Selective post-training time window for memory consolidation interference of cannabidiol into the prefrontal cortex: Reduced dopaminergic modulation and immediate gene expression in limbic circuits

Cannabidiol effects on fear processing and implications for PTSD: Evidence from rodent and human studies

Cannabidiol (CBD) modulates aversive memory and its extinction, with potential implications for treating anxiety- and stress-related disorders. Here, we summarize and discuss scientific evidence showing that CBD administered after the acquisition (consolidation) and retrieval (reconsolidation) of fear memory attenuates it persistently in rats and mice. CBD also reduces fear expression and enhances fear extinction. These effects involve the activation of cannabinoid type-1 (CB1) receptors in the dorsal hippocampus, bed nucleus of stria terminalis, and medial prefrontal cortex, comprising the anterior cingulate, prelimbic, and infralimbic subregions. Serotonin type-1A (5-HT1A) receptors also mediate some CBD effects on fear memory. CBD effects on fear memory acquisition vary, depending on the aversiveness of the conditioning procedure. While rodent findings are relatively consistent and encouraging, human studies investigating CBD's efficacy in modulating aversive/traumatic memories are still limited. More studies are needed to investigate CBD's effects on maladaptive, traumatic memories, particularly in post-traumatic stress disorder patients.

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

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

Effect of Cannabis on Memory Consolidation, Learning and Retrieval and Its Current Legal Status in India: A Review

Cannabis is one of the oldest crops grown, traditionally held religious attachments in various cultures for its medicinal use much before its introduction to Western medicine. Multiple preclinical and clinical investigations have explored the beneficial effects of cannabis in various neurocognitive and neurodegenerative diseases affecting the cognitive domains. Tetrahydrocannabinol (THC), the major psychoactive component, is responsible for cognition-related deficits, while cannabidiol (CBD), a non-psychoactive phytocannabinoid, has been shown to elicit neuroprotective activity. In the present integrative review, the authors focus on the effects of cannabis on the different cognitive domains, including learning, consolidation, and retrieval. The present study is the first attempt in which significant focus has been imparted on all three aspects of cognition, thus linking to its usage. Furthermore, the investigators have also depicted the current legal position of cannabis in India and the requirement for reforms.

The NLRP3 Inflammasome in Stress Response: Another Target for the Promiscuous Cannabidiol

Many psychiatric patients do not respond to conventional therapy. There is a vast effort to investigate possible mechanisms involved in treatment resistance, trying to provide better treatment options, and several data points toward a possible involvement of inflammatory mechanisms. Microglia, glial, and resident immune cells are involved in complex responses in the brain, orchestrating homeostatic functions, such as synaptic pruning and maintaining neuronal activity. In contrast, microglia play a major role in neuroinflammation, neurodegeneration, and cell death. Increasing evidence implicate microglia dysfunction in neuropsychiatric disorders. The mechanisms are still unclear, but one pathway in microglia has received increased attention in the last 8 years, i.e., the NLRP3 inflammasome pathway. Stress response and inflammation, including microglia activation, can be attenuated by Cannabidiol (CBD). CBD has antidepressant, anti-stress, antipsychotic, anti-inflammatory, and other properties. CBD effects are mediated by direct or indirect modulation of many receptors, enzymes, and other targets. This review will highlight some findings for neuroinflammation and microglia involvement in stress-related psychiatric disorders, particularly addressing the NLRP3 inflammasome pathway. Moreover, we will discuss evidence and mechanisms for CBD effects in psychiatric disorders and animal models and address its potential effects on stress response via neuroinflammation and NLRP3 inflammasome modulation.

Cannabidiol impairs the rewarding effects of methamphetamine: Involvement of dopaminergic receptors in the nucleus accumbens

Cannabidiol, as component of cannabis, can potentially hinder the rewarding impact of drug abuse; however, its mechanism is ambiguous. Moreover, the nucleus accumbens (NAc), as a key area in the reward circuit, extensively receives dopaminergic projections from the ventral tegmentum area. To elucidate the role of accumbal D1 and D2 dopamine receptor families in Cannabidiol's inhibitory impact on the acquisition and expression phases of methamphetamine (MET), the conditioned place preference (CPP) procedure as a common method to assay reward characteristics of drugs was carried out. Six groups of rats were treated by various doses of SCH23390 or Sulpiride (0.25, 1, and 4 μg/0.5 μL) in the NAc as D1 or D2 dopamine receptor family antagonists, respectively, prior to infusion of Cannabidiol (10 μg/5 μL) in the lateral ventricle (LV) over conditioning phase in the acquisition experiments. In the second step of the study, animals received SCH23390 or Sulpiride in the NAc before Cannabidiol (50 μg/5 μL) infusion into the LV in the expression phase of MET to illuminate the influence of SCH23390 or Sulpiride on the inhibitory impact of Cannabidiol on the expression of MET-induced CPP. Intra-NAc administration of either SCH23390 or Sulpiride impaired Cannabidiol's suppressive impact on the expression phase, while just Sulpiride could suppress the Cannabidiol's impact on the acquisition phase of the MET-induced CPP. Also, the inhibitory impact of Sulpiride was stranger in both phases of MET reward. It seems that Cannabidiol prevents the expression and acquisition phases of MET-induced CPP partly through the dopaminergic system in the NAc.

Cannabidiol reverses memory impairments and activates components of the Akt/GSK3β pathway in an experimental model of estrogen depletion

Clinical and preclinical evidence has indicated that estrogen depletion leads to memory impairments and increases the susceptibility to neural damage. Here, we have sought to investigate the effects of Cannabidiol (CBD) a non-psychotomimetic compound from Cannabis sativa, on memory deficits induced by estrogen depletion in rats, and its underlying mechanisms. Adult rats were subjected to bilateral ovariectomy, an established estrogen depletion model in rodents, or sham surgery and allowed to recover for three weeks. After that, they received daily injections of CBD (10 mg/kg) for fourteen days. Rats were tested in the inhibitory avoidance task, a type of emotionally-motivated memory. After behavioral testing they were euthanized, and their hippocampi were isolated for analysis of components of the Akt/GSK3β survival pathway and the antiapoptotic protein Bcl2. Results revealed that ovariectomy impaired avoidance memory, and CBD was able to completely reverse estrogen depletion-induced memory impairment. Ovariectomy also reduced Akt/GSK3β pathway's activation by decreasing the phosphorylation levels of Akt and GSK3β and Bcl2 levels, which were ameliorated by CBD. The present results indicate that CBD leads to a functional recovery accompanied by the Akt/GSK3β survival pathway's activation, supporting its potential as a treatment for estrogen decline-induced deterioration of neural functioning and maintenance.

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.

Medial prefrontal cortex mechanisms of cannabidiol-induced aversive memory reconsolidation impairments

Growing evidence indicates that cannabidiol (CBD), a substance present in the Cannabis sativa plant, has potential therapeutic value to regulate abnormal emotional memories associated with post-traumatic stress and drug use disorders. CBD can attenuate their valence after retrieval (i.e., during reconsolidation) or potentiate their suppression by extinction. Pharmacological research has now focused on elucidating how it acts. Systemic antagonism of cannabinoid type-1 (CB1) receptors has often prevented the abovementioned effects of CBD. However, it is unknown in which brain regions CBD stimulates CB1 receptors and how it interferes with local activity-related plasticity to produce these effects. The present study addressed these questions considering the reconsolidation of contextual fear memories in rats. We focused on the medial prefrontal cortex (mPFC), which comprises the anterior cingulate (AC), prelimbic (PL), and infralimbic (IL) subregions, as local activity or plasticity has been associated with the process to-be-investigated. Animals that received post-retrieval systemic CBD treatment presented relatively fewer cells expressing Zif268/Egr1 protein, a proxy for synaptic plasticity related to reconsolidation, in the AC and PL. At the same time, there were no significant differences in the IL. Pretreatment with the CB1 receptor antagonist/inverse agonist AM251 into the AC, PL, or IL prevented the impairing effects of systemic CBD treatment on reconsolidation. CBD also caused reconsolidation impairments when injected directly into the AC or PL but not the IL. Together, these findings show complementary mechanisms through which CBD may hinder the reconsolidation of destabilized aversive memories along the dorsoventral axis of the mPFC.

Cannabidiol and the corticoraphe circuit in post-traumatic stress disorder

Post-Traumatic Stress Disorder (PTSD), characterized by re-experiencing, avoidance, negative affect, and impaired memory processing, may develop after traumatic events. PTSD is complicated by impaired plasticity and medial prefrontal cortex (mPFC) activity, hyperactivity of the amygdala, and impaired fear extinction. Cannabidiol (CBD) is a promising candidate for treatment due to its multimodal action that enhances plasticity and calms hyperexcitability. CBD’s mechanism in the mPFC of PTSD patients has been explored extensively, but literature on the mechanism in the dorsal raphe nucleus (DRN) is lacking. Following the PRISMA guidelines, we examined current literature regarding CBD in PTSD and overlapping symptomologies to propose a mechanism by which CBD treats PTSD via corticoraphe circuit. Acute CBD inhibits excess 5-HT release from DRN to amygdala and releases anandamide (AEA) onto amygdala inputs. By first reducing amygdala and DRN hyperactivity, CBD begins to ameliorate activity disparity between mPFC and amygdala. Chronic CBD recruits the mPFC, creating harmonious corticoraphe signaling. DRN releases enough 5-HT to ameliorate mPFC hypoactivity, while the mPFC continuously excites DRN 5-HT neurons via glutamate. Meanwhile, AEA regulates corticoraphe activity to stabilize signaling. AEA prevents DRN GABAergic interneurons from inhibiting 5-HT release so the DRN can assist the mPFC in overcoming its hypoactivity. DRN-mediated restoration of mPFC activity underlies CBD’s mechanism on fear extinction and learning of stress coping.

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CBD reduces PTSD symptoms via the DRN and corticoraphe circuit.

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Acute effects of CBD reduce DRN-amygdala excitatory signaling to lessen the activity disparity between amygdala and mPFC.

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Chronic CBD officially resolves mPFC hypoactivity by facilitating 5-HT release from DRN to mPFC.

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CBD-facilitated endocannabinoid signaling stabilizes DRN activity and restores mPFC inhibitory control.

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Chronically administered CBD acts via the corticoraphe circuit to favor fear extinction over fear memory reconsolidation.

Forgetting Unwanted Memories: Active Forgetting and Implications for the Development of Psychological Disorders

Intrusive memories are a common feature of many psychopathologies, and suppression-induced forgetting of unwanted memories appears as a critical ability to preserve mental health. In recent years, biological and cognitive studies converged in revealing that forgetting is due to active processes. Recent neurobiological studies provide evidence on the active role of main neurotransmitter systems in forgetting, suggesting that the brain actively works to suppress retrieval of unwanted memories. On the cognitive side, there is evidence that voluntary and involuntary processes (here termed "intentional" and "incidental" forgetting, respectively) contribute to active forgetting. In intentional forgetting, an inhibitory control mechanism suppresses awareness of unwanted memories at encoding or retrieval. In incidental forgetting, retrieval practice of some memories involuntarily suppresses the retrieval of other related memories. In this review we describe recent findings on deficits in active forgetting observed in psychopathologies, like post-traumatic stress disorder, depression, schizophrenia, and obsessive-compulsive disorder. Moreover, we report studies in which the role of neurotransmitter systems, known to be involved in the pathogenesis of mental disorders, has been investigated in active forgetting paradigms. The possibility that biological and cognitive mechanisms of active forgetting could be considered as hallmarks of the early onset of psychopathologies is also discussed.

Cannabidiol: A Potential New Alternative for the Treatment of Anxiety, Depression, and Psychotic Disorders

The potential therapeutic use of some Cannabis sativa plant compounds has been attracting great interest, especially for managing neuropsychiatric disorders due to the relative lack of efficacy of the current treatments. Numerous studies have been carried out using the main phytocannabinoids, tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD displays an interesting pharmacological profile without the potential for becoming a drug of abuse, unlike THC. In this review, we focused on the anxiolytic, antidepressant, and antipsychotic effects of CBD found in animal and human studies. In rodents, results suggest that the effects of CBD depend on the dose, the strain, the administration time course (acute vs. chronic), and the route of administration. In addition, certain key targets have been related with these CBD pharmacological actions, including cannabinoid receptors (CB₁r and CB₂r), 5-HT_1A receptor and neurogenesis factors. Preliminary clinical trials also support the efficacy of CBD as an anxiolytic, antipsychotic, and antidepressant, and more importantly, a positive risk-benefit profile. These promising results support the development of large-scale studies to further evaluate CBD as a potential new drug for the treatment of these psychiatric disorders.

Adolescent cannabinoid exposure interacts with other risk factors in schizophrenia: A review of the evidence from animal models

Many factors and their interaction are linked to the aetiology of schizophrenia, leading to the development of animal models of multiple risk factors and adverse exposures. Differentiating between separate and combined effects for each factor could better elucidate schizophrenia pathology, and drive development of preventative strategies for high-load risk factors. An epidemiologically valid risk factor commonly associated with schizophrenia is adolescent cannabis use. The aim of this review is to evaluate how early-life adversity from various origins, in combination with adolescent cannabinoid exposure interact, and whether these interactions confer main, synergistic or protective effects in animal models of schizophrenia-like behavioural, cognitive and morphological alterations. Patterns emerge regarding which models show consistent synergistic or protective effects, particularly those models incorporating early-life exposure to maternal deprivation and maternal immune activation, and sex-specific effects are observed. It is evident that more research needs to be conducted to better understand the risks and alterations of interacting factors, with particular interest in sex differences, to better understand the translatability of these preclinical models to humans.

A time-dependent contribution of hippocampal CB1 , CB2 and PPARγ receptors to cannabidiol-induced disruption of fear memory consolidation

BACKGROUND AND PURPOSE

In preclinical studies, cannabidiol (CBD) mitigates fear memories by facilitating their extinction or interfering with their generalization and reconsolidation. The brain regions and mechanisms underlying these effects, and their temporal window, are still poorly understood. Here, we have investigated related questions in the dorsal hippocampus (DH) during contextual fear consolidation.

EXPERIMENTAL APPROACH

Adult male Wistar rats received CBD (10-30 pmol) intra-DH immediately, 1 or 3 hr after fear conditioning. Effects of CBD on consolidation were inferred behaviourally and by analysing expression of the activity-regulated, cytoskeleton-associated (Arc) protein. The contribution of anandamide, CB₁ , CB₂ , 5-HT_1A , A_2A , and PPARγ receptors was also assessed.

KEY RESULTS

CBD impaired memory consolidation when given immediately or 1 hr after fear conditioning, but not after 3 hr. Expression of Arc protein in DH was reduced by systemic CBD treatment in both cases. Immediately after fear conditioning, CBD effects were abolished by CB₁ or CB₂ receptor blockade, partly reduced by 5-HT_1A or A_2A antagonism, and remained unchanged after antagonism of PPARγ receptors. One hour after fear conditioning, CBD effects were prevented only by PPARγ receptor antagonism. Also, inhibition of fatty acid amide hydrolase by URB597, impaired memory consolidation when infused immediately, but not 1 hr after fear conditioning.

CONCLUSIONS AND IMPLICATIONS

CBD disrupts memory consolidation up to 1 hr after fear conditioning, allowing an extended window of opportunity to mitigate aversive memories after their acquisition. Our results suggest time-dependent participation of anandamide, CB₁ , CB₂ and PPARγ receptors in the DH, during this process.

Retrieval of contextual aversive memory and induction of Zenk expression in the hippocampus of pigeons

The hippocampus has a fundamental role in many learning and memory processes, which include the formation and retrieval of context-fear associations, as evidenced by studies in rodents and birds. The present paper has analyzed contextual memory and Zenk expression in the hippocampus of the pigeon after fear conditioning. Pigeons were trained under four conditions: with 3 tone-shock associations (Paired), with shock and tone presented randomly (Unpaired), with exposure to the experimental chamber without stimulation (Control) and with only daily handling (Naive). The testing was conducted 24 h after training. All sessions were digitally recorded. The level of freezing expressed by the Paired and Unpaired groups differed significantly from that of the control group during both training and test sessions. Pigeons from the Paired group revealed a significantly greater density of Zenk positive nuclei in the ventromedial region of the hippocampus than did the Unpaired, Control and Naive groups. These data suggest that Zenk-mediated processes of synaptic plasticity in the hippocampus are induced during the retrieval of conditioned fear memory in the pigeon.

Pharmacological interventions during the process of reconsolidation of aversive memories: A systematic review

Reconsolidation is the return of a memory to a transient state of lability, following memory consolidation, that can occur when memories are evoked. During the process of reconsolidation, memories may be modified by different means, including the administration of drugs, during a period called the "reconsolidation window”. This process has been widely studied in animals, but human studies are limited and include several methodological pitfalls. Our objective was to conducte a systematic review of the literature that utilizes pharmacological interventions during the process of reconsolidation of aversive memories in humans, with a critical analysis of the methodologies used. Searches were made in the electronic databases PubMed, Scopus, Web of Science and SciELO using the following search terms: (memory) AND (consolidation OR reconsolidation) AND (pharmacological manipulation OR pharmacological intervention). We found 294 references and ten (3.4%) were included in the review, based on preestablished eligibility criteria. All studies were randomized, double-blind clinical trials. The most commonly studied drug was propranolol. Two studies used a protocol involving autobiographical aversive memories, while in the remaining aversive memories were produced in the laboratory. The timing of pharmacological interventions is a controversial issue in the field, as drug activity must occur within the reconsolidation window. The small number of studies and some methodological difficulties of this type of research highlights the need for studies that individually evaluate some of the issues discussed, particularly the timing of pharmacological interventions and the duration of reconsolidation windows.

Cannabinoid interventions for PTSD: Where to next?

Cannabinoids are a promising method for pharmacological treatment of post-traumatic stress disorder (PTSD). Despite considerable research devoted to the effect of cannabinoid modulation on PTSD symptomology, there is not a currently agreed way by which the cannabinoid system should be targeted in humans. In this review, we present an overview of recent research identifying neurological pathways by which different cannabinoid-based treatments may exert their effects on PTSD symptomology. We evaluate the strengths and weaknesses of each of these different approaches, including recent challenges presented to favourable options such as fatty acid amide hydrolase (FAAH) inhibitors. This article makes the strengths and challenges of different potential cannabinoid treatments accessible to psychological researchers interested in cannabinoid therapeutics and aims to aid selection of appropriate tools for future clinical trials.

Fear conditioning and extinction induce opposing changes in dendritic spine remodeling and somatic activity of layer 5 pyramidal neurons in the mouse motor cortex

Multiple brain regions including the amygdala and prefrontal cortex are crucial for modulating fear conditioning and extinction. The primary motor cortex is known to participate in the planning, control, and execution of voluntary movements. Whether and how the primary motor cortex is involved in modulating freezing responses related to fear conditioning and extinction remains unclear. Here we show that inactivation of the mouse primary motor cortex impairs both the acquisition and extinction of freezing responses induced by auditory-cued fear conditioning. Fear conditioning significantly increases the elimination of dendritic spines on apical dendrites of layer 5 pyramidal neurons in the motor cortex. These eliminated spines are further apart from each other than expected from random distribution along dendrites. On the other hand, fear extinction causes the formation of new spines that are located near the site of spines eliminated previously after fear conditioning. We further show that fear conditioning decreases and fear extinction increases somatic activities of layer 5 pyramidal neurons in the motor cortex respectively. Taken together, these findings indicate fear conditioning and extinction induce opposing changes in synaptic connections and somatic activities of layer 5 pyramidal neurons in the primary motor cortex, a cortical region important for the acquisition and extinction of auditory-cued conditioned freezing responses.

Remote fear memory is sensitive to reconditioning

Exposure of some individuals to recurring traumatic events from the same perpetrator or situation, such as during child abuse or domestic violence, is quite prevalent. Studies have shown that the number of traumatic events experienced is positively related to the severity of post-traumatic stress disorder and other mental disorders. Using a contextual fear conditioning (Cond1) and reconditioning (Cond2) paradigm, which were separated by either 1 or 35 days, we examined fear responses to immediate extinction and retrieval-extinction procedures after repeated fear conditioning stress. Based on the time interval between Cond1 and Cond2, the animals were divided into recent and remote fear memory groups. We observed that when Cond2 was performed in the original conditioning context in which Cond1 was performed, the reconditioned remote fear memory was resistant to the disruptive effect of immediate extinction and retrieval-extinction paradigms. Furthermore, the resistance to disruptive effects could be induced by very low shock intensities, which cannot even induce any fear response in naive animals. When Cond2 was performed in a novel context, animals with remote fear memory acquired a significantly higher fear response to the novel context. Our findings suggest that remote fear memory may be more sensitive to reconditioning and resistant to post-reconditioning disruption.

Cannabinoid Regulation of Fear and Anxiety: an Update

PURPOSE OF REVIEW

Anxiety- and trauma-related disorders are prevalent and debilitating mental illnesses associated with a significant socioeconomic burden. Current treatment approaches often have inadequate therapeutic responses, leading to symptom relapse. Here we review recent preclinical and clinical findings on the potential of cannabinoids as novel therapeutics for regulating fear and anxiety.

RECENT FINDINGS

Evidence from preclinical studies has shown that the non-psychotropic phytocannabinoid cannabidiol and the endocannabinoid anandamide have acute anxiolytic effects and also regulate learned fear by dampening its expression, enhancing its extinction and disrupting its reconsolidation. The findings from the relevant clinical literature are still very preliminary but are nonetheless encouraging. Based on this preclinical evidence, larger-scale placebo-controlled clinical studies are warranted to investigate the effects of cannabidiol in particular as an adjunct to psychological therapy or medication to determine its potential utility for treating anxiety-related disorders in the future.

Manual Hippocampal Subfield Segmentation Using High-Field MRI: Impact of Different Subfields in Hippocampal Volume Loss of Temporal Lobe Epilepsy Patients

In patients with temporal lobe epilepsy (TLE), presurgical magnetic resonance imaging (MRI) often reveals hippocampal atrophy, while neuropathological assessment indicates the different types of hippocampal sclerosis (HS). Different HS types are not discriminated in MRI so far. We aimed to define the volume of each hippocampal subfield on MRI manually and to compare automatic and manual segmentations for the discrimination of HS types. The T2-weighted images from 14 formalin-fixed age-matched control hippocampi were obtained with 4.7T MRI to evaluate the volume of each subfield at the anatomical level of the hippocampal head, body, and tail. Formalin-fixed coronal sections at the level of the body of 14 control cases, as well as tissue samples from 24 TLE patients, were imaged with a similar high-resolution sequence at 3T. Presurgical three-dimensional (3D) T1-weighted images from TLE went through a FreeSurfer 6.0 hippocampal subfield automatic assessment. The manual delineation with the 4.7T MRI was identified using Luxol Fast Blue stained 10-μm-thin microscopy slides, collected at every millimeter. An additional section at the level of the body from controls and TLE cases was submitted to NeuN immunohistochemistry for neuronal density estimation. All TLE cases were classified according to the International League Against Epilepsy's (ILAE's) HS classification. Manual volumetry in controls revealed that the dentate gyrus (DG)+CA4 region, CA1, and subiculum accounted for almost 90% of the hippocampal volume. The manual 3T volumetry showed that all TLE patients with type 1 HS (TLE-HS1) had lower volumes for DG+CA4, CA2, and CA1, whereas those TLE patients with HS type 2 (TLE-HS2) had lower volumes only in CA1 (p ≤ 0.038). Neuronal cell densities always decreased in CA4, CA3, CA2, and CA1 of TLE-HS1 but only in CA1 of TLE-HS2 (p ≤ 0.003). In addition, TLE-HS2 had a higher volume (p = 0.016) and higher neuronal density (p < 0.001) than the TLE-HS1 in DG + CA4. Automatic segmentation failed to match the manual or histological findings and was unable to differentiate TLE-HS1 from TLE-HS2. Total hippocampal volume correlated with DG+CA4 and CA1 volumes and neuronal density. For the first time, we also identified subfield-specific pathology patterns in the manual evaluation of volumetric MRI scans, showing the importance of manual segmentation to assess subfield-specific pathology patterns.

Pharmacological Comparisons Between Cannabidiol and KLS-13019

Cannabidiol (CBD) exhibits neuroprotective properties in many experimental systems. However, development of CBD as a drug has been confounded by the following: (1) low potency; (2) a large number of molecular targets; (3) marginal pharmacokinetic properties; and (4) designation as a schedule 1 controlled substance. The present work compared the properties of CBD with a novel molecule (KLS-13019) that has structural similarities to CBD. The design strategy for KLS-13019 was to increase hydrophilicity while optimizing neuroprotective potency against oxidative stress toxicity relevant to hepatic encephalopathy. The protective responses of CBD and KLS-13019 were compared in dissociated rat hippocampal cultures co-treated with toxic levels of ethanol and ammonium acetate. This comparison revealed that KLS-13019 was 31-fold more potent than CBD in preventing neuronal toxicity from the combined toxin treatment, while both compounds exhibited complete protective efficacy back to control values. In addition, treatment with KLS-13019 alone was 5-fold less toxic (TC50) than CBD. Previous studies suggested that CBD targeted the Na⁺-Ca²⁺ exchanger in mitochondria (mNCX) to regulate intracellular calcium levels, an important determinant of neuronal survival. After treatment with an inhibitor of mNCX (CGP-37157), no detectable neuroprotection from ethanol toxicity was observed for either CBD or KLS-13019. Furthermore, AM630 (CB2 antagonist) significantly attenuated CBD-mediated neuroprotection, while having no detectable effect on neuroprotection from KLS-13019. Our studies indicated KLS-13019 was more potent and less toxic than CBD. Both compounds can act through mNCX. KLS-13019 may provide an alternative to CBD as a therapeutic candidate to treat diseases associated with oxidative stress.

Systemic Injections of Cannabidiol Enhance Acetylcholine Levels from Basal Forebrain in Rats

Cannabis sativa is a plant that contains more than 500 components, of which the most studied are Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD). Several studies have indicated that CBD displays neurobiological effects, including wake promotion. Moreover, experimental evidence has shown that injections of CBD enhance wake-related compounds, such as monoamines (dopamine, serotonin, epinephrine, and norepinephrine). However, no clear evidence is available regarding the effects of CBD on additional wake-related neurochemicals such as acetylcholine (ACh). Here, we demonstrate that systemic injections of CBD (0, 5, 10 or 30 mg/kg, i.p.) at the beginning of the lights-on period, increase the extracellular levels of ACh collected from the basal forebrain and measured by microdialysis and HPLC means. Moreover, the time course effects on the contents of ACh were present 5 h post-injection of CBD. Altogether, these data demonstrate that CBD increases ACh levels in a brain region related to wake control. This study is the first to show the effects of ACh levels in CBD-treated rats and suggests that the basal forebrain might be a site of action of CBD for wakefulness modulation.

Integrating Endocannabinoid Signaling and Cannabinoids into the Biology and Treatment of Posttraumatic Stress Disorder

Exposure to stress is an undeniable, but in most cases surmountable, part of life. However, in certain individuals, exposure to severe or cumulative stressors can lead to an array of pathological conditions including posttraumatic stress disorder (PTSD), characterized by debilitating trauma-related intrusive thoughts, avoidance behaviors, hyperarousal, as well as depressed mood and anxiety. In the context of the rapidly changing political and legal landscape surrounding use of cannabis products in the USA, there has been a surge of public and research interest in the role of cannabinoids in the regulation of stress-related biological processes and in their potential therapeutic application for stress-related psychopathology. Here we review the current state of knowledge regarding the effects of cannabis and cannabinoids in PTSD and the preclinical and clinical literature on the effects of cannabinoids and endogenous cannabinoid signaling systems in the regulation of biological processes related to the pathogenesis of PTSD. Potential therapeutic implications of the reviewed literature are also discussed. Finally, we propose that a state of endocannabinoid deficiency could represent a stress susceptibility endophenotype predisposing to the development of trauma-related psychopathology and provide biologically plausible support for the self-medication hypotheses used to explain high rates of cannabis use in patients with trauma-related disorders.