Adolescent Δ9-THC exposure and astrocyte-specific genetic vulnerability converge on NF-κB-COX-2 signaling to impair memory in adulthood
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ABSTRACT: Adolescent cannabis use has been associated with long-term cognitive dysfunction attributed to action of the main cannabis ingredient, delta-9-tetrahydrocannabinol (Δ9-THC), on the cannabinoid receptor 1 (CNR1). However, not all marijuana users develop cognitive impairment, suggesting a genetic vulnerability to adverse effects of cannabis. As both neurons and glial cells express CNR1, genetic vulnerability could influence Δ9-THC-induced signaling in a cell type-specific manner. Here we use an animal model of inducible expression of dominant-negative Disrupted-In-Schizophrenia-1 (DN-DISC1) selectively in astrocytes to evaluate the molecular mechanisms whereby an astrocyte genetic vulnerability could synergistically interact with adolescent Δ9-THC exposure to impair recognition memory in adulthood. We report that selective expression of DN-DISC1 in astrocytes and adolescent treatment with Δ9-THC synergistically affected recognition memory in adult mice. Similar deficits in recognition memory were observed following knockdown of endogenous Disc1 in hippocampal astrocytes in mice treated with Δ9-THC during adolescence. At the molecular level, DN-DISC1 and Δ9-THC synergistically activated the NF-kB-COX-2 (encoded by Ptgs2 gene) pathway in astrocytes and decreased immunoreactivity of parvalbumin-positive pre-synaptic inhibitory boutons around pyramidal neurons of the CA3 area of the hippocampus. The cognitive abnormalities were prevented in DN-DISC1 mice exposed to Δ9-THC by simultaneous adolescent treatment with the COX-2 inhibitor, NS389. Our data demonstrate that individual vulnerability to cannabis can be exclusively mediated by astrocytes. Results of this work suggest that genetic predisposition within astrocytes can exaggerate Δ9-THC-produced cognitive impairments via convergent inflammatory signaling, suggesting possible targets for preventing adverse effects of cannabis within susceptible individuals.
Project description:Adolescent cannabis use increases the risk for cognitive impairments and psychiatric disorders. Cannabinoid receptor type 1 (Cnr1) is expressed not only in neurons and astrocytes, but also in microglia, which shape synaptic connections during adolescence. Nonetheless, until now, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, has been unexplored. Here, we report that adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in the mouse model of 16p11.2 duplication, a representative copy number variation (CNV) risk factor for psychiatric disorders. These effects are mediated by microglial Cnr1, leading to reduction in the excitability of mPFC pyramidal-tract neurons and deficits in social memory in adulthood. Our findings highlight the importance of microglial Cnr1 to produce the adverse effect of cannabis exposure in genetically vulnerable individuals.
Project description:Background: Adolescent cannabis use leads to long-lasting behavioral changes involving cognitive and reward processes. However, the underlying molecular mechanisms are not well understood. To address this limitation, we performed gene network analyses using transcriptomic data from mice exposed during adolescence to Δ-9-tetrahydrocannabinol (THC), the major psychoactive component of cannabis. Methods: We injected vehicle or THC in female and male mice during the entire adolescence period. Two weeks following the last exposure, we measured recognition memory, social interaction and anxiety-related behaviors. We generated 120 RNA-seq datasets from 5 brain regions for each mouse. We performed differential gene expression analysis and constructed co-expression networks to identify THC-induced transcriptional alterations at the level of individual genes, gene networks, biological pathways, and cellular specificity. Further, we integrated THC-correlated gene networks with human traits from genome-wide association studies and performed key driver analysis to identify potential regulators of disorder-associated networks. Results: THC impaired cognitive behaviors of mice, with memory being more impacted in females, which coincided with larger transcriptional alterations in the female brain. Gene network analyses identified brain region-, cell type- and sex- specific co-expressed genes (“modules”) dysregulated by THC. THC-induced memory deficits in females were correlated with disruption of gene networks involved in endocannabinoid signaling and inflammation. Additional THC-correlated modules in both sexes involved converging pathways related to dopamine signaling and addiction processes. Moreover, the connectivity map of THC-correlated modules uncovered intra- and inter-region molecular circuitries influenced by THC. Further, modules altered by THC treatment were enriched in genes relevant for human cognition and schizophrenia. Conclusions: These findings provide novel insights concerning the genes, cell types, and pathways underlying persistent behavioral deficits induced by adolescent exposure to THC in a sex-specific manner, and highlight the connection between adolescent cannabis use and neuropsychiatric disorders in humans.
Project description:An increasing number of women report cannabis use during their pregnancy, with little knowledge on the repercussions of such an exposure onto early embryonic processes. In particular, exposure to the most abundant phytocannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), could alter the development of embryonic germ cells, with potential consequences across generations. Here, we extensively characterized the impact of gestational exposure to Δ9-THC onto the developmental trajectory of an in vitro model for primordial germ cells. Our data reveals that Δ9-THC exposure increases glycolytic rates in embryonic stem cells, with consequences on their proliferation. We further show that, in the absence of continuous exposure, Δ9-THC has long-lasting adverse consequences on the metabolome and transcriptome of embryonic germ cells. These results constitute the first characterization of the impact of gestational Δ9-THC exposure onto the embryonic germline.
Project description:Drug exposure during critical periods of development is known to have lasting effects, increasing one’s risk for developing mental health disorders. Emerging evidence has also indicated the possibility for drug exposure to even impact subsequent generations. Our previous work demonstrated that adolescent exposure to Δ9-tetrahydrocannabinol (THC), the main psychoactive component of marijuana (Cannabis sativa), in a Long-Evans rat model affects reward-related behavior and gene regulation in the subsequent (F1) generation unexposed to the drug. Questions, however, remained regarding potential epigenetic consequences. In the current study, using the same rat model, we employed Enhanced Reduced Representation Bisulfite Sequencing to interrogate the epigenome of the nucleus accumbens, a key brain area involved in reward processing. This analysis compared 16 animals with parental-THC exposure and 16 without to characterize relevant systems-level changes in DNA methylation. We identified 1,027 differentially methylated regions (DMRs) associated with parental THC exposure in F1 adults, each represented by multiple CpGs. These DMRs fell predominantly within introns, exons, and intergenic intervals, while showing a significant depletion in gene promoters. From these, we identified a network of DMR-associated genes involved in glutamatergic synaptic regulation, which also exhibited altered mRNA expression in the nucleus accumbens. These data provide novel insight into drug-related cross-generational epigenetic effects, and serve as a useful resource for investigators to explore novel neurobiological systems underlying drug abuse vulnerability. Study consisted of a total of 32 F1 individuals (Long-Evan rats); 16 animals (8 female, 8 male) were offspring from THC-exposed parents, and the remaining 16 animals (8 female, 8 male) were offspring from saline-exposed parents ("controls"; "VEH-exposed").
Project description:Medicinal cannabis has garnered worldwide attention in recent years but has been hampered by the psychotropic activity of Δ9-tetrahydro-cannabinol (Δ9-THC). However, the biological activity of its precursor Δ9-THC acid (Δ9-THCA) remain largely unexplored; yet, it is known that Δ9-THCA is not psychotropic and displays PPARg agonistic activity. We report here that Δ9-THCA is a partial and selective PPARg, albeit with lower adipogenic activity than the full PPARg agonist, rosiglitazone (RGZ). In addition, Δ9-THCA enhanced osteoblastogenesis in human mesenchymal stem cells. Docking and in vitro functional assays indicated that Δ9-THCA binds and activated PPARg by acting at both the canonical and the alternative binding sites in the PPARg ligand-binding pocket. Indeed, transcriptomic signature at inguinal white adipose tissue (iWAT) from mice treated with Δ9-THCA confirmed its mode of action at PPARg. Administration of Δ9-THCA for 3-weeks in a mouse model of high fat diet (HFD)-induced obesity significantly reduced fat mass and body weight gain, and markedly ameliorated glucose intolerance and insulin resistance, while largely preventing liver steatosis, adipogenesis and macrophage infiltration in fat tissues. In addition, immunohistochemistry, transcriptomic and plasmatic biomarkers analyses showed that treatment with Δ9-THCA caused browning of iWAT and displayed potent anti-inflammatory actions in HFD mice. Altogether, our studies collectively document the potent biological activity of Δ9-THCA as a PPARggonist with capacity to substantially improve metabolic syndrome and inflammation associated to obesity. Our findings also imply that non-decarboxylated, Cannabis sativa extracts could be added to the arsenal of cannabis preparations already available in countries where medicinal cannabis is authorized.
Project description:Increased availability of cannabis and cannabinoid-containing products necessitates the need for understanding how exposure to these compounds can affect development. Using cannabinoid receptor-null zebrafish (cnr1-/- and cnr2-/-), we conducted experiments to assess the roles of these receptors in ∆9-tetrahydrocannabinol (THC) and cannabidiol (CBD) developmental and behavioral toxicity. THC increased mortality and deformities (pericardial and yolk sac edemas, a reduction in size) in cnr1-/- and cnr2-/- fish. Conversely, CBD-induced malformations and mortality were significantly reduced in the cnr1-/- and cnr2-/- larvae. THC and CBD exposure caused significantly decreased larval behavior (96 hpf), however, decreased distance travelled was protected in the cnr1-/- and cnr2-/- fish, suggesting these receptors are responsible for mediating behavioral toxicity. Transcriptomic profiling in cnr+/+ embryos developmentally exposed to 4 μM THC or 0.5 μM CBD revealed that a significant portion of differentially expressed genes were targets of PPARγ, a predicted upstream regulator. In Cnr-positive embryos, co-exposure to the PPARγ inhibitor GW9662 and THC or CBD, there was increased toxicity compared to exposure with THC or CBD alone. Co-treatment in the cnr2-/- fish with GW9662 did not alter the CBD-induced decrease in activity. However, co-treatment with GW9662 did remove the protective effect observed in cnr1-/- fish treated to CBD alone. Collectively, these results indicate that PPARγ, Cnr1, and Cnr2 all play crucial roles in the developmental toxicity of THC and CBD.
Project description:Adolescence is a time of experimentation with cannabis. We evaluated whether adolescent exposure to the drug's psychotropic consituent, delta-9-tetrahydrocannabidiol (THC), might persistently alter microglia function and brain immune responses to lipopolysaccaride administration.
Project description:THC, the active ingredient of cannabis has been reported to impair learning and memory in humans and in laboratory animals when administered acutely. Unfortunately, most studies have been performed with young individuals although the activity of the endocannabinoid system changes during the aging process. Here we report that low doses of Δ9-THC (Delta-9-Tetrahydrocannabinol) improves learning and memory in old mice, enhances synaptic density, increases the expression of anti-ageing genes and decreases expression of pro-ageing genes in old but not in young animals. Δ9-THC elicited its beneficial effect through the CB1 receptors and increased histone acetylation was crucial for the long lasting effect. Elevation of the cannabinoid signaling may thus represent an exciting new approach to improve brain functions in old individuals.
Project description:Drug exposure during critical periods of development is known to have lasting effects, increasing one’s risk for developing mental health disorders. Emerging evidence has also indicated the possibility for drug exposure to even impact subsequent generations. Our previous work demonstrated that adolescent exposure to Δ9-tetrahydrocannabinol (THC), the main psychoactive component of marijuana (Cannabis sativa), in a Long-Evans rat model affects reward-related behavior and gene regulation in the subsequent (F1) generation unexposed to the drug. Questions, however, remained regarding potential epigenetic consequences. In the current study, using the same rat model, we employed Enhanced Reduced Representation Bisulfite Sequencing to interrogate the epigenome of the nucleus accumbens, a key brain area involved in reward processing. This analysis compared 16 animals with parental-THC exposure and 16 without to characterize relevant systems-level changes in DNA methylation. We identified 1,027 differentially methylated regions (DMRs) associated with parental THC exposure in F1 adults, each represented by multiple CpGs. These DMRs fell predominantly within introns, exons, and intergenic intervals, while showing a significant depletion in gene promoters. From these, we identified a network of DMR-associated genes involved in glutamatergic synaptic regulation, which also exhibited altered mRNA expression in the nucleus accumbens. These data provide novel insight into drug-related cross-generational epigenetic effects, and serve as a useful resource for investigators to explore novel neurobiological systems underlying drug abuse vulnerability.
Project description:Cannabinoid administration before and after simian immunodeficiency virus (SIV)-inoculation ameliorated disease progression and decreased inflammation in male rhesus macaques. Δ9-tetrahydrocannabinol (Δ9-THC) did not increase viral load in brain tissue or produce additive neuropsychological impairment in SIV-infected macaques. To determine if the neuroimmunomodulation of Δ9-THC involved differential microRNA (miR) expression, miR expression in the striatum of uninfected macaques receiving vehicle (VEH) or Δ9-THC (THC) and SIV-infected macaques administered either vehicle (VEH/SIV) or Δ9-THC (THC/SIV) was profiled using next generation deep sequencing.