the disorder, and avoiding the potential side effects of direct CB1 and CB2 activation. However, the realization that endocannabinoids, and AEA in particular, also act at other molecular targets, and that these mediators can be deactivated by redundant pathways, has recently led to question the efficacy of such approach, thus opening the way to new multi-target therapeutic strategies, and to the use of non-psychotropic cannabinoids, such as cannabidiol (CBD), which act via several parallel mechanisms, including indirect interactions with the ECS. The state of the art of the possible therapeutic use of endocannabinoid deactivation inhibitors and phytocannabinoids in mood disorders is discussed in this review article.”