Publications
Posted below are publications and articles written by members of the UCR Center for Cannabinoid Research. They are listed with the most recent publication at the top.
Cholinergic neurotransmission controls orexigenic endocannabinoid signaling in the gut in diet-induced obesity
Publication date: April 9, 2024
The brain bidirectionally communicates with the gut to control food intake and energy balance, which becomes dysregulated in obesity. For example, endocannabinoid (eCB) signaling in the small-intestinal epithelium (SI) is upregulated in diet-induced obese mice (DIO) and promotes overeating by a mechanism that includes inhibiting gut-brain satiation signaling. Upstream neural and molecular mechanism(s) involved in overproduction of orexigenic gut eCBs in DIO, however, are unknown. We tested the hypothesis that overactive parasympathetic signaling at muscarinic acetylcholine receptors (mAChRs) in the SI increases biosynthesis of the eCB, 2-arachidonoyl-sn-glycerol (2-AG), which drives hyperphagi¬a via local CB1Rs in DIO. Male mice were maintained on a high-fat/high-sucrose western-style diet for 60 days, then administered several mAChR antagonists 30 min prior tissue harvest or a food intake test. Levels of 2-AG and activity of its metabolic enzymes in the SI were quantitated. DIO mice, when compared to those fed a low-fat/no-sucrose diet, displayed increased expression of cFos protein in the dorsal motor nucleus of the vagus, which suggests increased activity of efferent cholinergic neurotransmission. These mice exhibited elevated levels of 2-AG biosynthesis in the SI, which was reduced to control levels by mAChR antagonists. Moreover, the peripherally-restricted mAChR antagonist, methylhomatropine bromide, and the peripherally-restricted CB1R antagonist, AM6545, reduced food intake in DIO mice for up to 24 h but had no effect in mice conditionally deficient in SI CB1Rs. These results suggest that hyperactivity at mAChRs in the periphery increases formation of 2-AG in the SI and activates local CB1Rs, which drives hyperphagia in DIO.
Read more at the Journal of Neuroscience
Pseudocannabinoid H4CBD improves glucose response during advanced metabolic syndrome in OLETF rats independent of increase in insulin signaling proteins
A sexually dimorphic role for intestinal cannabinoid receptor subtype-1 in the behavioral expression of anxiety
Publication date: October 10, 2023
Background: Increasing evidence suggests that the endocannabinoid system (ECS) in the brain controls anxiety and may be a therapeutic target for the treatment of anxiety disorders. For example, both pharmacological and genetic disruption of cannabinoid receptor subtype-1 (CB1R) signaling in the central nervous system is associated with increased anxiety-like behaviors in rodents, while activating the system is anxiolytic. Sex is also a critical factor that controls the behavioral expression of anxiety; however, roles for the ECS in the gut in these processes and possible differences between sexes are largely unknown.
Objective: In the current study, we aimed to determine if CB1Rs in the intestinal epithelium exert control over anxiety-like behaviors in a sex-dependent manner.
Methods: We subjected male and female mice with conditional deletion of CB1Rs in the intestinal epithelium (intCB1-/-) and controls (intCB1+/+) to the elevated plus maze (EPM), light/dark box, and open field test. Corticosterone (CORT) levels in plasma were measured at baseline and immediately following EPM exposure.
Results: When compared to intCB1+/+ male mice, intCB1-/- male mice exhibited reduced levels of anxiety-like behaviors in the EPM and light/dark box. In contrast to male mice, no differences were found between female intCB1+/+ and intCB1-/- mice. Circulating CORT was higher in female versus male mice for both genotype groups at baseline and following EPM exposure; however, there was no effect of genotype on CORT levels.
Conclusions: Collectively, these results indicate that genetic deletion of CB1Rs in the intestinal epithelium is associated with an anxiolytic phenotype in a sex-dependent manner.
Adolescent exposure to low-dose THC disrupts energy balance and adipose organ homeostasis in adulthood
Authors: L Lin , KM Jung, J Le, G Colleluori, A Giordano , C Wood , H Lee , F Palese , C Yu, E Squire , S Su , A Torrens , Y Fotio, Q Yang , L Huang , N DiPatrizio, C Jang C, S Cinti , D Piomelli
Publication date: June 01, 2023
Abstract: One of cannabis' most iconic effects is the stimulation of hedonic high-calorie eating-the "munchies"-yet habitual cannabis users are, on average, leaner than non-users. We asked whether this phenotype might result from lasting changes in energy balance established during adolescence, when use of the drug often begins. We found that daily low-dose administration of cannabis' intoxicating constituent, Δ9-tetrahydrocannabinol (THC), to adolescent male mice causes an adult metabolic phenotype characterized by reduced fat mass, increased lean mass and utilization of fat as fuel, partial resistance to diet-induced obesity and dyslipidemia, enhanced thermogenesis, and impaired cold- and β-adrenergic receptor-stimulated lipolysis. Further analyses revealed that this phenotype is associated with molecular anomalies in the adipose organ, including ectopic overexpression of muscle-associated proteins and heightened anabolic processing. Thus, adolescent exposure to THC may promote an enduring "pseudo-lean" state that superficially resembles healthy leanness but might in fact be rooted in adipose organ dysfunction.
Read the full article at Cell Metabolism
Cannabidiol attenuates hyperalgesia in a mouse model of sickle cell disease
Authors: Hemanth M. Cherukury, Donovan A. Argueta, Natalie Garcia, Raghda Fouda, Stacy Kiven, Jianxun Lei, Varun Sagi, Graham J. Velasco, Bryant Avalos, Nicholas V. DiPatrizio, Kalpna Gupta
Pre-publication date: September 19, 2022
Abstract: Cannabidiol (CBD), a major constituent of Cannabis sativa L., is widely used for the treatment of pain. CBD has been shown to modulate inflammation, oxidative stress, ischemia-reperfusion injury, gliosis, neuropathic pain, and allodynia. These pathobiological features and pain are associated with sickle cell disease (SCD). Cannabis use in patients with SCD is relatively higher than in the general population owing to an unmet need for safe and satisfactory pain control. CBD has significantly psychotropic effects compared to tetrahydrocannibinol (THC), thus offers a relatively safer alternative to cannabis. SCD patients treated with vaporized cannabis containing ~1:1 CBD:THC for 5 days showed reduced pain, though not statistically significant due to small sample size. We examined if CBD has the potential to ameliorate hyperalgesia and the inflammatory pathobiology of SCD.
Read the full article at Ash Publications.
Diet-induced gut barrier dysfunction is exacerbated in mice lacking cannabinoid 1 receptors in the intestinal epithelium
Authors: Mark B. Wiley, Nicholas V. DiPatrizio
Publication date: September 11, 2022
Abstract: The gut barrier provides protection from pathogens and its function is compromised in diet-induced obesity (DIO). The endocannabinoid system in the gut is dysregulated in DIO and participates in gut barrier function; however, whether its activity is protective or detrimental for gut barrier integrity is unclear. We used mice conditionally deficient in cannabinoid receptor subtype-1 (CB1R) in the intestinal epithelium (intCB1−/−) to test the hypothesis that CB1Rs in intestinal epithelial cells provide protection from diet-induced gut barrier dysfunction. Control and intCB1−/− mice were placed for eight weeks on a high-fat/sucrose Western-style diet (WD) or a low-fat/no-sucrose diet. Endocannabinoid levels and activity of their metabolic enzymes were measured in the large-intestinal epithelium (LI). Paracellular permeability was tested in vivo, and expression of genes for gut barrier components and inflammatory markers were analyzed. Mice fed WD had (i) reduced levels of endocannabinoids in the LI due to lower activity of their biosynthetic enzymes, and (ii) increased permeability that was exacerbated in intCB1−/− mice. Moreover, intCB1−/− mice fed WD had decreased expression of genes for tight junction proteins and increased expression of inflammatory markers in LI. These results suggest that CB1Rs in the intestinal epithelium serve a protective role in gut barrier function in DIO.
Endocannabinoids and the gut-brain control of food intake and obesity
Authors: Nicholas V. DiPatrizio
Publication date: April 7, 2021
Abstract: Gut-brain signaling controls food intake and energy homeostasis, and its activity is thought to be dysregulated in obesity. We will explore new studies that suggest the endocannabinoid (eCB) system in the upper gastrointestinal tract plays an important role in controlling gut-brain neurotransmission carried by the vagus nerve and the intake of palatable food and other reinforcers. A focus will be on studies that reveal both indirect and direct interactions between eCB signaling and vagal afferent neurons. These investigations identify (i) an indirect mechanism that controls nutrient-induced release of peptides from the gut epithelium that directly interact with corresponding receptors on vagal afferent neurons, and (ii) a direct mechanism via interactions between eCBs and cannabinoid receptors expressed on vagal afferent neurons. Moreover, the impact of diet-induced obesity on these pathways will be considered.
UPLC/MS/MS method for analysis of endocannabinoid and related lipid metabolism in mouse mucosal tissue
Authors: Mark B. Wiley, Pedro A. Perez, Donovan A. Argueta, Bryant Avalos, Courtney P. Wood, Nicholas V. DiPatrizio
Publication date: July 14, 2021
Abstract: The endocannabinoid system is expressed in cells throughout the body and controls a variety of physiological and pathophysiological functions. We describe robust and reproducible UPLC-MS/MS-based methods for analyzing metabolism of the endocannabinoids, 2-arachidonoyl-sn-glycerol and arachidonoyl ethanolamide, and related monoacylglycerols (MAGs) and fatty acid ethanolamides (FAEs), respectively, in mouse mucosal tissues (i.e., intestine and lung). These methods are optimized for analysis of activity of the MAG biosynthetic enzyme, diacylglycerol lipase (DGL), and MAG degradative enzymes, monoacylglycerol lipase (MGL) and alpha/beta hydrolase domain containing-6 (ABHD6). Moreover, we describe a novel UPLC-MS/MS-based method for analyzing activity of the FAE degradative enzyme, fatty acid amide hydrolase (FAAH), that does not require use of radioactive substrates. In addition, we describe in vivo pharmacological methods to inhibit MAG biosynthesis selectively in the mouse small-intestinal epithelium. These methods will be useful for profiling endocannabinoid metabolism in rodent mucosal tissues in health and disease.
Cannabinoid receptor subtype-1 controls allergic airway eosinophilia during lung helminth infection
Authors: Mark B. Wiley, Sara Bobardt, Tara Nordgren, Meera Nair, Nicholas V. DiPatrizio
Publication date: June 6, 2021
Abstract: Over one billion humans carry infectious helminth parasites that can lead to chronic co-morbidities such as anemia and growth retardation in children. Helminths induce a T-helper type 2 (Th2) immune response in the host and can cause severe tissue damage and fibrosis if chronic. We recently reported that mice infected with the soil-transmitted helminth, Nippostrongylus brasiliensis (Nb), displayed elevated levels of endocannabinoids (eCBs) in the lung and intestine. eCBs are lipid-signaling molecules that control inflammation; however, their function in infection is not well defined. A combination of pharmacological approaches and genetic mouse models were employed to investigate roles for the eCB system in inflammatory responses and lung injury in mice during parasitic infection with Nb. Hemorrhaging of lung tissue in mice infected with Nb was exacerbated by inhibiting peripheral CB1Rs with the peripherally restricted CB1R antagonist, AM6545. In addition, these mice exhibited an increase in non-functional alveolar space and prolonged airway eosinophilia when compared to vehicle-treated infected mice. In contrast to mice treated with AM6545, infected cannabinoid receptor subtype-2-null mice (Cnr2-/-) did not display any changes in these parameters when compared to wild-type mice. Roles for the eCB system in Th2 immune responses are not well understood; however, increases in its activity in response to infection suggests an immunomodulatory role. Moreover, these findings suggest a role for eCB signaling at CB1Rs but not CB2Rs in the resolution of Th2 inflammatory responses, which become host-destructive over time.
Effects of selective breeding, voluntary exercise, and sex on endocannabinoid levels in the mouse small-intestinal epithelium
Authors: Margaret Schmill, Zoe Thompson, Donovan A. Argueta, Nicholas V. DiPatrizio, Ted Garland
Publication date: March 1, 2022
Abstract: The endocannabinoid (eCB) system in the gut communicates with the body and brain as part of the homeostatic mechanisms that affect energy balance. Although perhaps best known for its effects on energy intake, the eCB system also regulates voluntary locomotor behavior. Here, we examined gut eCB concentrations in relation to voluntary exercise, specifically in mice selectively bred for high voluntary wheel running behavior. We measured gut eCBs in four replicate non-selected Control (C) lines and four replicate lines of High Runner (HR) mice that had been selectively bred for 74 generations based on the average number of wheel revolutions on days 5 and 6 of a 6-day period of wheel access when young adults. On average, mice from HR lines run voluntarily on wheels ∼3-fold more than C mice on a daily basis. A recent study showed that circulating levels of primary endocannabinoids 2-arachidonoyl-sn-glycerol (2-AG) and anandamide (AEA) are altered by six days of wheel access, by acute wheel running, and differ between HR and C mice in sex-specific ways [1]. We hypothesized that eCBs in the upper small-intestinal epithelium (i.e., proximal jejunum), a region firmly implicated in eCB signaling, would differ between HR and C mice (linetype), between the sexes, between mice housed with vs. without wheels for six days, and would covary with amounts of acute running and/or home-cage activity (during the previous 30 minutes). We used the same 192 mice as in [1] , half males and half females, half HR and half C (all 8 lines), and half either given or not given access to wheels for six days. We assessed the eCBs, 2-AG and AEA, and their analogs docosahexaenoylglycerol (DHG), docosahexaenoylethanolamide (DHEA), and oleoylethanolamide (OEA). Both 2-AG and DHG showed a significant 3-way interaction of linetype, wheel access, and sex. In addition, HR mice had lower concentrations of 2-AG in the small-intestinal epithelium when compared to C mice, which may be functionally related to differences in locomotor activity or to differences in body composition and/or food consumption. Moreover, the amount of home-cage activity during the prior 30 min was a negative predictor of 2-AG and AEA concentrations in jejunum mucosa, particularly in the mice with no wheel access. Lastly, 2-AG, but not AEA, was significantly correlated with 2-AG in plasma in the same mice.
Increased 2-arachidonoyl-sn-glycerol levels normalize cortical responses to sound and improve behaviors in Fmr1 KO mice
Authors: Patricia Pirbhoy, Carrie Jonak, Rashid Syed, Donovan A. Argueta, Pedro Perez, Mark B. Wiley, Keon Hessmian, Jonathan Lovelace, Khaleel Razak, Nicholas V. DiPatrizio, Iryna Ethell, Devin Binder
Publication date: October 13, 2021
Abstract: Individuals with Fragile X syndrome (FXS) and autism spectrum disorder (ASD) exhibit an array of symptoms, including sociability deficits, increased anxiety, hyperactivity, and sensory hyperexcitability. It is unclear how endocannabinoid (eCB) modulation can be targeted to alleviate neurophysiological abnormalities in FXS as behavioral research reveals benefits to inhibiting cannabinoid (CB) receptor activation and increasing endocannabinoid ligand levels. Here, we hypothesize that enhancement of 2-arachidonoyl-sn-glycerol (2-AG) in Fragile X mental retardation 1 gene knock-out (Fmr1 KO) mice may reduce cortical hyperexcitability and behavioral abnormalities observed in FXS. To test whether an increase in 2-AG levels normalized cortical responses in a mouse model of FXS, animals were subjected to electroencephalography (EEG) recording and behavioral assessment following treatment with JZL- 184, an irreversible inhibitor of monoacylglycerol lipase (MAGL). Assessment of 2-AG was performed using lipidomic analysis in conjunction with various doses and time points post-administration of JZL-184. Baseline electrocortical activity and evoked responses to sound stimuli were measured using a 30-channel multielectrode array (MEA) in adult male mice before, 4 h, and 1 day post-intraperitoneal injection of JZL-184 or vehicle. Behavior assessment was done using the open field and elevated plus maze 4 h post-treatment. Lipidomic analysis showed that 8 mg/kg JZL-184 significantly increased the levels of 2-AG in the auditory cortex of both Fmr1 KO and WT mice 4 h post-treatment compared to vehicle controls. EEG recordings revealed a reduction in the abnormally enhanced baseline gamma-band power in Fmr1 KO mice and significantly improved evoked synchronization to auditory stimuli in the gamma-band range post-JZL-184 treatment. JZL-184 treatment also ameliorated anxiety-like and hyperactivity phenotypes in Fmr1 KO mice. Overall, these results indicate that increasing 2-AG levels may serve as a potential therapeutic approach to normalize cortical responses and improve behavioral outcomes in FXS and possibly other ASDs.