Cannabinoid CB1 Receptor Research Articles

Terminal type-specific cannabinoid CB1 receptor alterations in patients with schizophrenia: A pilot study

BackgroundIndividuals with schizophrenia are at elevated genetic risks for comorbid cannabis use, and often experience exacerbations of cognitive and psychotic symptoms when exposed to cannabis. These findings have led a number of investigators to examine cannabinoid CB1 receptor (CB1R) alterations in schizophrenia, though with conflicting results. We recently demonstrated the presence of CB1R in both excitatory and inhibitory boutons in the human prefrontal cortex, with differential levels of the receptor between bouton types. We hypothesized that the differential enrichment of CB1R between bouton types – a factor previously unaccounted for when examining CB1R changes in schizophrenia – may resolve prior discrepant reports and increase our insight into the effects of CB1R alterations on the pathophysiology of schizophrenia. MethodsUsing co-labeling immunohistochemistry and fluorescent microscopy, we examined total CB1R levels and CB1R levels within excitatory (vGlut1-positive) and inhibitory (vGAT-positive) boutons of prefrontal cortex samples from ten pairs of individuals (nine male pairs and one female pair) diagnosed with schizophrenia and non-psychiatric comparisons. ResultsSignificantly higher total CB1R levels were found within samples from individuals with schizophrenia. Terminal type-specific analyses identified significantly higher CB1R levels within excitatory boutons in samples from individuals with schizophrenia relative to comparisons. In contrast, CB1R levels within the subset of inhibitory boutons that normally express high CB1R levels (presumptive cholecystokinin neuron boutons) were lower in samples from individuals with schizophrenia relative to comparison samples. ConclusionGiven CB1R's role in suppressing neurotransmission upon activation, these results suggest an overall shift in excitatory and inhibitory balance regulation toward a net reduction of excitatory activity in schizophrenia.

Therapeutic Potential of Cannabinoids in Glaucoma.

Glaucoma is a leading cause of irreversible blindness worldwide. To date, intraocular pressure (IOP) is the only modifiable risk factor in glaucoma treatment, but even in treated patients, the disease can progress. Cannabinoids, which have been known to lower IOP since the 1970s, have been shown to have beneficial effects in glaucoma patients beyond their IOP-lowering properties. In addition to the classical cannabinoid receptors CB1 and CB2, knowledge of non-classical cannabinoid receptors and the endocannabinoid system has increased in recent years. In particular, the CB2 receptor has been shown to mediate anti-inflammatory, anti-apoptotic, and neuroprotective properties, which may represent a promising therapeutic target for neuroprotection in glaucoma patients. Due to their vasodilatory effects, cannabinoids improve blood flow to the optic nerve head, which may suggest a vasoprotective potential and counteract the altered blood flow observed in glaucoma patients. The aim of this review was to assess the available evidence on the effects and therapeutic potential of cannabinoids in glaucoma patients. The pharmacological mechanisms underlying the effects of cannabinoids on IOP, neuroprotection, and ocular hemodynamics have been discussed.

Cannabinoid CB2 receptor orthologues; in vitro function and perspectives for preclinical to clinical translation.

Cannabinoid CB2 receptor agonists are in development as therapeutic agents, including for immune modulation and pain relief. Despite promising results in rodent preclinical studies, efficacy in human clinical trials has been marginal to date. Fundamental differences in ligand engagement and signalling responses between the human CB2 receptor and preclinical model species orthologues may contribute to mismatches in functional outcomes. This is a tangible possibility for the CB2 receptor in that there is a relatively large degree of primary amino acid sequence divergence between human and rodent. Here, we summarise CB2 receptor gene and protein structure, assess comparative molecular pharmacology between CB2 receptor orthologues, and review the current status of preclinical to clinical translation for drugs targeted at the CB2 receptor, focusing on comparisons between human, mouse and rat receptors. We hope that raising wider awareness of, and proposing strategies to address, this additional challenge in drug development will assist in ongoing efforts toward successful therapeutic translation of drugs targeted at the CB2 receptor. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.

Involvement of cannabinoid receptors and neuroinflammation in early sepsis: Implications for posttraumatic stress disorder

Sepsis is associated with several comorbidities in survivors, such as posttraumatic stress disorder (PTSD). This study investigated whether rats that survive sepsis develop the generalization of fear memory as a model of PTSD. Responses to interventions that target the endothelin-1 (ET-1)/cannabinoid system and glial activation in the initial stages of sepsis were evaluated. As a control, we evaluated hyperalgesia before fear conditioning. Sepsis was induced by cecal ligation and puncture (CLP) in Wistar rats. CLP-induced sepsis with one or three punctures resulted in fear generalization in the survivors 13 and 20 days after the CLP procedure, a process that was not associated with hyperalgesia. Septic animals were intracerebroventricularly treated with vehicle, the endothelin receptor A (ETA) antagonist BQ123, the cannabinoid CB1 and CB2 receptor antagonists AM251 and AM630, respectively, and the glial blocker minocycline 4 h after CLP. The blockade of either CB1 or ETA receptors increased the survival rate, but only the former reversed fear memory generalization. The endothelinergic system blockade is important for improving survival but not for fear memory. Treatment with the CB2 receptor antagonist or minocycline also reversed the generalization of fear memory but did not increase the survival rate that was associated with CLP. Minocycline treatment also reduced tumor necrosis factor-α levels in the hippocampus suggesting that neuroinflammation is important for the generalization of fear memory induced by CLP. The influence of CLP on the generalization of fear memory was not related to Arc protein expression, a regulator of synaptic plasticity, in the dorsal hippocampus.

CB1 receptor expression and signaling are required for dexamethasone-induced aversive memory consolidation

The molecular processes that underlie long-term memory formation involve signaling pathway activation by neurotransmitter release, which induces the expression of immediate early genes, such as Zif268, having a key role in memory formation. In this work, we show that the cannabinoid CB1 receptor signaling is necessary for the effects of dexamethasone on the behavioral response in an inhibitory avoidance task, on dexamethasone-induced ERK phosphorylation, and on dexamethasone-dependent Zif268 expression. Furthermore, we provide primary evidence for the mechanism responsible for this crosstalk between cannabinoid and glucocorticoid-mediated signaling pathways, showing that dexamethasone regulates endocannabinoid metabolism by inhibiting the activity of the Fatty acid amide hydrolase (FAAH), an integral membrane enzyme that hydrolyzes endocannabinoids and related amidated signaling lipids. Our results provide novel evidence regarding the role of the endocannabinoid system, and in particular of the CB1 receptor, as a mediator of the effects of glucocorticoids on the consolidation of aversive memories.

A cortico-amygdala neural substrate for endocannabinoid modulation of fear extinction

Preclinical and clinical studies implicate endocannabinoids (eCBs) in fear extinction, but the underlying neural circuit basis of these actions is unclear. Here, we employed invivo optogenetics, eCB biosensor imaging, exvivo electrophysiology, and CRISPR-Cas9 gene editing in mice to examine whether basolateral amygdala (BLA)-projecting medial prefrontal cortex (mPFC) neurons represent a neural substrate for the effects of eCBs on extinction. We found that photoexcitation of mPFC axons in BLA during extinction mobilizes BLA eCBs. eCB biosensor imaging showed that eCBs exhibit a dynamic stimulus-specific pattern of activity at mPFC→BLA neurons that tracks extinction learning. Furthermore, using CRISPR-Cas9-mediated gene editing, we demonstrated that extinction memory formation involves eCB activity at cannabinoid CB1 receptors expressed at vmPFC→BLA synapses. Our findings reveal the temporal characteristics and a neural circuit basis of eCBs' effects on fear extinction and inform efforts to target the eCB system as a therapeutic approach in extinction-deficient neuropsychiatric disorders.

Impact of Cannabinoid Receptors in the Design of Therapeutic Agents against Human Ailments.

The Cannabinoid (CB) signalling cascade is widely located in the human body and is associated with several pathophysiological processes. The endocannabinoid system comprises cannabinoid receptors CB1 and CB2, which belong to G-protein Coupled Receptors (GPCRs). CB1 receptors are primarily located on nerve terminals, prohibiting neurotransmitter release, whereas CB2 are present predominantly on immune cells, causing cytokine release. The activation of CB system contributes to the development of several diseases which might have lethal consequences, such as CNS disorders, cancer, obesity, and psychotic disorders on human health. Clinical evidence revealed that CB1 receptors are associated with CNS ailments such as Alzheimer's disease, Huntington's disease, and multiple sclerosis, whereas CB2 receptors are primarily connected with immune disorders, pain, inflammation, etc. Therefore, cannabinoid receptors have been proved to be promising targets in therapeutics and drug discovery. Experimental and clinical outcomes have disclosed the success story of CB antagonists, and several research groups have framed newer compounds with the binding potential to these receptors. In the presented review, we have summarized variously reported heterocycles with CB receptor agonistic/antagonistic properties against CNS disorders, cancer, obesity, and other complications. The structural activity relationship aspects have been keenly described along with enzymatic assay data. The specific outcomes of molecular docking studies have also been highlighted to get insights into the binding patterns of the molecules to CB receptors.

An α-hemoglobin-derived peptide (m)VD-hemopressin (α) promotes NREM sleep via the CB1 cannabinoid receptor.

Hemopressin and related peptides have shown to function as the endogenous ligands or the regulator of cannabinoid receptors. The previous studies demonstrated that the endocannabinoid system played important roles in modulating several physiological functions such as sleep, olfaction, emotion, learning and memory, and reward behaviors. Mouse VD-hemopressin (α) [(m)VD-HPα], an 11-residue peptide derived from the α1 chain of hemoglobin, was recently presumed as a selective agonist of the CB1 receptor. The present study was undertaken to investigate the effects of (m)VD-HPα on the sleep-wake cycle and power spectrum of cortical EEG in freely moving rats and the potential neurons in the brain activated by (m)VD-HPα. The results showed that 20.1nmol of (m)VD-HPα i.c.v. administration increased non-rapid eye movement (NREM) sleep in the first 2h section accompanied by an increase in EEG delta (0.5-4Hz) activity. The (m)VD-HPα-induced NREM sleep enhancement was due to extended episode duration instead of the episode number. In addition, the effect of (m)VD-HPα (20.1nmol) on sleep-wake states was significantly attenuated by an antagonist of the CB1 receptor, AM251 (20nmol, i.c.v.) but not by the CB2 receptor antagonist, AM630 (20nmol, i.c.v.). In comparison with vehicle, (m)VD-HPα increased Fos-immunoreactive (-ir) neurons in the ventrolateral preoptic nucleus (VLPO), but reduced Fos-ir neurons in the lateral hypothalamus (LH), tuberomammillary nucleus (TMN), and locus coeruleus (LC). These findings suggest that (m)VD-HPα promotes NREM sleep via the CB1 cannabinoid receptor to probably activate VLPO GABAergic neurons, but inactivates the LH orexinergic, LC noradrenergic, and TMN histaminergic neurons.

Conditional deletion of CB2 cannabinoid receptors from peripheral sensory neurons eliminates CB2-mediated antinociceptive efficacy in a mouse model of carrageenan-induced inflammatory pain

CB2 cannabinoid receptor agonists suppress pathological pain in animal models and lack unwanted side effects commonly associated with direct activation of CB1 receptors. However, the types of pain most responsive to CB2 agonists are incompletely understood and cell types which underlie CB2-mediated therapeutic efficacy remain largely unknown. We previously reported that the CB2 receptor agonist LY2828360 reduced neuropathic nociception induced by toxic challenge with chemotherapeutic and anti-retroviral agents in mice. Whether these findings generalize to models of inflammatory pain is not known. Here we show that LY2828360 (10 mg/kg i.p.) reversed the maintenance of carrageenan-induced mechanical allodynia in female mice. Anti-allodynic efficacy was fully preserved in global CB1 knock out (KO) mice but absent in CB2 KO mice. The anti-allodynic efficacy of LY2828360 was absent in conditional KO (cKO) mice lacking CB2 receptors in peripheral sensory neurons (AdvillinCRE/+; CB2f/f) and preserved in cKO mice lacking CB2 receptors in microglia/macrophages expressing C-X3-C Motif Chemokine Receptor 1 (CX3CR1CRE/+; CB2f/f). Intraplantar administration of LY2828360 (30 μg i.pl.) reversed carrageenan-induced mechanical allodynia in CB2f/f but not AdvillinCRE/+; CB2f/f mice of both sexes. Thus, CB2 receptors in peripheral sensory neurons likely underlie the therapeutic effects of LY2828360 injection in the paw. Lastly, qRT-PCR analyses revealed that LY2828360 reduced carrageenan-induced increases in IL-1β and IL-10 mRNA in paw skin. Our results suggest that LY2828360 suppresses inflammatory nociception in mice through a neuronal CB2-dependent mechanism that requires peripheral sensory neuron CB2 receptors and suggest that the clinical applications of LY2828360 as an anti-hyperalgesic agent should be re-evaluated.

RAMP and MRAP accessory proteins have selective effects on expression and signalling of the CB1, CB2, GPR18 and GPR55 cannabinoid receptors.

Receptor activity-modifying proteins (RAMPs) and melanocortin receptor accessory proteins (MRAPs) modulate expression and signalling of calcitonin and melanocortin GPCRs. Interactions with other GPCRs have also been reported. The cannabinoid receptors, CB1 and CB2, and two putative cannabinoid receptors, GPR18 and GPR55, exhibit substantial intracellular expression and there are discrepancies in ligand responsiveness between studies. We investigated whether interactions with RAMPs or MRAPs could explain these phenomena. Receptors and accessory proteins were co-expressed in HEK-293 cells. Selected receptors were studied at basal expression levels and also with enhanced expression produced by incorporation of a preprolactin signal sequence/peptide (pplss). Cell surface and total expression of receptors and accessory proteins were quantified using immunocytochemistry. Signalling was measured using cAMP (CAMYEL) and G protein dissociation (TRUPATH Gα13) biosensors. MRAP2 enhanced surface and total expression of GPR18. Pplss-GPR18 increased detection of cell surface MRAP2. MRAP1α and MRAP2 reduced GPR55 surface and total expression, correlating with reduced constitutive, but not agonist-induced, signalling. GPR55, pplss-CB1 and CB2 reduced detection of MRAP1α at the cell surface. Pplss-CB1 agonist potency was reduced by MRAP2 in Gα13 but not cAMP assays, consistent with MRAP2 reducing pplss-CB1 expression. Some cannabinoid receptors increased RAMP2 or RAMP3 total expression without influencing surface expression. Mutual influences on expression and/or function for specific accessory protein-receptor pairings raises the strong potential for physiological and disease-relevant consequences. Sequestration and/or hetero-oligomerisation of cannabinoid receptors with accessory proteins is a possible novel mechanism for receptor crosstalk. This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.

The microbiota-gut-brain axis regulates motivation for exercise.

The microbiota-gut-brain axis regulates motivation for exercise.

Adolescent exposure to the Spice/K2 cannabinoid JWH-018 impairs sensorimotor gating and alters cortical perineuronal nets in a sex-dependent manner

The consumption of synthetic cannabinoids during adolescence is reported to be a risk factor for the appearance of psychiatric disorders later in life. JWH-018 was identified as one of the primary psychoactive components present in Spice/K2 preparations. This study evaluated the short- and long-term consequences of exposure to JWH-018 during the adolescence in anxiety-like behavior, fear extinction, and sensorimotor gating in male and female mice. Alterations in anxiety varied depending on the time interval between treatment and behavioral analysis along with sex, while no changes were observed in the extinction of fear memory. A decrease in prepulse inhibition of the startle reflex was revealed in male, but not female, mice at short- and long-term. This behavioral disturbance was associated with a reduction in the number of perineuronal nets in the prelimbic and infralimbic regions of the prefrontal cortex in the short-term. Furthermore, adolescent exposure to JWH-018 induced an activation of microglia and astrocytes in the prefrontal cortex of male mice at both time intervals. A transitory decrease in the expression of GAD67 and CB2 cannabinoid receptors in the prefrontal cortex was also found in male mice exposed to JWH-018. These data reveal that the treatment with JWH-018 during the adolescence leads to long-lasting neurobiological changes related to psychotic-like symptoms, which were sex-dependent.

Role of mesolimbic cannabinoid receptor 1 in stress-driven increases in cocaine self-administration in male rats.

Stress is prevalent in the lives of those with substance use disorders (SUDs) and influences SUD outcomes. Understanding the neurobiological mechanisms through which stress promotes drug use is important for the development of effective SUD interventions. We have developed a model wherein exposure to a stressor, uncontrollable electric footshock, daily at the time of cocaine self-administration escalates intake in male rats. Here we test the hypothesis that stress-induced escalation of cocaine self-administration requires the CB1 cannabinoid receptor. Male Sprague-Dawley rats self-administered cocaine (0.5 mg/kg/inf, i.v.) during 2-h sessions comprised of four 30-min self-administration components separated by 5-min shock sequences or 5-min shock-free periods for 14 days. Footshock produced an escalation of cocaine self-administration that persisted following shock removal. Systemic administration of the cannabinoid receptor type 1 (CB1R) antagonist/inverse agonist, AM251, attenuated cocaine intake only in rats with a history of stress. This effect was localized to the mesolimbic system, as intra-nucleus accumbens (NAc) shell and intra-ventral tegmental area (VTA) micro-infusions of AM251 attenuated cocaine intake only in stress-escalated rats. Cocaine self-administration, regardless of stress history, increased CB1R binding site density in the VTA, but not NAc shell. Following extinction, cocaine-primed reinstatement (10 mg/kg, ip) was increased in rats with prior footshock during self-administration. AM251 attenuated reinstatement only in rats with a stress history. Altogether, these data demonstrate that mesolimbic CB1Rs are required to escalate intake and heighten relapse susceptibility and suggest that repeated stress at the time of cocaine use regulates mesolimbic CB1R activity through a currently unknown mechanism.

Effect of N-oleoyl dopamine on myofibroblast trans-differentiation of retinal pigment epithelial cells

Retinal pigment epithelial (RPE) cells contribute to several clinical conditions resulting in retinal fibrotic scars. Myofibroblast trans-differentiation of RPE cells is a critical step in the process of retinal fibrosis. In this study, we investigated the effects of N-oleoyl dopamine (OLDA), a newer endocannabinoid with a structure distinct from classic endocannabinoids, on TGF-β2-induced myofibroblast trans-differentiation of porcine RPE cells. Using an in vitro collagen matrix contraction assay, OLDA was found to inhibit TGF-β2 induced contraction of collagen matrices by porcine RPE cells. This effect was concentration-dependent, with significant inhibition of contraction observed at 3 μM and 10 μM. OLDA did not affect the proliferation of porcine RPE cells. Immunocytochemistry showed that at 3 μM, OLDA decreased incorporation of α-SMA in the stress fibers of TGF-β2-treated RPE cells. In addition, western blot analysis showed that 3 μM OLDA significantly downregulated TGF-β2-induced α-SMA protein expression. Taken together these results demonstrate that OLDA inhibits TGF-β induced myofibroblast trans-differentiation of RPE cells. It has been established that classic endocannabinoid such as anandamide, by activating the CB1 cannabinoid receptor, promote fibrosis in multiple organ systems. In contrast, this study demonstrates that OLDA, an endocannabinoid with a chemical structure distinct from classic endocannabinoids, inhibits myofibroblast trans-differentiation, an important step in fibrosis. Unlike classic endocannabinoids, OLDA has weak affinity for the CB1 receptor. Instead, OLDA acts on non-classic cannabinoid receptors such as GPR119, GPR6, and TRPV1. Therefore, our study indicates that the newer endocannabinoid OLDA and its non-classic cannabinoid receptors could potentially be novel therapeutic targets for treating ocular diseases involving retinal fibrosis and fibrotic pathologies in other organ systems.

Aqueous cannabidiol β-cyclodextrin complexed polymeric micelle nasal spray to attenuate in vitro and ex vivo SARS-CoV-2-induced cytokine storms

Cannabidiol (CBD) has a number of biological effects by acting on the cannabinoid receptors CB1 and CB2. CBD may be involved in anti-inflammatory processes via CB1 and CB2 receptors, resulting in a decrease of pro-inflammatory cytokines. However, CBD's poor aqueous solubility is a major issue in pharmaceutical applications. The aim of the present study was to develop and evaluate a CBD nasal spray solution. A water-soluble CBD was prepared by complexation with β-cyclodextrin (β-CD) at a stoichiometric ratio of 1:1 and forming polymeric micelles using poloxamer 407. The mixture was then lyophilized and characterized using FT-IR, DSC, and TGA. CBD-β-CD complex-polymeric micelles were formulated for nasal spray drug delivery. The physicochemical properties of the CBD-β-CD complex-polymeric micelle nasal spray solution (CBD-β-CDPM-NS) were assessed. The results showed that the CBD content in the CBD-β-CD complex polymeric micelle powder was 102.1 ± 0.5% labeled claim. The CBD-β-CDPM-NS was a clear colorless isotonic solution. The particle size, zeta potential, pH value, and viscosity were 111.9 ± 0.7 nm, 0.8 ± 0.1 mV, 6.02 ± 0.02, and 12.04 ± 2.64 cP, respectively. This formulation was stable over six months at ambient temperature. The CBD from CBD-β-CDPM-NS rapidly released to 100% within 1 min. Ex vivo permeation studies of CBD-β-CDPM-NS through porcine nasal mucosa revealed a permeation rate of 4.8 μg/cm2/min, which indicated that CBD was effective in penetrating nasal epithelial cells. CBD-β-CDPM-NS was tested for its efficacy and safety in terms of cytokine production from nasal immune cells and toxicity to nasal epithelial cells. The CBD-β-CDPM-NS was not toxic to nasal epithelial at the concentration of CBD equivalent to 3.125–50 μg/mL. When the formulation was subjected to bioactivity testing against monocyte-like macrophage cells, it proved that the CBD-β-CDPM-NS has the potential to inhibit inflammatory cytokines. CBD-β-CDPM-NS demonstrated the formulation's ability to reduce the cytokine produced by S-RBD stimulation in ex vivo porcine nasal mucosa in both preventative and therapeutic modes.

NAPE-PLD deletion in stress-TRAPed neurons results in an anxiogenic phenotype

Anandamide (AEA) is an endogenous ligand of the cannabinoid CB1 and CB2 receptors, being a component of the endocannabinoid signaling system, which supports the maintenance or regaining of neural homeostasis upon internal and external challenges. AEA is thought to play a protective role against the development of pathological states after prolonged stress exposure, including depression and generalized anxiety disorder. Here, we used the chronic social defeat (CSD) stress as an ethologically valid model of chronic stress in male mice. We characterized a genetically modified mouse line where AEA signaling was reduced by deletion of the gene encoding the AEA synthesizing enzyme N-acyl-phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) specifically in neurons activated at the time of CSD stress. One week after the stress, the phenotype was assessed in behavioral tests and by molecular analyses. We found that NAPE-PLD deficiency in neurons activated during the last three days of CSD stress led to an increased anxiety-like behavior. Investigating the molecular mechanisms underlying this phenotype may suggest three main altered pathways to be affected: (i) desensitization of the negative feedback loop of the hypothalamic-pituitary-adrenal axis, (ii) disinhibition of the amygdala by the prefrontal cortex, and (iii) altered neuroplasticity in the hippocampus and prefrontal cortex.

Cannabidiol reduces LPS-induced nociception via endocannabinoid system activation.

Bacterial infections are often accompanied by fever and generalized muscle pain. However, the treatment of pain with an infectious etiology has been overlooked. Thus, we investigated the impact of cannabidiol (CBD) in bacterial lipopolysaccharide (LPS)-induced nociception. Male Swiss mice received intrathecal (i.t.) LPS injection, and the nociceptive threshold was measured by the von Frey filaments test. Spinal involvement of the cannabinoid CB2 receptor, toll-like receptor 4 (TLR4), microglia and astrocytes were evaluated by i.t. administration of their respectively antagonists or inhibitors. Western blot, immunofluorescence, ELISA and liquid chromatography-mass spectrometry were used to assess Cannabinoid CB2 receptors and TLR4 spinal expression, proinflammatory cytokines and endocannabinoid levels. CBD was administered intraperitoneally at 10 mg/kg. The pharmacological assay demonstrated TLR4 participation in LPS-induced nociception. In addition, spinal TLR4 expression and proinflammatory cytokine levels were increased in this process. CBD treatment prevented LPS-induced nociception and TLR4 expression. AM630 reversed antinociception and reduced CBD-induced endocannabinoids upregulation. Increased spinal expression of the cannabinoid CB2 receptor was also found in animals receiving LPS, which was accompanied by reduced TLR4 expression in CBD-treated mice. Taken together, our findings indicated that CBD is a potential treatment strategy to control LPS-induced pain by attenuating TLR4 activation via the endocannabinoid system.

Immunoexpression of the cannabinoid CB2 receptor protein in canine benign and malignant mammary tumours

Immunoexpression of the cannabinoid CB2 receptor protein in canine benign and malignant mammary tumours

Activation of ventral hippocampal CB1 receptors inhibits ketamine-induced anxiogenic-like behavior: Alteration of BDNF/c-Fos levels in the mouse hippocampus

Considering the increasing usage of ketamine as a recreational drug with hallucinogenic properties and also scarce studies about receptor systems responsible for its effects, in the present study we aimed to investigate whether the activation of the ventral hippocampal (VH) CB1 cannabinoid receptors affects the anxiety-like behaviors induced by ketamine. Also, the levels of BDNF and c-Fos proteins in the mouse hippocampus were measured following the treatments. For this purpose, male NMRI mice were cannulated bilaterally in the VH with a stereotaxic apparatus. Anxiety properties and protein changes were measured using elevated plus-maze (EPM) and western blotting respectively. The results revealed that intraperitoneal (i.p.) administration of ketamine (5–20 mg/kg) significantly decreased the percentage of open arm time (%OAT) and open arm entry (%OAE) in the EPM with no alteration in the locomotor activity suggesting an anxiogenic-like behavior to ketamine. Furthermore, ketamine administration (10 mg/kg, i.p.) increased BDNF and c-Fos levels in the hippocampus. Interestingly, activation of the VH CB1 receptors by ACPA (0.5–4 ng/mouse) inhibited the anxiogenic-like behaviors produced by ketamine, whereas the microinjection of the same doses of ACPA into VH by itself had no effect on the EPM parameters. Hippocampal levels of BDNF and c-Fos decreased after treatment with combined ketamine with ACPA. These results suggest the therapeutic potency of cannabinoid receptor agonists for ketamine-induced anxiogenic-related responses. This effect might be at least partially mediated by the alteration of BDNF and c-Fos signaling in the hippocampus.

The electrophysiological and behavioral evaluation of the peptide hemopressin and cannabinoid CB1 receptor agonist and antagonist in pentylenetetrazol model of epilepsy in rats.

This study endeavoured to assess the effect of hemopressin (Hp), a nano peptide obtained from the alpha chain of hemoglobin, on chronic epileptic activity and its potential correlation with cannabinoid receptor type 1 (CB1). Male Wistar albino rats (230-260g) were used. The kindling process was conducted by administering a sub-convulsant dose of pentylenetetrazol (PTZ) (35mg/kg, i.p) three times a week for a maximum of 10weeks. Tripolar electrodes and external cannula guides for intracerebroventricular (i.c.v) injections were surgically implanted in the skulls of kindled rats. On the day of the experiment, doses of Hp, AM-251, and ACEA were administered prior to the PTZ injections. Electroencephalography recordings and behavioural observations were conducted simultaneously for 30min after the PTZ injection. The administration of Hp (0.6μg, i.c.v) resulted in a decrease in epileptic activity. The CB1 receptor agonist ACEA (7.5μg, i.c.v) showed an anticonvulsant effect, but the CB1 receptor antagonist AM-251 (0.5μg, i.c.v) displayed a proconvulsant effect. The co-administration of Hp (0.6μg, i.c.v) and ACEA (7.5μg, i.c.v) and of Hp (0.6μg, i.c.v) and AM-251 (0.5μg, i.c.v) produced an anticonvulsant effect. However, when AM-251 was administered prior to Hp, it produced a proconvulsant impact that overrode Hp's intended anticonvulsant effect. Interestingly, the co-administration of Hp (0.03μg) + AM-251 (0.125μg) unexpectedly exhibited an anticonvulsant effect. Electrophysiological and behavioural evaluations demonstrated the anticonvulsant effect of Hp in the present model, highlighting the possibility that Hp may act as an agonist for the CB1 receptor.