ACUTE AND LONG-TERM EFFECTS OF APP-DELIVERED HEARTFULNESS MEDITATION ON PSYCHOLOGICAL OUTCOMES AND THE ENDOCANNABINOID SIGNALING SYSTEM IN CYCLIC VOMITING SYNDROME

BACKGROUND

Cyclic vomiting syndrome (CVS) is a disorder of gut brain interaction (DGBI) often triggered by stress. Interventions like meditation may improve psychological outcomes and Health-Related Quality of Life (HRQoL), but their efficacy and the underlying mechanism are unknown.

METHODS

We conducted a 6-week single-arm pilot study to assess the effects of Heartfulness meditation (HFM) in CVS using a custom-designed meditation app. Primary outcomes included state and trait anxiety and mood state changes pre- vs. post-meditation, and secondary outcomes were psychological distress, coping, sleep quality and HRQoL at baseline and weeks 3 and 6. Serum concentrations of endocannabinoids N-arachidonylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) and related lipids were measured pre-and-post HFM at baseline and week 6.

RESULTS

In 30 treatment completers, there was a significant improvement in state anxiety (p<0.001), total mood disturbance (p<0.001), and other mood states (all p values <0.05) across the three time points. Trait anxiety was also improved at week 6. There was a significant improvement in psychological distress (global severity index), sleep quality (daytime dysfunction), coping (using religion/spirituality) and HRQoL (mental and physical) across the three time points (all p <0.05). Significant increases in AEA and related lipids N-oleoylethanolamine and palmitoylethanolamide post-vs.-pre HFM were observed at week 6 (p<0.001, 0.002, 0.003, respectively). No adverse effects were noted.

DISCUSSION

App-delivered HFM is feasible, safe and effective and improves psychological outcomes and augments endocannabinoids. This provides insight into the mechanism underlying HFM and has potential for widespread use as a digital therapeutic in CVS and other DGBI.Study Highlights.

Type 2 cannabinoid receptor expression on microglial cells regulates neuroinflammation during graft versus host disease

Neuroinflammation is a recognized complication of immunotherapeutic approaches such as immune checkpoint inhibitor treatment, chimeric antigen receptor therapy, and graft versus host disease (GVHD) occurring after allogeneic hematopoietic stem cell transplantation. While T cells and inflammatory cytokines play a role in this process, the precise interplay between the adaptive and innate arms of the immune system that propagates inflammation in the central nervous system remains incompletely understood. Using a murine model of GVHD, we demonstrate that type 2 cannabinoid receptor (CB2R) signaling plays a critical role in the pathophysiology of neuroinflammation. In these studies, we identify that CB2R expression on microglial cells induces an activated inflammatory phenotype which potentiates the accumulation of donor-derived proinflammatory T cells, regulates chemokine gene regulatory networks, and promotes neuronal cell death. Pharmacological targeting of this receptor with a brain penetrant CB2R inverse agonist/antagonist selectively reduces neuroinflammation without deleteriously affecting systemic GVHD severity. Thus, these findings delineate a therapeutically targetable neuroinflammatory pathway and has implications for the attenuation of neurotoxicity after GVHD and potentially other T cell-based immunotherapeutic approaches.

Cannabinoid CB 2 receptors in primary sensory neurons are implicated in CB 2 agonist-mediated suppression of paclitaxel-induced neuropathic nociception and sexually-dimorphic sparing of morphine tolerance

Cannabinoid CB 2 agonists show therapeutic efficacy without the unwanted side effects commonly associated with direct activation of CB 1 receptors. The G protein-biased CB 2 receptor agonist LY2828360 attenuates the maintenance of chemotherapy-induced neuropathic nociception in male mice and blocks the development of morphine tolerance in this model. However, the specific cell types involved in this phenomenon have never been investigated and whether this therapeutic profile is observed in female mice remains poorly understood. We used conditional deletion of CB 2 receptors from specific cell populations to determine the population(s) mediating the anti-allodynic and morphine-sparing effects of CB 2 agonists. Anti-allodynic effects of structurally distinct CB 2 agonists (LY2828360 and AM1710) were present in paclitaxel-treated CB 2 f/f mice of either sex. The anti-allodynic effect of the CB 2 agonists were absent in conditional knockout (KO) mice lacking CB 2 receptors in peripheral sensory neurons (Advillin CRE/+ ; CB 2 f/f ) but preserved in mice lacking CB 2 receptors in CX3CR1 expressing microglia/macrophages (CX3CR1 CRE/+ ; CB 2 f/f ). The morphine-sparing effect of LY28282360 occurred in a sexually-dimorphic manner, being present in male mice but absent in female mice of any genotype. In mice with established paclitaxel-induced neuropathy, prior LY2828360 treatment (3 mg/kg per day i.p. x 12 days) blocked the subsequent development of morphine tolerance in male CB 2 f/f mice but was absent in male (or female) Advillin CRE/+ ; CB 2 f/f mice. LY2828360-induced sparing of morphine tolerance was preserved in male CX3CR1 CRE/+ ; CB 2 f/f mice, but this effect was not observed in female CX3CR1 CRE/+ ; CB 2 f/f mice. Similarly, co-administration of morphine with a low dose of LY2828360 (0.1 mg/kg per day i.p. x 6 days) reversed tolerance to the anti-allodynic efficacy of morphine in paclitaxel-treated male CB 2 f/f mice, but this effect was absent in female CB 2 f/f mice and Advillin CRE/+ ; CB 2 f/f mice of either sex. Additionally, LY2828360 (3 mg/kg per day i.p. x 8 days) delayed, but did not prevent, the development of paclitaxel-induced mechanical and cold allodynia in either CB 2 f/f or CX3CR1 CRE/+ ; CB 2 f/f mice of either sex. Our studies reveal that CB 2 receptors in primary sensory neurons are required for the anti-allodynic effects of CB 2 agonists in a mouse model of paclitaxel-induced neuropathic nociception. We also find that CB 2 agonists acting on primary sensory neurons produce a sexually-dimorphic sparing of morphine tolerance in males, but not female, paclitaxel-treated mice.

Dysfunction in endocannabinoids, palmitoylethanolamide, and degradation of tryptophan into kynurenine in individuals with depressive symptoms

BACKGROUND

The endocannabinoid (eCB) system and the serotonin (5-HT) are both implicated in the severity of the depression. 5-HT is synthesized from the amino acid tryptophan (Trp), which is also a precursor for kynurenine (Kyn) whose production is increased at the expense of 5-HT in depressed patients. No clinical studies have investigated the crosstalk between the eCB system and the Trp/5-HT/Kyn pathways. Here, we hypothesized that the eCB system is associated with an enhanced Kyn production in relation to the severity of depressive symptoms.

METHODS

Eighty-two subjects (51 patients with a diagnosis of depressive disorder (DSM-5) and 31 healthy volunteers), were assessed with the Montgomery-Åsberg Depression Rating Scale (MADRS), Beck Depression Scale, and Global Clinical Impression. Serum concentrations of eCBs (N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG)); structurally related fatty acyl compounds 2-oleoylglycerol (2-OG), oleoylethanolamide (OEA), and palmitoylethanolamide (PEA); Trp, Kyn, Kyn/Trp ratio (an index of Trp degradation into Kyn) and 5-HT were also determined.

RESULTS

Following a principal component analysis including the severity of depression, Kyn and the Kyn/Trp ratio appear to be directly associated with 2-AG, AEA, and PEA. Interestingly, these biomarkers also permitted to distinguish the population into two main clusters: one of individuals having mild/severe depressive symptoms and the other with an absence of depressive symptoms. Using parametric analysis, higher serum levels of 2-AG, Kyn, and the ratio Kyn/Trp and lower levels of Trp and 5-HT were found in individuals with mild/severe depressive symptoms than in those without depressive symptoms. While in asymptomatic people, PEA was directly associated to Trp, and OEA indirectly linked to 5-HT, in individuals with depressive symptoms, these correlations were lost, and instead, positive correlations between AEA and 2-AG, PEA and AEA, and PEA vs 2-AG and OEA concentrations were found.

CONCLUSIONS

Parametric and non-parametric analyses suggest a possible association between eCBs, tryptophan/kynurenine biomarkers, and severity of depression, confirming a likely interplay among inflammation, stress, and depression. The enhanced relationships among the biomarkers of the 2-AG and AEA pathways and related lipids seen in individuals with depressive symptoms, but not in asymptomatics, suggest an altered metabolism of the eCB system in depression.

Endocannabinoid and psychological responses to acute resistance exercise in trained and untrained adults

INTRODUCTION

This study examined the effects of acute resistance exercise on circulating endocannabinoid (eCB) and mood responses in trained and untrained healthy adults.

METHODS

Thirty-two healthy adults (22.1 ± 2.9 years) were recruited from trained (reporting resistance exercise at least twice per week for ≥ previous three months) and untrained (performing no resistance exercise for ≥ previous three months) groups. Participants (13 male, 19 female) completed three sets of resistance exercise (16 repetitions at 50% 1-repetition max, 12 repetitions at 70% 1-repetition max, 8 repetitions at 80% 1-repetition max). Resistance machines targeted the legs, chest, back, and abdominal muscles. Mood states, affect, and circulating eCB concentrations were evaluated before and after resistance exercise.

RESULTS

There were significant decreases in AEA, PEA, and OEA levels following acute resistance exercise (p <0.05; ds = -0.39, -0.48, -0.65, respectively), with no significant group differences or group by time interactions. 2-AG did not change significantly. Positive affect increased significantly following resistance exercise (p = 0.009), while negative affect decreased (p <0.001). Depressive symptoms, anger, confusion, and total mood disturbance decreased significantly (p <0.05), while vigor increased significantly following resistance exercise (p = 0.005). There were no significant group differences or group by time interactions for any psychological outcomes.

CONCLUSION

These results indicate that acute resistance exercise may reduce eCB and related lipid concentrations, which is opposite to the increase in lipids typically observed with acute aerobic exercise. Furthermore, psychological improvements occur after resistance exercise regardless of decreases in eCBs, supporting the notion that psychological changes with exercise likely occur through a wide variety of biological and environmental mechanisms.

The endocannabinoid system as a putative target for the development of novel drugs for the treatment of psychiatric illnesses

Cannabis is well established to impact affective states, emotion and perceptual processing, primarily through its interactions with the endocannabinoid system. While cannabis use is quite prevalent in many individuals afflicted with psychiatric illnesses, there is considerable controversy as to whether cannabis may worsen these conditions or provide some form of therapeutic benefit. The development of pharmacological agents which interact with components of the endocannabinoid system in more localized and discrete ways then via phytocannabinoids found in cannabis, has allowed the investigation if direct targeting of the endocannabinoid system itself may represent a novel approach to treat psychiatric illness without the potential untoward side effects associated with cannabis. Herein we review the current body of literature regarding the various pharmacological tools that have been developed to target the endocannabinoid system, their impact in preclinical models of psychiatric illness and the recent data emerging of their utilization in clinical trials for psychiatric illnesses, with a specific focus on substance use disorders, trauma-related disorders, and autism. We highlight several candidate drugs which target endocannabinoid function, particularly inhibitors of endocannabinoid metabolism or modulators of cannabinoid receptor signaling, which have emerged as potential candidates for the treatment of psychiatric conditions, particularly substance use disorder, anxiety and trauma-related disorders and autism spectrum disorders. Although there needs to be ongoing clinical work to establish the potential utility of endocannabinoid-based drugs for the treatment of psychiatric illnesses, the current data available is quite promising and shows indications of several potential candidate diseases which may benefit from this approach.

Endocannabinoids, cortisol, and development of post-traumatic psychopathological trajectories

OBJECTIVE

Our prior published work using the 2-factor model of PTSD identified four subgroups of trauma survivors on average 6 months following trauma: Resilient, Dysphoria, High Comorbid, and Severe Comorbid. Some findings indicate that low and high cortisol responses may increase risk for the development of PTSD and depression respectively, yet ways in which cortisol interacts with other physiological systems to enhance risk is unclear. This study examined the role of circulating eCBs in the development of previously identified psychopathological trajectories that is differentiated by cortisol in traumatically injured adults (N = 169).

METHODS

Circulating concentrations of eCBs, 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA) were measured during post-injury hospitalization and on average 6 months following trauma. Differences in 2-AG and AEA among the subgroups were tested using multivariate ANCOVA.

RESULTS

Dysphoria (with highest cortisol levels) and High Comorbid subgroups exhibited higher post-injury AEA compared to the Resilient group. Dysphoria subgroup showed a significant decline in AEA by 6 months compared to Resilient and High Comorbid subgroups.

CONCLUSION

Change in AEA over time in individuals with high post-injury cortisol may serve as a buffer against risk for severe psychopathology. Assessing AEA and cortisol levels concurrently across time may serve as indicators of risk.

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

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

MICROGLIAL CELL EXPRESSION OF THE TYPE 2 CANNABINOID RECEPTOR REGULATES IMMUNE-MEDIATED NEUROINFLAMMATION

Neuroinflammation is a recognized complication of immunotherapeutic approaches such as immune checkpoint inhibitor treatment, chimeric antigen receptor therapy, and graft versus host disease (GVHD) occurring after allogeneic hematopoietic stem cell transplantation. While T cells and inflammatory cytokines play a role in this process, the precise interplay between the adaptive and innate arms of the immune system that propagates inflammation in the central nervous system remains incompletely understood. Using a murine model of GVHD, we demonstrate that type 2 cannabinoid receptor (CB2R) signaling plays a critical role in the pathophysiology of neuroinflammation. In these studies, we identify that CB2R expression on microglial cells induces an activated inflammatory phenotype which potentiates the accumulation of donor-derived proinflammatory T cells, regulates chemokine gene regulatory networks, and promotes neuronal cell death. Pharmacological targeting of this receptor with a brain penetrant CB2R inverse agonist/antagonist selectively reduces neuroinflammation without deleteriously affecting systemic GVHD severity. Thus, these findings delineate a therapeutically targetable neuroinflammatory pathway and has implications for the attenuation of neurotoxicity after GVHD and potentially other T cell-based immunotherapeutic approaches.

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

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

Altered glial expression of the cannabinoid 1 receptor in the subiculum of a mouse model of Alzheimer's disease

The alteration of the endocannabinoid tone usually associates with changes in the expression and/or function of the cannabinoid CB₁ receptor. In Alzheimer's disease (AD), amyloid beta (Aβ)-containing aggregates induce a chronic inflammatory response leading to reactivity of both microglia and astrocytes. However, how this glial response impacts on the glial CB₁ receptor expression in the subiculum of a mouse model of AD, a brain region particularly affected by large accumulation of plaques and concomitant subcellular changes in microglia and astrocytes, is unknown. The CB₁ receptor localization in both glial cells was investigated in the subiculum of male 5xFAD/CB₂ ^EGFP/f/f (AD model) and CB₂ ^EGFP/f/f mice by immuno-electron microscopy. The findings revealed that glial CB₁ receptors suffer remarkable changes in the AD mouse. Thus, CB₁ receptor expression increases in reactive microglia in 5xFAD/CB₂ ^EGFP/f/f , but remains constant in astrocytes with CB₁ receptor labeling rising proportionally to the perimeter of the reactive astrocytes. Not least, the CB₁ receptor localization in microglial processes in the subiculum of controls and closely surrounding amyloid plaques and dystrophic neurites of the AD model, supports previous suggestions of the presence of the CB₁ receptor in microglia. These findings on the correlation between glial reactivity and the CB₁ receptor expression in microglial cells and astrocytes, contribute to the understanding of the role of the endocannabinoid system in the pathophysiology of Alzheimer's disease.

Endocannabinoid signaling in the central nervous system

It is hard to overestimate the influence of the endocannabinoid signaling (ECS) system on central nervous system (CNS) function. In the 40 years since cannabinoids were found to trigger specific cell signaling cascades, studies of the ECS system continue to cause amazement, surprise, and confusion! CB1 cannabinoid receptors are expressed widely in the CNS and regulate cell-cell communication via effects on the release of both neurotransmitters and gliotransmitters. CB2 cannabinoid receptors are difficult to detect in the CNS but seem to "punch above their weight" as compounds targeting these receptors have significant effects on inflammatory state and behavior. Positive and negative allosteric modulators for both receptors have been identified and examined in preclinical studies. Concentrations of the endocannabinoid ligands, N-arachidonoylethanolamine and 2-arachidonoylglycerol (2-AG), are regulated by a combination of enzymatic synthesis and degradation and inhibitors of these processes are available and making their way into clinical trials. Importantly, ECS regulates many essential brain functions, including regulation of reward, anxiety, inflammation, motor control, and cellular development. While the field is on the cusp of preclinical discoveries providing impactful clinical and therapeutic insights into many CNS disorders, there is still much to be learned about this remarkable and versatile modulatory system.

Circulating endocannabinoids and psychological outcomes in women with PTSD

BACKGROUND

Recent research has attempted to elucidate the relationship between blood-based biomarkers (e.g., endocannabinoids; eCBs: including N-arachidonoylethanolamine [AEA] and 2-arachidonoylglycerol [2-AG]) and mental health outcomes in psychiatric populations such as posttraumatic stress disorder (PTSD). Prior research suggests that adults with PTSD may have altered circulating eCB tone and a blunted mobilization of eCBs (particularly 2-AG) in response to stress (e.g., aerobic exercise), although our understanding has been limited in part due to heterogenous samples and small sample sizes.

METHODS

A subset of data was pooled from five studies in which women with and without PTSD (N = 98) completed questionnaires related to mood states and a blood draw prior to and following a bout of moderate-intensity aerobic exercise in order to determine: 1) whether circulating eCBs differ between groups and whether depressive and PTSD symptom severity are associated with baseline eCBs, 2) whether a bout of aerobic exercise increases circulating eCBs in adult women with PTSD, and 3) whether circulating eCBs are associated with overall mood states and exercise-induced improvements in mood states in women with and without PTSD.

RESULTS

PTSD diagnoses were not associated with baseline concentrations of eCBs. Greater depressive symptom severity and PTSD symptom severity within the negative alteration in cognition and mood cluster were associated with lower circulating AEA. Circulating AEA significantly increased following aerobic exercise for both groups, whereas circulating 2-AG only increased in women without PTSD. Greater circulating AEA within the PTSD group was associated with lower depressive mood, confusion, and total mood disturbance.

CONCLUSIONS

These findings suggest that greater circulating AEA is associated with better overall mood and lower depressive and PTSD symptom severity, and that an acute bout of moderate-intensity aerobic exercise increases circulating AEA (but not 2-AG) in adult women with PTSD. These findings are consistent with the idea that greater eCB tone (particularly AEA) following pharmacological and/or non-pharmacological manipulations may be beneficial for improving psychological outcomes (e.g., mood, cognition) among PTSD, and possibly other psychiatric populations.

Machine learning prediction of posttraumatic stress disorder trajectories following traumatic injury: Identification and validation in two independent samples

Due to its heterogeneity, the prediction of posttraumatic stress disorder (PTSD) development after traumtic injury is difficult. Recent machine learning approaches have yielded insight into predicting PTSD symptom trajectories. Using data collected within 1 month of traumatic injury, we applied eXtreme Gradient Boosting (XGB) to classify admitted and discharged patients (hospitalized, n = 192; nonhospitalized, n = 214), recruited from a Level 1 trauma center, according to PTSD symptom trajectories. Trajectories were identified using latent class mixed models on PCL-5 scores collected at baseline, 1-3 months posttrauma, and 6 months posttrauma. In both samples, nonremitting, remitting, and resilient PTSD symptom trajectories were identified. In the admitted patient sample, a unique delayed trajectory emerged. Machine learning classifiers (i.e., XGB) were developed and tested on the admitted patient sample and externally validated on the discharged sample with biological and clinical self-report baseline variables as predictors. For external validation sets, prediction was fair for nonremitting versus other trajectories, areas under the curve (AUC = .70); good for nonremitting versus resilient trajectories, AUCs = .73-.76; and prediction failed for nonremitting versus remitting trajectories, AUCs = .46-.48. However, poor precision (< .57) across all models suggests limited generalizability of nonremitting symptom trajectory prediction from admitted to discharged patient samples. Consistency in symptom trajectory identification across samples supports prior studies on the stability of PTSD symptom trajectories following trauma exposure; however, continued work and replication with larger samples are warranted to understand overlapping and unique predictive features of PTSD in different traumatic injury populations.

Fatty acid amide hydrolase activity in the dorsal periaqueductal gray attenuates neuropathic pain and associated dysautonomia

The complexity of neuropathic pain and its associated comorbidities, including dysautonomia, make it difficult to treat. Overlap of anatomical regions and pharmacology of sympathosensory systems in the central nervous system (CNS) provide targets for novel treatment strategies. The dorsal periaqueductal gray (dPAG) is an integral component of both the descending pain modulation system and the acute stress response and is critically involved in both analgesia and the regulation of sympathetic activity. Local manipulation of the endocannabinoid signaling system holds great promise to provide analgesia without excessive adverse effects and also influence autonomic output. Inhibition of fatty acid amide hydrolase (FAAH) increases brain concentrations of the endocannabinoid N-arachidonoylethanolamine (AEA) and reduces pain-related behaviors in neuropathic pain models. Neuropathic hyperalgesia and reduced sympathetic tone are associated with increased FAAH activity in the dPAG, which suggests the hypothesis that inhibition of FAAH in the dPAG will normalize pain sensation and autonomic function in neuropathic pain. To test this hypothesis, the effects of systemic or intra-dPAG FAAH inhibition on hyperalgesia and dysautonomia developed after spared nerve injury (SNI) were assessed in male and female rats. Administration of the FAAH inhibitor PF-3845 into the dPAG reduces hyperalgesia behavior and the decrease in sympathetic tone induced by SNI. Prior administration of the CB1 receptor antagonist AM281, attenuated the antihyperalgesic and sympathetic effects of FAAH inhibition. No sex differences were identified. These data support an integrative role for AEA/CB1 receptor signaling in the dPAG contributing to the regulation of both hyperalgesia behavior and altered sympathetic tone in neuropathic pain.

CB2 Agonist GW842166x Protected against 6-OHDA-Induced Anxiogenic- and Depressive-Related Behaviors in Mice

In addition to motor dysfunction, patients with Parkinson’s disease (PD) are often affected by neuropsychiatric disorders, such as anxiety and depression. In animal models, activation of the endocannabinoid (eCB) system produces anxiolytic and antidepressant-like behavioral effects. CB2 agonists have demonstrated neuroprotective effects against neurotoxin-induced dopamine neuron loss and deficits in motor function. However, it remains unknown whether CB2 agonism ameliorates anxiogenic- and depressive-like behaviors in PD models. Here, we report that the selective CB2 agonist GW842166x exerted neuroprotective effects against 6-hydroxydopamine (6-OHDA)-induced loss of dopaminergic terminals and dopamine release in the striatum, which were blocked by the CB2 antagonist AM630. We found that 6-OHDA-treated mice exhibited anxiogenic- and depressive-like behaviors in the open-field, sucrose preference, novelty-suppressed feeding, marble burying, and forced swim tests but did not show significant changes in the elevated plus-maze and light–dark box test. GW842166x treatments ameliorated 6-OHDA-induced anxiogenic- and depressive-like behaviors, but the effects were blocked by CB2 antagonism, suggesting a CB2-dependent mechanism. These results suggest that the CB2 agonist GW842166x not only reduces 6-OHDA-induced motor function deficits but also anxiogenic- and depressive-like behaviors in 6-OHDA mouse models of PD.

Cannabinoid CB2 Receptors Modulate Microglia Function and Amyloid Dynamics in a Mouse Model of Alzheimer's Disease

The distribution and roles of the cannabinoid CB₂ receptor in the CNS are still a matter of debate. Recent data suggest that, in addition to its presence in microglial cells, the CB₂ receptor may be also expressed at low levels, yet biologically relevant, in other cell types such as neurons. It is accepted that the expression of CB₂ receptors in the CNS is low under physiological conditions and is significantly elevated in chronic neuroinflammatory states associated with neurodegenerative diseases such as Alzheimer's disease. By using a novel mouse model (CB₂ ^EGFP/f/f), we studied the distribution of cannabinoid CB₂ receptors in the 5xFAD mouse model of Alzheimer's disease (by generating 5xFAD/CB₂ ^EGFP/f/f mice) and explored the roles of CB₂ receptors in microglial function. We used a novel selective and brain penetrant CB₂ receptor agonist (RO6866945) as well as mice lacking the CB₂ receptor (5xFAD/CB₂ ^-/-) for these studies. We found that CB₂ receptors are expressed in dystrophic neurite-associated microglia and that their modulation modifies the number and activity of microglial cells as well as the metabolism of the insoluble form of the amyloid peptide. These results support microglial CB₂ receptors as potential targets for the development of amyloid-modulating therapies.

Detection of cannabinoid receptor type 2 in native cells and zebrafish with a highly potent, cell-permeable fluorescent probe

Despite its essential role in the (patho)physiology of several diseases, CB₂R tissue expression profiles and signaling mechanisms are not yet fully understood. We report the development of a highly potent, fluorescent CB₂R agonist probe employing structure-based reverse design. It commences with a highly potent, preclinically validated ligand, which is conjugated to a silicon-rhodamine fluorophore, enabling cell permeability. The probe is the first to preserve interspecies affinity and selectivity for both mouse and human CB₂R. Extensive cross-validation (FACS, TR-FRET and confocal microscopy) set the stage for CB₂R detection in endogenously expressing living cells along with zebrafish larvae. Together, these findings will benefit clinical translatability of CB₂R based drugs.

Detection and visualization of the cannabinoid receptor type 2 by a cell-permeable high affinity fluorescent probe platform enables tracing receptor trafficking in live cells and in zebrafish.

Patient-reported outcomes and neurotoxicity markers in patients treated with bispecific LV20.19 CAR T cell therapy

Background

With the rising number of chimeric antigen receptor (CAR) T cell treated patients, it is increasingly important to understand the treatment's impact on patient-reported outcomes (PROs) and, ideally, identify biomarkers of central nervous system (CNS) adverse effects.

Methods

The purpose of this exploratory study was to assess short-term PROs and serum kynurenine metabolites for associated neurotoxicity among patients treated in an anti-CD20, anti-CD19 (LV20.19) CAR T cell phase I clinical trial (NCT03019055). Fifteen CAR T treated patients from the parent trial provided serum samples and self-report surveys 15 days before and 14, 28, and 90 days after treatment.

Results

Blood kynurenine concentrations increased over time in patients with evidence of neurotoxicity (p = 0.004) and were increased in self-reported depression (r = 0.52, p = 0.002). Depression improved after CAR T infusion (p = 0.035). Elevated 3-hydroxyanthranilic acid (3HAA) concentrations prior to cell infusion were also predictive of neurotoxicity onset (p = 0.031), suggesting it is a biomarker of neurotoxicity following CAR T cell therapy.

Conclusions

Elevated levels of kynurenine pathway metabolites among CAR T cell recipients are associated with depressed mood and neurotoxicity. Findings from this exploratory study are preliminary and warrant validation in a larger cohort.

Amygdalar CB2 cannabinoid receptor mediates fear extinction deficits promoted by orexin-A/hypocretin-1

Anxiety and stress disorders are often characterized by an inability to extinguish learned fear responses. Orexins/hypocretins are involved in the modulation of aversive memories, and dysregulation of this system may contribute to the aetiology of anxiety disorders characterized by pathological fear. The mechanisms by which orexins regulate fear are unknown. Here we investigated the role of the endogenous cannabinoid system in the impaired fear extinction induced by orexin-A (OXA) in male mice. The selective inhibitor of 2-arachidonoylglycerol (2-AG) biosynthesis O7460 abolished the fear extinction deficits induced by OXA. Accordingly, increased 2-AG levels were observed in the amygdala and hippocampus of mice treated with OXA that do not extinguish fear, suggesting that high levels of this endocannabinoid are related to poor extinction. Impairment of fear extinction induced by OXA was associated with increased expression of CB2 cannabinoid receptor (CB2R) in microglial cells of the basolateral amygdala. Consistently, the intra-amygdala infusion of the CB2R antagonist AM630 completely blocked the impaired extinction promoted by OXA. Microglial and CB2R expression depletion in the amygdala with PLX5622 chow also prevented these extinction deficits. These results show that overactivation of the orexin system leads to impaired fear extinction through 2-AG and amygdalar CB2R. This novel mechanism could be of relevance for the development of novel potential approaches to treat diseases associated with inappropriate retention of fear, such as post-traumatic stress disorder, panic anxiety and phobias.

A peripheral CB2 cannabinoid receptor mechanism suppresses chemotherapy-induced peripheral neuropathy: evidence from a CB2 reporter mouse

ABSTRACT

CB2 cannabinoid receptors (CB2) are a promising therapeutic target that lacks unwanted side effects of CB1 activation. However, the cell types expressing CB2 that mediate these effects remain poorly understood. We used transgenic mice with CB2 promoter-driven expression of enhanced green fluorescent protein (EGFP) to study cell types that express CB2 and suppress neuropathic nociception in a mouse model of chemotherapy-induced peripheral neuropathy. Structurally distinct CB2 agonists (AM1710 and LY2828360) suppressed paclitaxel-induced mechanical and cold allodynia in CB2EGFP reporter mice with established neuropathy. Antiallodynic effects of AM1710 were blocked by SR144528, a CB2 antagonist with limited CNS penetration. Intraplantar AM1710 administration suppressed paclitaxel-induced neuropathic nociception in CB2EGFP but not CB2 knockout mice, consistent with a local site of antiallodynic action. mRNA expression levels of the anti-inflammatory cytokine interleukin-10 were elevated in the lumbar spinal cord after intraplantar AM1710 injection along with the proinflammatory cytokine tumor necrosis factor alpha and chemokine monocyte chemoattractant protein-1. CB2EGFP, but not wildtype mice, exhibited anti-GFP immunoreactivity in the spleen. However, the anti-GFP signal was below the threshold for detection in the spinal cord and brain of either vehicle-treated or paclitaxel-treated CB2EGFP mice. EGFP fluorescence was coexpressed with CB2 immunolabeling in stratified patterns among epidermal keratinocytes. EGFP fluorescence was also expressed in dendritic cells in the dermis, Langerhans cells in the epidermis, and Merkel cells. Quantification of the EGFP signal revealed that Langerhans cells were dynamically increased in the epidermis after paclitaxel treatment. Our studies implicate CB2 expressed in previously unrecognized populations of skin cells as a potential target for suppressing chemotherapy-induced neuropathic nociception.

Circulating endocannabinoids and genetic polymorphisms as predictors of posttraumatic stress disorder symptom severity: heterogeneity in a community-based cohort

The endocannabinoid signaling system (ECSS) regulates fear and anxiety. While ECSS hypoactivity can contribute to symptoms of established post-traumatic stress disorder (PTSD), the role of the ECSS in PTSD development following trauma is unknown. A prospective, longitudinal cohort study of 170 individuals (47% non-Hispanic Caucasian and 70% male) treated at a level 1 trauma center for traumatic injury was carried out. PTSD symptom assessments and blood were obtained during hospitalization and at follow-up (6-8 months post injury). Serum concentrations of the endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) were determined at both time points and selected genetic polymorphisms in endocannabinoid genes, including rs324420 in fatty acid amide hydrolase, were assessed. For the entire sample, serum concentrations of AEA at hospitalization were significantly higher in those diagnosed with PTSD at follow-up (p = 0.030). Serum concentrations of 2-AG were significantly, positively correlated with PTSD symptom severity at follow-up only in minorities (p = 0.014). Minority participants (mostly Black/African American) also demonstrated significant, negative correlations between serum AEA concentrations and PTSD symptom severity both measured at hospitalization (p = 0.015). The A/A genotype at rs324420 was associated with significantly higher PTSD symptom severity (p = 0.025) and occurred exclusively in the Black participants. Collectively, these results are contrary to our hypothesis and find positive associations between circulating endocannabinoids and risk for PTSD. Minority status is an important modulator of the association between endocannabinoids and risk for PTSD, suggesting that the ECSS contributes to risk most significantly in these individuals and the contextual factors related to these findings should be further explored.

A cluster analytic approach to examining the role of cortisol in the development of post-traumatic stress and dysphoria in adult traumatic injury survivors

Identification of specific risk factors for posttraumatic stress disorder (PTSD) versus depression after trauma has been challenging, in part due to the high comorbidity of these disorders. As exposure to trauma triggers activation of the hypothalamic-pituitary-adrenal (HPA)-axis, examining atypical stress responses via HPA-axis hormones, namely cortisol, may help in the delineation of these disorders. Indeed, extant research demonstrates that, following stress, individuals with chronic PTSD exhibit hypocortisolism (e.g., lower cortisol response than controls), while those with chronic depression exhibit hypercortisolism (e.g., higher response than controls). Less is known about the role of cortisol and these seemingly disparate profiles immediately following traumatic injury as well as whether cortisol can be used as a predictor of future development of PTSD versus depression symptoms. In this study cortisol was measured blood from 172 traumatic injury survivors during hospitalization (on average 2.5 days post-injury). PTSD and depression severity were assessed from Clinician Assessed PTSD Scale (CAPS-5) six-eight months later using a two-factor dimensional approach that measures trauma-specific symptoms of PTSD versus dysphoria (akin to depression). Cluster analysis was used to group individuals based on post-injury cortisol, PTSD, and dysphoria. Results demonstrated that trauma survivors who only developed symptoms of dysphoria at six months (with minimal symptoms of PTSD) were differentiated by high post-injury cortisol compared to other groups. By contrast, individuals who developed symptoms of both PTSD and dysphoria were differentiated by low post-injury cortisol and most severe symptoms of PTSD. Findings provide support for the presence of subgroups of trauma survivors defined, in part, by post-trauma cortisol.

Adolescent THC Treatment Does Not Potentiate the Behavioral Effects in Adulthood of Maternal Immune Activation

Both in utero exposure to maternal immune activation and cannabis use during adolescence have been associated with increased risk for the development of schizophrenia; however, whether these exposures exert synergistic effects on brain function is not known. In the present study, mild maternal immune activation (MIA) was elicited in mice with prenatal exposure to polyinosinic-polycytidylic acid (poly(I:C)), and ∆9-tetrahydrocannabinol (THC) was provided throughout adolescence in cereal (3 mg/kg/day for 5 days). Neither THC nor MIA pretreatments altered activity in assays used to characterize hyperdopaminergic states in adulthood: amphetamine hyperlocomotion and prepulse inhibition of the acoustic startle reflex. Adolescent THC treatment elicited deficits in spatial memory and enhanced spatial reversal learning in adult female mice in the Morris water maze, while exposure to MIA elicited female-specific deficits in fear extinction learning in adulthood. There were no effects in these assays in adult males, nor were there interactions between THC and MIA in adult females. While doses of poly(I:C) and THC were sufficient to elicit behavioral effects, particularly relating to cognitive performance in females, there was no evidence that adolescent THC exposure synergized with the risk imposed by MIA to worsen behavioral outcomes in adult mice of either sex.

The influence of depression on the relationship between loneliness and grief trajectories in bereaved older adults

Loneliness is associated with adverse mental health outcomes in older adults. Bereavement triggers intense feelings of loneliness. This pilot study explored the association between baseline loneliness and grief symptom trajectories in bereaved elders and explored if this association is moderated by depressive symptom changes. 56 individuals aged 50 years and older, within 13-months following bereavement, completed assessments. Loneliness was measured at baseline using the UCLA loneliness scale-version 3. Grief and depressive symptoms were measured over 26 weeks using the inventory of complicated grief (ICG) and the 17-item Hamilton Depressive Rating (HAM-D) scales, respectively. Linear regression explored the cross-sectional association between loneliness and grief symptoms, after adjusting for covariates including depressive symptoms. A mixed-effects linear model tested whether baseline loneliness was related to grief symptom trajectory over 26 weeks, after accounting for depressive symptom changes. Loneliness was associated with grief symptom severity at baseline; however, this cross-sectional association was not significant after adjusting for depressive symptoms. Longitudinally, baseline loneliness was positively associated with grief symptom trajectories; however, depressive symptom changes moderated this association. Depressive symptom alterations appear to weaken the loneliness-grief symptom change association. These exploratory findings point to opportunities for interventions targeting loneliness and depression that may reduce grief intensity over time in bereaved elders.

Exercise-induced increases in Anandamide and BDNF during extinction consolidation contribute to reduced threat following reinstatement: Preliminary evidence from a randomized controlled trial

INTRODUCTION

We recently demonstrated that moderate-intensity aerobic exercise delivered during the consolidation of fear extinction learning reduced threat expectancy during a test of extinction recall among women with posttraumatic stress disorder (PTSD). These findings suggest that exercise may be a potential candidate for improving the efficacy of exposure-based therapies, which are hypothesized to work via the mechanisms of fear extinction learning. The purpose of this secondary analysis was to examine whether exercise-induced increases in circulating concentrations of candidate biomarkers: endocannabinoids (anandamide [AEA]; 2-arachidonoylglycerol [2-AG], brain-derived neurotrophic factor (BDNF), and homovanillic acid (HVA), mediate the effects of exercise on extinction recall.

METHODS

Participants (N = 35) completed a 3-day fear acquisition (day 1), extinction (day 2), and extinction recall (day 3) protocol, in which participants were randomly assigned to complete either moderate-intensity aerobic exercise (EX) or a light-intensity control (CON) condition following extinction training (day 2). Blood was obtained prior to and following EX or CON. Threat expectancy ratings during tests of extinction recall (i.e., initial fear recall and fear recall following reinstatement) were obtained 24 h following EX or CON. Mediation was tested using linear-mixed effects models and bootstrapping of the indirect effect.

RESULTS

Circulating concentrations of AEA and BDNF (but not 2-AG and HVA) were found to mediate the relationship between moderate-intensity aerobic exercise and reduced threat expectancy ratings following reinstatement (AEA 95% CI: -0.623 to -0.005; BDNF 95% CI: -0.941 to -0.005).

CONCLUSIONS

Exercise-induced increases in peripheral AEA and BDNF appear to play a role in enhancing consolidation of fear extinction learning, thereby leading to reduced threat expectancies following reinstatement among women with PTSD. Future mechanistic research examining these and other biomarkers (e.g., brain-based biomarkers) is warranted.

Contribution of the Adenosine 2A Receptor to Behavioral Effects of Tetrahydrocannabinol, Cannabidiol and PECS-101

The cannabis-derived molecules, ∆⁹ tetrahydrocannabinol (THC) and cannabidiol (CBD), are both of considerable therapeutic interest for a variety of purposes, including to reduce pain and anxiety and increase sleep. In addition to their other pharmacological targets, both THC and CBD are competitive inhibitors of the equilibrative nucleoside transporter-1 (ENT-1), a primary inactivation mechanism for adenosine, and thereby increase adenosine signaling. The goal of this study was to examine the role of adenosine A2A receptor activation in the effects of intraperitoneally administered THC alone and in combination with CBD or PECS-101, a 4′-fluorinated derivative of CBD, in the cannabinoid tetrad, elevated plus maze (EPM) and marble bury assays. Comparisons between wild-type (WT) and A2AR knock out (A2AR-KO) mice were made. The cataleptic effects of THC were diminished in A2AR-KO; no other THC behaviors were affected by A2AR deletion. CBD (5 mg/kg) potentiated the cataleptic response to THC (5 mg/kg) in WT but not A2AR-KO. Neither CBD nor THC alone affected EPM behavior; their combination produced a significant increase in open/closed arm time in WT but not A2AR-KO. Both THC and CBD reduced the number of marbles buried in A2AR-KO but not WT mice. Like CBD, PECS-101 potentiated the cataleptic response to THC in WT but not A2AR-KO mice. PECS-101 also reduced exploratory behavior in the EPM in both genotypes. These results support the hypothesis that CBD and PECS-101 can potentiate the cataleptic effects of THC in a manner consistent with increased endogenous adenosine signaling.

Dynamic Change of Endocannabinoid Signaling in the Medial Prefrontal Cortex Controls the Development of Depression After Neuropathic Pain

Many patients with chronic pain conditions suffer from depression. The mechanisms underlying pain-induced depression are still unclear. There are critical links of medial prefrontal cortex (mPFC) synaptic function to depression, with signaling through the endocannabinoid (eCB) system as an important contributor. We hypothesized that afferent noxious inputs after injury compromise activity-dependent eCB signaling in the mPFC, resulting in depression. Depression-like behaviors were tested in male and female rats with traumatic neuropathy [spared nerve injury (SNI)], and neuronal activity in the mPFC was monitored using the immediate early gene c-fos and in vivo electrophysiological recordings. mPFC eCB Concentrations were determined using mass spectrometry, and behavioral and electrophysiological experiments were used to evaluate the role of alterations in eCB signaling in depression after pain. SNI-induced pain induced the development of depression phenotypes in both male and female rats. Pyramidal neurons in mPFC showed increased excitability followed by reduced excitability in the onset and prolonged phases of pain, respectively. Concentrations of the eCBs, 2-arachidonoylglycerol (2-AG) in the mPFC, were elevated initially after SNI, and our results indicate that this resulted in a loss of CB1R function on GABAergic interneurons in the mPFC. These data suggest that excessive release of 2-AG as a result of noxious stimuli triggers use-dependent loss of function of eCB signaling leading to excessive GABA release in the mPFC, with the final result being behavioral depression.SIGNIFICANCE STATEMENT Pain has both somatosensory and affective components, so the complexity of mechanisms underlying chronic pain is best represented by a biopsychosocial model that includes widespread CNS dysfunction. Many patients with chronic pain conditions develop depression. The mechanism by which pain causes depression is unclear. Although manipulation of the eCB signaling system as an avenue for providing analgesia per se has not shown much promise in previous studies. An important limitation of past research has been inadequate consideration of the dynamic nature of the connection between pain and depression as they develop. Here, we show that activity-dependent synthesis of eCBs during the initial onset of persistent pain is the critical link leading to depression when pain is persistent.

Role of endocannabinoid signaling in a septohabenular pathway in the regulation of anxiety- and depressive-like behavior

Enhancing endocannabinoid signaling produces anxiolytic- and antidepressant-like effects, but the neural circuits involved remain poorly understood. The medial habenula (MHb) is a phylogenetically-conserved epithalamic structure that is a powerful modulator of anxiety- and depressive-like behavior. Here, we show that a robust endocannabinoid signaling system modulates synaptic transmission between the MHb and its sole identified GABA input, the medial septum and nucleus of the diagonal band (MSDB). With RNAscope in situ hybridization, we demonstrate that key enzymes that synthesize or degrade the endocannabinoids 2-arachidonylglycerol (2-AG) or anandamide are expressed in the MHb and MSDB, and that cannabinoid receptor 1 (CB1) is expressed in the MSDB. Electrophysiological recordings in MHb neurons revealed that endogenously-released 2-AG retrogradely depresses GABA input from the MSDB. This endocannabinoid-mediated depolarization-induced suppression of inhibition (DSI) was limited by monoacylglycerol lipase (MAGL) but not by fatty acid amide hydrolase. Anatomic and optogenetic circuit mapping indicated that MSDB GABA neurons monosynaptically project to cholinergic neurons of the ventral MHb. To test the behavioral significance of this MSDB-MHb endocannabinoid signaling, we induced MSDB-specific knockout of CB1 or MAGL via injection of virally-delivered Cre recombinase into the MSDB of Cnr1^loxP/loxP or Mgll^loxP/loxP mice. Relative to control mice, MSDB-specific knockout of CB1 or MAGL bidirectionally modulated 2-AG signaling in the ventral MHb and led to opposing effects on anxiety- and depressive-like behavior. Thus, depression of synaptic GABA release in the MSDB-ventral MHb pathway may represent a potential mechanism whereby endocannabinoids exert anxiolytic and antidepressant-like effects.

Inactivation of the CB2 receptor accelerated the neuropathological deterioration in TDP-43 transgenic mice, a model of amyotrophic lateral sclerosis

The activation of the cannabinoid receptor type‐2 (CB₂) afforded neuroprotection in amyotrophic lateral sclerosis (ALS) models. The objective of this study was to further investigate the relevance of the CB₂ receptor through investigating the consequences of its inactivation. TDP‐43(A315T) transgenic mice were crossed with CB₂ receptor knock‐out mice to generate double mutants. Temporal and qualitative aspects of the pathological phenotype of the double mutants were compared to TDP‐43 transgenic mice expressing the CB₂ receptor. The double mutants exhibited significantly accelerated neurological decline, such that deteriorated rotarod performance was visible at 7 weeks, whereas rotarod performance was normal up to 11 weeks in transgenic mice with intact expression of the CB₂ receptor. A morphological analysis of spinal cords confirmed an earlier death (visible at 65 days) of motor neurons labelled with Nissl staining and ChAT immunofluorescence in double mutants compared to TDP‐43 transgenic mice expressing the CB₂ receptor. Evidence of glial reactivity, measured using GFAP and Iba‐1 immunostaining, was seen in double mutants at 65 days, but not in TDP‐43 transgenic mice expressing the CB₂ receptor. However, at 90 days, both genotypes exhibited similar changes for all these markers, although surviving motor neurons of transgenic mice presented some morphological abnormalities in absence of the CB₂ receptor that were not as evident in the presence of this receptor. This faster deterioration seen in double mutants led to premature mortality compared with TDP‐43 transgenic mice expressing the CB₂ receptor. We also investigated the consequences of a pharmacological inactivation of the CB₂ receptor using the selective antagonist AM630 in TDP‐43 transgenic mice, but results showed only subtle trends towards a greater deterioration. In summary, our results confirmed the potential of the CB₂ receptor agonists as a neuroprotective therapy in ALS and strongly support the need to progress towards an evaluation of this potential in patients.

Adverse maternal environment and western diet impairs cognitive function and alters hippocampal glucocorticoid receptor promoter methylation in male mice

Adverse maternal environment (AME) and high‐fat diet in early childhood increase the risk of cognitive impairment and depression later in life. Cognitive impairment associates with hippocampal dysfunction. A key regulator of hippocampal function is the glucocorticoid receptor. Increased hippocampal GR expression associates with cognitive impairment and depression. Transcriptional control of GR relies in part upon the DNA methylation status at multiple alternative initiation sites that are tissue specific, with exon 1.7 being hippocampal specific. Increased exon 1.7 expression associates with upregulated hippocampal GR expression in early life stress animal models. However, the effects of AME combined with postweaning western diet (WD) on offspring behaviors and the expression of GR exon 1 variants in the hippocampus are unknown. We hypothesized that AME and postweaning WD would impair cognitive function and cause depression‐like behavior in offspring in conjunction with dysregulated hippocampal expression of total GR and exon 1.7 variant in mice. We found that AME‐WD impaired learning and memory in male adult offspring concurrently with increased hippocampal expression of total GR and GR 1.7. We also found that increased GR 1.7 expression was associated with decreased DNA methylation at the GR 1.7 promoter. We speculate that decreased DNA methylation at the GR 1.7 promoter plays a role in AME‐WD induced increase of GR in the hippocampus. This increased GR expression may subsequently contribute to hippocampus dysfunction and lead to the cognitive impairment seen in this model.

Signaling through the type 2 cannabinoid receptor regulates the severity of acute and chronic graft-versus-host disease

Graft-versus-host disease (GVHD) pathophysiology is a complex interplay between cells that comprise the adaptive and innate arms of the immune system. Effective prophylactic strategies are therefore contingent upon approaches that address contributions from both immune cell compartments. In the current study, we examined the role of the type 2 cannabinoid receptor (CB2R), which is expressed on nearly all immune cells, and demonstrated that absence of the CB2R on donor CD4+ or CD8+ T cells or administration of a selective CB2R pharmacological antagonist exacerbated acute GVHD lethality. This was accompanied primarily by the expansion of proinflammatory CD8+ T cells, indicating that constitutive CB2R expression on T cells preferentially regulated CD8+ T-cell alloreactivity. Using a novel CB2ReGFP reporter mouse, we observed significant loss of CB2R expression on T cells, but not macrophages, during acute GVHD, indicative of differential alterations in receptor expression under inflammatory conditions. Therapeutic targeting of the CB2R with the agonists Δ9-tetrahydrocannabinol (THC) and JWH-133 revealed that only THC mitigated lethal T cell-mediated acute GVHD. Conversely, only JWH-133 was effective in a sclerodermatous chronic GVHD model where macrophages contributed to disease biology. In vitro, both THC and JWH-133 induced arrestin recruitment and extracellular regulated kinase phosphorylation via CB2R, but THC had no effect on CB2R-mediated inhibition of adenylyl cyclase. This study shows that the CB2R plays a critical role in the regulation of GVHD and suggests that effective therapeutic targeting is dependent upon agonist signaling characteristics and receptor selectivity in conjunction with the composition of pathogenic immune effector cells.

Aerobic exercise reduces anxiety and fear ratings to threat and increases circulating endocannabinoids in women with and without PTSD

Reductions in state anxiety have been reported following an acute bout of aerobic exercise. However, less is known regarding anxiety and fear ratings to specific threatening stimuli following an acute bout of aerobic exercise in women with PTSD. Moreover, the mechanisms responsible for the anxiolytic effects of exercise are not fully understood, although recent studies suggest a role for the endocannabinoid (eCB) system. Thus, this study utilized a randomized, counterbalanced approach to examine anxiety and fear ratings to predictable or unpredictable electric shock administration and circulating concentrations of eCBs and mood states immediately following moderate-intensity aerobic exercise (30 min on treadmill at 70-75% maximum heart rate) and a quiet rest control condition in women with and without a history of trauma, and in women with PTSD (N=42). Results revealed that anxiety and fear ratings to unpredictable and predictable threats were significantly (p<.05) lower following exercise compared to quiet rest, with correlational analyses indicating those with greater increases in circulating eCBs had greater reductions in anxiety and fear ratings to unpredictable and predictable threats following exercise. Also, there were significant (p<.05) reductions in fatigue, confusion, total mood disturbance, and increases in positive affect following exercise for the entire sample. Non-trauma controls and PTSD groups reported significant (p<.05) increases in vigor, with additional mood improvements following exercise for the PTSD group (i.e., decreases in state anxiety, negative affect, tension, anger, and depression). Results from this study suggest that aerobic exercise exerts psychological benefits in women with PTSD, potentially due to exercise-induced increases in circulating concentrations of eCBs.

Inhibition of Fatty Acid Amide Hydrolase (FAAH) During Adolescence and Exposure to Early Life Stress may Exacerbate Depression-like Behaviors in Male and Female Rats

Early-life stress (ELS) is associated with later onset of depression. Early cannabis use may be a risk factor that interacts with environmental factors to increase the risk of psychopathologies. We aimed to examine the long-term effects of ELS on depression- and anxiety-like behavior, and examine whether chronic fatty acid amide hydrolase (FAAH) inhibition during mid-adolescence could ameliorate or exacerbate ELS effects on behavior. Male and female rats were exposed to ELS during post-natal days (P) 7-14, injected with the FAAH inhibitor URB597 (0.4 mg/kg, i.p.) or vehicle for 2 weeks during mid-adolescence (P30-45) or late-adolescence (P45-60). Rats were tested in adulthood for behavior and alterations in CB1 receptors (CB1r) and glucocorticoid receptors (GRs) in the brains' stress circuit. ELS produced decreased social preference, impaired social recognition, increased learned helplessness and anxiety-like behavior. Administering URB597 during mid-adolescence did not prevent the deleterious long-term effects of ELS on behavior in males and females. When URB597 was administered during late-adolescence, it ameliorated ELS-induced depression- and anxiety-like behavior. Moreover, in males, ELS and URB597 decreased CB1r levels in the prefrontal cortex (PFC) and CA1 and GRs in the PFC and basolateral amygdala (BLA). In females, ELS and URB decreased CB1r in the BLA and GRs in the CA1 and BLA. The findings suggest that mid-adolescence, as opposed to late-adolescence, may not be a potential developmental period for chronic treatment with FAAH inhibitors and that sex-dependent alterations in CB1r and GRs expression in the BLA-PFC-CA1 circuit may contribute to the depressive behavioral phenotype.

Loneliness, Circulating Endocannabinoid Concentrations, and Grief Trajectories in Bereaved Older Adults: A Longitudinal Study

Background: Loneliness is one of the most distressing grief symptoms and is associated with adverse mental health in bereaved older adults. The endocannabinoid signaling (ECS) system is stress-responsive and circulating endocannabinoid (eCB) concentrations are elevated following bereavement. This study examined the association between loneliness and circulating eCB concentrations in grieving older adults and explored the role of eCBs on the association between baseline loneliness and grief symptom trajectories. Methods: A total of 64 adults [grief with high loneliness: n = 18; grief with low loneliness: n = 26; and healthy comparison (HC): n = 20] completed baseline clinical assessments for the UCLA loneliness scale. In grief participants, longitudinal clinical assessments, including the Inventory of Complicated Grief and 17-item Hamilton Depression Rating scales, were collected over 6 months. Baseline circulating eCB [N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG)] concentrations were quantified in the serum using isotope dilution, liquid chromatography-mass spectrometry; cortisol concentrations were measured in the same samples using radioimmunoassay. Results: Circulating AEA concentrations were higher in severely lonely grieving elders than in HC group; cortisol concentrations were not different among the groups. Cross-sectionally, loneliness scores were positively associated with AEA concentrations in grievers; this finding was not significant after accounting for depressive symptom severity. Grieving individuals who endorsed high loneliness and had higher 2-AG concentrations at baseline showed faster grief symptom resolution. Conclusions: These novel findings suggest that in lonely, bereaved elders, increased circulating eCBs, a reflection of an efficient ECS system, are associated with better adaptation to bereavement. Circulating eCBs as potential moderators and mediators of the loneliness-grief trajectory associations should be investigated.

Endocannabinoids and related lipids in serum from patients with amyotrophic lateral sclerosis

BACKGROUND

The goals of this study were to determine whether serum concentrations of endocannabinoids (eCB) and related lipids predict disease status in patients with amyotrophic lateral sclerosis (ALS) relative to healthy controls, and whether concentrations correlate with disease duration and severity.

METHODS

Serum concentrations of the eCBs 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA), and related lipids palmitoylethanolamine (PEA), oleoylethanolamine (OEA), and 2-oleoylglycerol (2-OG), were measured in samples from 47 patients with ALS and 19 healthy adults. Hierarchical binary logistic and linear regression analyses assessed whether lipid concentrations predicted disease status (ALS or healthy control), duration, or severity.

RESULTS

Binary logistic regression revealed that, after controlling for age and gender, 2-AG, 2-OG and AEA concentrations were unique predictors of the presence of ALS, demonstrating odds ratios of 0.86 (P = .039), 1.03 (P = .023), and 42.17 (P = .026), respectively. When all five lipids and covariates (age, sex, race, ethnicity, body mass index, presence of a feeding tube) were included, the resulting model had an overall classification accuracy of 92.9%. Hierarchical linear regression analyses indicated that in patients with ALS, AEA and OEA inversely correlated with disease duration (P = .030 and .031 respectively), while PEA demonstrated a positive relationship with disease duration (P = .013). None of the lipids examined predicted disease severity.

CONCLUSIONS

These findings support previous studies indicating significant alterations in concentrations of circulating lipids in patients with ALS. They suggest that arachidonic and oleic acid containing small lipids may serve as biomarkers for identifying the presence and duration of this disease.

Sex, stress, and prefrontal cortex: influence of biological sex on stress-promoted cocaine seeking

Clinical reports suggest that females diagnosed with substance use disorder experience enhanced relapse vulnerability compared with males, particularly during stress. We previously demonstrated that a stressor (footshock) can potentiate cocaine seeking in male rats via glucocorticoid-dependent cannabinoid type-1 receptor (CB1R)-mediated actions in the prelimbic prefrontal cortex (PrL-PFC). Here, we investigated the influence of biological sex on stress-potentiated cocaine seeking. Despite comparable self-administration and extinction, females displayed a lower threshold for cocaine-primed reinstatement than males. Unlike males, footshock, tested across a range of intensities, failed to potentiate cocaine-primed reinstatement in females. However, restraint potentiated reinstatement in both sexes. While sex differences in stressor-induced plasma corticosterone (CORT) elevations and defensive behaviors were not observed, differences were evident in footshock-elicited ultrasonic vocalizations. CORT administration, at a dose which recapitulates stressor-induced plasma levels, reproduced stress-potentiated cocaine-primed reinstatement in both sexes. In females, CORT effects varied across the estrous cycle; CORT-potentiated reinstatement was only observed during diestrus and proestrus. As in males, CORT-potentiated cocaine seeking in females was localized to the PrL-PFC and both CORT- and restraint-potentiated cocaine seeking required PrL-PFC CB1R activation. In addition, ex vivo whole-cell electrophysiological recordings from female layer V PrL-PFC pyramidal neurons revealed CB1R-dependent CORT-induced suppression of inhibitory synaptic activity, as previously observed in males. These findings demonstrate that, while stress potentiates cocaine seeking via PrL-PFC CB1R in both sexes, sensitivity to cocaine priming injections is greater in females, CORT-potentiating effects vary with the estrous cycle, and whether reactivity to specific stressors may manifest as drug seeking depends on biological sex.

Antidepressant-like effects of URB597 and JZL184 in male and female rats exposed to early life stress

Early life stress (ELS) may increase predisposition to depression. Despite extensive research, there is still a lack of knowledge of how to optimally treat depression. We aimed to establish a role for the endocannabinoid (ECB) system within the hippocampal-nucleus accumbens (NAc) network as a possible effective target in combating the pathophysiological development of depression-like behavior and neuronal alterations that are precipitated by ELS. Male and female rats were exposed to ELS during post-natal days (P) 7-14, injected with the fatty acid amide hydrolase (FAAH) inhibitor URB597 or the monoacylglycerol lipase (MAGL) inhibitor JZL184 for 2 weeks during late-adolescence (P45-60). Rats were tested starting at P90 for depressive- and anxiety-like behaviors as well as social preference and recognition; alterations in FAAH and MAGL activity; the expression of brain-derived neurotrophic factor (BDNF); and plasticity in the hippocampal-NAc pathway. FAAH and MAGL inhibitors during late-adolescence prevented: (i) the long-term effects of ELS on depression- and anxiety-like behavior and the impairment in social behavior and neuronal plasticity in males and females; (ii) ELS-induced alterations in MAGL activity in males' hippocampus and females' hippocampus and NAc; and (iii) ELS-induced alterations in BDNF in males' hippocampus and NAc and females' hippocampus. Significant correlations were observed between alterations in MAGL and BDNF levels and the behavioral phenotype. The findings suggest that alterations in MAGL activity and BDNF expression in the hippocampal-NAc network contribute to the depressive-like behavioral phenotype in ELS males and females. Moreover, the study suggests FAAH and MAGL inhibitors as potential intervention drugs for depression.

Circulating endocannabinoid concentrations in grieving adults

Bereavement is one of the most intense, distressing, and traumatic events an elderly person will experience. The symptom responses to bereavement vary, particularly during the first year. However, the neurobiology underlying the symptom variance in grief is poorly understood. The endocannabinoid signaling (ECS) system is stress-responsive; mounting evidence implicates the central ECS in psychopathology. The current study aimed to investigate the hypothesis that the ECS is abnormal in grief, using circulating eCB concentrations as a biomarker of central ECS. A predominantly older sample of grief participants, within 13 months following the death of a loved one, and healthy comparison (HC) participants were studied. Associations of circulating eCBs with symptom variance in grievers were also examined. A total of 61 (grief: n = 44; HC: n = 17) adults completed cross-sectional clinical assessments and a fasting blood draw. Assessments included the Inventory of Complicated Grief scale; the 17-item Hamilton Depression Rating Scale; and the Hamilton Anxiety scale. Serum eCB concentrations (i.e., N-arachidonoylethanolamine [AEA] and 2-arachidonoylglycerol [2-AG]) were quantified using isotope dilution, liquid chromatography-mass spectrometry. Relative to HC participants, grievers had significantly elevated serum AEA but similar 2-AG concentrations. In grievers, serum AEA concentrations were positively associated with depressive and anxiety symptoms, but only in those with low grief symptoms. These novel findings indicate that elevated circulating eCB concentrations are found following bereavement. The eCB signaling response varies based on the degree of grief severity. Circulating eCB measures may have the potential to serve as biomarkers of prolonged grief disorder.

Traumatic Brain Injury and Alcohol Drinking Alter Basolateral Amygdala Endocannabinoids in Female Rats

Traumatic brain injury (TBI) affects approximately 3 million Americans yearly and increases vulnerability to developing psychiatric comorbidities. Alcohol use disorder (AUD) is the most prevalent psychiatric diagnosis preceding injury and TBI may increase subsequent alcohol use. The basolateral amygdala (BLA) is a limbic structure commonly affected by TBI that is implicated in anxiety and AUD. Endocannabinoids (eCBs) regulate synaptic activity in the BLA, and BLA eCB modulation alters anxiety-like behavior and stress reactivity. Previous work from our laboratories showed that systemic eCB degradation inhibition ameliorates TBI-induced increases in anxiety-like behavior and motivation to respond for alcohol in male rats. Here, we used a lateral fluid percussion model to test moderate TBI effects on anxiety-like behavior, alcohol drinking, and eCB levels and cell signaling in BLA, as well as the effect of alcohol drinking on anxiety-like behavior and the BLA eCB system, in female rats. Our results show that TBI does not promote escalation of operant alcohol self-administration or increase anxiety-like behavior in female rats. In the BLA, TBI and alcohol drinking alter tissue amounts of 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide; AEA) 1 h post-injury, and 2-AG levels remain low 11 days post-injury. Eleven days after injury, BLA pyramidal neurons were hyperexcitable, but measures of synaptic transmission and eCB signaling were unchanged. These data show that TBI impacts BLA 2-AG tissue levels, that this effect is modified by alcohol drinking, and also that TBI increases BLA cell excitability.

Development of High-Specificity Fluorescent Probes to Enable Cannabinoid Type 2 Receptor Studies in Living Cells

Pharmacological modulation of cannabinoid type 2 receptor (CB₂R) holds promise for the treatment of numerous conditions, including inflammatory diseases, autoimmune disorders, pain, and cancer. Despite the significance of this receptor, researchers lack reliable tools to address questions concerning the expression and complex mechanism of CB₂R signaling, especially in cell-type and tissue-dependent contexts. Herein, we report for the first time a versatile ligand platform for the modular design of a collection of highly specific CB₂R fluorescent probes, used successfully across applications, species, and cell types. These include flow cytometry of endogenously expressing cells, real-time confocal microscopy of mouse splenocytes and human macrophages, as well as FRET-based kinetic and equilibrium binding assays. High CB₂R specificity was demonstrated by competition experiments in living cells expressing CB₂R at native levels. The probes were effectively applied to FACS analysis of microglial cells derived from a mouse model relevant to Alzheimer's disease.

Meet Your Stress Management Professionals: The Endocannabinoids

The endocannabinoid signaling system (ECSS) is altered by exposure to stress and mediates and modulates the effects of stress on the brain. Considerable preclinical data support critical roles for the endocannabinoids and their target, the CB1 cannabinoid receptor, in the adaptation of the brain to repeated stress exposure. Chronic stress exposure increases vulnerability to mental illness, so the ECSS has attracted attention as a potential therapeutic target for the prevention and treatment of stress-related psychopathology. We discuss human genetic studies indicating that the ECSS contributes to risk for mental illness in those exposed to severe stress and trauma early in life, and we explore the potential difficulties in pharmacological manipulation of the ECSS.

Patterns of Cannabis Use in Patients With Cyclic Vomiting Syndrome

BACKGROUND & AIMS

Some patients with cyclic vomiting syndrome (CVS) use cannabis to relieve stress and for its antiemetic properties. However, chronic cannabis use has been associated paradoxically with cannabinoid hyperemesis syndrome (CHS) and some patients with CVS are thought to have CHS. We sought to characterize patterns of cannabis use by patients with CVS and identify those who could be reclassified as having CHS.

METHODS

We performed a cross-sectional study of 140 patients with CVS (72% female; mean age, 37 ± 13 y) seen at a specialized clinic. Patients were screened for cannabis use with the cannabis use disorder identification test. Patients were classified as regular (use ≥4 times/wk) or occasional users (<4 times/wk).

RESULTS

Forty-one percent of patients were current cannabis users, with 21% reporting regular use. Regular users were more likely to be male and to report an anxiety diagnosis, and smoked cannabis with higher tetrahydrocannabinol content and for a longer duration. Most users reported that cannabis helped control CVS symptoms. Among all cannabis users, 50 of 57 (88%) reported that they had abstained for longer than 1 month, but only 1 user reported resolution of CVS episodes during the abstinence period. This patient subsequently resumed using cannabis but remains free of symptoms.

CONCLUSIONS

Cannabis is used commonly among patients with CVS-patients report relief of symptoms with use. We found 21% of patients with CVS to be regular users, but only 1 met the Rome IV criteria for CHS. Longitudinal studies are needed to determine the relationships among cannabis use, hyperemesis, and mood symptoms.

Circadian Misalignment of the 24-hour Profile of Endocannabinoid 2-Arachidonoylglycerol (2-AG) in Obese Adults

CONTEXT

The endocannabinoid (eCB) system partly controls hedonic eating, a major cause of obesity. While some studies suggested an overactivation of the eCB system in obesity, peripheral levels of eCBs across the 24-hour cycle have not been characterized in obese individuals despite the fact that in lean adults, levels of the eCB 2-arachidonoylglycerol (2-AG) vary across the day.

OBJECTIVE

We sought to examine 24-hour profiles of serum concentrations of 2-AG in healthy obese and nonobese adults, under well-controlled laboratory conditions. We also simultaneously assessed 24-hour profiles of 2-oleoylglycerol (2-OG), leptin, and cortisol in each participant.

DESIGN

With fixed light-dark and sleep-wake cycles, blood sampling was performed over an entire 24-hour period, including identical meals at 0900, 1400, and 1900.

PARTICIPANTS

Twelve obese (8 women, mean body mass index [BMI]: 39.1 kg/m2) and 15 nonobese (6 women; mean BMI: 23.6 kg/m2) healthy adults were studied.

RESULTS

We observed a 24-hour variation of 2-AG levels in obese individuals but, relative to nonobese adults, the amplitude was dampened and the timings of the nadir and peak were delayed by 4 to 5 hours. The profile of 2-OG was similarly misaligned. In contrast, when expressed relative to the 24-hour mean level, the 24-hour rhythm of cortisol and leptin were similar in obese and nonobese participants.

CONCLUSIONS

Obesity appears to be associated with a dampening and delay of the 24-hour variation of eCB activity relative to the central circadian signal as well as to the daily leptin rhythm. This misalignment may play a role in the pathophysiology of obesity.