Neuroprotective effect of chronic administration of cannabidiol during the abstinence period on methamphetamine-induced impairment of recognition memory in the rats

Cannabidiol and addiction

Cannabidiol (CBD) has been investigated for several therapeutic applications, having reached the clinics for the treatment of certain types of epilepsies. This chapter reviews the potential of CBD for the treatment of substance use disorders (SUD). We will present a brief introduction on SUD and current treatments. In the second part, preclinical and clinical studies with CBD are discussed, focusing on its potential therapeutic application for SUD. Next, we will consider the potential molecular mechanism of action of CBD in SUD. Finally, we will summarize the main findings and perspectives in this field. There is a lack of studies on CBD and SUD in comparison to the extensive literature investigating the use of this phytocannabinoid for other neurological and psychiatric disorders, such as epilepsy. However, the few studies available do suggest a promising role of CBD in the pharmacotherapy of SUD, particularly related to cocaine and other psychostimulant drugs.

Effects of acute cannabidiol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

Background

Some evidence suggests that cannabidiol (CBD) has potential to help alleviate HIV symptoms due to its antioxidant and anti-inflammatory properties. Here we examined acute CBD effects on various behaviors and the endocannabinoid system in HIV Tat transgenic mice.

Methods

Tat transgenic mice (female/male) were injected with CBD (3, 10, 30 mg/kg) and assessed for antinociception, activity, coordination, anxiety-like behavior, and recognition memory. Brains were taken to quantify endocannabinoids, cannabinoid receptors, and cannabinoid catabolic enzymes. Additionally, CBD and metabolite 7-hydroxy-CBD were quantified in the plasma and cortex.

Results

Tat decreased supraspinal-related nociception and locomotion. CBD and sex had little to no effects on any of the behavioral measures. For the endocannabinoid system male sex was associated with elevated concentration of the proinflammatory metabolite arachidonic acid in various CNS regions, including the cerebellum that also showed higher FAAH expression levels for Tat(+) males. GPR55 expression levels in the striatum and cerebellum were higher for females compared to males. CBD metabolism was altered by sex and Tat expression.

Conclusion

Findings indicate that acute CBD effects are not altered by HIV Tat, and acute CBD has no to minimal effects on behavior and the endocannabinoid system.

Cannabis use may attenuate neurocognitive performance deficits resulting from methamphetamine use disorder

OBJECTIVE

Methamphetamine and cannabis are two widely used, and frequently co-used, substances with possibly opposing effects on the central nervous system. Evidence of neurocognitive deficits related to use is robust for methamphetamine and mixed for cannabis. Findings regarding their combined use are inconclusive. We aimed to compare neurocognitive performance in people with lifetime cannabis or methamphetamine use disorder diagnoses, or both, relative to people without substance use disorders.

METHOD

423 (71.9% male, aged 44.6 ± 14.2 years) participants, stratified by presence or absence of lifetime methamphetamine (M-/M+) and/or cannabis (C-/C+) DSM-IV abuse/dependence, completed a comprehensive neuropsychological, substance use, and psychiatric assessment. Neurocognitive domain T-scores and impairment rates were examined using multiple linear and binomial regression, respectively, controlling for covariates that may impact cognition.

RESULTS

Globally, M+C+ performed worse than M-C- but better than M+C-. M+C+ outperformed M+C- on measures of verbal fluency, information processing speed, learning, memory, and working memory. M-C+ did not display lower performance than M-C- globally or on any domain measures, and M-C+ even performed better than M-C- on measures of learning, memory, and working memory.

CONCLUSIONS

Our findings are consistent with prior work showing that methamphetamine use confers risk for worse neurocognitive outcomes, and that cannabis use does not appear to exacerbate and may even reduce this risk. People with a history of cannabis use disorders performed similarly to our nonsubstance using comparison group and outperformed them in some domains. These findings warrant further investigation as to whether cannabis use may ameliorate methamphetamine neurotoxicity.

Effects of the Acute and Chronic Administration of Cannabidiol on Cognition in Humans and Animals: A Systematic Review

Introduction: The effects of cannabidiol (CBD) on cognition has been investigated in recent years to determine the therapeutic potential of this cannabinoid for a broad gamut of medical conditions, including neuropsychiatric disorders. The aim of the present study was to perform a systematic review of studies that analyzed the effects of the acute and chronic administration of CBD on cognition in humans and animals both to assess the cognitive safety of CBD and to determine a beneficial potential of CBD on cognition. Methods: The PubMed, Web of Science, PsycINFO, and Scopus databases were searched in December of 2022 for relevant articles using the following combinations of keywords: ("cannabidiol" OR "CBD") AND ("cognition" OR "processing cognitive" OR "memory" OR "language" OR "attention" OR "executive function" OR "social cognition" OR "perceptual motor ability" OR "processing speed"). Results: Fifty-nine articles were included in the present review (36 preclinical and 23 clinical trials). CBD seems not to have any negative effect on cognitive processing in rats. The clinical trials confirmed these findings in humans. One study found that repeated dosing with CBD may improve cognitive in people who use cannabis heavily but not individuals with neuropsychiatric disorders. Considering the context of neuropsychiatric disorders in animal models, CBD seems to reverse the harm caused by the experimental paradigms, such that the performance of these animals becomes similar to that of control animals. Conclusions: The results demonstrate that the chronic and acute administration of CBD seems not to impair cognition in humans without neuropsychiatric disorders. In addition, preclinical studies report promising results regarding the effects of CBD on the cognitive processing of animals. Future double-blind, placebo-controlled, randomized clinical trials with larger, less selective samples, with standardized tests, and using different doses of CBD in outpatients are of particular interest to elucidate the cognitive effects of CBD.

Immunotherapeutic treatment of inflammation in mice exposed to methamphetamine

Introduction

Currently, there are no FDA-approved medications to treat methamphetamine addiction, including the inflammatory, neurotoxic, and adverse neuropsychiatric effects. We have shown that partial (p)MHC class II constructs (i.e., Recombinant T-cell receptor Ligand - RTL1000), comprised of the extracellular α1 and β1 domains of MHC class II molecules linked covalently to myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide, can address the neuroimmune effects of methamphetamine addiction through its ability to bind to and down-regulate CD74 expression, block macrophage migration inhibitory factor (MIF) signaling, and reduce levels of pro-inflammatory chemokine ligand 2 (CCL2). The present study evaluated the effects of our third-generation pMHC II construct, DRmQ, on cognitive function and concentration of inflammatory cytokines in the frontal cortex, a region critical for cognitive functions such as memory, impulse control, and problem solving.

Methods

Female and male C57BL/6J mice were exposed to methamphetamine (or saline) via subcutaneous (s.c.) injections administered four times per day every other day for 14 days. Following methamphetamine exposure, mice received immunotherapy (DRmQ or ibudilast) or vehicle s.c. injections daily for five days. Cognitive function was assessed using the novel object recognition test (NORT). To evaluate the effects of immunotherapy on inflammation in the frontal cortex, multiplex immunoassays were conducted. ANOVA was used to compare exploration times on the NORT and immune factor concentrations.

Results

Post hoc analysis revealed increased novel object exploration time in MA-DRmQ treated mice, as compared to MA-VEH treated mice (non-significant trend). One-way ANOVA detected a significant difference across the groups in the concentration of macrophage inflammatory protein-2 (MIP-2) (p = 0.03). Post hoc tests indicated that mice treated with methamphetamine and DRmQ or ibudilast had significantly lower levels of MIP-2 in frontal cortex, as compared to mice treated with methamphetamine and vehicle (p > 0.05).

Discussion

By specifically targeting CD74, our DRQ constructs can block the signaling of MIF, inhibiting the downstream signaling and pro-inflammatory effects that contribute to and perpetuate methamphetamine addiction.

The inhibitory effect of cannabidiol on the rewarding properties of methamphetamine in part mediates by interacting with the hippocampal D1-like dopamine receptors

Cannabidiol (CBD) is a potential treatment to decrease the rewarding properties of psychostimulants. However, the exact mechanism and distinct neuroanatomical areas responsible for the CBD's effects remain unclear. Indicatively, the D1-like dopamine receptors (D1R) in the hippocampus (HIP) are essential for expressing and acquiring drug-associated conditioned place preference (CPP). Therefore, given that involving D1Rs in reward-related behaviors and the encouraging results of CBD in attenuating the psychostimulant's rewarding effects, the present study sought to investigate the role of D1Rs of the hippocampal dentate gyrus (DG) in the inhibitory effects of CBD on the acquisition and expression of METH-induced CPP. To this end, over a 5-day conditioning period by METH (1 mg/kg; sc), different groups of rats were given intra-DG SCH23390 (0.25, 1, or 4 μg/0.5 μl, saline) as a D1Rs antagonist before ICV administration of CBD (10 μg/5 μl, DMSO12%). In addition, a different set of animals, after the conditioning period, received a single dose of SCH23390 (0.25, 1, or 4 μg/0.5 μl) before CBD (50 μg/5 μl) administration on the expression day. The results showed that SCH23390 (1 and 4 μg) significantly reduced the suppressive effects of CBD on the acquisition of METH place preference (P < 0.05 and P < 0.001, respectively). Furthermore, the highest dose of SCH23390 (4 μg) in the expression phase remarkably abolished the preventive effects of CBD on the expression of METH-seeking behavior (P < 0.001). In conclusion, the current study revealed that CBD's inhibitory effect on rewarding properties of METH partially acts through D1Rs in the DG area of the HIP.

The Combined Effects of Cannabis, Methamphetamine, and HIV on Neurocognition

OBJECTIVE

Methamphetamine and cannabis are two widely used substances among people living with HIV (PLWH). Whereas methamphetamine use has been found to worsen HIV-associated neurocognitive impairment, the effects of combined cannabis and methamphetamine use disorder on neurocognition in PLWH are not understood. In the present study, we aimed to determine the influence of these substance use disorders on neurocognition in PLWH and to explore if methamphetamine-cannabis effects interacted with HIV status.

METHOD AND PARTICIPANTS

After completing a comprehensive neurobehavioral assessment, PLWH (n = 472) were stratified by lifetime methamphetamine (M-/M+) and cannabis (C-/C+) DSM-IV abuse/dependence disorder into four groups: M-C- (n = 187), M-C+ (n = 68), M+C-, (n = 82), and M+C+ (n = 135). Group differences in global and domain neurocognitive performances and impairment were examined using multiple linear and logistic regression, respectively, while holding constant other covariates that were associated with study groups and/or cognition. Data from participants without HIV (n = 423) were added, and mixed-effect models were used to examine possible interactions between HIV and substance use disorders on neurocognition.

RESULTS

Compared with M+C+, M+C- performed worse on measures of executive functions, learning, memory, and working memory and were more likely to be classified as impaired in those domains. M-C- performed better than M+C+ on measures of learning and memory but worse than M-C+ on measures of executive functions, learning, memory, and working memory. Detectable plasma HIV RNA and nadir CD4 < 200 were associated with lower overall neurocognitive performance, and these effects were greater for M+C+ compared with M-C-.

CONCLUSIONS

In PLWH, lifetime methamphetamine use disorder and both current and legacy markers of HIV disease severity are associated with worse neurocognitive outcomes. There was no evidence of an HIV × M+ interaction across groups, but neurocognition was most impacted by HIV among those with polysubstance use disorder (M+C+). Better performance by C+ groups is consistent with findings from preclinical studies that cannabis use may protect against methamphetamine's deleterious effects.

Cannabidiol: Bridge between Antioxidant Effect, Cellular Protection, and Cognitive and Physical Performance

The literature provides scientific evidence for the beneficial effects of cannabidiol (CBD), and these effects extend beyond epilepsy treatment (e.g., Lennox-Gastaut and Dravet syndromes), notably the influence on oxidative status, neurodegeneration, cellular protection, cognitive function, and physical performance. However, products containing CBD are not allowed to be marketed everywhere in the world, which may ultimately have a negative effect on health as a result of the uncontrolled CBD market. After the isolation of CBD follows the discovery of CB1 and CB2 receptors and the main enzymatic components (diacylglycerol lipase (DAG lipase), monoacyl glycerol lipase (MAGL), fatty acid amino hydrolase (FAAH)). At the same time, the antioxidant potential of CBD is due not only to the molecular structure but also to the fact that this compound increases the expression of the main endogenous antioxidant systems, superoxide dismutase (SOD), and glutathione peroxidase (GPx), through the nuclear complex erythroid 2-related factor (Nrf2)/Keep1. Regarding the role in the control of inflammation, this function is exercised by inhibiting (nuclear factor kappa B) NF-κB, and also the genes that encode the expression of molecules with a pro-inflammatory role (cytokines and metalloproteinases). The other effects of CBD on cognitive function and physical performance should not be excluded. In conclusion, the CBD market needs to be regulated more thoroughly, given the previously listed properties, with the mention that the safety profile is a very good one.

In utero exposure to cannabidiol disrupts select early-life behaviors in a sex-specific manner

Cannabidiol (CBD), one of the main components of cannabis, is generally considered safe. CBD crosses the placenta and its use during pregnancy is steadily increasing, the impact of gestational CBD's effects on prenatal life and neurodevelopment are poorly understood. Here, we combined behavioral approaches and deep learning analysis to assess the sex-dependent neonatal behavior of CBD exposed progeny. Gestating C57BL6/J dams were exposed daily with vehicle or CBD (3 mg/Kg, s.c.), from gestational day 5 to 18. Body weight, pup ultrasound vocalizations (USVs, PND 10) and homing behavior (PND 13) were quantified in the progeny. Thus, male (but not female) pups from CBD-treated dams gained more weight than sham. There were sex-dependent differences in the coarse characteristics of ultrasonic vocalizations. Prenatally-CBD exposed male pups emitted shorter calls, whereas CBD females made more high frequency calls when compared with their control counterparts. There were significant qualitative changes in the syllabic USV repertoire reflected in call typologies and communication patterns. Finally, the homing behavior test showed that CBD-exposed females presented a greater vulnerability to gestational CBD than males. Only CBD-exposed female pups showed reduced motor and discriminatory abilities. Together the results suggest a sexual divergence in the consequences of in utero CBD exposure on neonates at early developmental ages, which may be predictive of adult psychopathology. Given the extent of cannabis and CBD use worldwide, these findings challenge the idea that CBD is a universally safe compound and reveal the need for additional studies on the effect of perinatal CBD exposure.

Cannabidiol in the context of substance use disorder treatment: A systematic review

INTRODUCTION

Cannabidiol (CBD) is a phytocannabinoid found in the Cannabis plant. CBD has received significant medical attention in relation to its anticonvulsant, anxiolytic, and antipsychotic characteristics. An increasing number of studies focusing on the anti-addictive properties of CBD have recently been published. In this systematic review, we aim to offer a comprehensive overview of animal and human studies regarding the impact of CBD on substance use disorders (SUDs).

METHODS

A systematic search was performed on the PubMed database in February 2021. We included all articles assessing the effects of CBD on substance use disorders.

RESULTS

The current systematic review suggests that CBD might offer promising therapeutic potential for the treatment of SUD, based on available animal and human studies. Animal studies showed a positive impact of CBD in the context of alcohol, opioids, and methamphetamine use (e.g., diminishing of drug-seeking behaviors). The results for cocaine use were mixed among reviewed studies, and CBD was not found to have an effect in animal studies on cannabis use. No animal study was identified that focused on the impact of CBD on nicotine use. Human studies showed a positive impact of CBD in the context of nicotine, cannabis, and opioid use (e.g., frequency and quantity of consumption). In contrast, CBD was not found to have an effect in human studies on cocaine or alcohol use. No human study was identified that investigated the impact of CBD on methamphetamine use.

CONCLUSIONS

CBD might offer promising therapeutic potential for the treatment of SUD, especially for nicotine, cannabis, and opioid use disorders, based on available human studies. The available research evidence is, however, sparse and more research on humans is needed.

Dopamine activity on the perceptual salience for recognition memory

To survive, animals must recognize relevant stimuli and distinguish them from inconspicuous information. Usually, the properties of the stimuli, such as intensity, duration, frequency, and novelty, among others, determine the salience of the stimulus. However, previously learned experiences also facilitate the perception and processing of information to establish their salience. Here, we propose “perceptual salience” to define how memory mediates the integration of inconspicuous stimuli into a relevant memory trace without apparently altering the recognition of the physical attributes or valence, enabling the detection of stimuli changes in future encounters. The sense of familiarity is essential for successful recognition memory; in general, familiarization allows the transition of labeling a stimulus from the novel (salient) to the familiar (non-salient). The novel object recognition (NOR) and object location recognition (OLRM) memory paradigms represent experimental models of recognition memory that allow us to study the neurobiological mechanisms involved in episodic memory. The catecholaminergic system has been of vital interest due to its role in several aspects of recognition memory. This review will discuss the evidence that indicates changes in dopaminergic activity during exposure to novel objects or places, promoting the consolidation and persistence of memory. We will discuss the relationship between dopaminergic activity and perceptual salience of stimuli enabling learning and consolidation processes necessary for the novel-familiar transition. Finally, we will describe the effect of dopaminergic deregulation observed in some pathologies and its impact on recognition memory.

Cannabidiol and substance use disorder: Dream or reality

BACKGROUND

Cannabidiol (CBD) is one of the major constituents of Cannabis sativa L. that lacks psychotomimetic and rewarding properties and inhibits the rewarding and reinforcing effects of addictive drugs such as cocaine, methamphetamine (METH), and morphine. Additionally, CBD's safety profile and therapeutic potential are currently evaluated in several medical conditions, including pain, depression, movement disorders, epilepsy, multiple sclerosis, Alzheimer's disease, ischemia, and substance use disorder. There is no effective treatment for substance use disorders such as addiction, and this review aims to describe preclinical and clinical investigations into the effects of CBD in various models of opioid, psychostimulant, cannabis, alcohol, and nicotine abuse. Furthermore, the possible mechanisms underlying the therapeutic potential of CBD on drug abuse disorders are reviewed.

METHODS

The current review considers and summarizes the preclinical and clinical investigations into CBD's effects in various models of drug abuse include opioids, psychostimulants, cannabis, alcohol, and nicotine.

RESULTS

Several preclinical and clinical studies have proposed that CBD may be a reliable agent to inhibit the reinforcing and rewarding impact of drugs.

CONCLUSIONS

While the currently available evidence converges to suggest that CBD could effectively reduce the rewarding and reinforcing effects of addictive drugs, more preclinical and clinical studies are needed before CBD can be added to the therapeutic arsenal for treating addiction.

Co-exposure of cannabinoids with amphetamines and biological, behavioural and health outcomes: a scoping review of animal and human studies

RATIONALE

The growing prevalence of psychostimulant (including amphetamine) use and associated health harms, with limited treatment options, present a global challenge. There is an increasing availability and medical applications of cannabinoids, and growing interest in their therapeutic potential for addictive disorders.

OBJECTIVES

The objective of this study is to review available data regarding cannabis/cannabinoid co-use or exposure on amphetamine-related outcomes.

METHODS

Towards the present scoping review, we systematically searched four databases (Medline, Web-of-Science, CINAHL Plus and PsycInfo) using cannabis/cannabinoid and amphetamine text-terms identifying peer-reviewed, English-language studies published in 2000-2020 involving multiple methods approaches among both human and animal study samples, assessing the association of co-use/administration of cannabis/cannabinoids products with non-medical amphetamines on biological, behavioural or health outcomes.

RESULTS

Twenty-five articles were included. Pre-clinical studies (n = 15) found mostly protective effects of single or repeated cannabinoids administration on rodents in amphetamine addiction models, amphetamine-induced models of human mental disorders (e.g. schizophrenia) and amphetamine-induced neurotoxicity. Human studies (n = 10) were more heterogeneously designed (e.g. cross-sectional, case-control, longitudinal) and assessed natural ongoing cannabis and methamphetamine use or dependence, showing mostly enhanced harms in a diversity of outcomes (e.g. mental health, methamphetamine use, cognition).

CONCLUSIONS

While human studies suggest cannabis use as an adverse risk factor among non-medical amphetamine users, pre-clinical studies suggest therapeutic potential of cannabinoids, especially cannabidiol, to alleviate amphetamine addiction and harms, including treatment outcomes. Given increasing psychostimulant harms but lack of care options, rigorous, high-quality design studies should aim to translate and investigate pre-clinical study results for potential therapeutic benefits of cannabinoids for amphetamine use/abuse in human subjects.

Methamphetamine exacerbates pathophysiology of traumatic brain injury at high altitude. Neuroprotective effects of nanodelivery of a potent antioxidant compound H-290/51

Military personnel are often exposed to high altitude (HA, ca. 4500-5000m) for combat operations associated with neurological dysfunctions. HA is a severe stressful situation and people frequently use methamphetamine (METH) or other psychostimulants to cope stress. Since military personnel are prone to different kinds of traumatic brain injury (TBI), in this review we discuss possible effects of METH on concussive head injury (CHI) at HA based on our own observations. METH exposure at HA exacerbates pathophysiology of CHI as compared to normobaric laboratory environment comparable to sea level. Increased blood-brain barrier (BBB) breakdown, edema formation and reductions in the cerebral blood flow (CBF) following CHI were exacerbated by METH intoxication at HA. Damage to cerebral microvasculature and expression of beta catenin was also exacerbated following CHI in METH treated group at HA. TiO2-nanowired delivery of H-290/51 (150mg/kg, i.p.), a potent chain-breaking antioxidant significantly enhanced CBF and reduced BBB breakdown, edema formation, beta catenin expression and brain pathology in METH exposed rats after CHI at HA. These observations are the first to point out that METH exposure in CHI exacerbated brain pathology at HA and this appears to be related with greater production of oxidative stress induced brain pathology, not reported earlier.

Involvement of Hippocampal D1-Like Dopamine Receptors in the Inhibitory Effect of Cannabidiol on Acquisition and Expression of Methamphetamine-Induced Conditioned Place Preference

Cannabidiol (CBD) is a non-psychotomimetic compound with strong potential to decrease the psychostimulant's rewarding effect with unclear receptors. Furthermore, as a part of the reward circuit, the hippocampus plays a crucial role in regulating the reward properties of drugs as determined by conditioned place preference (CPP). In the current research, CPP was used to evaluate the role of intra-CA1 microinjection of D1-like dopamine receptor antagonists in CBD's inhibitory effect on the acquisition and expression phases of methamphetamine (METH). Animals were treated by METH (1 mg/kg; sc) in a five-day schedule to induce CPP. To find out the impact of D1-like dopamine receptor antagonist, SCH23390, in the CA1 on the inhibitory influence of CBD on the acquisition of METH, the rats received intra-CA1 administration of SCH23390 (0.25, 1, and 4 µg/0.5 µl) following ICV treatment of CBD (10 µg/5 µl) over conditioning phase of METH. Furthermore, animals were given SCH23390 in the CA1 ensuing ICV microinjection of CBD (50 µg/5 µl) in the expression phase of METH to rule out the influence of SCH23390 on the suppressive effect of CBD on the expression of METH CPP. Intra-CA1 microinjection of SCH23390 abolished CBD's suppressive impact on both METH-induced CPP phases without any side effect on the locomotion. The current research disclosed that CBD inhibited the rewarding characteristic of METH via D1-like dopamine receptors in the CA1 region of the hippocampus.

Cannabidiol promotes neurogenesis in the dentate gyrus during an abstinence period in rats following chronic exposure to methamphetamine

Chronic methamphetamine (meth) abuse can lead to certain deficits in the hippocampal function by affecting the hippocampal neurogenesis and plasticity. To determine whether cannabidiol (CBD) can promote proliferation and maturation of neuronal progenitor cells, this study investigated the CBD effect on neurogenesis in the hippocampal dentate gyrus (DG) following chronic exposure to meth in rats. The rats received 2 mg/kg of meth twice a day for ten days. Next, immunofluorescence was performed to evaluate the effect of intracerebroventricular (ICV) administration of CBD (50 μg/5 μL) over an abstinence period (ten days) on the expression levels of neurogenesis markers, such as Ki67, NeuN, and doublecortin (DCX). Moreover, neuronal degeneration in the hippocampus was assessed using Nissl staining. According to our findings, repeated ICV administration of CBD improved cell proliferation and neurogenesis and increased the number of Ki-67 and DCX-positive cells in the abstinence period. Meanwhile, meth treatment subjects caused a significant decrease in the number of neurogenesis makers, as compared to the control group. The neurogenesis markers (Ki-67 and DCX) could be somewhat reversed, while NeuN did not show any significant increase in the CBD group. Our findings demonstrated that CBD can induce neuroprotective effects by modulating neurogenesis. Therefore, it can provide a promising therapeutic approach to improve cognitive performance following chronic exposure to psychostimulant drugs, including meth.

Role of hippocampal orexin receptors in antinociception elicited by chemical stimulation of the lateral hypothalamus in the tail-flick test

The lateral hypothalamus (LH) orexinergic neurons project to numerous brain regions implicated in pain perception, including the CA1 part of the hippocampal formation. Moreover, the roles of orexin receptors (OXRs) in the CA1 in anti-analgesic consequences of the LH chemical stimulation by carbachol, muscarinic receptor agonist, in acute pain have not been clarified. The current research showed OXRs antagonist administration's effect in the CA1 on analgesia elicited by the LH chemical stimulation in a tail-flick test as an acute model of pain. The control groups, including vehicle-control groups, were given intra-LH administration of saline (0.5 μL), following intra-CA1 infusion of DMSO (12 %; 0.5 μL), and carbachol-control groups were treated with carbachol (250 nM/0.5 μL saline) into the LH following DMSO in the CA1. Treated groups received SB334867 (1, 3, 10, and 30 nM/0.5 μL DMSO) or TCS OX2 29 (0.1, 1, 10, and 20 nM/0.5 μL DMSO) as OX1R or OX2R antagonist, respectively, in the CA1 prior intra-LH administration of carbachol. After all injections, all rats underwent the tail-flick test over a 60-min time. Infusion of SB334867 or TCS OX2 29 in the CA1 impaired the analgesic consequences following chemical stimulation of the LH in acute pain. Meanwhile suppressive impact of the OX1R or OX2R antagonist on the analgesic impact of LH chemical stimulation was approximately identical. The current investigation provided a new document about the critical involvement of hippocampal orexinergic system in the modulatory role of the LH-CA1 path in pain perception.

Role of Cannabidiol in the Therapeutic Intervention for Substance Use Disorders

Drug treatments available for the management of substance use disorders (SUD) present multiple limitations in efficacy, lack of approved treatments or alarming relapse rates. These facts hamper the clinical outcome and the quality of life of the patients supporting the importance to develop new pharmacological agents. Lately, several reports suggest that cannabidiol (CBD) presents beneficial effects relevant for the management of neurological disorders such as epilepsy, multiple sclerosis, Parkinson's, or Alzheimer's diseases. Furthermore, there is a large body of evidence pointing out that CBD improves cognition, neurogenesis and presents anxiolytic, antidepressant, antipsychotic, and neuroprotective effects suggesting potential usefulness for the treatment of neuropsychiatric diseases and SUD. Here we review preclinical and clinical reports regarding the effects of CBD on the regulation of the reinforcing, motivational and withdrawal-related effects of different drugs of abuse such as alcohol, opioids (morphine, heroin), cannabinoids, nicotine, and psychostimulants (cocaine, amphetamine). Furthermore, a special section of the review is focused on the neurobiological mechanisms that might be underlying the 'anti-addictive' action of CBD through the regulation of dopaminergic, opioidergic, serotonergic, and endocannabinoid systems as well as hippocampal neurogenesis. The multimodal pharmacological profile described for CBD and the specific regulation of addictive behavior-related targets explains, at least in part, its therapeutic effects on the regulation of the reinforcing and motivational properties of different drugs of abuse. Moreover, the remarkable safety profile of CBD, its lack of reinforcing properties and the existence of approved medications containing this compound (Sativex®, Epidiolex®) increased the number of studies suggesting the potential of CBD as a therapeutic intervention for SUD. The rising number of publications with substantial results on the valuable therapeutic innovation of CBD for treating SUD, the undeniable need of new therapeutic agents to improve the clinical outcome of patients with SUD, and the upcoming clinical trials involving CBD endorse the relevance of this review.

Cannabidiol enhanced the development of sensitization to the expression of methamphetamine-induced conditioned place preference in male rats

Cannabis and ecstasy are illicit substances, and currently, there are no approved treatments for methamphetamine (METH) use disorder. Some studies have proposed that cannabidiol (CBD) decreases the motivation for METH seeking, but reports indicate that the therapeutic benefits are only for heroin. Here, we studied the interaction between CBD and METH during the sensitization phase on the rewarding effect of METH, using the conditioned place preference (CPP) paradigm to measure possible alterations in sensitivity. Our data showed that i. p. injection of METH created METH-induced CPP at two of the highest applied doses (1 and 2 mg/kg), and injection of METH during the sensitization period caused an establishment of METH-induced CPP at lower doses (0.25 and 0.5 mg/kg). Data also revealed that i. c.v. administration of CBD during the sensitization phase, shifted the establishment of METH-induced CPP toward a lower dose (0.5 mg/kg). Concurrent administration of CBD (10 μg/5 μl, i. c.v.) and METH (0.25 mg/kg, i. p.) during sensitization phase established METH-induced CPP with sub-threshold doses of METH (0.125, 0.25, and 0.5 mg/kg). Our results suggest the involvement of CBD and prior exposure to METH in creating sensitization to METH CPP.

Cannabidiol efficiently suppressed the acquisition and expression of methamphetamine-induced conditioned place preference in the rat

Methamphetamine (MET) is one of the most prevalently abused psychostimulants in the world with drastic repercussions. Several studies emphasized the inhibitory effect of Cannabidiol (CBD) on the reward properties of psychostimulants. The current investigation utilized conditioned place preference (CPP) to assay CBD's impact on MET's reward characteristic, including acquisition and expression phases of MET-induced CPP. Like our prior researches, animals received MET (1 mg/kg; sc) in a five-day schedule to induce CPP. The rats were given intracerebroventricular (ICV) microinjection of CBD (2, 10, and 50 μg/5 μL DMSO) during the 5-day conditioning phase in the CPP paradigm to highlight the CBD's impact on the development (acquisition) of MET-induced place preference. Furthermore, animals were treated with CBD (2, 10 and 50 μg/5 μL) in the lateral ventricle on the post-conditioning day to elucidate the effect of ICV injection of CBD on the expression of MET-induced CPP. It was revealed that CBD (10 and 50 μg/5 μL) microinjection profoundly inhibited both phases of MET-induced CPP without any side effect on the locomotion in animals were treated by MET injection over conditioning phase. Also, CBD's inhibitory impact was more potent in the acquisition phase than the expression phase of MET-induced CPP. Ultimately, the current research reported that CBD could be a beneficial compound to treat drug abuse however more investigations are needed.

Cannabidiol attenuated the maintenance and reinstatement of extinguished methylphenidate-induced conditioned place preference in rats

Methylphenidate (MPH) is a mild CNS stimulant that has been used in hyperactive children, and patients with neurodegenerative and major depressive disorders. Exposure to MPH-associated cues enhances craving and arousal in drug users. On the other hand, cannabidiol (CBD) has antipsychotic potential that might be useful in alleviating symptoms of drug addiction. The aim of this study was to investigate the effect of CBD administration on extinction and reinstatement of MPH-induced conditioning place preference (CPP) in rats. Male rats received MPH (1, 2.5 or 5 mg/kg, i.p) or morphine (5 or 10 mg/kg, s.c.) during the conditioning phase. Following the establishment of CPP, during extinction training, 60 min prior to every CPP session, animals were given daily ICV CBD (10 or 50 μg/5 μL), vehicle alone (DMSO) 10 % or were treatment-naïve. On the reinstatement day animals after receiving the initial dose of MPH, 0.5 mg/kg, and were placed into the CPP box to evaluate the CPP scoring for 10-min. Our findings indicated that morphine (5 and 10 mg/kg; s.c.) and MPH (1 and 2.5 mg/kg; i.p.) induced a CPP. The ICV administration of both doses of CBD (10 and 50 μg/5 μL) prevented the reinstatement of MPH-induced CPP, which displayed shorter extinction latency compared to treatment-naïve or DMSO 10 % groups. Therefore, CBD's site of action is a potential target for reducing the risk of MPH relapse; however, more investigation is required.