THC Exposure Research Articles

Dynamic overrepresentation of accumbal cues in food- and opioid-seeking rats after prenatal THC exposure

Dynamic overrepresentation of accumbal cues in food- and opioid-seeking rats after prenatal THC exposure

Proteomic Profile of Circulating Extracellular Vesicles in the Brain after Δ9-Tetrahydrocannabinol Inhalation.

Given the increasing use of cannabis in the US, there is an urgent need to better understand the drug's effects on central signaling mechanisms. Extracellular vesicles (EVs) have been identified as intercellular signaling mediators that contain a variety of cargo, including proteins. Here, we examined whether the main psychoactive component in cannabis, Δ9-tetrahydrocannabinol (THC), alters EV protein signaling dynamics in the brain. We first conducted in vitro studies, which found that THC activates signaling in choroid plexus epithelial cells, resulting in transcriptional upregulation of the cannabinoid 1 receptor and immediate early gene c-fos, in addition to the release of EVs containing RNA cargo. Next, male and female rats were examined for the effects of either acute or chronic exposure to aerosolized ('vaped') THC on circulating brain EVs. Cerebrospinal fluid was extracted from the brain, and EVs were isolated and processed with label-free quantitative proteomic analyses via high-resolution tandem mass spectrometry. Interestingly, circulating EV-localized proteins were differentially expressed based on acute or chronic THC exposure in a sex-specific manner. Taken together, these findings reveal that THC acts in the brain to modulate circulating EV signaling, thereby providing a novel understanding of how exogenous factors can regulate intercellular communication in the brain.

Can the THC concentration predict the number of patients with cannabis-related diagnoses?

The use of high-potency cannabis products is associated with an increased risk of mental disorders. This study investigates whether the rising THC concentration in Germany is associated with an increase in cannabis-related diagnoses. The number of insured persons with at least one cannabis-related ICD-10 F12 diagnosis (e.g., harmful use, dependence) in outpatient care was provided by statutory health insurance funds between 2009 and 2021. The dependent variable is the ratio of (a) the number of insured persons with at least one F12 diagnosis to (b) all insured persons who have used cannabis in the last year. Information on THC concentration in cannabis flower was provided by law enforcement agencies. Using generalised mixed linear models, the dependent variable was predicted by the median THC concentration in cannabis flower. The regression results show that an increase in THC concentration by one percentage point is significantly associated with an increase in the proportion of diagnoses (women: +0.17; men: +0.42). THC concentration positively predicted the proportion of diagnoses in all 16 federal states for men and in 15 federal states for women. Compared to low-potency products, using high-potency products may pose additional health risks, which may be particularly pronounced in men. Acknowledging the limitations of the ecological study design and uncertainties inherent to the analysed data, further investigations on the sex-specific impact of THC exposure are required. Limiting the THC concentration in cannabis products and closely monitoring THC consumption in the population appears necessary.

THC Vapor Inhalation Attenuates Hyperalgesia in Rats Using a Chronic Inflammatory Pain Model

Humans use cannabinoid drugs to alleviate pain. As cannabis and cannabinoids are legalized in the United States for medicinal and recreational use, it has become critical to determine the potential utilities and harms of cannabinoid drugs in individuals living with chronic pain. Here, we tested the effects of repeated ∆9-tetrahydrocannabinol (THC) vapor inhalation on thermal nociception and mechanical sensitivity, in adult male and female Wistar rats using a chronic inflammatory pain model (ie, treated with complete Freund’s adjuvant [CFA]). We report that repeated THC vapor inhalation rescues thermal hyperalgesia in males and females treated with CFA and also reduces mechanical hypersensitivity in CFA males but not females. Many of the antihyperalgesic effects of chronic THC vapor were still observable 24 hours after cessation of the last THC exposure. We also report plasma levels of THC and its major metabolites, some of which are cannabinoid type-1 receptor agonists, after the first and tenth days of THC vapor inhalation. Finally, we report that systemic administration of the cannabinoid type-1 receptor inverse agonist AM251 (1 mg/kg, I.P.) blocks the antihyperalgesic effects of THC vapor in males and females. These data provide a foundation for future work that will explore the cells and circuits underlying the antihyperalgesic effects of THC vapor inhalation in individuals with chronic inflammatory pain. PerspectiveCannabinoids are thought to have potential utility in the treatment of chronic pain, but few animal studies have tested the effects of chronic THC or cannabis in animal models of chronic pain. We tested the effects of repeated THC vapor inhalation on chronic pain-related outcomes in male and female animals.

Effects of in utero delta-9-tetrahydrocannabinol (THC) exposure on fetal and infant musculoskeletal development in a preclinical nonhuman primate model.

The endocannabinoid system (ECS) plays a major role in the maintenance of bodily homeostasis and adaptive response to external insults. It has been shown to regulate crucial physiological processes and behaviors, spanning nervous functions, anxiety, cognition, and pain sensation. Due to this broad activity, the ECS has been explored as a potential therapeutic target in the treatment of select diseases. However, until there is a more comprehensive understanding of how ECS activation by exogenous and endogenous ligands manifests across disparate tissues and cells, discretion should be exercised. Previous work has investigated how endogenous cannabinoid signaling impacts skeletal muscle development and differentiation. However, the effects of activation of the ECS by delta-9-tetrahydrocannabinol (THC, the most psychoactive component of cannabis) on skeletal muscle development, particularly in utero, remain unclear. To address this research gap, we used a highly translational non-human primate model to examine the potential impact of chronic prenatal THC exposure on fetal and infant musculoskeletal development. RNA was isolated from the skeletal muscle and analyzed for differential gene expression using a Nanostring nCounter neuroinflammatory panel comprised of 770 genes. Histomorphological evaluation of muscle morphology and composition was also performed. Our findings suggest that while prenatal THC exposure had narrow overall effects on fetal and infant muscle development, the greatest impacts were observed within pathways related to inflammation and cytokine signaling, which suggest the potential for tissue damage and atrophy. This pilot study establishes feasibility to evaluate neuroinflammation due to prenatal THC exposure and provides rationale for follow-on studies that explore the longer-term implications and functional consequences encountered by offspring as they continue to mature.

DNA methylation, but not microRNA expression, is affected by in vitro THC exposure in bovine granulosa cells

BackgroundA global increase in cannabis use has led to questions about its effects on fertility. The rise in consumption amongst women of reproductive age is a growing concern, as this group is vulnerable in terms of reproductive health. Ample evidence suggests that the psychoactive component of cannabis, Δ9-Tetrahydrocannabinol (THC), interacts with the endocannabinoid system (ECS), that helps regulate mammalian reproduction. This study aimed to research the epigenetic effects of THC in bovine granulosa cells (GCs) by (1) investigating global DNA methylation via measuring 5-mC and 5-hmC levels; (2) measuring key methylation regulators, including the methylating enzymes DNMT1, DNMT3a, DNMT3b and the demethylases TDG and TET1/2/3; and (3) assessing fertility-associated miRNAs key in developmental competency, including miR-21, -155, -33b, -324 and -346.MethodsBovine GCs were used as a translational model for reproductive toxicity in humans. To determine THC effects, GCs were isolated from Cumulus-Oocyte-Complexes (COCs) from bovine ovaries, cultured in vitro for 7 days, or until confluent, and cryopreserved at passage 1 (P1). For experimentation, cells were thawed, cultured until passage 2 (P2), serum restricted for 24-h and treated for 24-h in one of five groups: control, vehicle (1:1:18 ethanol: tween: saline) and three clinically relevant THC doses (0.032, 0.32 and 3.2 μM). Global methylation was assessed by measuring 5-mC and 5-hmC levels with flow cytometry. To assess mRNA and protein expression of methylation regulators and miRNA profiles, qPCR and Western Blotting were utilized. Shapiro-Wilk test was used to determine normality within datasets. One-way ANOVA was applied to determine statistical significance using GraphPad Prism 6.0.0.ResultsResults indicate a significant decrease (p = 0.0435) in 5-mC levels following low THC exposure, while no changes were observed in 5-hmC levels. A significant increase in DNMT1 following high THC exposure at the RNA level (p < 0.05) and a significant increase following low THC exposure at the protein level (p = 0.0048) were also observed. No significant differences were observed in DNMT3a/3b, TDG, TET1/2/3 mRNAs or in any of the miRNAs analyzed.ConclusionsThis research suggests that THC mainly affects DNA methylation, but not miRNA profiles, ultimately altering gene expression and likely impairing oocyte competence, maturation, and fertilization potential.

Prenatal tetrahydrocannabinol and cannabidiol exposure produce sex-specific pathophysiological phenotypes in the adolescent prefrontal cortex and hippocampus

Clinical and preclinical evidence has demonstrated an increased risk for neuropsychiatric disorders following prenatal cannabinoid exposure. However, given the phytochemical complexity of cannabis, there is a need to understand how specific components of cannabis may contribute to these neurodevelopmental risks later in life. To investigate this, a rat model of prenatal cannabinoid exposure was utilized to examine the impacts of specific cannabis constituents (Δ9-tetrahydrocannabinol [THC]; cannabidiol [CBD]) alone and in combination on future neuropsychiatric liability in male and female offspring. Prenatal THC and CBD exposure were associated with low birth weight. At adolescence, offspring displayed sex-specific behavioural changes in anxiety, temporal order and social cognition, and sensorimotor gating. These phenotypes were associated with sex and treatment-specific neuronal and gene transcriptional alterations in the prefrontal cortex, and ventral hippocampus, regions where the endocannabinoid system is implicated in affective and cognitive development. Electrophysiology and RT-qPCR analysis in these regions implicated dysregulation of the endocannabinoid system and balance of excitatory and inhibitory signalling in the developmental consequences of prenatal cannabinoids. These findings reveal critical insights into how specific cannabinoids can differentially impact the developing fetal brains of males and females to enhance subsequent neuropsychiatric risk.

Vaporized Δ9-tetrahydrocannabinol exposure in utero has negative effects on attention in a dose- and sex-dependent manner

There has been an increasing use of cannabis during pregnancy in recent years. Studies have indicated that THC exposure in utero may increase the risk of attention deficits and memory impairments in adolescence. The goal of the present study is to investigate the effects of vaporized THC exposure during pregnancy on offspring memory and attention performance in early and late adolescence. Pregnant dams were exposed to vaporized THC (10 mg or 40 mg) daily from gestational day 2 until labor. Pups were given either a standard or a high-fat diet at weaning and tested in early and late adolescence in two memory tests, the Novel Object Recognition (NOR) test and the Morris Water Maze (MWM) test, and a test of attention, the Object-Based Attention (OBA) test. Rats exposed to low-dose THC showed significantly decreased object exploration in both the NOR and OBA tests, indicating decreased attention. Object exploration time in OBA was significantly lower in females than males. Additionally, post hoc analysis of MWM tests showed some differences in learning patterns for HD THC offspring in early adolescence, possibly due to diet interaction, but ultimate performance was not impacted. While there are existing studies examining prenatal exposure to THC in rodents, this is the first to our knowledge examining memory and attention in adolescence following vaporized THC exposure in utero, and we find indications that prenatal THC exposure may lead to attention deficits and altered memory performance.

Prenatal ethanol and cannabis exposure have sex- and region-specific effects on somatostatin and neuropeptide Y interneurons in the rat hippocampus.

Cannabis is increasingly being legalized and socially accepted around the world and is often used with alcohol in social settings. We recently showed that in utero exposure to both substances can alter the density of parvalbumin-expressing interneurons in the hippocampus. Here we investigate the effects of in utero alcohol and cannabis exposure, alone or in combination, on somatostatin- and neuropeptide Y-positive (NPY) interneurons. These are separate classes of interneurons important for network synchrony and inhibition in the hippocampus. A 2 (Ethanol, Air) × 2 (tetrahydrocannabinol [THC], Vehicle) design was used to expose pregnant Sprague-Dawley rats to either ethanol or air, in addition to either THC or the inhalant vehicle solution, during gestational days 5-20. Immunohistochemistry for somatostatin- and NPY-positive interneurons was performed in 50 μm tissue sections obtained at postnatal day 70. Exposure to THC in utero had region-specific and sex-specific effects on the density of somatostatin-positive interneurons in the adult rat hippocampus. A female-specific decrease in NPY interneuron cell density was observed in the CA1 region following THC exposure. Combined exposure to alcohol and THC reduced NPY neurons selectively in the ventral dentate gyrus hippocampal subfield. However, overall, co-exposure to alcohol and cannabis had neither additive nor synergistic effects on interneuron populations in other areas of the hippocampus. These results illustrate how alcohol and cannabis exposure in utero may affect hippocampal function by altering inhibitory processes in a sex-specific manner.

From Decisions to Molecular Mechanisms: Investigating the Influence of Adolescent THC Exposure on Adult Decision Making

From Decisions to Molecular Mechanisms: Investigating the Influence of Adolescent THC Exposure on Adult Decision Making

THC and sperm: Impact on fertilization capability, pre-implantation in vitro development and epigenetic modifications.

Global cannabis use has risen 23% since 2010, with 209 million reported users, most of whom are males of reproductive age. Delta-9-tetrahydrocannabinol (THC), the main psychoactive phytocannabinoid in cannabis, disrupts pro-homeostatic functions of the endocannabinoid system (ECS) within the male reproductive system. The ECS is highly involved in regulating morpho-functional and intrinsic sperm features that are required for fertilization and pre-implantation embryo development. Previous work by our group demonstrated that THC altered sperm capacitation and the transcriptome, including several fertility-associated microRNAs (miRs). Despite the prevalent use of cannabis among males of reproductive age, clinical and pre-clinical research investigating the impact of paternal cannabis on sperm function and the outcomes of artificial reproductive technologies (ARTs) remains inconclusive. Therefore, the present study investigates the impact of in vitro THC exposure on morpho-functional and intrinsic sperm functions, including contributions to embryo development following IVF. Bovine sperm were used as a translational model for human and treated with concentrations of THC that reflect plasma levels after therapeutic (0.032μM), and low (0.32μM)-high (4.8μM) recreational cannabis use. After 6-hours of treatment, THC did not alter the acrosomal reaction, but 4.8μM significantly reduced mitochondrial membrane potential (MMP) (p<0.05), primarily through agonistic interactions with CB-receptors. Fertilization of bovine oocytes with THC-treated sperm did not alter developmental rates, but blastocysts generated from sperm treated with 0.32-4.8μM THC had fewer trophoblasts (p<0.05), while blastocysts generated from sperm exposed to any concentration of THC had fewer cells in the inner cell mass (ICM), particularly within the 0.032μM group (p<0.001). Fertility associated miRs, including miR-346, miR-324, miR-33b, and miR-34c were analyzed in THC-exposed sperm and associated blastocysts generated by IVF, with lower levels of miRs-346, -324, and -33b found in sperm treated with 0.32μM THC, while miR-34c levels were higher in sperm treated with 0.032μM THC (p<0.05). Levels of miR-346 were also lower in sperm treated with 0.032μM THC, but higher in blastocysts generated from sperm exposed to 0.32μM THC (p<0.05). Our findings suggest that THC may alter key morpho-functional and epigenetic sperm factors involved in fertilization and embryo development. This is the first study to demonstrate that sperm exposed to THC in vitro negatively affects embryo quality following IVF.

Risk of motor vehicle collisions and culpability among older drivers using cannabis: a meta‐analysis

AbstractBackgroundWhile the effects of cannabis use on driving have been established in younger populations, limited studies have investigated this association among older adults, who represent the fastest growing segment of drivers globally.MethodWe conducted a systematic review and meta‐analysis to evaluate the effect of THC exposure on (1) risk of motor vehicle collisions (MVC) and (2) risk of culpability (being responsible for the collision), among adults 50 years and older. Three reviewers screened 7,022 studies identified through MEDLINE, EMBASE, CENTRAL, and PsycINFO and published between inception and 2021. Odds Ratios (OR) were calculated with a random‐effects model using the Mantel‐Haenszel method in Review Manager 5.4.1. Heterogeneity was assessed using I2. An adapted version of the National Heart, Lung, and Blood Institute quality assessment tool was used to assess the quality of each study.Result7 cross‐sectional studies were included. Three studies were rated ‘Good’ quality, one rated ‘Fair’, and three rated ‘Poor’. Three of the included studies evaluated culpability (NTHC+ = 239 NTHC‐ = 4609) while four evaluated MVC risk (NTHC+ = 158, NTHC‐ = 6152). We found that the pooled risk of MVC was not significantly different between older drivers exposed to THC and those who were not (OR, 95% CI 1.15 [0.40, 3.31]; I2 = 72%). In the studies assessing driver culpability, THC exposure was not significantly associated with an increased risk of being culpable for MVC among adults over the age of 50 (OR, 95% CI 1.24 [0.95, 1.61]; I2 = 0%). A visual inspection of the funnel plots did not indicate any publication bias.ConclusionOur review found that THC exposure was not associated with MVC involvement nor with culpability. However, it would be an oversimplification to conclude that cannabis use does not pose a safety risk to older drivers. Rather, our results may reflect several methodological limitations of the studies included in this review. Due to the increasing prevalence of cannabis use worldwide, we are optimistic that future research will be able to address this research question using more objective methodologies.

62 Exploration of Sex Differences in Cannabis Use Patterns, Driving Performance, and Subjective Intoxication Effects

Objective:Although some animal research suggests possible sex differences in response to THC exposure (e.g., Cooper &amp; Craft, 2018), there are limited human studies. One study found that among individuals rarely using cannabis, when given similar amounts of oral and vaporized THC females report greater subjective intoxication compared to males (Sholler et al., 2020). However, in a study of daily users, females reported indistinguishable levels of intoxication compared to males after smoking similar amounts (Cooper &amp; Haney, 2014), while males and females using 1–4x/week showed similar levels of intoxication, despite females having lower blood THC and metabolite concentrations (Matheson et al., 2020). It is important to elucidate sex differences in biological indicators of cannabis intoxication given potential driving/workplace implications as states increasingly legalize use. The current study examined if when closely matching males and females on cannabis use variables there are predictable sex differences in residual whole blood THC and metabolite concentrations, and THC/metabolites, subjective appraisals of intoxication, and driving performance following acute cannabis consumption.Participants and Methods:The current study was part of a randomized clinical trial (Marcotte et al., 2022). Participants smoked ad libitum THC cigarettes and then completed driving simulations, blood draws, and subjective measures of intoxication. The main outcomes were the change in Composite Drive Score (CDS; global measure of driving performance) from baseline, whole blood THC, 11-OH-THC, and THC-COOH levels (ng/mL), and subjective ratings of how “high” participants felt (0 = not at all, 100 = extremely). For this analysis of participants receiving active THC, males were matched to females on 1) estimated THC exposure (g) in the last 6 months (24M, 24F) or 2) whole blood THC concentrations immediately post-smoking (23M, 23F).Results:When matched on THC exposure in the past 6 months (overall mean of 46 grams; p = .99), there were no sex differences in any cannabinoid/metabolite concentrations at baseline (all p &gt; .83) or after cannabis administration (all p &gt; .72). Nor were there differences in the change in CDS from pre-to-post-smoking (p = .26) or subjective “highness” ratings (p = .53). When matched on whole blood THC concentrations immediately after smoking (mean of 34 ng/mL for both sexes, p = .99), no differences were found in CDS change from pre-to-post smoking (p = .81), THC metabolite concentrations (all p &gt; .25), or subjective “highness” ratings (p = .56). For both analyses, males and females did not differ in BMI (both p &gt; .7).Conclusions:When male/female cannabis users are well-matched on use history, we find no significant differences in cannabinoid concentrations following a mean of 5 days of abstinence, suggesting that there are no clear biological differences in carryover residual effects. We also find no significant sex differences following ad libitum smoking in driving performance, subjective ratings of “highness,” nor whole blood THC and metabolite concentrations, indicating that there are no biological differences in acute response to THC. This improves upon previous research by closely matching participants over a wider range of use intensity variables, although the small sample size precludes definitive conclusions.

Lack of interactions between prenatal immune activation and Δ9-tetrahydrocannabinol exposure during adolescence in behaviours relevant to symptom dimensions of schizophrenia in rats

The causality in the association between cannabis use and the risk of developing schizophrenia has been the subject of intense debate in the last few years. The development of animal models recapitulating several aspects of the disease is crucial for shedding light on this issue. Given that maternal infections are a known risk for schizophrenia, here, we used the maternal immune activation (MIA) model combined with THC exposure during adolescence to examine several behaviours in rats (working memory in the Y maze, sociability in the three-chamber test, sucrose preference as a measure, prepulse inhibition and formation of incidental associations) that are similar to the different symptom clusters of the disease. To this end, we administered LPS to pregnant dams and when the offspring reached adolescence, we exposed them to a mild dose of THC to examine their behaviour in adulthood. We also studied several parameters in the dams, including locomotor activity in the open field, elevated plus maze performance and their response to LPS, that could predict symptom severity of the offspring, but found no evidence of any predictive value of these variables. In the adult offspring, MIA was associated with impaired working memory and sensorimotor gating, but surprisingly, it increased sociability, social novelty and sucrose preference. THC, on its own, impaired sociability and social memory, but there were no interactions between MIA and THC exposure. These results suggest that, in this model, THC during adolescence does not trigger or aggravate symptoms related to schizophrenia in rats.

Microglial cannabinoid receptor type 1 mediates social memory deficits in mice produced by adolescent THC exposure and 16p11.2 duplication

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. However, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, is not fully understood. Here, we report that in mice, adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in a 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 suggest the microglial Cnr1 may contribute to adverse effect of cannabis exposure in genetically vulnerable individuals.

Prenatal delta-9-tetrahydrocannabinol exposure is associated with changes in rhesus macaque DNA methylation enriched for autism genes

BackgroundWith the growing availability of cannabis and the popularization of additional routes of cannabis use beyond smoking, including edibles, the prevalence of cannabis use in pregnancy is rapidly increasing. However, the potential effects of prenatal cannabis use on fetal developmental programming remain unknown.ResultsWe designed this study to determine whether the use of edible cannabis during pregnancy is deleterious to the fetal and placental epigenome. Pregnant rhesus macaques consumed a daily edible containing either delta-9-tetrahydrocannabinol (THC) (2.5 mg/7 kg/day) or placebo. DNA methylation was measured in 5 tissues collected at cesarean delivery (placenta, lung, cerebellum, prefrontal cortex, and right ventricle of the heart) using the Illumina MethylationEPIC platform and filtering for probes previously validated in rhesus macaque. In utero exposure to THC was associated with differential methylation at 581 CpGs, with 573 (98%) identified in placenta. Loci differentially methylated with THC were enriched for candidate autism spectrum disorder (ASD) genes from the Simons Foundation Autism Research Initiative (SFARI) database in all tissues. The placenta demonstrated greatest SFARI gene enrichment, including genes differentially methylated in placentas from a prospective ASD study.ConclusionsOverall, our findings reveal that prenatal THC exposure alters placental and fetal DNA methylation at genes involved in neurobehavioral development that may influence longer-term offspring outcomes. The data from this study add to the limited existing literature to help guide patient counseling and public health polices focused on prenatal cannabis use in the future.

O-074 THC reduces sperm mitochondrial membrane potential, but does not affect the acrosome reaction or in-vitro embryo developmental rates.

Abstract Study question Does THC alter sperm function and early embryo development following in vitro fertilization with THC-exposed sperm? Summary answer THC reduces sperm mitochondrial membrane potential (MMP), mainly through cannabinoid receptor agonism, but does not alter the acrosome reaction or rates of embryo development. What is known already Cannabis is the most commonly used recreational drug among males of reproductive age. THC is the main psychoactive component of cannabis and can cross the blood-testis barrier, disrupting the endocannabinoid system (ECS) in sperm. However, the mechanisms by which THC affect sperm function and early embryo development are unclear. In sperm, endogenous cannabinoids influence the acrosome reaction and MMP, which are critical for motility, viability and, ultimately, fertilization. To date, no studies have investigated how sperm exposed to physiologically relevant doses of THC may impact in-vitro early embryo development, and cannabis use recommendations remain unclear for patients undergoing IVF procedures. Study design, size, duration Bovine sperm and cumulus oocyte complexes (COCs) were used as a translational model for humans. Cryo-thawed sperm was separated using a Percoll gradient and incubated for 6-hours in one of five treatment groups: control, vehicle (0.01% ethanol), low-THC (0.032µM), mid-THC (0.32µM), and high-THC (4.8µM) – concentrations equivalent to THC plasma levels following therapeutic and mid-high recreational use, respectively (Whan et al., 2006). A minimum of 30,000 sperm and 60 COCs were analyzed per group. Participants/materials, setting, methods Sperm were treated for 6-hours prior to all experiments. Flow cytometry using sperm (1-2x106) stained with propidium iodide (PI) and FITC-conjugated peanut agglutinin (FITC-PNA) or JC-1 was used to measure either the acrosomal reaction or MMP, respectively. COCs were aspirated from slaughterhouse ovaries and matured in-vitro for 24-hours. IVF was performed with THC-treated sperm (1x106/mL/drop) for 10-hours. Presumptive zygotes were cultured in-vitro for 8-days. Cleavage and blastocyst rates were measured 48-hours and 8-days post-fertilization, respectively. Main results and the role of chance Measuring PI and FITC-PNA fluorescence showed the percent of sperm that were acrosome-reacted and either alive or necrotic. There were no significant differences in acrosome-reacted sperm among groups (n = 9). Measuring JC-1 fluorescence showed the percentage of sperm with high MMP. Results indicate a significant reduction in sperm with high MMP (37%) following high THC (4.8µM) exposure (p = 0.002418, n = 4). No significant differences in MMP were observed among other groups. To elicit the mechanism by which THC was reducing sperm MMP, we repeated experiments using only JC-1-stained sperm exposed to high THC treated with SR141716 and SR144528, which are CB-1 and -2 antagonists, respectively. Additional groups included: SR141716 (4.8.µM), SR144528 (4.8µM), THC + SR141716 and THC + SR144528. Results indicate a significant reduction in sperm with high MMP (38%) in the THC group (4.8µM) compared to control (51%) (p = 0.0417, n = 6), vehicle (54%) (p = 0.0069, n = 6), and SR141716 (65%) (p &amp;lt; 0.0001, n = 6). There were no significant differences in sperm with high MMP in THC + SR141716 or THC + SR144528 groups, indicating that THC is acting agonistically, primarily at CB1 receptors. Following IVF with THC-treated sperm, there were no significant differences in cleavage or blastocyst rates among treatment groups. Limitations, reasons for caution The use of bovine instead of human cells could be considered a limitation. However, as studying effects of THC-treated sperm on IVF outcomes would not be possible using human samples, it is actually an advantage. The similarity between bovine and human gametes makes bovine an ideal translational model for humans Wider implications of the findings As cannabis use and THC concentrations increase, this research addresses the growing concern of how cannabis impacts fertility and, ultimately, pregnancy outcome. Understanding how THC affects sperm function and embryo development will provide physicians with science-based recommendations concerning cannabis use for patients trying to conceive, pregnant, or undergoing fertility treatments. Trial registration number not applicable

Prenatal alcohol and tetrahydrocannabinol exposure: Effects on spatial and working memory.

Alcohol and cannabis are widely used recreational drugs that can negatively impact fetal development, leading to cognitive impairments. However, these drugs may be used simultaneously and the effects of combined exposure during the prenatal period are not well understood. Thus, this study used an animal model to investigate the effects of prenatal exposure to ethanol (EtOH), Δ-9-tetrahydrocannabinol (THC), or the combination on spatial and working memory. Pregnant Sprague-Dawley rats were exposed to vaporized ethanol (EtOH; 68 ml/h), THC (100 mg/ml), the combination, or vehicle control during gestational days 5-20. Adolescent male and female offspring were evaluated using the Morris water maze task to assess spatial and working memory. Prenatal THC exposure impaired spatial learning and memory in female offspring, whereas prenatal EtOH exposure impaired working memory. The combination of THC and EtOH did not exacerbate the effects of either EtOH or THC, although subjects exposed to the combination were less thigmotaxic, which might represent an increase in risk-taking behavior. Our results highlight the differential effects of prenatal exposure to THC and EtOH on cognitive and emotional development, with substance- and sex-specific patterns. These findings highlight the potential harm of THC and EtOH on fetal development and support public health policies aimed at reducing cannabis and alcohol use during pregnancy.

The long-term effects of adolescent Δ9-tetrahydrocannabinol on brain structure and function assessed through neuroimaging techniques in male and female rats

Several studies performed on human subjects have examined the effects of adolescent cannabis consumption on brain structure or function using brain imaging techniques. However, the evidence from these studies is usually heterogenous and affected by several confounding variables. Animal models of adolescent cannabinoid exposure may help to overcome these difficulties. In this exploratory study, we aim to increase our understanding of the protracted effects of adolescent Δ9-tetrahydrocannabinol (THC) in rats of both sexes using magnetic resonance (MR) to obtain volumetric data, assess grey and white matter microstructure with diffusion tensor imaging (DTI) and measure brain metabolites with 1H-MR spectroscopy (MRS); in addition, we studied brain function using positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-glucose as the tracer. THC-exposed rats exhibited volumetric and microstructural alterations in the striatum, globus pallidus, lateral ventricles, thalamus, and septal nuclei in a sex-specific manner. THC administration also reduced fractional anisotropy in several white matter tracts, prominently in rostral sections, while in vivo MRS identified lower levels of cortical choline compounds. THC-treated males had increased metabolism in the cerebellum and olfactory bulb and decreased metabolism in the cingulate cortex. By contrast, THC-treated females showed hypermetabolism in a cluster of voxels comprising the entorhinal piriform cortices and in the cingulate cortex. These results indicate that mild THC exposure during adolescence leaves a lingering mark on brain structure and function in a sex-dependant manner. Some of the changes found here resemble those observed in human studies and highlight the importance of studying sex-specific effects in cannabinoid research.

THC exposure during adolescence increases impulsivity-like behavior in adulthood in a WIN 55,212-2 self-administration mouse model.

Cannabis addiction is a chronically relapsing disorder lacking effective treatment. Regular cannabis consumption typically begins during adolescence, and this early cannabinoid exposure may increase the risk for drug addiction in adulthood. This study investigates the development of cannabis addiction-like behavior in adult mice after adolescent exposure to the main psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC). Adolescent male mice were exposed to 5 mg/kg of THC from postnatal days 37 to 57. Operant self-administration sessions of WIN 55,212-2 (12.5 μg/kg/infusion) were conducted for 10 days. Mice were tested for three addiction-like criteria (persistence of response, motivation, and compulsivity), two parameters related to craving (resistance to extinction and drug-seeking behavior), and two phenotypic vulnerability traits related to substance use disorders (impulsivity and reward sensitivity). Additionally, qPCR assays were performed to detect differentially expressed genes in medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum, and hippocampus (HPC) of "addicted" and "non-addicted" mice. Adolescent THC exposure did not modify WIN 55,212-2 reinforcement nor the development of cannabis addiction-like behavior. Inversely, THC pre-exposed mice displayed impulsive-like behavior in adulthood, which was more pronounced in mice that developed the addiction-like criteria. Moreover, downregulated drd2 and adora2a gene expression in NAc and HPC was revealed in THC pre-exposed mice, as well as a downregulation of drd2 expression in mPFC of vehicle pre-treated mice that developed addiction-like behaviors. These findings suggest that adolescent THC exposure may promote impulsivity-like behavior in adulthood, associated with downregulated drd2 and adora2a expression in NAc and HPC.