Sexually dimorphic effects of cannabinoid compounds on emotion and cognition

Cannabidiol improves maternal obesity-induced behavioral, neuroinflammatory and neurochemical dysfunctions in the juvenile offspring

Maternal obesity is associated with an increased risk of psychiatric disorders such as anxiety, depression, schizophrenia and autism spectrum disorder in the offspring. While numerous studies focus on preventive measures targeting the mothers, only a limited number provide practical approaches for addressing the damages once they are already established. We have recently demonstrated the interplay between maternal obesity and treatment with cannabidiol (CBD) on hypothalamic inflammation and metabolic disturbances, however, little is known about this relationship on behavioral manifestations and neurochemical imbalances in other brain regions. Therefore, here we tested whether CBD treatment could mitigate anxiety-like and social behavioral alterations, as well as neurochemical disruptions in both male and female offspring of obese dams. Female Wistar rats were fed a cafeteria diet for 12 weeks prior to mating, and during gestation and lactation. Offspring received CBD (50 mg/kg) from weaning for 3 weeks. Behavioral tests assessed anxiety-like manifestations and social behavior, while neuroinflammatory and neurochemical markers were evaluated in the prefrontal cortex (PFC) and hippocampus. CBD treatment attenuated maternal obesity-induced anxiety-like and social behavioral alterations, followed by rescuing effects on imbalanced neurotransmitter and endocannabinoid concentrations and altered expression of glial markers, CB1, oxytocin and dopamine receptors, with important differences between sexes. Overall, the findings of this study provide insight into the signaling pathways for the therapeutic benefits of CBD on neuroinflammation and neurochemical imbalances caused by perinatal maternal obesity in the PFC and the hippocampus, which translates into the behavioral manifestations, highlighting the sexual dimorphism encompassing both the transgenerational effect of obesity and the endocannabinoid system.

Association Between the Endocannabinoid System-Related Gene Variants and Epilepsy

The endocannabinoid system (ECS) is an intricate network consisting of receptors, enzymes, and endogenous ligands that play a pivotal role in various neurological processes. It has been implicated in the pathophysiology of several neurological disorders, including epilepsy. Extensive research has demonstrated the involvement of genetic factors in influencing the susceptibility to and progression of epilepsy. In this study, we focused on investigating the connection between genetic variations in genes related to the ECS and the occurrence of epilepsy. Some ECS-related gene variants were selected and genotyping was performed using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) technique. Interestingly, CNR1 rs12720071 genotype (OR 16.33, 95% CI 1.8-149; p = 0.001) showed an association with generalized epilepsy and MGLL rs604300 genotype (OR 2, 95% CI 1.1-3.4; p = 0.013) demonstrated a relationship with females diagnosed with focal epilepsy. So, studying CNR1, MGLL, and their genetic variations provides insights into the role of the endocannabinoid system in health and diseases. Moreover, they hold the potential to pave the way for the development of novel therapeutic approaches specifically targeting them.

A case for seeking sex-specific treatments in Alzheimer's disease

There is no satisfactory explanation for the sex-related differences in the incidence of many diseases and this is also true of Alzheimer's disease (AD), where females have a higher lifetime risk of developing the disease and make up about two thirds of the AD patient population. The importance of understanding the cause(s) that account for this disproportionate distribution cannot be overestimated, and is likely to be a significant factor in the search for therapeutic strategies that will combat the disease and, furthermore, potentially point to a sex-targeted approach to treatment. This review considers the literature in the context of what is known about the impact of sex on processes targeted by drugs that are in clinical trial for AD, and existing knowledge on differing responses of males and females to these drugs. Current knowledge strongly supports the view that trials should make assessing sex-related difference in responses a priority with a focus on exploring the sex-stratified treatments.

Anti-allodynic and medullary modulatory effects of a single dose of delta-9-tetrahydrocannabinol (THC) in neuropathic rats tolerant to morphine

Neuropathic pain (NP) is often treated with opioids, the prolonged use of which causes tolerance to their analgesic effect and can potentially cause death by overdose. The phytocannabinoid delta-9-tetrahydrocannabinol (THC) may be an effective alternative analgesic to treat NP in morphine-tolerant subjects. Male Wistar rats developed NP after spared nerve injury, and were then treated with increasing doses of THC (1, 1.5, 2, 2.5, and 5 mg/kg, intraperitoneally), which reduced mechanical allodynia at the dose of 2.5 and 5 mg/kg. Another group of NP rats were treated with morphine (5 mg/kg, twice daily for 7 days, subcutaneously), until tolerance developed, and on day 8 received a single dose of THC (2.5 mg/kg), which significantly reduced mechanical allodynia. To evaluate the modulation of THC in the descending pain pathway, in vivo electrophysiological recordings of pronociceptive ON cells and antinociceptive OFF cells in the rostroventral medulla (RVM) were recorded after intra-PAG microinjection of THC (10 μg/μl). NP rats with morphine tolerance, compared to the control one, showed a tonic reduction of the spontaneous firing rate of ON cells by 44%, but the THC was able to further decrease it (a hallmark of many analgesic drugs acting at supraspinal level). On the other hand, the firing rate, of the antinociceptive OFF cells was increased after morphine tolerance by 133%, but the THC failed to further activate it. Altogether, these findings indicate that a single dose of THC produces antiallodynic effect in individuals with NP who are tolerant to morphine, acting mostly on the ON cells of the descending pain pathways, but not on OFF cells.

Electroacupuncture attenuates inflammatory pain via peripheral cannabinoid receptor type 1 signaling pathway in mice

Pain is strongly associated with neuro-immune activation. Thus, the emerging role of the endocannabinoid system in neuro-inflammation is important. Acupuncture has been used for over 2500 years and is widely accepted for the management of pain. Our study aimed to investigate the effects of electroacupuncture on the regulation of cannabinoid receptor type 1 within the peripheral nervous system. Inflammatory pain was induced by injecting Complete Freund's adjuvant to induce mechanical and thermal hyperalgesia. Electroacupuncture significantly attenuated the mechanical and thermal sensitivities, and AM251, a cannabinoid receptor type 1 antagonist, eliminated these effects. Dual immunofluorescence staining demonstrated that electroacupuncture elevated expression of cannabinoid receptor type 1, co-localized with Nav 1.8. Furthermore, electroacupuncture significantly reduced levels of Nav 1.8 and COX-2 by western blot analysis, but not vice versa as AM251 treatment. Our data indicate that electroacupuncture mediates antinociceptive effects through peripheral endocannabinoid system signaling pathway and provide evidence that electroacupuncture is beneficial for pain treatment.

A Sexually Dimorphic Role for Intestinal Cannabinoid Receptor Subtype-1 in the Behavioral Expression of Anxiety

Background: Increasing evidence suggests that the endocannabinoid system (ECS) in the brain controls anxiety and may be a therapeutic target for the treatment of anxiety disorders. For example, both pharmacological and genetic disruption of cannabinoid receptor subtype-1 (CB1R) signaling in the central nervous system is associated with increased anxiety-like behaviors in rodents, while activating the system is anxiolytic. Sex is also a critical factor that controls the behavioral expression of anxiety; however, roles for the ECS in the gut in these processes and possible differences between sexes are largely unknown. Objective: In this study, we aimed to determine if CB1Rs in the intestinal epithelium exert control over anxiety-like behaviors in a sex-dependent manner. Methods: We subjected male and female mice with conditional deletion of CB1Rs in the intestinal epithelium (intCB1-/-) and controls (intCB1+/+) to the elevated plus maze (EPM), light/dark box, and open field test. Corticosterone (CORT) levels in plasma were measured at baseline and immediately after EPM exposure. Results: When compared with intCB1+/+ male mice, intCB1-/- male mice exhibited reduced levels of anxiety-like behaviors in the EPM and light/dark box. In contrast to male mice, no differences were found between female intCB1+/+ and intCB1-/- mice. Circulating CORT was higher in female versus male mice for both genotype groups at baseline and after EPM exposure; however, there was no effect of genotype on CORT levels. Conclusions: Collectively, these results indicate that genetic deletion of CB1Rs in the intestinal epithelium is associated with an anxiolytic phenotype in a sex-dependent manner.

Cognitive dysfunction and impaired neuroplasticity following repeated exposure to the synthetic cannabinoid JWH-018 in male mice

BACKGROUND AND PURPOSE

Psychotic disorders have been reported in long-term users of synthetic cannabinoids. This study aims at investigating the long-lasting effects of repeated JWH-018 exposure.

EXPERIMENTAL APPROACH

Male CD-1 mice were injected with vehicle, JWH-018 (6 mg·kg-1 ), the CB1 -antagonist NESS-0327 (1 mg·kg-1 ) or co-administration of NESS-0327 and JWH-018, every day for 7 days. After 15 or 16 days washout, we investigated the effects of JWH-018 on motor function, memory, social dominance and prepulse inhibition (PPI). We also evaluated glutamate levels in dialysates from dorsal striatum, striatal dopamine content and striatal/hippocampal neuroplasticity focusing on the NMDA receptor complex and the neurotrophin BDNF. These measurements were accompanied by in vitro electrophysiological evaluations in hippocampal preparations. Finally, we investigated the density of CB1 receptors and levels of the endocannabinoid anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and their main synthetic and degrading enzymes in the striatum and hippocampus.

KEY RESULTS

The repeated treatment with JWH-018 induced psychomotor agitation while reducing social dominance, recognition memory and PPI in mice. JWH-018 disrupted hippocampal LTP and decreased BDNF expression, reduced the synaptic levels of NMDA receptor subunits and decreased the expression of PSD95. Repeated exposure to JWH-018, reduced hippocampal CB1 receptor density and induced a long-term alteration in AEA and 2-AG levels and their degrading enzymes, FAAH and MAGL, in the striatum.

CONCLUSION AND IMPLICATIONS

Our findings suggest that repeated administration of a high dose of JWH-018 leads to the manifestation of psychotic-like symptoms accompanied by alterations in neuroplasticity and change in the endocannabinoid system.

An enquiry to the role of CB1 receptors in neurodegeneration

Neurodegenerative disorders are debilitating conditions that impair patient quality of life and that represent heavy social-economic burdens to society. Whereas the root of some of these brain illnesses lies in autosomal inheritance, the origin of most of these neuropathologies is scantly understood. Similarly, the cellular and molecular substrates explaining the progressive loss of brain functions remains to be fully described too. Indeed, the study of brain neurodegeneration has resulted in a complex picture, composed of a myriad of altered processes that include broken brain bioenergetics, widespread neuroinflammation and aberrant activity of signaling pathways. In this context, several lines of research have shown that the endocannabinoid system (ECS) and its main signaling hub, the type-1 cannabinoid (CB1) receptor are altered in diverse neurodegenerative disorders. However, some of these data are conflictive or poorly described. In this review, we summarize the findings about the alterations in ECS and CB1 receptors signaling in three representative brain illnesses, the Alzheimer's, Parkinson's and Huntington's diseases, and we discuss the relevance of these studies in understanding neurodegeneration development and progression, with a special focus on astrocyte function. Noteworthy, the analysis of ECS defects in neurodegeneration warrant much more studies, as our conceptual understanding of ECS function has evolved quickly in the last years, which now include glia cells and the subcellular-specific CB1 receptors signaling as critical players of brain functions.

Naturalistic examination of the anxiolytic effects of medical cannabis and associated gender and age differences in a Canadian cohort

BACKGROUND

The aim of the current study was to examine patterns of medical cannabis use in those using it to treat anxiety and to investigate if the anxiolytic effects of cannabis were impacted by gender and/or age.

METHODS

Patient-reported data (n = 184 participants, 61% female, 34.7 ± 8.0 years) was collected through the Strainprint^® app. Tracked sessions were included if the method of administration was inhalation, treatment was for anxiety and the product used was dried flower. The final analyzed dataset encompassed three of the most commonly utilized dried flower products in anxiety sessions. Independent sample t-tests were used. The core analysis examined within subject changes overtime (pre-medication to post-medication) and interactions between time with two candidate moderators [gender (male, female) and age (18-29, 30-39, and 40 + years old)] by using analysis of variance (ANOVA). For significant main effects of interactions, post hoc tests were conducted using a Bonferroni correction. A secondary analysis examined differences in proportion of emotives endorsed as a function of gender or age using chi-square test of independence.

RESULTS

Cannabis consumption resulted in a significant decrease in anxiety scores among both males and females (average efficacy of 50%) and efficacy was similar across the three cultivars. However, gender differences in efficacy were identified in two of the cultivars. All age groups experienced significant reductions in their anxiety post cannabis consumption; however, the 40 + year old group had significantly less efficacy than the other groups. The overall optimal dosing for the entire cohort was 9-11 inhalations for males and 5-7 inhalations for females, with some variation in dosing across the different cultivars, genders and age groups.

CONCLUSIONS

We found all three cultivars had significant anxiolytic effects and were well-tolerated. Some limitations of the study are the moderate sample size, self-reported diagnosis of anxiety, unknown comorbidities and experience with cannabis, whether other drugs or cannabis products were used, and restriction to solely inhaled administration. We suggest that the gender and age differences in optimal dosing could support both healthcare practitioners and patients initiate medical cannabis treatment for anxiety.

Cannabidiol's neuroprotective properties and potential treatment of traumatic brain injuries

Cannabidiol (CBD) has numerous pharmacological targets that initiate anti-inflammatory, antioxidative, and antiepileptic properties. These neuroprotective benefits have generated interest in CBD's therapeutic potential against the secondary injury cascade from traumatic brain injury (TBI). There are currently no effective broad treatment strategies for combating the damaging mechanisms that follow the primary injury and lead to lasting neurological consequences or death. However, CBD's effects on different neurotransmitter systems, the blood brain barrier, oxidative stress mechanisms, and the inflammatory response provides mechanistic support for CBD's clinical utility in TBI. This review describes the cascades of damage caused by TBI and CBD's neuroprotective mechanisms to counter them. We also present challenges in the clinical treatment of TBI and discuss important future clinical research directions for integrating CBD in treatment protocols. The mechanistic evidence provided by pre-clinical research shows great potential for CBD as a much-needed improvement in the clinical treatment of TBI. Upcoming clinical trials sponsored by major professional sport leagues are the first attempts to test the efficacy of CBD in head injury treatment protocols and highlight the need for further clinical research.

Age, gender and body-mass-index relationships with in vivo CB1 receptor availability in healthy humans measured with [11C]OMAR PET

Brain cannabinoid 1 receptors (CB1Rs) contribute importantly to the regulation of autonomic tone, appetite, mood and cognition. Inconsistent results have been reported from positron emission tomography (PET) studies using different radioligands to examine relationships between age, gender and body mass index (BMI) and CB1R availability in healthy individuals. In this study, we examined these variables in 58 healthy individuals (age range: 18-55 years; 44 male; BMI=27.01±5.56), the largest cohort of subjects studied to date using the CB1R PET ligand [¹¹C]OMAR. There was a significant decline in CB1R availability (V_T) with age in the pallidum, cerebellum and posterior cingulate. Adjusting for BMI, age-related decline in V_T remained significant in the posterior cingulate among males, and in the cerebellum among women. CB1R availability was higher in women compared to men in the thalamus, pallidum and posterior cingulate. Adjusting for age, CB1R availability negatively correlated with BMI in women but not men. These findings differ from those reported using [¹¹C]OMAR and other radioligands such as [¹⁸F]FMPEP-d₂ and [¹⁸F]MK-9470. Although reasons for these seemingly divergent findings are unclear, the choice of PET radioligand and range of BMI in the current dataset may contribute to the observed differences. This study highlights the need for cross-validation studies using both [¹¹C]OMAR and [¹⁸F]FMPEP-d₂ within the same cohort of subjects.

Endocannabinoid levels in peripheral blood mononuclear cells of multiple sclerosis patients treated with dimethyl fumarate

The endocannabinoid system (ECS), a signalling network with immunomodulatory properties, is a potential therapeutic target in multiple sclerosis (MS). Dimethyl fumarate (DMF) is an approved drug for MS whose mechanism of action has not been fully elucidated; the possibility exists that its therapeutic effects could imply the ECS. With the aim of studying if DMF can modulate the ECS, the endocannabinoids 2-arachidonoylglycerol (2-AG), anandamide (AEA), oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) were determined by liquid chromatography-mass spectrometry in peripheral blood mononuclear cells from 21 healthy donors (HD) and 32 MS patients at baseline and after 12 and 24 months of DMF treatment. MS patients presented lower levels of 2-AG and PEA compared to HD. 2-AG increased at 24 months, reaching HD levels. AEA and PEA remained stable at 12 and 24 months. OEA increased at 12 months and returned to initial levels at 24 months. Patients who achieved no evidence of disease activity (NEDA3) presented the same modulation over time as EDA3 patients. PEA was modulated differentially between females and males. Our results show that the ECS is dysregulated in MS patients. The increase in 2-AG and OEA during DMF treatment suggests a possible role of DMF in ECS modulation.

Evaluating the Antinociceptive Efficacy of Cannabidiol Alone or in Combination with Morphine Using the Formalin Test in Male and Female Mice

Introduction: Phytocannabinoids have emerged as a potential alternative treatment option for individuals experiencing persistent pain. However, evidence-based research regarding their clinical utility in both males and females remains incomplete. In addition, it is unknown whether combining readily available cannabinoids with opioids has a synergistic or subadditive effect on pain modulation. To begin to fill this knowledge gap, we investigated the antinociceptive effects of the phytocannabinoid, CBD, either alone or in combination with opioids in male and female C57BL/6J mice. Results: Using the formalin test, our results show that CBD (10 mg/kg, i.p.) treatment evoked antinociception in phase I, but not in phase II, of the formalin test in male mice. However, in female mice, CBD showed no significant antinociceptive effect. In addition, a direct sex comparison showed that CBD evoked a significant increase in nociceptive behaviors in female versus male mice during phase I of the formalin test. Furthermore, we show that CBD (10 mg/kg, i.p.) in combination with low-dose morphine (1 mg/kg, i.p.) was ineffective at eliciting a synergistic antinociceptive response in both male and female mice. Lastly, consistent with previous literature, we showed that females treated with a relatively higher dose of morphine (10 mg/kg, i.p.) displayed a significant increase in the variability of nociceptive behaviors compared to morphine-treated male mice. Conclusion: Overall, our results suggest that CBD treatment may have beneficial antinociceptive effects during the acute phase of persistent pain, but these effects are more beneficial to males than females. We provide further pre-clinical support that treatments geared toward reducing nociceptive behaviors differentially affect males and females.

Cannabidiol (CBD) drives sex-dependent impairments in omission, but has no effect on reinforcer devaluation

Habits are inflexible behaviors that persist despite changes in outcome value. While habits allow for efficient responding, neuropsychiatric diseases such as drug addiction and obsessive-compulsive disorder are characterized by overreliance on habits. Recently, the commercially popular drug cannabidiol (CBD) has emerged as a potential treatment for addictive behaviors, though it is not entirely clear how it exerts this therapeutic effect. As brain endocannabinoids play a key role in habit formation, we sought to determine how CBD modifies goal-directed behaviors and habit formation. To explore this, mice were administered CBD (20mg/kg i.p.) or vehicle as a control and trained on random interval (RI30/60) or random ratio (RR10/20) schedules designed to elicit habitual or goal-directed lever pressing, respectively. Mice were tested for habitual responding using probe trials following reinforcer-specific devaluation as well as omission trials, where mice had to withhold responding to earn rewards. We found that while CBD had little effect on operant behaviors or reward devaluation, CBD inhibited goal-directed behavior in a sex-specific and contextdependent manner during the omission task. Beyond drug treatment, we found an effect of sex throughout training, reward devaluation, and omission. This work provides evidence that CBD has no effect on habit formation in a reward devaluation paradigm. However, the omission results suggest that CBD may slow learning of novel actionoutcome contingencies or decrease goal-directed behavior. This work calls for further examination of sex-dependent outcomes of CBD treatment and highlights the importance of investigating sex effects in habit-related experiments.

Unexpected short- and long-term effects of chronic adolescent HU-210 exposure on emotional behavior

Chronic adolescent cannabinoid receptor agonist exposure has been shown to lead to persistent increases in depressive-like behaviors. This has been a key obstacle to the development of cannabinoid-based therapeutics. However, most of the published work has been performed with only three compounds, namely Δ9-tetrahydrocannabinol, CP55,940 and WIN55,212-2. Hypothesizing that different compounds may lead to distinct outcomes, we herein used the highly potent CB₁R/CB₂R full agonist HU-210, and first aimed at replicating cannabinoid-induced long-lasting effects, by exposing adolescent female Sprague-Dawley rats to increasing doses of HU-210, for 11 days and testing them at adulthood, after a 30-day drug washout. Surprisingly, HU-210 did not significantly impact adult anxious- or depressive-like behaviors. We then tested whether chronic adolescent HU-210 treatment resulted in short-term (24h) alterations in depressive-like behavior. Remarkably, HU-210 treatment simultaneously induced marked antidepressant- and prodepressant-like responses, in the modified forced swim (mFST) and sucrose preference tests (SPT), respectively. Hypothesizing that mFST results were a misleading artifact of HU-210-induced behavioral hyperreactivity to stress, we assessed plasmatic noradrenaline and corticosterone levels, under basal conditions and following an acute swim-stress episode. Notably, we found that while HU-210 did not alter basal noradrenaline or corticosterone levels, it greatly augmented the stress-induced increase in both. Our results show that, contrary to previously studied cannabinoid receptor agonists, HU-210 does not induce persisting depressive-like alterations, despite inducing marked short-term increases in stress-induced reactivity. By showing that not all cannabinoid receptor agonists may induce long-term negative effects, these results hold significant relevance for the development of cannabinoid-based therapeutics.

Gene Expression Analysis of the Endocannabinoid System in Presymptomatic APP/PS1 Mice

Alzheimer’s disease (AD) is the most common type of dementia and neurodegeneration. The actual cause of AD progression is still unknown and no curative treatment is available. Recently, findings in human samples and animal models pointed to the endocannabinoid system (ECS) as a promising therapeutic approach against AD. However, the specific mechanisms by which cannabinoid drugs induce potential beneficial effects are still undefined. For this reason, it is required a full characterization of the ECS at different time points of AD progression considering important factors such as sex or the analysis of different brain regions to improve future cannabinoid-dependent therapies in AD. Thus, the main aim of the present study is to expand our knowledge of the status of the ECS in a presymptomatic period (3 months of age) using the AD mouse model APP/PS1 mice. First, we evaluated different behavioral domains including anxiety, cognitive functions, and social interactions in male and female APP/PS1 mice at 4 months of age. Although a mild working memory impairment was observed in male APP/PS1 mice, in most of the behaviors assessed we found no differences between genotypes. At 3 months of age, we performed a characterization of the ECS in different brain regions of the APP/PS1 mice considering the sex variable. We assessed the expression of the ECS components by quantitative Real-Time Polymerase Chain Reaction in the hippocampus, prefrontal cortex, hypothalamus, olfactory bulb, and cerebellum. Interestingly, gene expression levels of the type-1 and type-2 cannabinoid receptors and the anabolic and catabolic enzymes, differed depending on the brain region and the sex analyzed. For example, CB1R expression levels decreased in both hippocampus and prefrontal cortex of male APP/PS1 mice but increased in female mice. In contrast, CB2R expression was decreased in females, whereas males tended to have higher levels. Overall, our data indicated that the ECS is already altered in APP/PS1 mice at the presymptomatic stage, suggesting that it could be an early event contributing to the pathophysiology of AD or being a potential predictive biomarker.

Chronic edible dosing of Δ9-tetrahydrocannabinol (THC) in nonhuman primates reduces systemic platelet activity and function

Cannabis usage has steadily increased as acceptance is growing for both medical and recreational reasons. Medical cannabis is administered for treatment of chronic pain based on the premise that the endocannabinoid system signals desensitize pain sensor neurons and produce anti-inflammatory effects. The major psychoactive ingredient of cannabis is Δ9-tetrahydrocannabinol (THC) that signals mainly through cannabinoid receptor-1 (CBr), which is also present on nonneuron cells including blood platelets of the circulatory system. In vitro, CBr-mediated signaling has been shown to acutely inhibit platelet activation downstream of the platelet collagen receptor glycoprotein (GP)VI. The systemic effects of chronic THC administration on platelet activity and function remain unclear. This study investigates the effects of chronic THC administration on platelet function using a nonhuman primate (NHP) model. Our results show that female and male NHPs consuming a daily THC edible had reduced platelet adhesion, aggregation, and granule secretion in response to select platelet agonists. Furthermore, a change in bioactive lipids (oxylipins) was observed in the female cohort after THC administration. These results indicate that chronic THC edible administration desensitized platelet activity and function in response to GPVI- and G-protein coupled receptor-based activation by interfering with primary and secondary feedback signaling pathways. These observations may have important clinical implications for patients who use medical marijuana and for providers caring for these patients.

Early Blockade of CB1 Receptors Ameliorates Schizophrenia-like Alterations in the Neurodevelopmental MAM Model of Schizophrenia

In agreement with the neurodevelopmental hypothesis of schizophrenia, prenatal exposure of Sprague-Dawley rats to the antimitotic agent methylazoxymethanol acetate (MAM) at gestational day 17 produces long-lasting behavioral alterations such as social withdrawal and cognitive impairment in adulthood, mimicking a schizophrenia-like phenotype. These abnormalities were preceded at neonatal age both by the delayed appearance of neonatal reflexes, an index of impaired brain maturation, and by higher 2-arachidonoylglycerol (2-AG) brain levels. Schizophrenia-like deficits were reversed by early treatment [from postnatal day (PND) 2 to PND 8] with the CB1 antagonist/inverse agonist AM251 (0.5 mg/kg/day). By contrast, early CB1 blockade affected the behavioral performance of control rats which was paralleled by enhanced 2-AG content in the prefrontal cortex (PFC). These results suggest that prenatal MAM insult leads to premorbid anomalies at neonatal age via altered tone of the endocannabinoid system, which may be considered as an early marker preceding the development of schizophrenia-like alterations in adulthood.

Persistent sexually dimorphic effects of adolescent THC exposure on hippocampal synaptic plasticity and episodic memory in rodents

There is evidence that cannabis use during adolescence leads to memory and cognitive problems in young adulthood but little is known about effects of early life cannabis exposure on synaptic operations that are critical for encoding and organizing information. We report here that a 14-day course of daily Δ⁹-tetrahydrocannabinol treatments administered to adolescent rats and mice (aTHC) leads to profound but selective deficits in synaptic plasticity in two axonal systems in female, and to lesser extent male, hippocampus as assessed in adulthood. Adolescent-THC exposure did not alter basic synaptic transmission (input/output curves) and had only modest effects on frequency facilitation. Nevertheless, aTHC severely impaired the endocannabinoid-dependent long-term potentiation in the lateral perforant path in females of both species, and in male mice; this was reliably associated with impaired acquisition of a component of episodic memory that depends on lateral perforant path function. Potentiation in the Schaffer-commissural (S-C) projection to field CA1 was disrupted by aTHC treatment in females only and this was associated with both a deficit in estrogen effects on S-C synaptic responses and impairments to CA1-dependent spatial (object location) memory. In all the results demonstrate sexually dimorphic and projection system-specific effects of aTHC exposure that could underlie discrete effects of early life cannabinoid usage on adult cognitive function. Moreover they suggest that some of the enduring, sexually dimorphic effects of cannabis use reflect changes in synaptic estrogen action.

Pharmacokinetic and pharmacodynamic properties of aerosolized ("vaped") THC in adolescent male and female rats

RATIONALE

Adolescent exposure to ∆9-tetrahydrocannabinol (THC), the psychotropic constituent of cannabis, might affect brain development, and in rodent models leads to long-term behavioral and physiological alterations. Yet, the basic pharmacology of this drug in adolescent rodents, especially when ingested via ecologically relevant routes like aerosol inhalation, commonly referred to as "vaping," is still poorly characterized. Moreover, sex differences exist in THC metabolism, kinetics, and behavioral effects, but these have not been rigorously examined after vapor dosing in adolescents.

OBJECTIVES

We investigated the pharmacokinetics and pharmacodynamics of aerosolized THC (30 min inhalation exposure, 25 or 100 mg/ml) in adolescent Wistar rats of both sexes.

METHODS

Liquid chromatography/mass spectrometry analysis of THC and its major metabolites was conducted on blood plasma and brain tissue at 5, 30, 60, and 120 min following a 30-min aerosol dosing session. Effects on activity in a novel environment for 120 min after aerosol, and temperature, were measured in separate rats.

RESULTS

We found sex-dependent differences in the pharmacokinetics of THC and its active (11-OH-THC) and inactive (11-COOH-THC) metabolites in the blood and brain, along with dose- and sex-dependent effects on anxiety-like and exploratory behaviors; namely, greater 11-OH-THC levels accompanied by greater behavioral effects in females at the low dose but similar hypothermic effects in both sexes at the high dose.

CONCLUSIONS

These results provide a benchmark for dosing adolescent rats with aerosolized (or "vaped") THC, which could facilitate adoption by other labs of this potentially human-relevant THC exposure model to understand cannabis effects on the developing brain.

Translation of animal endocannabinoid models of PTSD mechanisms to humans: Where to next?

The endocannabinoid system is known to be involved in mechanisms relevant to PTSD aetiology and maintenance, though this understanding is mostly based on animal models of the disorder. Here we review how human paradigms can successfully translate animal findings to human subjects, with the view that substantially increased insight into the effect of endocannabinoid signalling on stress responding, emotional and intrusive memories, and fear extinction can be gained using modern paradigms and methods for assessing the state of the endocannabinoid system in PTSD.

Maternal obesity reverses the resistance to LPS-induced adverse pregnancy outcome and increases female offspring metabolic alterations in cannabinoid receptor 1 knockout mice

Maternal overnutrition negatively impacts the offspring's health leading to an increased risk of developing chronic diseases or metabolic syndrome in adulthood. What we eat affects the endocannabinoid system (eCS) activity, which in turn modulates lipogenesis and fatty acids utilization in hepatic, muscle, and adipose tissues. This study aimed to evaluate the transgenerational effect of maternal obesity on cannabinoid receptor 1 knock-out (CB1 KO) animals in combination with a postnatal obesogenic diet on the development of metabolic disturbances on their offspring. CB1 KO mice were fed a control diet (CD) or a high-fat diet (HFD; 33% more energy from fat) for 3 months. Offspring born to control and obese mothers were also fed with CD or HFD. We observed that pups born to an HFD-fed mother presented higher postnatal weight, lower hepatic fatty acid amide hydrolase activity, and increased blood cholesterol levels when compared to the offspring born to CD-fed mothers. When female mice born to HFD-fed CB1 KO mothers were exposed to an HFD, they gained more weight, presented elevated blood cholesterol levels, and more abdominal adipose tissue accumulation than control-fed adult offspring. The eCS is involved in several reproductive physiological processes. Interestingly, we showed that CB1 KO mice in gestational day 15 presented resistance to LPS-induced deleterious effects on pregnancy outcome, which was overcome when these mice were obese. Our results suggest that an HFD in CB1 receptor-deficient mice contributes to a "nutritional programming" of the offspring resulting in increased susceptibility to metabolic challenges both perinatally and during adulthood.

Cannabinoids: Revealing their complexity and role in central networks of fear and anxiety

The first aim of the present review is to provide an in-depth description of the cannabinoids and their known effects at various neuronal receptors. It reveals that cannabinoids are highly diverse, and recent work has highlighted that their effects on the central nervous system (CNS) are surprisingly more complex than previously recognized. Cannabinoid-sensitive receptors are widely distributed throughout the CNS where they act as primary modulators of neurotransmission. Secondly, we examine the role of cannabinoid receptors at key brain sites in the control of fear and anxiety. While our understanding of how cannabinoids specifically modulate these networks is mired by their complex interactions and diversity, a plausible framework(s) for their effects is proposed. Finally, we highlight some important knowledge gaps in our understanding of the mechanism(s) responsible for their effects on fear and anxiety in animal models and their use as therapeutic targets in humans. This is particularly important for our understanding of the phytocannabinoids used as novel clinical interventions.

Regulation of stress-provoked aggressive behavior using endocannabinoids

Reactive impulsive aggression is characterized by outbursts of rage and violence when subjects encounter threatening stressful events. Although impulsive aggression and violence create a high-cost burden on health and society, relatively little is known about treatment. Early adolescent social isolation (SI) alters brain development and functions. It induces hyper-excitatory in the ventral hippocampus (vHip) to promote acute stress-provoked outbursts of aggression, referred to as impulsive aggression, in mouse models. Cannabinoid type 1 receptors (CB1Rs) act on presynaptic sites and suppress neurotransmitter release into synapses. Given that CB1R activation inhibits neurotransmitter releases and modulates excitatory network activity, we tested the hypothesis that CB1R activation reduces impulsive aggression in SI mice through decreasing excitatory activity in the vHip. Here, we report that CB1R agonists, WIN-552122 (WIN) or arachidonylcyclopropylamide (ACPA), ameliorated acute stress-provoked attack behavior in the resident-intruder test without affecting general locomotion activity. Increasing endocannabinoids (eCBs) by inhibiting degradation enzymes in the vHip reduced impulsive aggression, and the effect was blunted by administration of AM251, a CB1R antagonist. Acute stress in SI mice induced c-Fos expression, a marker of neuronal activation, on vHip neurons projecting to the ventromedial hypothalamus (VMH), a well-known brain area that controls attack behavior. eCB augmentation inhibited c-Fos expression in VMH-projecting vHip neurons surrounded by CB1Rs. These results suggest that enhancing eCB signaling in order to activate CB1Rs suppresses impulsive aggression via suppressing vHip→VMH neural activity and point to a role of CB1R activation in ameliorating impulsive aggression in adults who have had adverse experiences during early adolescence.

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Early adolescent social isolation (SI) promotes impulsive aggression.

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Treatment of CB1R agonists reduces impulsive aggression in SI mice.

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Increasing endocannabinoids (eCBs) to activate CB1Rs reduces impulsive aggression.

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Augmenting eCBs suppresses stress-provoked neuronal activation in the hippocampus.

A systematic review of neuroimaging and acute cannabis exposure in age-of-risk for psychosis

Acute exposure to cannabis has been associated with an array of cognitive alterations, increased risk for neuropsychiatric illness, and other neuropsychiatric sequelae including the emergence of acute psychotic symptoms. However, the brain alterations associating cannabis use and these behavioral and clinical phenotypes remains disputed. To this end, neuroimaging can be a powerful technique to non-invasively study the impact of cannabis exposure on brain structure and function in both humans and animal models. While chronic exposure studies provide insight into how use may be related to long-term outcomes, acute exposure may reveal interesting information regarding the immediate impact of use and abuse on brain circuits. Understanding these alterations could reveal the connection with symptom dimensions in neuropsychiatric disorders and, more specifically with psychosis. The purpose of the present review is to: 1) provide an update on the findings of pharmacological neuroimaging studies examining the effects of administered cannabinoids and 2) focus the discussion on studies that examine the sensitive window for the emergence of psychosis. Current literature indicates that cannabis exposure has varied effects on the brain, with the principal compounds in cannabis (delta-9-tetrahydrocannabinol and cannabidiol) altering activity across different brain regions. Importantly, we also discovered critical gaps in the literature, particularly regarding sex-dependent responses and long-term effects of chronic exposure. Certain networks often characterized as dysregulated in psychosis, like the default mode network and limbic system, were also impacted by THC exposure, identifying areas of particular interest for future work investigating the potential relationship between the two.

Pharmacokinetic, behavioral, and brain activity effects of Δ9-tetrahydrocannabinol in adolescent male and female rats

Δ⁹-tetrahydrocannabinol (THC) is the intoxicating constituent of cannabis and is responsible for the drug's reinforcing effects. Retrospective human studies suggest that cannabis use during adolescence is linked to long-term negative psychological outcomes, but in such studies it is difficult to distinguish the effects of THC from those of coexisting factors. Therefore, translationally relevant animal models are required to properly investigate THC effects in adolescents. However, though the relevance of these studies depends upon human-relevant dosing, surprisingly little is known about THC pharmacology and its effects on behavior and brain activity in adolescent rodents-especially in females. Here, we conducted a systematic investigation of THC pharmacokinetics, metabolism and distribution in blood and brain, and of THC effects upon behavior and neural activity in adolescent Long Evans rats of both sexes. We administered THC during an early-middle adolescent window (postnatal days 27-45) in which the brain may be particularly sensitive to developmental perturbation by THC. We determined the pharmacokinetic profile of THC and its main first-pass metabolites (11-hydroxy-THC and 11-nor-9-carboxy-THC) in blood and brain following acute injection (0.5 or 5 mg/kg, intraperitoneal). We also evaluated THC effects on behavioral assays of anxiety, locomotion, and place conditioning, as well as c-Fos expression in 14 brain regions. Confirming previous work, we find marked sex differences in THC metabolism, including a female-specific elevation in the bioactive metabolite 11-hydroxy-THC. Furthermore, we find dose-dependent and sex-dependent effects on behavior, neural activity, and functional connectivity across multiple nodes of brain stress and reward networks. Our findings are relevant for interpreting results of rat adolescent THC exposure studies, and may lend new insights into how THC impacts the brain in a sex-dependent manner.

Mini-review: The therapeutic role of cannabinoids in neuroHIV

In the era of combined antiretroviral therapy (cART), human immunodeficiency virus type 1 (HIV-1) is considered a chronic disease with an inflammatory component that specifically targets the brain and causes a high prevalence of HIV-1-associated neurocognitive disorders (HAND). The endocannabinoid (eCB) system has attracted interest as a target for treatment of neurodegenerative disorders, due to the potential anti-inflammatory and neuroprotective properties of cannabinoids, including its potential therapeutic use in HIV-1 neuropathogenesis. In this review, we summarize what is currently known about the structural and functional changes of the eCB system under conditions of HAND. This will be followed by summarizing the current clinical and preclinical findings on the effects of cannabis use and cannabinoids in the context of HIV-1 infection, with specifically focusing on viral load, cognition, inflammation, and neuroprotection. Lastly, we present some potential future directions to better understand the involvement of the eCB system and the role that cannabis use and cannabinoids play in neuroHIV.

Alterations of the endocannabinoid system and its therapeutic potential in autism spectrum disorder

Autism spectrum disorder (ASD) is a group of developmental disabilities, the aetiology of which remains elusive. The endocannabinoid (eCB) system modulates neurotransmission and neuronal plasticity. Evidence points to the involvement of this neuromodulatory system in the pathophysiology of ASD. We investigated whether there is a disruption to the eCB system in ASD and whether pharmacological modulation of the eCB system might offer therapeutic potential. We examined three major components of the eCB system—endogenous cannabinoids, their receptors and associated enzymes—in ASD children as well as in the valproic acid (VPA) induced animal model in autism. Furthermore, we specifically increased 2-arachidonoylglycerol (2-AG) levels by administering JZL184, a selective inhibitor of monoacylglycerol lipase which is the hydrolytic enzyme for 2-AG, to examine ASD-like behaviours in VPA-induced rats. Results showed that autistic children and VPA-induced rats exhibited reduced eCB content, increased degradation of enzymes and upregulation of CBRs. We found that repetitive and stereotypical behaviours, hyperactivity, sociability, social preference and cognitive functioning improved after acute and chronic JZL184 treatment. The major efficacy of JZL184 was observed after administration of a dosage regimen of 3 mg kg⁻¹, which affected both the eCB system and ASD-like behaviours. In conclusion, a reduced eCB signalling was observed in autistic children and in the ASD animal model, and boosting 2-AG could ameliorate ASD-like phenotypes in animals. Collectively, the results suggested a novel approach to ASD treatment.

Crosstalk between the transcriptional regulation of dopamine D2 and cannabinoid CB1 receptors in schizophrenia: Analyses in patients and in perinatal Δ9-tetrahydrocannabinol-exposed rats

Perinatal exposure to Δ9-tetrahydrocannabinol (THC) affects brain development and might increase the incidence of psychopathology later in life, which seems to be related to a dysregulation of endocannabinoid and/or dopaminergic systems. We here evaluated the transcriptional regulation of the genes encoding for the cannabinoid CB1 receptor (Cnr1) and the dopamine D2 receptor (Drd2) in perinatal THC-(pTHC) exposed male rats, focusing on the role of DNA methylation analyzed by pyrosequencing. Simultaneously, the molecular and behavioral abnormalities at two different time points (i.e., neonatal age and adulthood) and the potential preventive effect of peripubertal treatment with cannabidiol, a non-euphoric component of Cannabis, were assessed. The DRD2 methylation was also evaluated in a cohort of subjects with schizophrenia. We observed an increase in both Cnr1 and Drd2 mRNA levels selectively in the prefrontal cortex of adult pTHC-exposed rats with a consistent reduction in DNA methylation at the Drd2 regulatory region, paralleled by social withdrawal and cognitive impairment which were reversed by cannabidiol treatment. These adult abnormalities were preceded at neonatal age by delayed appearance of neonatal reflexes, higher Drd2 mRNA and lower 2-arachidonoylglycerol (2-AG) brain levels, which persisted till adulthood. Alterations of the epigenetic mark for DRD2 were also found in subjects with schizophrenia. Overall, reported data add further evidence to the dopamine-cannabinoid interaction in terms of DRD2 and CNR1 dysregulation which could be implicated in the pathogenesis of schizophrenia spectrum disorders, suggesting that cannabidiol treatment may normalize pTHC-induced psychopathology by modulating the altered dopaminergic activity.

Hypothalamic endocannabinoids in obesity: an old story with new challenges

The crucial role of the hypothalamus in the pathogenesis of obesity is widely recognized, while the precise molecular and cellular mechanisms involved are the focus of intense research. A disrupted endocannabinoid system, which critically modulates feeding and metabolic functions, through central and peripheral mechanisms, is a landmark indicator of obesity, as corroborated by investigations centered on the cannabinoid receptor CB1, considered to offer promise in terms of pharmacologically targeted treatment for obesity. In recent years, novel insights have been obtained, not only into relation to the mode of action of CB receptors, but also CB ligands, non-CB receptors, and metabolizing enzymes considered to be part of the endocannabinoid system (particularly the hypothalamus). The outcome has been a substantial expansion in knowledge of this complex signaling system and in drug development. Here we review recent literature, providing further evidence on the role of hypothalamic endocannabinoids in regulating energy balance and the implication for the pathophysiology of obesity. We discuss how these lipids are dynamically regulated in obesity onset, by diet and metabolic hormones in specific hypothalamic neurons, the impact of gender, and the role of endocannabinoid metabolizing enzymes as promising targets for tackling obesity and related diseases.

Sex differences in endocannabinoid modulation of rat CA1 dendritic neurotransmission

Endocannabinoid sex differences are present in the rat hippocampus. Specifically, at perisomatic GABAergic synapses, tonic anandamide (AEA) and estrogenic-AEA signaling are active in females but not males. Furthermore, in males, hippocampal eCB function varies along the CA1 pyramidal somatodendritic axis. Constitutive CB1 and tonic 2-AG activity are present at perisomatic GABAergic synapses and lacking at dendritic GABAergic synapses. It is unknown if these eCB somatodendritic differences occur at female GABAergic synapses. Moreover, it is unclear whether eCB sex differences occur at hippocampal glutamatergic synapses. In vitro, field potential (fEPSP) recordings were performed to assess eCB sex differences at rat CA3-CA1 dendritic synapses. At female GABAergic synapses, we observed: 1) constitutive CB1 function, 2) tonic AEA, 3) tonic 2-AG and 3) estrogen (ER_α)-driven 2-AG activity. In contrast, only constitutive CB1 and tonic 2-AG activity was observed in males. Sex differences in eCB/CB1 signaling at dendritic synapses appear to shift the basal excitatory/inhibitory balance towards excitation in females and towards inhibition in males. Chronic Mild Stress (CMS) exposure (21 days) in female rats reverses CB1constitutive function and impairs both tonic and ER_α-driven eCB signaling. Endocannabinoid sex differences under both normal and stress conditions may contribute to sexual disparities in stress-related neurobehavioral disorders.

Cerebrospinal fluid endocannabinoid levels in Gilles de la Tourette syndrome

Gilles de la Tourette syndrome (TS) is a complex neurodevelopmental disorder characterized by the presence of motor and vocal tics as well as psychiatric comorbidities such as attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), depression, and anxiety. The underlying cause of the disease is still unknown, but several lines of evidence suggest a paramount role of the dopaminergic system. Based on the clinical observation that cannabis-based medicine including cannabis and delta-9-tetrahydrocannabinol (THC, dronabinol) may improve TS, alternatively, an involvement of the endocannabinoid system (ECS) has been suggested. In this study we measured cerebrospinal fluid (CSF) levels of the two most important endocannabinoids "N"-arachidonoylethanolamine (AEA, anandamide) and 2-arachidonoylglycerol (2-AG), the endocannabinoid-like molecule palmitoyl ethanolamide (PEA), and the lipid arachidonic acid (AA) in a sample of adult patients with TS (n = 20) compared with controls (n = 19) using liquid-liquid lipid extraction and simultaneous quantification by liquid chromatography multiple reaction monitoring (LC/MRM). CSF levels of AEA (p = 0.0018), 2-AG (p = 0.0003), PEA (p = 0.02), and AA (p < 0.0001) were significantly increased in TS compared with controls. Levels of 2-AG correlated with the severity of comorbid ADHD (p < 0.01). This is the first study, demonstrating alterations in the ECS suggesting an involvement of this system in the pathophysiology of TS. It can be speculated that elevated endocannabinoid levels either represent secondary changes in order to compensate for alterations in other neurotransmitter systems such as the dopaminergic system, are simply an epiphenomenon or, alternatively, represent the primary cause of TS.

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.

Long-Term Aberrations To Cerebellar Endocannabinoids Induced By Early-Life Stress

Emerging evidence points to the role of the endocannabinoid system in long-term stress-induced neural remodeling with studies on stress-induced endocannabinoid dysregulation focusing on cerebral changes that are temporally proximal to stressors. Little is known about temporally distal and sex-specific effects, especially in cerebellum, which is vulnerable to early developmental stress and is dense with cannabinoid receptors. Following limited bedding at postnatal days 2-9, adult (postnatal day 70) cerebellar and hippocampal endocannabinoids, related lipids, and mRNA were assessed, and behavioral performance evaluated. Regional and sex-specific effects were present at baseline and following early-life stress. Limited bedding impaired peripherally-measured basal corticosterone in adult males only. In the CNS, early-life stress (1) decreased 2-arachidonoyl glycerol and arachidonic acid in the cerebellar interpositus nucleus in males only; (2) decreased 2-arachidonoyl glycerol in females only in cerebellar Crus I; and (3) increased dorsal hippocampus prostaglandins in males only. Cerebellar interpositus transcriptomics revealed substantial sex effects, with minimal stress effects. Stress did impair novel object recognition in both sexes and social preference in females. Accordingly, the cerebellar endocannabinoid system exhibits robust sex-specific differences, malleable through early-life stress, suggesting the role of endocannabinoids and stress to sexual differentiation of the brain and cerebellar-related dysfunctions.

Long-term hippocampal interneuronopathy drives sex-dimorphic spatial memory impairment induced by prenatal THC exposure

Prenatal exposure to Δ⁹-tetrahydrocannabinol (THC), the most prominent active constituent of cannabis, alters neurodevelopmental plasticity with a long-term functional impact on adult offspring. Specifically, THC affects the development of pyramidal neurons and GABAergic interneurons via cannabinoid CB₁ receptors (CB₁R). However, the particular contribution of these two neuronal lineages to the behavioral alterations and functional deficits induced by THC is still unclear. Here, by using conditional CB₁R knockout mice, we investigated the neurodevelopmental consequences of prenatal THC exposure in adulthood, as well as their potential sex differences. Adult mice that had been exposed to THC during embryonic development showed altered hippocampal oscillations, brain hyperexcitability, and spatial memory impairment. Remarkably, we found a clear sexual dimorphism in these effects, with males being selectively affected. At the neuronal level, we found a striking interneuronopathy of CCK-containing interneurons in the hippocampus, which was restricted to male progeny. This THC-induced CCK-interneuron reduction was not evident in mice lacking CB₁R selectively in GABAergic interneurons, thus pointing to a cell-autonomous THC action. In vivo electrophysiological recordings of hippocampal LFPs revealed alterations in hippocampal oscillations confined to the stratum pyramidale of CA1 in male offspring. In addition, sharp-wave ripples, a major high-frequency oscillation crucial for learning and memory consolidation, were also altered, pointing to aberrant circuitries caused by persistent reduction of CCK⁺ basket cells. Taken together, these findings provide a mechanistic explanation for the long-term interneuronopathy responsible for the sex-dimorphic cognitive impairment induced by prenatal THC.

Effects of cannabis exposure in the prenatal and adolescent periods: Preclinical and clinical studies in both sexes

Cannabis is the most commonly used illicit drug among adolescents and young adults, including pregnant women. There is substantial evidence for a significant association between prenatal cannabis exposure and lower birth weight in offspring, and mixed results regarding later behavioural outcomes in the offspring. Adolescent cannabis use, especially heavy use, has been associated with altered executive function, depression, psychosis and use of other drugs later in life. Human studies have limitations due to several confounding factors and have provided scarce information about sex differences. In general, animal studies support behavioural alterations reported in humans and have revealed diverse sex differences and potential underlying mechanisms (altered mesolimbic dopaminergic and hippocampal glutamatergic systems and interference with prefrontal cortex maturation). More studies are needed that analyse sex and gender influences on cannabis-induced effects with great clinical relevance such as psychosis, cannabis use disorder and associated comorbidities, to achieve more personalized and accurate treatments.

Endocannabinoid System Components as Potential Biomarkers in Psychiatry

The high heterogeneity of psychiatric disorders leads to a lack of diagnostic precision. Therefore, the search of biomarkers is a fundamental aspect in psychiatry to reach a more personalized medicine. The endocannabinoid system (ECS) has gained increasing interest due to its involvement in many different functional processes in the brain, including the regulation of emotions, motivation, and cognition. This article reviews the role of the main components of the ECS as biomarkers in certain psychiatric disorders. Studies carried out in rodents evaluating the effects of pharmacological and genetic manipulation of cannabinoid receptors or endocannabinoids (eCBs) degrading enzymes were included. Likewise, the ECS-related alterations occurring at the molecular level in animal models reproducing some behavioral and/or neuropathological aspects of psychiatric disorders were reviewed. Furthermore, clinical studies evaluating gene or protein alterations in post-mortem brain tissue or in vivo blood, plasma, and cerebrospinal fluid (CSF) samples were analyzed. Also, the results from neuroimaging studies using positron emission tomography (PET) or functional magnetic resonance (fMRI) were included. This review shows the close involvement of cannabinoid receptor 1 (CB1r) in stress regulation and the development of mood disorders [anxiety, depression, bipolar disorder (BD)], in post-traumatic stress disorder (PTSD), as well as in the etiopathogenesis of schizophrenia, attention deficit hyperactivity disorder (ADHD), or eating disorders (i.e. anorexia and bulimia nervosa). On the other hand, recent results reveal the potential therapeutic action of the endocannabinoid tone manipulation by inhibition of eCBs degrading enzymes, as well as by the modulation of cannabinoid receptor 2 (CB2r) activity on anxiolytic, antidepressive, or antipsychotic associated effects. Further clinical research studies are needed; however, current evidence suggests that the components of the ECS may become promising biomarkers in psychiatry to improve, at least in part, the diagnosis and pharmacological treatment of psychiatric disorders.

Effect of cannabidiol on endocannabinoid, glutamatergic and GABAergic signalling markers in male offspring of a maternal immune activation (poly I:C) model relevant to schizophrenia

The mainstay treatment for schizophrenia is antipsychotic drugs (APDs), which are mostly effective against the positive symptoms (e.g. hallucinations), but provide minimal benefits for the negative symptoms (e.g. social withdrawal) and cognitive deficits. We have recently shown that treatment with the non-intoxicating phytocannabinoid, cannabidiol (CBD), can improve cognition and social interaction deficits in a maternal immune activation (MIA) model relevant to the aetiology of schizophrenia, however, the mechanisms underlying this effect are unknown. An imbalance in the main excitatory (glutamate) and inhibitory (GABA) neurotransmitter systems in the brain plays a role in the pathophysiology of schizophrenia. Therefore, the endocannabinoid system could represent a therapeutic target for schizophrenia as a regulator of glutamate and GABA release via the CB1 receptor (CB1R). This study investigated the effects of chronic CBD treatment on markers of glutamatergic, GABAergic and endocannabinoid signalling in brain regions implicated in social behaviour and cognitive function, including the prefrontal cortex (PFC) and hippocampus (HPC). Time-mated pregnant Sprague-Dawley rats (n = 16) were administered poly I:C (4 mg/kg, i.v.) or saline (control) on gestational day 15. Male offspring were injected with CBD (10 mg/kg, i.p.) or vehicle twice daily from postnatal day 56 for 3 weeks. The prefrontal cortex (PFC) and hippocampus (HPC) were collected for post-mortem receptor binding and Western blot analyses (n = 8 per group). CBD treatment attenuated poly I:C-induced deficits in cannabinoid CB1 receptor binding in the PFC and glutamate decarboxylase 67, the enzyme that converts glutamate to GABA, in the HPC. CBD treatment increased parvalbumin levels in the HPC, regardless of whether offspring were exposed to poly I:C in utero. Conversely, CBD did not affect N-methyl-d-aspartate receptor and gamma-aminobutyric acid (GABA) A receptor binding or protein levels of fatty acid amide hydrolase, the enzyme that degrades the endocannabinoid, anandamide. Overall, these findings show that CBD can restore cannabinoid/GABAergic signalling deficits in regions of the brain implicated in schizophrenia pathophysiology following maternal poly I:C exposure. These findings provide novel evidence for the potential mechanisms underlying the therapeutic effects of CBD treatment in the poly I:C model.

Cannabidiol improves behavioural and neurochemical deficits in adult female offspring of the maternal immune activation (poly I:C) model of neurodevelopmental disorders

Cognitive impairment is a major source of disability in schizophrenia and current antipsychotic drugs (APDs) have minimal efficacy for this symptom domain. Cannabidiol (CBD), the major non-intoxicating component of Cannabis sativa L., exhibits antipsychotic and neuroprotective properties. We recently reported the effects of CBD on cognition in male offspring of a maternal immune activation (polyinosinic-polycytidilic acid (poly I:C)) model relevant to the aetiology of schizophrenia; however, the effects of CBD treatment in females are unknown. Sex differences are observed in the onset of schizophrenia symptoms and response to APD treatment. Furthermore, the endogenous cannabinoid system, a direct target of CBD, is sexually dimorphic in humans and rodents. Therefore, the present work aimed to assess the therapeutic impact of CBD treatment on behaviour and neurochemical signalling markers in female poly I:C offspring. Time-mated pregnant Sprague-Dawley rats (n = 16) were administered poly I:C (4 mg/kg; i.v.) or saline (control) on gestational day 15. From postnatal day 56, female offspring received CBD (10 mg/kg, i.p.) or vehicle treatment for approximately 3 weeks. Following 2 weeks of CBD treatment, offspring underwent behavioural testing, including the novel object recognition, rewarded alternation T-maze and social interaction tests to assess recognition memory, working memory and sociability, respectively. After 3 weeks of CBD treatment, the prefrontal cortex (PFC) and hippocampus (HPC) were collected to assess effects on endocannabinoid, glutamatergic and gamma-aminobutyric acid (GABA) signalling markers. CBD attenuated poly I:C-induced deficits in recognition memory, social interaction and glutamatergic N-methyl-d-aspartate receptor (NMDAR) binding in the PFC of poly I:C offspring. Working memory performance was similar between treatment groups. CBD also increased glutamate decarboxylase 67, the rate-limiting enzyme that converts glutamate to GABA, and parvalbumin protein levels in the HPC. In contrast to the CBD treatment effects observed in poly I:C offspring, CBD administration to control rats reduced social interaction, cannabinoid CB1 receptor and NMDAR binding density in the PFC, suggesting that CBD administration to healthy rats may have negative consequences on social behaviour and brain maturation in adulthood. Overall, the findings of this study support the therapeutic benefits of CBD on recognition memory and sociability in female poly I:C offspring, and provide insight into the neurochemical changes that may underlie the therapeutic benefits of CBD in the poly I:C model.

Effect of cannabidiol on muscarinic neurotransmission in the pre-frontal cortex and hippocampus of the poly I:C rat model of schizophrenia

Cognitive impairment is a core symptom of schizophrenia; however, current antipsychotic drugs have limited efficacy to treat these symptoms and can cause serious side-effects, highlighting a need for novel therapeutics. Cannabidiol (CBD) is a non-intoxicating phytocannabinoid that has demonstrated pro-cognitive effects in multiple disease states, including a maternal immune activation (poly I:C) model of schizophrenia, but the mechanisms underlying the efficacy of CBD require investigation. Muscarinic neurotransmission is highly implicated in the cognitive impairments of schizophrenia; however, the effect of CBD on this system is unknown. We examined alterations in markers of muscarinic neurotransmission in the pre-frontal cortex (PFC) and hippocampus (HPC) following CBD treatment. Pregnant Sprague-Dawley rats (n = 16) were administered poly I:C (4 mg/kg) or saline. Adult offspring were treated (3-weeks) with CBD (10 mg/kg) or vehicle. Receptor autoradiography (using [³H]pirenzepine) was used to examine changes in muscarinic M1/M4 receptor (M1/M4R) binding density. Levels of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) protein expression were examined using Western blot. M1/M4R binding density was downregulated in the PFC and CA1/CA2 and CA3 subregions in male poly I:C offspring. M1/M4R deficits were normalised after CBD treatment. ChAT protein expression was reduced in the HPC of male poly I:C offspring, while CBD treated poly I:C offspring exhibited control-like ChAT levels. AChE levels were unaltered in any of the groups. There were also no changes in muscarinic signalling in female offspring. These findings demonstrate that CBD can normalise muscarinic neurotransmission imbalances in male poly I:C offspring in regions of the brain implicated in cognition.

Prenatal cannabinoid exposure and altered neurotransmission

Marijuana is one of the most commonly used illicit drugs worldwide. In addition, use of synthetic cannabinoids is increasing, especially among adolescents and young adults. Although human studies have shown that the use of marijuana during pregnancy leads to adverse behavioral effects, such as deficiencies in attention and executive function in affected offspring, the rate of marijuana use among pregnant women is steadily increasing. Various aspects of human behavior including emotion, learning, and memory are dependent on complex interactions between multiple neurotransmitter systems that are especially vulnerable to alterations during the developmental period. Thus, exploration of neurotransmitter changes in response to prenatal cannabinoid exposure is crucial to develop an understanding of how homeostatic imbalance and various long-term neurobehavioral deficits manifest following the abuse of marijuana or other synthetic cannabinoids during pregnancy. Current literature confirms that vast alterations to neurotransmitter systems are present following prenatal cannabinoid exposure, and many of these alterations within the brain are region specific, time-dependent, and sexually dimorphic. In this review, we aim to provide a summary of observed changes to various neurotransmitter systems following cannabinoid exposure during pregnancy and to draw possible correlations to reported behavioral alterations in affected offspring.

Cannabinoid Actions on Neural Stem Cells: Implications for Pathophysiology

With the increase of life expectancy, neurodegenerative disorders are becoming not only a health but also a social burden worldwide. However, due to the multitude of pathophysiological disease states, current treatments fail to meet the desired outcomes. Therefore, there is a need for new therapeutic strategies focusing on more integrated, personalized and effective approaches. The prospect of using neural stem cells (NSC) as regenerative therapies is very promising, however several issues still need to be addressed. In particular, the potential actions of pharmacological agents used to modulate NSC activity are highly relevant. With the ongoing discussion of cannabinoid usage for medical purposes and reports drawing attention to the effects of cannabinoids on NSC regulation, there is an enormous, and yet, uncovered potential for cannabinoids as treatment options for several neurological disorders, specifically when combined with stem cell therapy. In this manuscript, we review in detail how cannabinoids act as potent regulators of NSC biology and their potential to modulate several neurogenic features in the context of pathophysiology.

Multiple endocannabinoid-mediated mechanisms in the regulation of energy homeostasis in brain and peripheral tissues

The endocannabinoid (eCB) system is widely expressed in many central and peripheral tissues, and is involved in a plethora of physiological processes. Among these, activity of the eCB system promotes energy intake and storage, which, however, under pathophysiological conditions, can favour the development of obesity and obesity-related disorders. It is proposed that eCB signalling is evolutionary beneficial for survival under periods of scarce food resources. Remarkably, eCB signalling is increased both in hunger and in overnutrition conditions, such as obesity and type-2 diabetes. This apparent paradox suggests a role of the eCB system both at initiation and at clinical endpoint of obesity. This review will focus on recent findings about the role of the eCB system controlling whole-body metabolism in mice that are genetically modified selectively in different cell types. The current data in fact support the notion that eCB signalling is not only engaged in the development but also in the maintenance of obesity, whereby specific cell types in central and peripheral tissues are key sites in regulating the entire body's energy homeostasis.

Sex Differences in the Behavioral and Synaptic Consequences of a Single in vivo Exposure to the Synthetic Cannabimimetic WIN55,212-2 at Puberty and Adulthood

Heavy cannabis consumption among adolescents is associated with significant and lasting neurobiological, psychological and health consequences that depend on the age of first use. Chronic exposure to cannabinoid agonists during the perinatal period or adolescence alters social behavior and prefrontal cortex (PFC) activity in adult rats. However, sex differences on social behavior as well as PFC synaptic plasticity after acute cannabinoid activation remain poorly explored. Here, we determined that the consequences of a single in vivo exposure to the synthetic cannabimimetic WIN55,212-2 differently affected PFC neuronal and synaptic functions after 24 h in male and female rats during the pubertal and adulthood periods. During puberty, single cannabinoid exposure (SCE) reduced play behavior in females but not males. In contrast, the same treatment impaired sociability in both sexes at adulthood. General exploration and memory recognition remained normal at both ages and both sexes. At the synaptic level, SCE ablated endocannabinoid-mediated synaptic plasticity in the PFC of females of both ages and heightened excitability of PFC pyramidal neurons at adulthood, while males were spared. In contrast, cannabinoid exposure was associated with impaired long-term potentiation (LTP) specifically in adult males. Together, these data indicate behavioral and synaptic sex differences in response to a single in vivo exposure to cannabinoid at puberty and adulthood.

Cannabis Use: Neurobiological, Behavioral, and Sex/Gender Considerations

PURPOSE OF REVIEW

To summarize the current literature on the effects of cannabinoids in humans and to discuss the existing literature on the sex- and gender-related differences in the effects of cannabinoids.

RECENT FINDINGS

Cannabis and its constituent cannabinoids are associated with risk of addiction, cognitive deficits and mood/psychotic disorders. Preclinical and emerging clinical data suggest greater sensitivity to the effects of cannabinoids in women.

SUMMARY

Cannabis is one of the most commonly used drugs with increasing rates of use. Women in particular may be at a greater risk of adverse outcomes given the previously described "telescoping effect" of substance use in women. Human data examining the sex- and gender-related differences in the effects of cannabinoids and factors underlying these differences are very limited. This represents a critical gap in the literature and needs to be systematically examined in future studies.

Highway to hell or magic smoke? The dose-dependence of Δ9-THC in place conditioning paradigms

The prerequisites for responsible cannabis use are at the heart of current inquiries into cannabis decriminalization by policy makers as well as academic and nonacademic stakeholders at a global scale. Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the prime psychoactive compound of the cannabis sativa, as well as cannabimimetics that resemble the pharmacological properties and psychological effects of Δ⁹-THC, lend themselves handsomely to the preclinical scrutiny of reward-related behavior because they carry marked translational value. Although a functional dichotomy of the psychological effects of Δ⁹-THC (rewarding versus aversive) has been abundantly reported in place conditioning (PC) paradigms, and might be best attributed to a dose-dependence of Δ⁹-THC, most PC studies with Δ⁹-THC feature no significant effects at all. Therefore, after decades of rigorous research, it still remains undetermined whether Δ⁹-THC generally exerts rewarding or aversive effects in rodents. Here, we set out to extrapolate the commonly alleged dose-dependence of the rewarding and aversive effects of Δ⁹-THC from the existing literature, at the behavioral pharmacological level of analysis. Specifically, our meta-analysis investigated: (i) the alleged bidirectional effects and dose-dependence of Δ⁹-THC in the PC test; (ii) methodological inconsistencies between PC studies; and (iii) other pharmacological studies on cannabinoids (i.e., dopamine release, anxiety, stress, conditioned taste aversion, catalepsy) to substantiate the validity of PC findings. Our findings suggest that: (i) Δ⁹-THC dose-dependently generates rewarding (1 mg/kg) and aversive (5 mg/kg) effects in PC; (ii) an inconsistent use of priming injections hampers a clear establishment of the rewarding effects of Δ⁹-THC in PC tests and might explain the seemingly contradictory plethora of nonsignificant THC studies in the PC test; and (iii) other pharmacological studies on Δ⁹-THC substantiate the dose-dependent biphasic effects of Δ⁹-THC in PC. A standardized experimental design would advance evidence-based practice in future PC studies with Δ⁹-THC and facilitate the pointed establishment of rewarding and aversive effects of the substance.