Activational role of cannabinoids on movement

Oral pre- and early postnatal cannabis exposure disinhibits ventral tegmental area dopamine neuron activity but does not influence cocaine preference in offspring in mice

Cannabis consumption has increased from 1.5% to 2.5% in Canada between 2012 and 2019. Clinical studies have indicated effects of prenatal cannabis exposure on birth weight, substance use, and neurodevelopmental disorders, but are confounded by several difficult to control variables. Animal models allow for examination of the mechanism of cannabis-induced changes in neurodevelopment and behavior, while controlling dose and timing. Several animal models of prenatal cannabis exposure exist which provide varying levels of construct validity, control of dose, and exposure to maternal stress. Using a voluntary oral consumption model, mouse dams received 5 mg/kg Δ9-tetrahydrocannabinol (THC) whole cannabis oil in peanut butter daily from gestational day 1 (GD1) to postnatal day 10 (PD10). At GD1, GD18, PD1, PD10, and PD15, maternal plasma was collected; pup brains were collected from GD18 onward. Pup brains had higher levels of THC and cannabidiol at each time point, each of which persisted in maternal plasma and pup brains past the end of treatment (PD15). Male and female adolescent offspring were examined for changes to ventral tegmental area (VTA) dopamine neuron activity and cocaine-seeking behavior. Prenatal and early postnatal (GD1-PD10) cannabis-exposed male, but not female mice had decreased gamma-aminobutyric acid (GABAergic) input, depolarized resting membrane potential, and increased spontaneous firing of VTA dopamine neurons. Cannabis-exposed offspring showed faster decay of N-methyl-D-aspartate (NMDA) currents in both sexes. However, no differences in cocaine-seeking behavior were noted. These data characterize a voluntary prenatal cannabis exposure model and demonstrates VTA dopamine neuronal activity is disinhibited in offspring.

Gestational paracetamol exposure induces core behaviors of neurodevelopmental disorders in infant rats and modifies response to a cannabinoid agonist in females

Paracetamol (PAR) is an over-the-counter analgesic/antipyretic used during pregnancy worldwide. Epidemiological studies have been associating gestational PAR exposure with neurobehavioral alterations in the progeny resembling autism spectrum disorders and attention-deficit hyperactivity disorder symptoms. The endocannabinoid (eCB) dysfunction was previously hypothesized as one of the modes of action by which PAR may harm the developing nervous system. We aimed to evaluate possible effects of gestational exposure to PAR on male and female rat's offspring behavior and if an acute injection of WIN 55,212-2 (WIN, 0.3 mg/kg), a non-specific cannabinoid agonist, prior to behavioral tests, would induce different effects in PAR exposed and non-exposed animals. Pregnant Wistar rats were gavaged with PAR (350 mg/kg/day) or water from gestational day 6 until delivery. Nest-seeking, open field, apomorphine-induced stereotypy, marble burying and three-chamber tests were conducted in 10-, 24-, 25- or 30-days-old rats, respectively. PAR exposure resulted in increased apomorphine-induced stereotyped behavior and time spent in the central area of the open field in exposed female pups. Additionally, it induced hyperactivity in the open field and increased marble burying behavior in both male and female pups. WIN injection modified the behavioral response only in the nest seeking test, and opposite effects were observed in control and PAR-exposed neonate females. Reported alterations are relevant for the neurodevelopmental disorders that have been associated with maternal PAR exposure and suggest that eCB dysfunction may play a role in the action by which PAR may harm the developing brain.

Chronic Δ9-tetrahydrocannabinol treatment has dose-dependent effects on open field exploratory behavior and [3H] SR141716A receptor binding in the rat brain

AIMS

Acute and chronic Δ⁹-THC exposure paradigms affect the body differently. More must be known about the impact of chronic Δ⁹-THC on cannabinoid-1 (CB1R) and mu-opioid (MOR) receptor levels in the brain. The present study examined chronic Δ⁹-THC's effects on CB1R and MOR levels and locomotor activity.

MAIN METHODS

Adolescent Sprague-Dawley rats were given daily intraperitoneal injections of Δ⁹-THC [0.75mg/kg (low dose or LD) or 2.0 mg/kg (high dose or HD)] or vehicle for 24 days, and locomotion in the open field was tested after the first and fourth weeks of chronic Δ⁹-THC exposure. Brains were harvested at the end of treatment. [³H] SR141716A and [³H] DAMGO autoradiography assessed CB1R and MOR levels, respectively.

KEY FINDINGS

Relative to each other, chronic HD rats showed reduced vertical plane (VP) entries and time, while LD rats had increased VP entries and time for locomotion, as assessed by open-field testing; no effects were found relative to the control. Autoradiography analyses showed that HD Δ⁹-THC significantly decreased CB1R binding relative to LD Δ⁹-THC in the cingulate (33%), primary motor (42%), secondary motor (33%) somatosensory (38%), rhinal (38%), and auditory (50%) cortices; LD Δ⁹-THC rats displayed elevated binding in the primary motor (33% increase) and hypothalamic (33 % increase) regions compared with controls. No significant differences were observed in MOR binding for the LD or HD compared to the control.

SIGNIFICANCE

These results demonstrate that chronic Δ⁹-THC dose-dependently altered CB1R levels throughout the brain and locomotor activity in the open field.

Interactions between the Nicotinic and Endocannabinoid Receptors at the Plasma Membrane

Compartmentalization, together with transbilayer and lateral asymmetries, provide the structural foundation for functional specializations at the cell surface, including the active role of the lipid microenvironment in the modulation of membrane-bound proteins. The chemical synapse, the site where neurotransmitter-coded signals are decoded by neurotransmitter receptors, adds another layer of complexity to the plasma membrane architectural intricacy, mainly due to the need to accommodate a sizeable number of molecules in a minute subcellular compartment with dimensions barely reaching the micrometer. In this review, we discuss how nature has developed suitable adjustments to accommodate different types of membrane-bound receptors and scaffolding proteins via membrane microdomains, and how this "effort-sharing" mechanism has evolved to optimize crosstalk, separation, or coupling, where/when appropriate. We focus on a fast ligand-gated neurotransmitter receptor, the nicotinic acetylcholine receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as a paradigmatic example.

Cannabinoid tetrad effects of oral Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in male and female rats: sex, dose-effects and time course evaluations

RATIONALE

The legalization of medicinal use of Cannabis sativa in most US states and the removal of hemp from the Drug Enforcement Agency (DEA) controlled substances act has resulted in a proliferation of products containing Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) for oral consumption (e.g., edibles, oils, and tinctures) that are being used for recreational and medicinal purposes.

OBJECTIVE

This study examined the effects of cannabinoids THC and CBD when administered orally on measures of pain sensitivity, body temperature, locomotor activity, and catalepsy (i.e., cannabinoid tetrad) in male and female Sprague Dawley rats.

METHODS

Rats (N = 24, 6 per sex/drug group) were administered THC (1-20 mg/kg), CBD (3-30 mg/kg), or sesame oil via oral gavage. Thermal and mechanical pain sensitivity (tail flick assay, von Frey test), rectal measurements for body temperature, locomotor activity, and the bar-test of catalepsy were completed. A separate group of rats (N = 8/4 per sex) was administered morphine (5-20 mg/kg; intraperitoneal, IP) and evaluated for pain sensitivity as a positive control.

RESULTS

We observed classic tetrad effects of antinociception, hypothermia, hyper- and hypolocomotion, and catalepsy after oral administration of THC that were long lasting (> 7 h). CBD modestly increased mechanical pain sensitivity and produced sex-dependent effects on body temperature and locomotor activity.

CONCLUSIONS

Oral THC and CBD produced long lasting effects that differed in magnitude and time course when compared with other routes of administration. Examination of cannabinoid effects administered via different routes of administration, species, and in both males and females is critical to enhance translation.

Translational models of cannabinoid vapor exposure in laboratory animals

Cannabis is one of the most frequently used psychoactive substances in the world. The most common route of administration for cannabis and cannabinoid constituents such as Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is via smoking or vapor inhalation. Preclinical vapor models have been developed, although the vaporization devices and delivery methods vary widely across laboratories. This review examines the emerging field of preclinical vapor models with a focus on cannabinoid exposure in order to (1) summarize vapor exposure parameters and other methodological details across studies; (2) discuss the pharmacological and behavioral effects produced by exposure to vaporized cannabinoids; and (3) compare behavioral effects of cannabinoid vapor administration with those of other routes of administration. This review will serve as a guide for past and current vapor delivery methods in animals, synergize findings across studies, and propose future directions for this area of research.

Nanoscale Sub-Compartmentalization of the Dendritic Spine Compartment

Compartmentalization of the membrane is essential for cells to perform highly specific tasks and spatially constrained biochemical functions in topographically defined areas. These membrane lateral heterogeneities range from nanoscopic dimensions, often involving only a few molecular constituents, to micron-sized mesoscopic domains resulting from the coalescence of nanodomains. Short-lived domains lasting for a few milliseconds coexist with more stable platforms lasting from minutes to days. This panoply of lateral domains subserves the great variety of demands of cell physiology, particularly high for those implicated in signaling. The dendritic spine, a subcellular structure of neurons at the receiving (postsynaptic) end of central nervous system excitatory synapses, exploits this compartmentalization principle. In its most frequent adult morphology, the mushroom-shaped spine harbors neurotransmitter receptors, enzymes, and scaffolding proteins tightly packed in a volume of a few femtoliters. In addition to constituting a mesoscopic lateral heterogeneity of the dendritic arborization, the dendritic spine postsynaptic membrane is further compartmentalized into spatially delimited nanodomains that execute separate functions in the synapse. This review discusses the functional relevance of compartmentalization and nanodomain organization in synaptic transmission and plasticity and exemplifies the importance of this parcelization in various neurotransmitter signaling systems operating at dendritic spines, using two fast ligand-gated ionotropic receptors, the nicotinic acetylcholine receptor and the glutamatergic receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as paradigmatic examples.

Cannabinoid-Induced Conditioned Place Preference, Intravenous Self-Administration, and Behavioral Stimulation Influenced by Ghrelin Receptor Antagonism in Rats

Cannabis/cannabinoids are widely used for recreational and therapy purposes, but their risks are largely disregarded. However, cannabinoid-associated use disorders and dependence are alarmingly increasing and an effective treatment is lacking. Recently, the growth hormone secretagogue receptor (GHSR1A) antagonism was proposed as a promising mechanism for drug addiction therapy. However, the role of GHS-R1A and its endogenous ligand ghrelin in cannabinoid abuse remains unclear. Therefore, the aim of our study was to investigate whether the GHS-R1A antagonist JMV2959 could reduce the tetrahydrocannabinol (THC)-induced conditioned place preference (CPP) and behavioral stimulation, the WIN55,212-2 intravenous self-administration (IVSA), and the tendency to relapse. Following an ongoing WIN55,212-2 self-administration, JMV2959 3 mg/kg was administered intraperitoneally 20 min before three consequent daily 120-min IVSA sessions under a fixed ratio FR1, which significantly reduced the number of the active lever-pressing, the number of infusions, and the cannabinoid intake. Pretreatment with JMV2959 suggested reduction of the WIN55,212-2-seeking/relapse-like behavior tested in rats on the twelfth day of the forced abstinence period. On the contrary, pretreatment with ghrelin significantly increased the cannabinoid IVSA as well as enhanced the relapse-like behavior. Co-administration of ghrelin with JMV2959 abolished/reduced the significant efficacy of the GHS-R1A antagonist in the cannabinoid IVSA. Pretreatment with JMV2959 significantly and dose-dependently reduced the manifestation of THC-induced CPP. The THC-CPP development was reduced after the simultaneous administration of JMV2959 with THC during conditioning. JMV2959 also significantly reduced the THC-induced behavioral stimulation in the LABORAS cage. Our findings suggest that GHS-R1A importantly participates in the rewarding/reinforcing effects of cannabinoids.

Cannabis, a cause for anxiety? A critical appraisal of the anxiogenic and anxiolytic properties

BACKGROUND

Cannabis has been documented for use in alleviating anxiety. However, certain research has also shown that it can produce feelings of anxiety, panic, paranoia and psychosis. In humans, Δ9-tetrahydrocannabinol (THC) has been associated with an anxiogenic response, while anxiolytic activity has been attributed mainly to cannabidiol (CBD). In animal studies, the effects of THC are highly dose-dependent, and biphasic effects of cannabinoids on anxiety-related responses have been extensively documented. A more precise assessment is required of both the anxiolytic and anxiogenic potentials of phytocannabinoids, with an aim towards the development of the 'holy grail' in cannabis research, a medicinally-active formulation which may assist in the treatment of anxiety or mood disorders without eliciting any anxiogenic effects.

OBJECTIVES

To systematically review studies assessing cannabinoid interventions (e.g. THC or CBD or whole cannabis interventions) both in animals and humans, as well as recent epidemiological studies reporting on anxiolytic or anxiogenic effects from cannabis consumption.

METHOD

The articles selected for this review were identified up to January 2020 through searches in the electronic databases OVID MEDLINE, Cochrane Central Register of Controlled Trials, PubMed, and PsycINFO.

RESULTS

Acute doses of CBD were found to reduce anxiety both in animals and humans, without having an anxiogenic effect at higher doses. Epidemiological studies tend to support an anxiolytic effect from the consumption of either  CBD or THC, as well as whole plant cannabis. Conversely, the available human clinical studies demonstrate a common anxiogenic response to THC (especially at higher doses).

CONCLUSION

Based on current data, cannabinoid therapies (containing primarily CBD) may provide a more suitable treatment for people with pre-existing anxiety or as a potential adjunctive role in managing anxiety or stress-related disorders. However, further research is needed to explore other cannabinoids and phytochemical constituents present in cannabis (e.g. terpenes) as anxiolytic interventions. Future clinical trials involving patients with anxiety disorders are warranted due to the small number of available human studies.

Heteromer formation between cannabinoid type 1 and dopamine type 2 receptors is altered by combination cannabinoid and antipsychotic treatments

The cannabinoid type 1 (CB₁ ) receptor and the dopamine type 2 (D₂ ) receptor are co-localized on medium spiny neuron terminals in the globus pallidus where they modulate neural circuits involved in voluntary movement. Physical interactions between the two receptors have been shown to alter receptor signaling in cell culture. The objectives of the current study were to identify the presence of CB₁ /D₂ heteromers in the globus pallidus of C57BL/6J male mice, define how CB₁ /D₂ heteromer levels are altered following treatment with cannabinoids and/or antipsychotics, and determine if fluctuating levels of CB₁ /D₂ heteromers have functional consequences. Using in situ proximity ligation assays, we observed CB₁ /D₂ heteromers in the globus pallidus of C57BL/6J mice. The abundance of the heteromers increased following treatment with the nonselective cannabinoid receptor agonist, CP55,940. In contrast, treatment with the typical antipsychotic haloperidol reduced the number of CB₁ /D₂ heteromers, whereas the atypical antipsychotic olanzapine treatment had no effect. Co-treatment with CP55,940 and haloperidol had similar effects to haloperidol alone, whereas co-treatment with CP55,940 and olanzapine had similar effects to CP55,940. The observed changes were found to have functional consequences as the differential effects of haloperidol and olanzapine also applied to γ-aminobutyric acid release in STHdh^Q7/Q7 cells and motor function in C57BL/6J male mice. This work highlights the clinical relevance of co-exposure to cannabinoids and different antipsychotics over acute and prolonged time periods.

The short-acting synthetic cannabinoid AB-FUBINACA induces physical dependence in mice

BACKGROUND

Recent years have seen a rise in the diversity and use of synthetic cannabinoids. The present study evaluated the behavioral effects of the third-generation indazole-3-carboxamide-type synthetic cannabinoid, AB-FUBINACA.

METHODS

Adult male and female C57BL/6J mice were treated with AB-FUBINACA (0-3 mg/kg, i.p.) and tested repeatedly in the tetrad battery measuring catalepsy, antinociception, hypothermia, and locomotor activity. Mice treated with AB-FUBINACA (≥2 mg/kg, i.p.) displayed classic cannabinoid effects in the tetrad that were blocked by the CB₁ receptor selective antagonist rimonabant. To address tolerance and withdrawal effects, a second group of mice was injected with AB-FUBINACA (3 mg/kg, s.c.) or vehicle consisting of 5% ethanol, 5% Kolliphor EL, and 90 % saline every 12 h and tested daily in modified tetrad over the course of 5 days. On the 6th day, withdrawal was precipitated using rimonabant (3 mg/kg, s.c.), and somatic signs of withdrawal (i.e., head twitches and paw tremors) were quantified.

RESULTS

Although mice did not develop tolerance to AB-FUBINACA or cross-tolerance to Δ⁹-tetrahydrocannabinol (THC; 50 mg/kg, i.p.), somatic precipitated withdrawal signs were observed. Repeated tetrad testing up to 48 h post injection indicated that AB-FUBINACA effects are relatively short-lived, as compared with THC. Brain levels of AB-FUBINACA, as quantified by UHPLC-MS/MS, were undetectable 4 h post injection.

CONCLUSIONS

These data indicate that the cannabinoid effects of AB-FUBINACA are relatively short-lived, yet sufficient to induce dependence in mice.

Cannabis Extract CT-921 Has a High Efficacy-Adverse Effect Profile in a Neuropathic Pain Model

Background

Legalization of cannabis encourages the development of specific cultivars to treat disease such as neuropathic pain. Because of the large number of cultivars, it is necessary to prioritize extracts before proceeding to clinical trials.

Purpose

To compare extracts of two unique cannabis cultivars (CT-921, CT-928) for treatment of neuropathic pain induced by constriction of sciatic nerve in mice and to illustrate the use of this animal model to set priority for future trials.

Methods

Pain severity was measured by threshold force causing paw withdrawal. Dose-response relationships and time course were determined for intravenously injected extracts of cultivars and vehicle. The doses for allodynia relief were correlated with decreased respiratory rate, temperature and behavioral changes.

Results

Effective analgesic dose for 50 and 95% (ED_50An and ED_95An) was 15, and 29 mg/kg for CT-921 and 0.9 and 4.7 for CT-928. At ED_50An, for both extracts, the duration was 120 min. At ED_95An, administration of CT-928 significantly decreased respiratory rate while CT-921 did not. CT-928 decreased temperature more than CT-921. CT-928 produced frantic hyperactivity not seen with CT-921. At equivalent analgesic doses, THC was much less in CT-921 than in CT-928 suggesting interactions with components other than THC influenced the analgesia. At equivalent analgesic doses, efficacy-to-adverse effect profile for CT-928 was worse than for CT-921.

Conclusion

Both extracts relieved neuropathic pain; however, CT-921 had a better efficacy-to-adverse effect profile, a rational basis for prioritizing cultivars for future clinical evaluation.

Effects of chronic nicotine exposure on Δ9-tetrahydrocannabinol-induced locomotor activity and neural activation in male and female adolescent and adult rats

RATIONALE

High rates of comorbid tobacco and cannabis use in adolescents and young adults may be related to functional interactions between the nicotinic cholinergic and cannabinoid systems in the brain during development. This study examined the effects of chronic exposure to nicotine (the psychoactive component in tobacco) on acute exposure to delta-9-tetrahydrocannabinol (THC) (the psychoactive component of cannabis).

METHODS

Male and female adolescent and adult Sprague-Dawley rats (N = 112) were injected daily with nicotine (1 mg/kg, i.p.) or vehicle for 14 days, followed by a 14-day drug-free period. On test day, rats were injected with THC (5 mg/kg, i.p.) or vehicle, locomotor activity was recorded for 2 h, and brains harvested for c-Fos immunoreactivity (IR).

RESULTS

Locomotor activity and c-Fos IR changes induced by THC challenge were altered by nicotine pre-exposure and modified by age and sex. THC-induced suppression of locomotor activity was attenuated by nicotine pre-exposure in adult but not adolescent males. THC-induced suppression of locomotor activity was potentiated by nicotine pre-exposure in female adolescents, with no effects of THC or nicotine observed in female adults. THC increased c-Fos IR in the caudate, nucleus accumbens, stria terminalis, septum, amygdala, hypothalamus, and thalamus. Nicotine pre-exposure potentiated this effect in all regions. Several brain regions showed age and sex differences in c-Fos IR such that expression was greater in adults than adolescents and in females than males.

CONCLUSIONS

Chronic nicotine pre-exposure produces lasting effects on cannabinoid-mediated signalling in the brain and on behaviour that are mediated by age and sex.

FUNDING SUPPORT

NSERC.

Chronic nicotine exposure attenuates the effects of Δ9 -tetrahydrocannabinol on anxiety-related behavior and social interaction in adult male and female rats

INTRODUCTION

Anxiogenic and anxiolytic effects of cannabinoids are mediated by different mechanisms, including neural signaling via cannabinoid receptors (CBRs) and nicotinic cholinergic receptors (nAChRs). This study examined the effects of prior nicotine (the psychoactive component in tobacco) exposure on behavioral sensitivity to delta-9-tetrahydrocannabinol (THC; the psychoactive component of cannabis) challenge in animals.

METHODS

Male and female adult Sprague-Dawley rats (N = 96) were injected daily with nicotine (1 mg/kg, i.p.) or vehicle for 14 days, followed by a 14-day drug-free period. On test day, rats were injected with THC (0.5, 2.0, or 5.0 mg/kg, i.p.) or vehicle and anxiety-related behavior was assessed in the emergence (EM), elevated plus maze (EPM), and social interaction (SI) tests.

RESULTS

Chronic nicotine pretreatment attenuated some of the anxiogenic effects induced by THC challenge which can be summarized as follows: (a) THC dose-dependently affected locomotor activity, exploratory behavior, and social interaction in the EM, EPM, and SI tests of unconditioned anxiety; (b) these effects of acute THC challenge were greater in females compared with males except for grooming a conspecific; (c) prior nicotine exposure attenuated the effects of acute THC challenge for locomotor activity in the EPM test; and (d) prior nicotine exposure attenuated the effects of THC challenge for direct but not indirect physical interaction in the SI tests.

CONCLUSIONS

The ability of nicotine prior exposure to produce long-lasting changes that alter the effects of acute THC administration suggests that chronic nicotine may induce neuroplastic changes that influence the subsequent response to novel THC exposure.

Vaporized Cannabis differentially modulates sexual behavior of female rats according to the dose

Studies exploring the effect of compounds that modulate the endocannabinoid system on sexual behavior have yielded contradictory results. However, the effect of smoked Cannabis in women has been consistently associated with an increase in sexual drive. Therefore, it can be speculated that vaporized Cannabis will augment sexually motivated components of the sexual behavior of female rats. To test this hypothesis, we compared the sexual behavior of late-proestrous female rats in a bilevel chamber after vaporizing 0, 200 or 400 mg of Cannabis flowers (containing 18% of delta-9-THC and undetectable levels of cannabidiol) during 10 min. We found that both doses of Cannabis increased the duration of the lordosis response, whereas the highest dose also reduced the lordosis quotient of females. The lowest dose of Cannabis augmented the display of hops and darts without altering the expression of sexual solicitations of females, while the highest one did not affect the expression of hops and darts but reduced sexual solicitations. These effects were not accompanied by alterations of females' ambulatory behavior. The increment of the duration of lordosis response produced by both doses of Cannabis could be associated to a general effect of this drug in sensory processing, as can be an enhancement of females' sensory reactivity to male's stimulation. However, the reduction in the display of solicitations and lordosis in response to mounting observed in females exposed to the highest dose when compared to control and 200 mg of Cannabis groups indicates a reduction of sexual receptivity and motivation. This differential effect of vaporized Cannabis according to the dose employed, suggests that it modulates sexual behavior in a complex way, impacting neural circuits that control different aspects of this social behavior.

Assessment of Acute Motor Effects and Tolerance Following Self-Administration of Alcohol and Edible ∆9 -Tetrahydrocannabinol in Adolescent Male Mice

BACKGROUND

Cannabinoids and their principle psychoactive target, the cannabinoid type 1 receptor (CB1R), impact a number of alcohol-related properties, and although alcohol and cannabis are often co-used, particularly in adolescence, few animal models of this phenomenon exist. We modeled the co-use of alcohol and ∆⁹ -tetrahydrocannabinol (THC) in adolescent mice using ingestive methods popular during this developmental period in humans, namely binge-drinking and edible THC. With this model, we assessed levels of use, acute effects, and tolerance to each substance.

METHODS

Adolescent male C57BL/6J mice had daily, limited access to 1 of 2 edible doughs (THC or control), to 1 of 2 fluids (ethanol (EtOH) or water), and in 1 of 2 orders (dough-fluid or fluid-dough). Home cage locomotor activity was recorded both during access and after access. On the day following the final access session, a subset of mice were assessed for functional and metabolic tolerance to alcohol using accelerating rotarod and blood EtOH concentrations, respectively. The remaining mice were assessed for tolerance to THC-induced hypothermia, and whole-brain CB1R expression was assessed in all mice.

RESULTS

EtOH intake was on par with levels previously reported in adolescent mice. Edible THC was well-consumed, but consumption decreased at the highest dose provided. Locomotor activity increased following EtOH intake and decreased following edible THC consumption, and edible THC increased fluid intake in general. The use of alcohol produced neither functional nor metabolic tolerance to an alcohol challenge. However, the use of edible THC impaired subsequent drug-free rotarod performance and was associated with a reduction in THC's hypothermic effect.

CONCLUSIONS

Adolescent mice self-administered both alcohol and edible THC to a degree sufficient to acutely impact locomotor activity. However, only edible THC consumption had lasting effects during short-term abstinence. Thus, this adolescent co-use model could be used to explore sex differences in self-administration and the impact substance co-use might have on other domains such as mood and cognition.

Biological bases for a possible effect of cannabidiol in Parkinson's disease

Current pharmacotherapy of Parkinson’s disease (PD) is palliative and unable to modify the progression of neurodegeneration. Treatments that can improve patients’ quality of life with fewer side effects are needed, but not yet available. Cannabidiol (CBD), the major non-psychotomimetic constituent of cannabis, has received considerable research attention in the last decade. In this context, we aimed to critically review the literature on potential therapeutic effects of CBD in PD and discuss clinical and preclinical evidence supporting the putative neuroprotective mechanisms of CBD. We searched MEDLINE (via PubMed) for indexed articles published in English from inception to 2019. The following keywords were used: cannabis; cannabidiol and neuroprotection; endocannabinoids and basal ganglia; Parkinson’s animal models; Parkinson’s history; Parkinson’s and cannabidiol. Few studies addressed the biological bases for the purported effects of CBD on PD. Six preclinical studies showed neuroprotective effects, while three targeted the antidyskinetic effects of CBD. Three human studies have tested CBD in patients with PD: an open-label study, a case series, and a randomized controlled trial. These studies reported therapeutic effects of CBD on non-motor symptoms. Additional research is needed to elucidate the potential effectiveness of CBD in PD and the underlying mechanisms involved.

Voluntary oral consumption of Δ9-tetrahydrocannabinol by adolescent rats impairs reward-predictive cue behaviors in adulthood

Few preclinical approaches are available to study the health impact of voluntary consumption of edibles containing the psychoactive drug Δ⁹-tetrahydrocannabinol (THC). We developed and validated such approach by measuring voluntary oral consumption of THC-containing gelatin by rats and used it to study if and how THC consumption during adolescence impacts adult behavior. We found that adolescent rats of both sexes consumed enough THC to trigger acute hypothermia, analgesic, and locomotor responses, and that 15 days of access to THC-gelatin in adolescence resulted in the down-regulation of cannabinoid 1 receptors (CB₁Rs) in adulthood in a sex and brain area specific manner. Remarkably, THC consumption by adolescent male rats and not female rats led to impaired Pavlovian reward-predictive cue behaviors in adulthood consistent with a male-specific loss of CB₁R-expressing vGlut-1 synaptic terminals in the ventral tegmental area (VTA). Thus, voluntary oral consumption of THC during adolescence is associated with sex-dependent behavioral impairment in adulthood.

The Endocannabinoid System as a Target in Cancer Diseases: Are We There Yet?

The endocannabinoid system (ECS) has been placed in the anti-cancer spotlight in the last decade. The immense data load published on its dual role in both tumorigenesis and inhibition of tumor growth and metastatic spread has transformed the cannabinoid receptors CB1 (CB1R) and CB2 (CB2R), and other members of the endocannabinoid-like system, into attractive new targets for the treatment of various cancer subtypes. Although the clinical use of cannabinoids has been extensively documented in the palliative setting, clinical trials on their application as anti-cancer drugs are still ongoing. As drug repurposing is significantly faster and more economical than de novo introduction of a new drug into the clinic, there is hope that the existing pharmacokinetic and safety data on the ECS ligands will contribute to their successful translation into oncological healthcare. CB1R and CB2R are members of a large family of membrane proteins called G protein-coupled receptors (GPCR). GPCRs can form homodimers, heterodimers and higher order oligomers with other GPCRs or non-GPCRs. Currently, several CB1R and CB2R-containing heteromers have been reported and, in cancer cells, CB2R form heteromers with the G protein-coupled chemokine receptor CXCR4, the G protein-coupled receptor 55 (GPR55) and the tyrosine kinase receptor (TKR) human V-Erb-B2 Avian Erythroblastic Leukemia Viral Oncogene Homolog 2 (HER2). These protein complexes possess unique pharmacological and signaling properties, and their modulation might affect the antitumoral activity of the ECS. This review will explore the potential of the endocannabinoid network in the anti-cancer setting as well as the clinical and ethical pitfalls behind it, and will develop on the value of cannabinoid receptor heteromers as potential new targets for anti-cancer therapies and as prognostic biomarkers.

Combined ∆9-tetrahydrocannabinol and moderate alcohol administration: effects on ingestive behaviors in adolescent male rats

RATIONALE

Whereas co-use of alcohol and marijuana is prevalent in adolescents, the effects of such drug co-exposure on ingestive and cognitive behaviors remain largely unexplored. We hypothesized that co-exposure to alcohol and ∆⁹-tetrahydrocannabinol (THC), the main psychoactive constitute of marijuana, alters feeding behavior and cognition differently from either drug alone.

METHODS

Male rats received daily THC (3-20 mg/kg/day) or oil vehicle through subcutaneous injection or consumption of a cookie with access to saccharin or saccharin-sweetened alcohol during adolescence (P30-45). Barnes maze and sucrose preference tests were applied to assess spatial memory and behavioral flexibility and abstinence-related anhedonia, respectively.

RESULTS

Subcutaneous THC did not affect alcohol intake but dose-dependently increased acute (3 h) chow intake and reduced weight gain. Moderate alcohol consumption reduced the acute hyperphagic effect of subcutaneous THC. By contrast, oral THC at a dose > 5 mg/kg robustly reduced alcohol intake without affecting 3-h chow intake. At this dose, some rats stopped consuming the THC-laced cookies. Furthermore, oral THC reduced weight gain, and co-exposure to alcohol alleviated this effect. Chronic subcutaneous, but not oral, THC reduced sucrose intake during abstinence. Neither treatment impaired cognitive behaviors in the Barnes maze.

CONCLUSION

Moderate alcohol and THC consumption can interact to elicit unique outcomes on ingestive behaviors and energy balance. Importantly, this study established a novel model of voluntary alcohol and THC consumption for studying mechanisms underlying the consequences of adolescent onset co-use of the two drugs.

Selective and Context-Dependent Social and Behavioral Effects of Δ9-Tetrahydrocannabinol in Weakly Electric Fish

Cannabinoid (CB) receptors are widespread in the nervous system and influence a variety of behaviors. Weakly electric fish have been a useful model system in the study of the neural basis of behavior, but we know nothing of the role played by the CB system. Here, we determine the overall behavioral effect of a nonselective CB receptor agonist, namely Δ9-tetrahydrocannabinol (THC), in the weakly electric fish Apte-ronotus leptorhynchus. Using various behavioral paradigms involving social stimuli, we show that THC decreases locomotor behavior, as in many species, and influences communication and social behavior. Across the different experiments, we found that the propensity to emit communication signals (chirps) and seek social interactions was affected in a context-dependent manner. We explicitly tested this hypothesis by comparing the behavioral effects of THC injection in fish placed in a novel versus a familiar social and physical environment. THC-injected fish were less likely to chirp than control fish in familiar situations but not in novel ones. The tendency to be in close proximity to other fish was affected only in novel environments, with control fish clustering more than THC-injected ones. By identifying behaviors affected by CB agonists, our study can guide further comparative and neurophysiological studies of the role of the CB system using a weakly electric fish as a model.

Therapeutic endocannabinoid augmentation for mood and anxiety disorders: comparative profiling of FAAH, MAGL and dual inhibitors

Recent studies have demonstrated anxiolytic potential of pharmacological endocannabinoid (eCB) augmentation approaches in a variety of preclinical models. Pharmacological inhibition of endocannabinoid-degrading enzymes, such as fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), elicit promising anxiolytic effects in rodent models with limited adverse behavioral effects, however, the efficacy of dual FAAH/MAGL inhibition has not been investigated. In the present study, we compared the effects of FAAH (PF-3845), MAGL (JZL184) and dual FAAH/MAGL (JZL195) inhibitors on (1) anxiety-like behaviors under non-stressed and stressed conditions, (2) locomotor activity and body temperature, (3) lipid levels in the brain and (4) cognitive functions. Behavioral analysis showed that PF-3845 or JZL184, but not JZL195, was able to prevent restraint stress-induced anxiety in the light-dark box assay when administered before stress exposure. Moreover, JZL195 treatment was not able to reverse foot shock-induced anxiety-like behavior in the elevated zero maze or light-dark box. JZL195, but not PF-3845 or JZL184, decreased body temperature and increased anxiety-like behavior in the open-field test. Overall, JZL195 did not show anxiolytic efficacy and the effects of JZL184 were more robust than that of PF-3845 in the models examined. These results showed that increasing either endogenous AEA or 2-AG separately produces anti-anxiety effects under stressful conditions but the same effects are not obtained from simultaneously increasing both AEA and 2-AG.

The effect of dronabinol in a male patient with anorexia nervosa suffering from severe acute urge to be physically active

OBJECTIVE

A 27-year-old male suffering from chronic anorexia nervosa was admitted for inpatient psychotherapy suffering from severe urge to be physically active.

METHODS

An off-label treatment with dronabinol was initiated, to reduce his symptoms related to that urge. Several attempts to reduce symptoms including intensive psychotherapy and several psychopharmacological agents had failed in the past.

RESULTS

Following treatment with 7.5 mg dronabinol twice a day, the patient reported a significant reduction in his acute urge to be physically active. Also eating disorder-specific cognitions and compulsive behaviors remitted.

DISCUSSION

Previous studies have applied much lower doses and showed no effect of dronabinol upon the urge to be physically active. Up to date, the patient reported no side effects, especially no psychotropic effects. Implications of this case report are discussed.

Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice

Cannabis-induced acute psychotic-like states (CIAPS) represent a growing health issue, but their underlying neurobiological mechanisms are poorly understood. The use of antipsychotics and benzodiazepines against CIAPS is limited by side effects and/or by their ability to tackle only certain aspects of psychosis. Thus, safer wide-spectrum treatments are currently needed. Although the blockade of cannabinoid type-1 receptor (CB1) had been suggested as a therapeutical means against CIAPS, the use of orthosteric CB1 receptor full antagonists is strongly limited by undesired side effects and low efficacy. The neurosteroid pregnenolone has been recently shown to act as a potent endogenous allosteric signal-specific inhibitor of CB1 receptors. Thus, we tested in mice the potential therapeutic use of pregnenolone against acute psychotic-like effects of Δ⁹-tetrahydrocannabinol (THC), the main psychoactive component of cannabis. We found that pregnenolone blocks a wide spectrum of THC-induced endophenotypes typically associated with psychotic-like states, including impairments in cognitive functions, somatosensory gating and social interaction. In order to capture THC-induced positive psychotic-like symptoms (e.g. perceptual delusions), we adapted a behavioral paradigm based on associations between different sensory modalities and selective devaluation, allowing the measurement of mental sensory representations in mice. Acting at hippocampal CB1 receptors, THC impaired the correct processing of mental sensory representations (reality testing) in an antipsychotic- and pregnenolone-sensitive manner. Overall, this work reveals that signal-specific inhibitors mimicking pregnenolone effects can be considered as promising new therapeutic tools to treat CIAPS.

Single and combined effects of Δ9 -tetrahydrocannabinol and cannabidiol in a mouse model of chemotherapy-induced neuropathic pain

BACKGROUND AND PURPOSE

The non-psychoactive phytocannabinoid cannabidiol (CBD) can affect the pharmacological effects of Δ⁹ -tetrahydrocannabinol (THC). We tested the possible synergy between CBD and THC in decreasing mechanical sensitivity in a mouse model of paclitaxel-induced neuropathic pain. We also tested the effects of CBD on oxaliplatin- and vincristine-induced mechanical sensitivity.

EXPERIMENTAL APPROACH

Paclitaxel-treated mice (8.0 mg·kg^-1 i.p., days 1, 3, 5 and 7) were pretreated with CBD (0.625-20.0 mg·kg^-1 i.p.), THC (0.625-20.0 mg·kg^-1 i.p.) or CBD + THC (0.04 + 0.04-20.0 + 20.0 mg·kg^-1 i.p.), and mechanical sensitivity was assessed on days 9, 14 and 21. Oxaliplatin-treated (6.0 mg·kg^-1 i.p., day 1) or vincristine-treated mice (0.1 mg·kg^-1 i.p. days 1-7) were pretreated with CBD (1.25-10.0 mg·kg^-1 i.p.), THC (10.0 mg·kg^-1 i.p.) or THC + CBD (0.16 mg·kg^-1 THC + 0.16 mg·kg^-1 CBD i.p.).

KEY RESULTS

Both CBD and THC alone attenuated mechanical allodynia in mice treated with paclitaxel. Very low ineffective doses of CBD and THC were synergistic when given in combination. CBD also attenuated oxaliplatin- but not vincristine-induced mechanical sensitivity, while THC significantly attenuated vincristine- but not oxaliplatin-induced mechanical sensitivity. The low dose combination significantly attenuated oxaliplatin- but not vincristine-induced mechanical sensitivity.

CONCLUSIONS AND IMPLICATIONS

CBD may be potent and effective at preventing the development of chemotherapy-induced peripheral neuropathy, and its clinical use may be enhanced by co-administration of low doses of THC. These treatment strategies would increase the therapeutic window of cannabis-based pharmacotherapies.

The current status of artisanal cannabis for the treatment of epilepsy in the United States

The widespread patient use of artisanal cannabis preparations has preceded quality validation of cannabis use for epilepsy. Neurologists and cannabinoid specialists are increasingly in a position to monitor and guide the use of herbal cannabis in epilepsy patients. We report the retrospective data on efficacy and adverse effects of artisanal cannabis in Patients with medically refractory epilepsy with mixed etiologies in Washington State, California, and Maine. Clinical considerations, including potential risks and benefits, challenges related to artisanal preparations, and cannabinoid dosing, are discussed.

RESULTS

Of 272 combined patients from Washington State and California, 37 (14%) found cannabis ineffective at reducing seizures, 29 (15%) experienced a 1-25% reduction in seizures, 60 (18%) experienced a 26-50% reduction in seizures, 45 (17%) experienced a 51-75% reduction in seizures, 75 (28%) experienced a 76-99% reduction in seizures, and 26 (10%) experienced a complete clinical response. Overall, adverse effects were mild and infrequent, and beneficial side effects such as increased alertness were reported. The majority of patients used cannabidiol (CBD)-enriched artisanal formulas, some with the addition of delta-9-tetrahydrocannabinol (THC) and tetrahydrocannabinolic acid (THCA). Four case reports are included that illustrate clinical responses at doses <0.1mg/kg/day, biphasic dose-response effects, the use of THCA for seizure prevention, the use of THC for seizure rescue, and the synergy of cannabinoids and terpenoids in artisanal preparations. This article is part of a Special Issue entitled "Cannabinoids and Epilepsy".

Circulating levels of endocannabinoids respond acutely to voluntary exercise, are altered in mice selectively bred for high voluntary wheel running, and differ between the sexes

The endocannabinoid system serves many physiological roles, including in the regulation of energy balance, food reward, and voluntary locomotion. Signaling at the cannabinoid type 1 receptor has been specifically implicated in motivation for rodent voluntary exercise on wheels. We studied four replicate lines of high runner (HR) mice that have been selectively bred for 81 generations based on average number of wheel revolutions on days five and six of a six-day period of wheel access. Four additional replicate lines are bred without regard to wheel running, and serve as controls (C) for random genetic effects that may cause divergence among lines. On average, mice from HR lines voluntarily run on wheels three times more than C mice on a daily basis. We tested the general hypothesis that circulating levels of endocannabinoids (i.e., 2-arachidonoylglycerol [2-AG] and anandamide [AEA]) differ between HR and C mice in a sex-specific manner. Fifty male and 50 female mice were allowed access to wheels for six days, while another 50 males and 50 females were kept without access to wheels (half HR, half C for all groups). Blood was collected by cardiac puncture during the time of peak running on the sixth night of wheel access or no wheel access, and later analyzed for 2-AG and AEA content by ultra-performance liquid chromatography coupled to tandem mass spectrometry. We observed a significant three-way interaction among sex, linetype, and wheel access for 2-AG concentrations, with females generally having lower levels than males and wheel access lowering 2-AG levels in some but not all subgroups. The number of wheel revolutions in the minutes or hours immediately prior to sampling did not quantitatively predict plasma 2-AG levels within groups. We also observed a trend for a linetype-by-wheel access interaction for AEA levels, with wheel access lowering plasma concentrations of AEA in HR mice, while raising them in C mice. In addition, females tended to have higher AEA concentrations than males. For mice housed with wheels, the amount of running during the 30min before sampling was a significant positive predictor of plasma AEA within groups, and HR mice had significantly lower levels of AEA than C mice. Our results suggest that voluntary exercise alters circulating levels of endocannabinoids, and further demonstrate that selective breeding for voluntary exercise is associated with evolutionary changes in the endocannabinoid system.

Interactions between the endocannabinoid and nicotinic cholinergic systems: preclinical evidence and therapeutic perspectives

RATIONALE

Several lines of evidence suggest that endocannabinoid and nicotinic cholinergic systems are implicated in the regulation of different physiological processes, including reward, and in the neuropathological mechanisms of psychiatric diseases, such as addiction. A crosstalk between these two systems is substantiated by the overlapping distribution of cannabinoid and nicotinic acetylcholine receptors in many brain structures.

OBJECTIVE

We will review recent preclinical data showing how the endocannabinoid and nicotinic cholinergic systems interact bidirectionally at the level of the brain reward pathways, and how this interaction plays a key role in modulating nicotine and cannabinoid intake and dependence.

RESULTS

Many behavioral and neurochemical effects of nicotine that are related to its addictive potential are reduced by pharmacological blockade or genetic deletion of type-1 cannabinoid receptors, inhibition of endocannabinoid uptake or metabolic degradation, and activation of peroxisome proliferator-activated-receptor-α. On the other hand, cholinergic antagonists at α7 nicotinic acetylcholine receptors as well as endogenous negative allosteric modulators of these receptors are effective in blocking dependence-related effects of cannabinoids.

CONCLUSIONS

Pharmacological manipulation of the endocannabinoid system and endocannabinoid-like neuromodulators shows promise in the treatment of nicotine dependence and in relapse prevention. Likewise, drugs acting at nicotinic acetylcholine receptors might prove useful in the therapy of cannabinoid dependence. Research by Steven R. Goldberg has significantly contributed to the progress in this research field.

The hippocampal NMDA receptors may be involved in acquisition, but not expression of ACPA-induced place preference

Numerous studies have investigated the functional interactions between the endocannabinoid and glutamate systems in the hippocampus. The present study was made to test whether N-methyl-D-aspartate (NMDA) receptors of the CA1 region of the dorsal hippocampus (CA1) are implicated in ACPA (a selective cannabinoid CB1 receptor agonist)-induced place preference. Using a 3-day schedule of conditioning, it was found that intraperitoneal (i.p.) administration of ACPA (0.02mg/kg) caused a significant conditioned place preference (CPP) in male albino NMRI mice. Intra-CA1 microinjection of the NMDA or D-[1]-2-amino-7-Phosphonoheptanoic acid (D-AP7, NMDA receptor antagonist), failed to induce CPP or CPA (condition place aversion), while NMDA (0.5μg/mouse) potentiated the ACPA (0.01mg/kg)-induced CPP; and D-AP7 (a specific NMDA receptor antagonist; 0.5 and 1μg/mouse) reversed the ACPA (0.02mg/kg)-induced CPP. Moreover, microinjection of different doses of glutamatergic agents on the testing day did not alter the expression of ACPA-induced place preference. None of the treatments, with the exception of ACPA (0.04mg/kg), had an effect on locomotor activity. In conclusion, these observations provide evidence that glutamate NMDA receptors of the CA1 may be involved in the potentiation of ACPA rewarding properties in the acquisition, but not expression, of CPP in mice.

Assessment of the Abuse Liability of Synthetic Cannabinoid Agonists JWH-030, JWH-175, and JWH-176

The emergence and use of synthetic cannabinoids have greatly increased in recent years. These substances are easily dispensed over the internet and on the streets. Some synthetic cannabinoids were shown to have abuse liability and were subsequently regulated by authorities. However, there are compounds that are still not regulated probably due to the lack of abuse liability studies. In the present study, we assessed the abuse liability of three synthetic cannabinoids, namely JWH-030, JWH-175, and JWH-176. The abuse liability of these drugs was evaluated in two of the most widely used animal models for assessing the abuse potential of drugs, the conditioned place preference (CPP) and self-administration (SA) test. In addition, the open-field test was utilized to assess the effects of repeated (7 days) treatment and abrupt cessation of these drugs on the psychomotor activity of animals. Results showed that JWH-175 (0.5 mg/kg), but not JWH-030 or JWH-176 at any dose, significantly decreased the locomotor activity of mice. This alteration in locomotor activity was only evident during acute exposure to the drug and was not observed during repeated treatment and abstinence. Similarly, only JWH-175 (0.1 mg/kg) produced significant CPP in rats. On the other hand, none of the drugs tested was self-administered by rats. Taken together, the present results indicate that JWH-175, but not JWH-030 and JWH-176, may have abuse potential. More importantly, our findings indicate the complex psychopharmacological effects of synthetic cannabinoids and the need to closely monitor the production, dispensation, and use of these substances.

Cannabinoid CB1 receptors mediate the effects of dipyrone

Dipyrone is a non-steroidal anti-inflammatory drug used primarily as an analgesic and antipyretic. Some hypothesize that dipyrone activity can modulate other pathways, including endocannabinoid signalling. Thus, the aim of the present study was to evaluate the possible role of endocannabinoids in mediating dipyrone activity. This study is based on the tetrad effects of cannabinoids, namely an antinociceptive and cataleptic state, hypolocomotion and hypothermia. Dipyrone (500 mg/kg, i.p.) treatment decreased locomotor activity, increased the latency to a thermal analgesic response and induced a cataleptic and hypothermic state. These reactions are similar to the tetrad effects caused by the cannabinoid agonist WIN 55,212-2 (3 mg/kg, i.p.). The cannabinoid CB1 receptor antagonist AM251 (10 mg/kg, i.p.) reversed the effects of dipyrone on locomotor activity, the cataleptic response and thermal analgesia. Both AM251 (10 mg/kg, i.p.) and the transient receptor potential vanilloid 1 (TRPV1) antagonist capsazepine (10 mg/kg, i.p.) accentuated the reduction in body temperature caused by dipyrone. However, the CB2 receptor antagonist AM630 did not alter the hypothermic response to dipyrone. These results indicate involvement of the endocannabinoid system, especially CB1 receptors, in the analgesic and cataleptic effects of dipyrone, as well as hypolocomotion. However, cannabinoid receptors and TRPV1 were not involved in the hypothermic effects of dipyrone. We hypothesize that the mechanism of action of dipyrone may involve inhibition of cyclo-oxygenase and fatty acid amide hydrolase, which together provide additional arachidonic acid as substrate for endocannabinoid synthesis or other related molecules. This increase in endocannabinoid availability enhances CB1 receptor stimulation, contributing to the observed effects.

Role of cannabinoidergic system on food intake in neonatal layer-type chicken

Central regulatory mechanisms for neurotransmitters of food intake vary among animals. Endocannabinoids have crucial role on central food intake regulation in mammals but its role has not been studied in layer-type chicken. Thus, in this study 6 experiments designed to evaluate effects of intracerebroventricular (ICV) administration of 2-AG (2-Arachidonoylglycerol, selective CB1 receptors agonist), SR141716A (selective CB1 receptors antagonist), JWH015 (selective CB2 receptors agonist), AM630 (selective CB2 receptors antagonist) on feeding behavior in 3 h food deprived neonatal layer-type chickens. In experiment 1, birds ICV injected with control solution and 2-AG (0.25, 0.5 and 1 μg). In experiment 2: control solution, SR141716A (6.25, 12.5 and 25 μg) were ICV injected to birds. In experiment 3 animals received: control solution, SR141716A (6.25 μg), 2-AG (1 μg) and co-injection of SR141716A+2-AG. In experiment 4, chickens received control solution and JWH015 (6.25, 12.5 and 25 μg). In experiment 5, control solution and AM630 (1.25, 2.5 and 5 μg) were injected. In experiment 6, the birds received control solution, AM630 (1.25 μg), JWH015 (25 μg) and co-administration of AM630+JWH015. Then, cumulative food intake was recorded until 120 min after injection. According to the results, 2-AG dose dependently increased cumulative food intake while SR141716A reduced appetite compared to control group (P < 0.05). Injection of 2-AG (1 μg) amplified food intake and its effect minimized by SR141716A (6.25 μg) (P < 0.05). Also, ICV injection of JWH015 (25 μg) dose dependently increased food intake and co-injection of JWH015+AM630 decreased JWH015-induced food intake (P < 0.05). These results suggest CB1 and CB2 receptors have an important role on ingestive behavior in FD3 neonatal layer-type chicken.

Effect of dronabinol therapy on physical activity in anorexia nervosa: a randomised, controlled trial

PURPOSE

The level of physical activity is inappropriately high in up to 80% of the patients suffering of anorexia nervosa (AN), as a result of conscious efforts to lose weight, affect regulation and biological adaptive changes to starvation induced by hypothermia and neuroendocrine mechanisms. The purposes of this paper were to (1) assess the effect of dronabinol-a synthetic cannabinoid agonist-on physical activity in patients with chronic and stable AN, and to (2) unravel the role of leptin and cortisol in this process.

METHODS

This prospective, randomised, double-blind, crossover study was conducted at a specialised care centre for eating disorders. Twenty-four adult women with AN of at least 5-year duration received either the dronabinol-placebo or placebo-dronabinol sequence. Physical activity was monitored during the fourth week of each intervention. Body weight, leptin and urinary free cortisol excretion were measured repeatedly during the trial. Changes in behavioural dimensions related to AN were assessed by Eating Disorder Inventory-2.

RESULTS

The total duration of physical activity did not change, while its average intensity increased by 20% (P = 0.01) during dronabinol therapy, resulting in an increased energy expenditure with 68.2 kcal/day (P = 0.01) above placebo.

CONCLUSIONS

This randomised, double-blind study revealed that cannabinoid agonist treatment was associated with a modest increase in physical activity in adult women with severe and longstanding AN. Additionally, we detected a strong relationship between the circulating levels of leptin and physical activity in these chronically undernourished patients.

Behavioral and neurochemical changes in mesostriatal dopaminergic regions of the rat after chronic administration of the cannabinoid receptor agonist WIN55,212-2

BACKGROUND

The endocannabinoid system interacts extensively with other neurotransmitter systems and has been implicated in a variety of functions, including regulation of basal ganglia circuits and motor behavior. The present study examined the effects of repeated administration of the nonselective cannabinoid receptor 1 agonist WIN55,212-2 on locomotor activity and on binding and mRNA levels of dopamine receptors and transporters and GABAA receptors in mesostriatal dopaminergic regions of the rat.

METHODS

Rats received systemic injections of WIN55,212-2 (0, 0.1, 0.3, or 1mg/kg, intraperitoneally) for 20 consecutive days. Locomotor activity was measured on days 1, 10, and 20. Following the last measurement, rats were euthanized and prepared for in vitro binding and in situ hybridization experiments.

RESULTS

Acutely, 0.3 and 1mg/kg of WIN55,212-2 produced hypolocomotion, which was sustained for the next 2 measurements, compared to vehicle. Repeated administration of WIN55,212-2 decreased the mRNA levels of the D2 autoreceptors in substantia nigra and ventral tegmental area and increased D1 receptor mRNA and binding in nucleus accumbens. Furthermore, both dopamine receptor and transporter binding and mRNA levels were decreased in substantia nigra. Moreover, repeated administration of WIN55,212-2 decreased GABAA receptor binding levels in dorsal striatum and substantia nigra.

CONCLUSIONS

Our data indicate that chronic WIN55,212-2 administration results in sustained effects on locomotor activity, similar to those observed after acute administration, and modulates the dopaminergic and GABAergic systems in a region-, dose-, and neurotransmitter-selective manner.

Chronic THC during adolescence increases the vulnerability to stress-induced relapse to heroin seeking in adult rats

Cannabis derivatives are among the most widely used illicit substances among young people. The addictive potential of delta-9-tetrahydrocannabinol (THC), the major active ingredient of cannabis is well documented in scientific literature. However, the consequence of THC exposure during adolescence on occurrence of addiction for other drugs of abuse later in life is still controversial. To explore this aspect of THC pharmacology, in the present study, we treated adolescent rats from postnatal day (PND) 35 to PND-46 with increasing daily doses of THC (2.5-10mg/kg). One week after intoxication, the rats were tested for anxiety-like behavior in the elevated plus maze (EPM) test. One month later (starting from PND 75), rats were trained to operantly self-administer heroin intravenously. Finally, following extinction phase, reinstatement of lever pressing elicited by the pharmacological stressor, yohimbine (1.25mg/kg) was evaluated. Data revealed that in comparison to controls, animals treated with chronic THC during adolescence showed a higher level of anxiety-like behavior. When tested for heroin (20μg per infusion) self-administration, no significant differences were observed in both the acquisition of operant responding and heroin intake at baseline. Noteworthy, following the extinction phase, administration of yohimbine elicited a significantly higher level of heroin seeking in rats previously exposed to THC. Altogether these findings demonstrate that chronic exposure to THC during adolescence is responsible for heightened anxiety and increased vulnerability to drug relapse in adulthood.

A vapourized Δ(9)-tetrahydrocannabinol (Δ(9)-THC) delivery system part II: comparison of behavioural effects of pulmonary versus parenteral cannabinoid exposure in rodents

INTRODUCTION

Studies of the rewarding and addictive properties of cannabinoids using rodents as animal models of human behaviour often fail to replicate findings from human studies. Animal studies typically employ parenteral routes of administration, whereas humans typically smoke cannabis, thus discrepancies may be related to different pharmacokinetics of parenteral and pulmonary routes of administration. Accordingly, a novel delivery system of vapourized Δ(9)-tetrahydrocannabinol (Δ(9)-THC) was developed and assessed for its pharmacokinetic, pharmacodynamic, and behavioural effects in rodents. A commercially available vapourizer was used to assess the effects of pulmonary (vapourized) administration of Δ(9)-THC and directly compared to parenteral (intraperitoneal, IP) administration of Δ(9)-THC.

METHODS

Sprague-Dawley rats were exposed to pure Δ(9)-THC vapour (1, 2, 5, 10, and 20mg/pad), using a Volcano® vapourizing device (Storz and Bickel, Germany) or IP-administered Δ(9)-THC (0.1, 0.3, 0.5, 1.0mg/kg), and drug effects on locomotor activity, food and water consumption, and cross-sensitization to morphine (5mg/kg) were measured.

RESULTS

Vapourized Δ(9)-THC significantly increased feeding during the first hour following exposure, whereas IP-administered Δ(9)-THC failed to produce a reliable increase in feeding at all doses tested. Acute administration of 10mg of vapourized Δ(9)-THC induced a short-lasting stimulation in locomotor activity compared to control in the first of four hours of testing over 7days of repeated exposure; this chronic exposure to 10mg of vapourized Δ(9)-THC did not induce behavioural sensitization to morphine.

DISCUSSION

These results suggest vapourized Δ(9)-THC administration produces behavioural effects qualitatively different from those induced by IP administration in rodents. Furthermore, vapourized Δ(9)-THC delivery in rodents may produce behavioural effects more comparable to those observed in humans. We conclude that some of the conflicting findings in animal and human cannabinoid studies may be related to pharmacokinetic differences associated with route of administration.

Targeting CB2-GPR55 receptor heteromers modulates cancer cell signaling

The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. Because a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells. Here we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo. These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology.

Biphasic effects of Δ9-tetrahydrocannabinol on brain stimulation reward and motor activity

Δ(9)-tetrahydrocannabinol (Δ(9)-THC), the main psychoactive ingredient of marijuana, has led to equivocal results when tested with the intracranial self-stimulation (ICSS) procedure or the open-field test for motor activity, two behavioural models for evaluating the reward-facilitating and locomotor stimulating effects of drugs of abuse, respectively. Therefore, in the present study, the effects of high and low doses of Δ(9)-THC were compared in the ICSS procedure and the open-field test. Moreover, the involvement of CB(1) receptors in tentative Δ(9)-THC-induced effects was investigated by pre-treating the animals with the CB(1) receptor antagonist SR141716A (rimonabant). The results obtained show that low doses of Δ(9)-THC induce opposite effects from high doses of Δ(9)-THC. Specifically, 0.1 mg/kg Δ(9)-THC decreased ICSS thresholds and produced hyperactivity, whereas 1 mg/kg increased ICSS thresholds and produced hypoactivity. Both effects were reversed by pre-treatment with SR141716A, indicating the involvement of CB(1) receptors on these actions. Altogether, our results indicate that Δ(9)-THC can produce acute activating effects in locomotion that coincide with its reward-facilitating effects in the ICSS paradigm. The present findings provide further support that Δ(9)-THC induces behaviours typical of abuse and substantiate the notion that marijuana resembles other drugs of abuse.

Moving around the molecule: relationship between chemical structure and in vivo activity of synthetic cannabinoids

Originally synthesized for research purposes, indole- and pyrrole-derived synthetic cannabinoids are the most common psychoactive compounds contained in abused products marketed as "spice" or "herbal incense." While CB1 and CB2 receptor affinities are available for most of these research chemicals, in vivo pharmacological data are sparse. In mice, cannabinoids produce a characteristic profile of dose-dependent effects: antinociception, hypothermia, catalepsy and suppression of locomotion. In combination with receptor binding data, this tetrad battery has been useful in evaluation of the relationship between the structural features of synthetic cannabinoids and their in vivo cannabimimetic activity. Here, published tetrad studies are reviewed and additional in vivo data on synthetic cannabinoids are presented. Overall, the best predictor of likely cannabimimetic effects in the tetrad tests was good CB1 receptor affinity. Further, retention of good CB1 affinity and in vivo activity was observed across a wide array of structural manipulations of substituents of the prototypic aminoalkylindole molecule WIN55,212-2, including substitution of an alkyl for the morpholino group, replacement of an indole core with a pyrrole or phenylpyrrole, substitution of a phenylacetyl or tetramethylcyclopropyl group for JWH-018's naphthoyl, and halogenation of the naphthoyl group. This flexibility of cannabinoid ligand-receptor interactions has been a particular challenge for forensic scientists who have struggled to identify and regulate each new compound as it has appeared on the drug market. One of the most pressing future research needs is determination of the extent to which the pharmacology of these synthetic cannabinoids may differ from those of classical cannabinoids.