The Endocannabinoid System in the Postimplantation Period: A Role during Decidualization and Placentation

The First "Hit" to the Endocannabinoid System? Associations Between Prenatal Cannabis Exposure and Frontolimbic White Matter Pathways in Children

Background

Cannabis is the most used federally illicit substance among pregnant people in the United States. However, emerging preclinical data show that a significant portion of cannabis constituents, such as Δ9-tetrahydrocannabinol and its bioactive metabolites, readily cross the placenta and accumulate in the fetal brain, disrupting neurodevelopment. Recent research using the Adolescent Brain Cognitive Development (ABCD) Study cohort has linked prenatal cannabis exposure (PCE) to greater neurobehavioral problems and lower total gray and white matter volume in children. Here, we examined the impact of PCE on frontolimbic white matter pathways that are critical for cognitive- and emotion-related functioning, show a high density of cannabinoid receptors, and are susceptible to cannabis exposure during other periods of rapid neurodevelopment (e.g., adolescence).

Methods

This study included 11,530 children (mean ± SD age = 118.99 ± 7.49 months; 47% female) from the ABCD Study cohort. Linear mixed-effects models were used to examine the effects of caregiver-reported PCE on fractional anisotropy of 10 frontolimbic pathways (5 per hemisphere).

Results

PCE was associated with lower fractional anisotropy of the right (β = -0.005, p < .001) and left (β = -0.003, p = .007) fornix, and these results remained significant after adjusting for a variety of covariates, multiple comparisons, fractional anisotropy of all fibers, and using a quality-control cohort only.

Conclusions

In sum, we demonstrated small, yet reliable, effects of PCE on white matter integrity during childhood, particularly in the fornix, which plays a crucial role in emotion- and memory-related processes. Future studies are needed to understand the impacts of small changes in brain structure or function on neurodevelopment and risk of neurobehavioral problems.

The Endocannabinoid System and Its Relationship to Human Reproduction

The endocannabinoid system is among the most important regulators of human reproduction. It already applies at the level of the sperm and the egg, plays an important role in the fertilization of the egg, its implantation, regulates the function of the placenta and participates in childbirth. The aim of this work is to summarize the knowledge accumulated so far and to show that the endocannabinoid system must be perfectly regulated in order to maintain a physiological pregnancy from implantation to delivery. Only an exceptional interplay of enzymes such as NAPE-PDL or FAAH, endogenous cannabinoids and cannabinoid receptors CB1 and CB2 can ensure the proper functioning of the reproductive organs and thus lead to delivery on time. Changes in the endocannabinoid system can lead to a number of pathological conditions, e.g., during blastocyst implantation, retardation of embryo development, impaired placental function or miscarriage. Soon, we can expect not only an understanding of all the regulatory events associated with the endocannabinoid system and other regulatory systems that participate in reproduction, but also several possibilities for pharmacotherapeutic interventions that can modify the formation, degradation and effect of endocannabinoids. It cannot be ruled out that some components of the endocannabinoid system could become a marker for monitoring pregnancy and childbirth.

Emerging Roles of Endocannabinoids as Key Lipid Mediators for a Successful Pregnancy

In recent years, Cannabis use/misuse for treating pregnancy-related symptoms and other chronic conditions has increased among pregnant women, favored by decriminalization and/or legalization of its recreational uses in addition to its easy accessibility. However, there is evidence that prenatal Cannabis exposure might have adverse consequences on pregnancy progression and a deleterious impact on proper neurodevelopmental trajectories in the offspring. Maternal Cannabis use could interfere with the complex and finely controlled role performed by the endocannabinoid system in reproductive physiology, impairing multiple gestational processes from blastocyst implantation to parturition, with long-lasting intergenerational effects. In this review, we discuss current clinical and preclinical evidence regarding the role of endocannabinoids in development, function, and immunity of the maternal–fetal interface, focusing on the impact of Cannabis constituents on each of these gestational processes. We also discuss the intrinsic limitations of the available studies and the future perspectives in this challenging research field.

Effects of Prenatal Cannabinoids Exposure upon Placenta and Development of Respiratory Neural Circuits

Cannabis use has risen dangerously during pregnancy in the face of incipient therapeutic use and a growing perception of safety. The main psychoactive compound of the Cannabis sativa plant is the phytocannabinoid delta-9-tetrahydrocannabinol (A-9 THC), and its status as a teratogen is controversial. THC and its endogenous analogues, anandamide (AEA) and 2-AG, exert their actions through specific receptors (eCBr) that activate intracellular signaling pathways. CB1r and CB2r, also called classic cannabinoid receptors, together with their endogenous ligands and the enzymes that synthesize and degrade them, constitute the endocannabinoid system. This system is distributed ubiquitously in various central and peripheral tissues. Although the endocannabinoid system's most studied role is controlling the release of neurotransmitters in the central nervous system, the study of long-term exposure to cannabinoids on fetal development is not well known and is vital for understanding environmental or pathological embryo-fetal or postnatal conditions. Prenatal exposure to cannabinoids in animal models has induced changes in placental and embryo-fetal organs. Particularly, cannabinoids could influence both neural and nonneural tissues and induce embryo-fetal pathological conditions in critical processes such as neural respiratory control. This review aims at the acute and chronic effects of prenatal exposure to cannabinoids on placental function and the embryo-fetal neurodevelopment of the respiratory pattern. The information provided here will serve as a theoretical framework to critically evaluate the teratogen effects of the consumption of cannabis during pregnancy.

Cannabis significantly alters DNA methylation of the human ovarian follicle in a concentration-dependent manner

Cannabis is increasingly consumed by women of childbearing age, and the reproductive and epigenetic effects are unknown. The purpose of this study was to evaluate the potential epigenetic implications of cannabis use on the female ovarian follicle. Whole-genome methylation was assessed in granulosa cells from 14 matched case-control patients. Exposure status was determined by liquid chromatography-mass spectrometry (LC-MS/MS) measurements of five cannabis-derived phytocannabinoids in follicular fluid. DNA methylation was measured using the Illumina TruSeq Methyl Capture EPIC kit. Differential methylation, pathway analysis and correlation analysis were performed. We identified 3679 differentially methylated sites, with two-thirds affecting coding genes. A hotspot region on chromosome 9 was associated with two genomic features, a zinc-finger protein (ZFP37) and a long non-coding RNA (FAM225B). There were 2214 differentially methylated genomic features, 19 of which have been previously implicated in cannabis-related epigenetic modifications in other organ systems. Pathway analysis revealed enrichment in G protein-coupled receptor signaling, cellular transport, immune response and proliferation. Applying strict criteria, we identified 71 differentially methylated regions, none of which were previously annotated in this context. Finally, correlation analysis revealed 16 unique genomic features affected by cannabis use in a concentration-dependent manner. Of these, the histone methyltransferases SMYD3 and ZFP37 were hypomethylated, possibly implicating histone modifications as well. Herein, we provide the first DNA methylation profile of human granulosa cells exposed to cannabis. With cannabis increasingly legalized worldwide, further investigation into the heritability and functional consequences of these effects is critical for clinical consultation and for legalization guidelines.

Maternal obesity reverses the resistance to LPS-induced adverse pregnancy outcome and increases female offspring metabolic alterations in cannabinoid receptor 1 knockout mice

Maternal overnutrition negatively impacts the offspring's health leading to an increased risk of developing chronic diseases or metabolic syndrome in adulthood. What we eat affects the endocannabinoid system (eCS) activity, which in turn modulates lipogenesis and fatty acids utilization in hepatic, muscle, and adipose tissues. This study aimed to evaluate the transgenerational effect of maternal obesity on cannabinoid receptor 1 knock-out (CB1 KO) animals in combination with a postnatal obesogenic diet on the development of metabolic disturbances on their offspring. CB1 KO mice were fed a control diet (CD) or a high-fat diet (HFD; 33% more energy from fat) for 3 months. Offspring born to control and obese mothers were also fed with CD or HFD. We observed that pups born to an HFD-fed mother presented higher postnatal weight, lower hepatic fatty acid amide hydrolase activity, and increased blood cholesterol levels when compared to the offspring born to CD-fed mothers. When female mice born to HFD-fed CB1 KO mothers were exposed to an HFD, they gained more weight, presented elevated blood cholesterol levels, and more abdominal adipose tissue accumulation than control-fed adult offspring. The eCS is involved in several reproductive physiological processes. Interestingly, we showed that CB1 KO mice in gestational day 15 presented resistance to LPS-induced deleterious effects on pregnancy outcome, which was overcome when these mice were obese. Our results suggest that an HFD in CB1 receptor-deficient mice contributes to a "nutritional programming" of the offspring resulting in increased susceptibility to metabolic challenges both perinatally and during adulthood.

N-Acyl Dopamines Induce Apoptosis in Endometrial Stromal Cells from Patients with Endometriosis

Endometriosis is characterized by the formation and development of endometrial tissues outside the uterus, based on an imbalance between proliferation and cell death, leading to the uncontrolled growth of ectopic foci. The potential target for the regulation of these processes is the endocannabinoid system, which was found to be involved in the migration, proliferation, and survival of tumor cells. In this paper, we investigated the effect of endocannabinoid-like compounds from the N-acyl dopamine (NADA) family on the viability of stromal cells from ectopic and eutopic endometrium of patients with ovarian endometriosis. N-arachidonoyldopamine, N-docosahexaenoyldopamine, and N-oleoyldopamine have been shown to have a five-times-more-selective cytotoxic effect on endometrioid stromal cells. To study the mechanisms of the toxic effect, inhibitory analysis, measurements of caspase-3/9 activity, reactive oxygen species, and the mitochondrial membrane potential were performed. It was found that NADA induced apoptosis via an intrinsic pathway through the CB1 receptor and downstream serine palmitoyltransferase, NO synthase activation, increased ROS production, and mitochondrial dysfunction. The higher selectivity of NADA for endometriotic stromal cells and the current lack of effective drug treatment can be considered positive factors for further research of these compounds as possible therapeutic agents against endometriosis.

Metabolic Consequences of Gestational Cannabinoid Exposure

Up to 20% of pregnant women ages 18-24 consume cannabis during pregnancy. Moreover, clinical studies indicate that cannabis consumption during pregnancy leads to fetal growth restriction (FGR), which is associated with an increased risk of obesity, type II diabetes (T2D), and cardiovascular disease in the offspring. This is of great concern considering that the concentration of Δ9- tetrahydrocannabinol (Δ9-THC), a major psychoactive component of cannabis, has doubled over the last decade and can readily cross the placenta and enter fetal circulation, with the potential to negatively impact fetal development via the endocannabinoid (eCB) system. Cannabis exposure in utero could also lead to FGR via placental insufficiency. In this review, we aim to examine current pre-clinical and clinical findings on the direct effects of exposure to cannabis and its constituents on fetal development as well as indirect effects, namely placental insufficiency, on postnatal metabolic diseases.

The major endocannabinoid anandamide (AEA) induces apoptosis of human granulosa cells

The endocannabinoid system (ECS) plays a crucial role in human reproduction. Changes in anandamide (AEA) levels affect reproductive events and has already been suggested as biomarker of reproductive potential of male and female gametes. Although cannabinoid-receptor 1 (CB1) was already identified in human granulosa cells (hGCs) the ECS was not characterized on granulosa cells line COV434 nor the effects of AEA on GCs viability and function depicted. Therefore, the aim of this study was to characterize the ECS elements and explore the effects of AEA on both COV434 and hGCs. Our results revealed that hGCs express the full enzymatic machinery responsible for AEA metabolism as well as cannabinoid receptors. In addition, AEA induced a reduction in both COV434 and hGCs viability in a concentration and time-dependent manner. Nevertheless, the effects of AEA in cell viability was independent of either CB1 or CB2 receptors. There was no ROS release in both cell models; however, AEA induced morphological changes, presenting chromatin condensation at 72 h, and variation on mitochondrial membrane potential. Moreover, AEA induced an increase in caspase -3/-7 activities in both cell models, but in hGCs there was also an increase in caspase 8 activity. This study supports the idea that ECS balance is crucial for folliculogenesis and oocyte quality as dysregulated AEA levels may compromise female fertility.

The Cannabinoid Delta-9-tetrahydrocannabinol Disrupts Estrogen Signaling in Human Placenta

Cannabis consumption is increasing worldwide either for recreational or medical purposes. Its use during gestation is associated with negative pregnancy outcomes such as, intrauterine growth restriction, preterm birth, low birth weight, and increased risk of miscarriage, though the underlying molecular mechanisms are unknown. Cannabis sativa main psychoactive compound, Δ9-tetrahydrocannabinol (THC) is highly lipophilic, and as such, readily crosses the placenta. Consequently, THC may alter normal placental development and function. Here, we hypothesize alterations of placental steroidogenesis caused by THC exposure. The impact on placental estrogenic signaling was examined by studying THC effects upon the enzyme involved in estrogens production, aromatase and on estrogen receptor α (ERα), using placental explants, and the cytotrophoblast cell model BeWo. Aromatase expression was upregulated by THC, being this effect potentiated by estradiol. THC also increased ERα expression. Actions on aromatase were ERα-mediated, as were abolished by the selective ER downregulator ICI-182780 and dependent on the cannabinoid receptor CB1 activation. Furthermore, the presence of the aromatase inhibitor Exemestane did not affect THC-induced increase in ERα expression. However, THC effects on ERα levels were reversed by the antagonists of CB1 and CB2 receptors AM281 and AM630, respectively. Thus, we demonstrate major alterations in estrogen signaling caused by THC, providing new insight on how cannabis consumption leads to negative pregnancy outcomes, likely through placental endocrine alterations. Data presented in this study, together with our recently reported evidence on THC disruption of placental endocannabinoid homeostasis, represent a step forward into a deeper comprehension of the puzzling actions of THC.

Cannabis alters epigenetic integrity and endocannabinoid signalling in the human follicular niche

STUDY QUESTION

Do phytocannabinoids (PCs) affect follicular endocannabinoid signalling and the epigenome in the surrounding granulosa cells (GCs)?

SUMMARY ANSWER

Exposure to PCs increases the expression of endocannabinoid receptors and reduces DNA methylation enzyme expression and global DNA methylation in naïve GCs.

WHAT IS KNOWN ALREADY

Cannabis plant derivatives, known as PCs, are used for medicinal and recreational purposes. The main PC, tetrahydrocannabinol (THC), is the third most commonly used substance by women of childbearing age, hence knowledge of the effect it has on reproduction is of utmost importance. THC exerts its effects via receptors of the endocannabinoid system (ECS) and can interfere with folliculogenesis, oocyte development and ovulation. Endocannabinoids have been measured in follicular fluid (FF) obtained during oocyte retrieval and are implicated in controlling folliculogenesis. It has been established that in the placenta, PCs disrupt endocannabinoid homeostasis via impairment of the synthetic and degrading enzymes, leading to a net increase of endocannabinoid levels. Finally, previous studies have shown that THC alters methylation and histone modifications in sperm, brain and blood cells.

STUDY DESIGN, SIZE, DURATION

This study included an in vivo cohort assessment of cannabis exposure and its effects on the follicle and in vitro assays conducted to validate the in vivo findings and to explore possible mechanisms of action.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 318 FF samples, from 261 patients undergoing IVF treatment at a private fertility clinic who consented for biobanking biological waste material between January 2018 and July 2019, were included in this study. Concentrations of PCs and endocannabinoids were assessed in FF by liquid chromatography-mass spectrometry (LC-MS/MS). Exposure to PCs was determined based on these measured levels. Levels of both endocannabinoid receptors (CB1R, CB2R) and the de novo DNA methylating enzyme, DNMT3b, in GCs were assessed by flow cytometry both in vitro and in vivo and global DNA methylation was assessed in vitro by ELISA. In vivo effects were assessed by comparing samples positive for at least one PC, with samples negative for all measured PCs. In vitro effects were determined in naive GCs, obtained concurrently with FF samples that had tested negative for all PCs. These GCs were treated with different combinations of the main three PCs.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, 17 patients (6.4%) were positive for cannabis consumption. Furthermore, the prevalence of cannabis positivity in the FF increased from 4% of the tested samples that were collected prior to national legalisation in October 2018 to 12% of those collected following legalisation. Of note, 59% of patients who tested positive for PCs (10 of 17) reported previous or ongoing exposure to cannabis upon their initial intake. Endocannabinoid levels were not affected by the presence of PCs. CB2R was more prevalent than CB1R in GCs and its expression increased following acute and chronic in vitro exposure to PCs. The expression of DNMT3b and global methylation decreased following exposure, suggesting that cannabis may affect the epigenome in the follicular niche. The acute changes were sustained throughout chronic treatment.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Our study is limited by lack of details regarding mode, frequency and timing of PC consumption. Moreover, we were not able to adequately assess the effect of PCs on immediate or long-term clinical outcomes, due to the small sample size and the lack of follow up. Future, large-scale studies should focus on assess the clinical implications of cannabis exposure, validate our findings, and determine to what extent cannabis affects the epigenome ovarian follicle and the developing oocyte.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first study measuring PCs in FF by LC-MS/MS. We show that consuming cannabis alters the ECS in the developing follicle, and directly affects DNMT expression and global DNA methylation levels. Cannabis legalisation and use is increasing worldwide, therefore further understanding its role in female fertility and folliculogenesis is critical.

STUDY FUNDING/COMPETING INTEREST(S)

All funding was provided by CReATe Fertility Centre through the reinvestment of clinical earnings. The authors declare no competing interests.

Cannabis and Cannabinoids in Reproduction and Fertility: Where We Stand

Although cannabis use is increasing in general population, their prevalence among young adults is remarkably high. In recent years, their medical use gained a renewed interest. However, it can underline the reputation of cannabis being a harmless drug. Between cannabinoids, uniquely found on the cannabis plant, Δ⁹-tetrahydrocannabinol (THC) is the well-studied compound. It is responsible for the psychoactive effects via central cannabinoid receptors. Nevertheless, cannabinoids interact with other chemical signalling systems such as the hypothalamic-pituitary-gonadal axis. THC indirectly decreases gonadotropin-releasing hormone (GnRH) secretion by the hypothalamus. The consequences are diverse, and several key hormones are affected. THC disturbs important reproductive events like folliculogenesis, ovulation and sperm maturation and function. Although generally accepted that cannabinoid consumption impacts male and female fertility, prevailing evidence remains largely on pre-clinical studies. Here, we introduce cannabinoids and the endocannabinoid system, and we review the most prominent clinical evidence about cannabis consumption in reproductive potential and teratogenicity.

Cannabinoid Signalling in Immune-Reproductive Crosstalk during Human Pregnancy

Despite the intricate involvement of the endocannabinoid system in various physiological processes, it remains one of the most under-studied biological systems of the human body. The scope of endocannabinoid signalling is widespread, ranging from modulation of immune responses in innate and adaptive immunity to gestational processes in female physiology. Cannabinoid receptors are ubiquitously distributed in reproductive tissues and are thought to play a role in regulating the immune-reproductive interactions required for successful pregnancy, specifically among uterine natural killer cells and placental extravillous trophoblasts. The use of cannabis during pregnancy, however, can perturb endocannabinoid homeostasis through effects mediated by its major constituents, Δ-9-tetrahydrocannabinol and cannabidiol. Decidualization of the endometrium, invasion, and angiogenesis may be impaired as a consequence, leading to clinical complications such as miscarriage and preeclampsia. In this review, the crosstalk between endocannabinoid signalling in uterine natural killer cells and placental extravillous trophoblasts will be examined in healthy and complicated pregnancies. This lays a foundation for discussing the potential of targeting the endocannabinoid system for therapeutic benefit, particularly with regard to the emerging field of synthetic cannabinoids.

Impact of Endocannabinoid System Manipulation on Neurodevelopmental Processes Relevant to Schizophrenia

The neurodevelopmental hypothesis of schizophrenia has received much support from epidemiological and neuropathological studies and provides a framework to explain how early developmental abnormalities might manifest as psychosis in early adulthood. According to this theory, the onset of schizophrenia is likely the result of a complex interplay between a genetic predisposition and environmental factors whose respective influence might contribute to the etiology and progression of the disorder. The two most sensitive windows for neurodevelopment are the prenatal/perinatal and the adolescent windows, both of which are characterized by specific processes impinging upon brain structure and functionality, whose alterations may contribute to the onset of schizophrenia. An increasing number of articles suggest the involvement of the endocannabinoid system in the modulation of at least some of these processes, especially in the prenatal/perinatal window. Thus, it is not surprising that disturbing the physiological role of endocannabinoid signaling in these sensitive windows might alter the correct formation of neuronal networks, eventually predisposing to neuropsychiatric diseases later in life. We review the most recent preclinical studies that evaluated the impact of endocannabinoid system modulation in the two sensitive developmental windows on neurodevelopmental processes that possess a specific relevance to schizophrenia.

Characterization of Endocannabinoid System and Interleukin Profiles in Ovine AEC: Cannabinoid Receptors Type-1 and Type-2 as Key Effectors of Pro-Inflammatory Response

Amniotic epithelial cells (AEC) have been proposed as promising clinical candidates for regenerative medicine therapies due to their immunomodulatory capacity. In this context, the endocannabinoid system (ECS) has been identified as mediating the immune-stem cell dialogue, even if no information on AEC is available to date. Therefore, this study was designed to assess whether ECS is involved in tuning the constitutive and lipopolysaccharide (LPS)-induced ovine AEC anti-inflammatory and pro-inflammatory interleukin (IL-10, IL-4, and IL-12) profiles. Firstly, interleukins and ECS expressions were studied at different stages of gestation. Then, the role of cannabinoid receptors 1 and 2 (CB1 and CB2) on interleukin expression and release was investigated in middle stage AEC using selective agonists and antagonists. AEC displayed a degradative more than a synthetic endocannabinoid metabolism during the early and middle stages of gestation. At the middle stage, cannabinoid receptors mediated the balance between pro-inflammatory (IL-12) and anti-inflammatory (IL-4 and IL-10) interleukins. The activation of both receptors mediated an overall pro-inflammatory shift-CB1 reduced the anti-inflammatory and CB2 increased the pro-inflammatory interleukin release, particularly after LPS stimulation. Altogether, these data pave the way for the comprehension of AEC mechanisms tuning immune-modulation, crucial for the development of new AEC-based therapy protocols.

The use of cannabis and perceptions of its effect on fertility among infertility patients

STUDY QUESTION

What is the prevalence of cannabis use and the perceptions of its impact on fertility among infertility patients?

SUMMARY ANSWER

A total of 13% of infertility patients used cannabis within the last year, and current usage is associated with patient perceptions of negative effects of cannabis on fertility and pregnancy.

WHAT IS KNOWN ALREADY

Cannabis use is increasing among the general population and pregnant women, particularly in places where cannabis use is legal despite having known and potential negative effects on fertility and pregnancy.

STUDY DESIGN, SIZE, DURATION

A cross-sectional patient survey study was performed between July 2017 and September 2017. Patients attending a university-affiliated hospital-based fertility clinic (n = 290) were invited to complete a written survey. Inclusion criteria were limited to the ability to read English. There were no exclusion criteria.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Of the 290 patients approached, 270 (93%) agreed to participate. The questions covered demographics, cannabis usage, perceptions of the effect of cannabis on fertility and pregnancy, cessation of use due to infertility and personal history of disclosing cannabis use to healthcare providers (HCP).

MAIN RESULTS AND THE ROLE OF CHANCE

The results showed that 13% of respondents disclosed use of cannabis in the past year (past year users) and 38% had not used cannabis in the past year but had previously used cannabis (>1 year users) while 49% had never used cannabis (never users). Baseline demographics were similar for the three groups, but across four measures of fertility and pregnancy health, past-year users perceived less of a negative effect compared to >1 year users, and never users (P values of 0.02, 0.03, 0.01, <0.001 for questions on pregnancy, offspring health, male fertility and female fertility, respectively). Of past year users, 72% said they had or would disclose use to their HCP, but only 9.4% reported that their HCP had actually instructed them to discontinue use.

LIMITATIONS, REASONS FOR CAUTION

Self-reported patient surveys are subject to reporting bias and may not reflect actual use and perceptions.

WIDER IMPLICATIONS OF THE FINDINGS

This study suggests that cannabis use is common among infertility patients. Given the known negative impacts of cannabis on pregnancy, the authors would have expected informed infertility patients to cease cannabis use as part of their efforts to conceive. As the prevalence of cannabis use in the last year among infertility patients is similar to that in the general Canadian population, it is unclear whether the prevalence of cannabis use in the sample population merely reflects the average usage in society or, after taking into account those who reduced their usage to improve their fertility, is a factor contributing to infertility and thus prompting fertility referral. Given concern about the potential negative impact of cannabis use on fertility, and that only 9% of past year users had been instructed by an HCP to cease cannabis use, HCPs should consider the benefits of counselling about cannabis cessation for patients who are attempting to conceive. Future research should focus on analysing the effects of cannabis use on female fertility and determining whether a reduction in use among patients with infertility can improve conception rates.

STUDY FUNDING/COMPETING INTEREST(S)

Michelle Shin, Clinical Research Associate, is supported by the University of Toronto GREI Fellowship Fund, which is sponsored by unrestricted research grants from EMD Serono, Merck Canada and Ferring Pharmaceuticals. The authors have no potential conflicts of interest to disclose.

Chinese Herbal Medicine (MaZiRenWan) Improves Bowel Movement in Functional Constipation Through Down-Regulating Oleamide

In a prospective, randomized, three-arms, controlled clinical study, Chinese Herbal Medicine MaZiRenWan (MZRW, also known as Hemp Seed Pill) demonstrates comparable efficacy with Senna for functional constipation (FC) during an 8-week treatment period. Both MZRW and Senna are better than a placebo; relative to Senna and a placebo, MZRW displayed a more sustained effect during the 8-week follow-up period. The characteristic pharmacological mechanism responsible for this observation is still unclear. To explore this, we collected pre- and post-treatment serum samples of 85 FC patients from MZRW/Senna/placebo treatment groups for pharmacometabolomic analysis. An ultrahigh-performance liquid chromatography-mass spectrometer (UPLC-MS) was used for metabolic profiling and quantification. In vivo studies were conducted in constipated C57BL/6J mice to verify the effects and corresponding mechanism(s) of the action of MZRW. Pearson correlation analysis, paired t-test, one-way ANOVA analysis, χ2 test, and Student t-test were used to interpret the clinical and preclinical data. Changes in levels of circulating oleamide and its derivatives negatively correlate with improvement in complete spontaneous bowel movement (CSBM) in the MZRW group (Pearson r = -0.59, p = 0.00057). The same did not hold true for either Senna or placebo groups. Oleamide is a known regulator of intestinal motility. MZRW treatment resulted in reduced levels of circulating oleamide in FC patients. Experimental verification showed that MZRW attenuated oleamide-induced slow intestinal motility in mice. MZRW decreased oleamide levels in serum, ileum, and colon in normal mice, but increased expression of colonic fatty acid amide hydrolase (FAAH). In conclusion, MZRW improved bowel movement in FC by down-regulating oleamide, possibly by enhancing FAAH-mediated degradation. Our findings suggest a novel therapeutic strategy for FC.

The (endo)cannabinoid signaling in female reproduction: What are the latest advances?

Cannabis extracts like marijuana have the highest consumption rate worldwide. Yet, their societal acceptance as recreational and therapeutic drugs could represent a serious hazard to female human reproduction, because cannabis ingredients [termed (phyto)cannabinoids] can perturb an endogenous system of lipid signals known as endocannabinoids. Accumulated evidence on animal models and humans has demonstrated a crucial role of these endogenous signals on different aspects of female reproduction, where they act through an ensamble of proteins that synthesize, transport, degrade and traffic them. Several reports have recently evidenced the potential role of endocannabinoids as biomarkers of female infertility for disease treatment and prevention, as well as their possible epigenetic effects on pregnancy. The purpose of this review is to provide an update of data collected in the last decade on the effects of cannabinoids and endocannabinoids on female reproductive events, from development and maturation of follicles and oocytes, to fertilization, oviductal transport, implantation and labor. In this context, a particular attention has been devoted to the ovary and the production of fertilizable oocytes, because recent studies have addressed this hot topic with conflicting results among species.

Synthetic cannabinoids JWH-018, JWH-122, UR-144 and the phytocannabinoid THC activate apoptosis in placental cells

The increasing use of synthetic cannabinoids (SCBs) in recreational settings is becoming a new paradigm of drug abuse. Although SCBs effects mimic those of the Cannabis sativa plant, these drugs are frequently more potent and hazardous. It is known that endocannabinoid signalling plays a crucial role in diverse reproductive events such as placental development. Moreover, the negative impact of the phytocannabinoid Δ⁹-tetrahydrocannabinol (THC) in pregnancy outcome, leading to prematurity, intrauterine growth restriction and low birth weight is well recognized, which makes women of childbearing age a sensitive group to developmental adverse effects of cannabinoids. Placental trophoblast turnover relies on regulated processes of proliferation and apoptosis for normal placental development. Here, we explored the impact of the SCBs JWH-018, JWH-122 and UR-144 and of the phytocannabinoid THC in BeWo cell line, a human placental cytotrophoblast cell model. All the cannabinoids caused a significant decrease in cell viability without LDH release, though this effect was only detected for the highest concentrations of THC. Moreover, a cell cycle arrest at the G₂/M phase was also observed. JWH-018 and JWH-122 increased reactive oxygen species (ROS) production and THC, UR-144 and JWH-122 caused loss of mitochondrial membrane potential. All the compounds were able to induce caspase-9 activation. The involvement of apoptotic pathways was further confirmed through the significant increase in caspase -3/-7 activities. For UR-144, this effect was reversed by the CB1 antagonist AM281, for JWH-018 and THC this effect was mediated by both cannabinoid receptors CB1 and CB2 while for JWH-122 it was cannabinoid receptor-independent. This work demonstrates that THC and SCBs are able to induce apoptotic cell death. Although they may act through different mechanisms and potencies, the studied cannabinoids have the potential to disrupt gestational fundamental events.

Anandamide targets aromatase: A breakthrough on human decidualization

In each menstrual cycle endometrial stromal cells (hESC) proliferate and differentiate into specialized decidual cells, a process termed decidualization, which regulates endometrial receptivity. Decidualization is mainly controlled by sex ovarian hormones, estradiol (E₂) and progesterone. E₂ plays an important role in the expression of the progesterone receptor and promotes the endometrial stromal cells differentiation. Our group previously reported that anandamide (AEA) impairs decidualization through cannabinoid receptor 1 (CB1). In this study, we hypothesized whether AEA inhibitory effect on cell decidualization could be mediated through interaction with aromatase and consequent interference in estradiol production/signaling. We used an immortalized human endometrial stromal cell line (St-T1b) and human decidual fibroblasts (HdF) derived from human term placenta. In cells exposed to a differentiation stimulus, AEA-treatment prevents the increase of the expression of CYP19A1 gene encoding aromatase, E₂ levels and of estradiol receptor expression, that are observed in differentiating cells. Regarding CYP19A1 mRNA levels, the effect was partially reverted by a CB1 receptor antagonist and by a COX2 inhibitor. In addition, we report that AEA presents anti-aromatase activity in placental microsomes, the nature of the inhibition being the uncommon mixed type as revealed by the kinetic studies. Structural analysis of the AEA-Aromatase complexes determined that AEA may bind to the active site pocket of the enzyme. In overall we report that AEA inhibits aromatase activity and may affect E₂ signaling crucial for the decidualization process, indicating that a deregulation of the endocannabinoid system may be implicated in endometrial dysfunction and in fertility/infertility disorders.

Effects of cannabis tetrahydrocannabinol on endocannabinoid homeostasis in human placenta

Cannabis use has become a hot topic in several countries due to the debate about its legalization for medical purposes. However, data are limited regarding adverse events, safety and potential impact on reproductive health. Cannabis consumption during pregnancy has been associated with gestational disorders such as preterm birth, intrauterine growth restriction, low birth weight and increased risk of miscarriage, though the underlying biochemical mechanisms are still unknown. Given that the endocannabinoid system (ECS) is involved in several reproductive processes, we tested the hypothesis that the negative outcomes may result from the impact on the ECS homeostasis caused by the main psychoactive compound of cannabis, Δ⁹-tetrahydrocannabinol (THC). We demonstrate that THC (10-40 µM) impairs placental endocannabinoid system by disrupting the endocannabinoid anandamide (AEA) levels and the expression of AEA synthetic and degrading enzymes N-arachidonoylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH), respectively. Although, no alterations in cannabinoid receptors CB1 and CB2 expression were observed. Thus, long-term local AEA levels are associated with a shift in the enzymatic profile to re-establish ECS homeostasis. In chronic cannabis users, high AEA levels in placenta may disturb the delicate balance of trophoblast cells turnover leading to alterations in normal placental development and foetal growth.

Current model systems for the study of preeclampsia

Preeclampsia (PE) is a pregnancy complex disease, distinguished by high blood pressure and proteinuria, diagnosed after the 20th gestation week. Depending on the values of blood pressure, urine protein concentrations, symptomatology, and onset of disease there is a wide range of phenotypes, from mild forms developing predominantly at the end of pregnancy to severe forms developing in the early stage of pregnancy. In the worst cases severe forms of PE could lead to systemic endothelial dysfunction, eclampsia, and maternal and/or fetal death. Worldwide the fetal morbidity and mortality related to PE is calculated to be around 8% of the total pregnancies. PE still being an enigma regarding its etiology and pathophysiology, in general a deficient trophoblast invasion during placentation at first stage of pregnancy, in combination with maternal conditions are accepted as a cause of endothelial dysfunction, inflammatory alterations and appearance of symptoms. Depending on the PE multifactorial origin, several in vitro, in vivo, and in silico models have been used to evaluate the PE pathophysiology as well as to identify or test biomarkers predicting, diagnosing or prognosing the syndrome. This review focuses on the most common models used for the study of PE, including those related to placental development, abnormal trophoblast invasion, uteroplacental ischemia, angiogenesis, oxygen deregulation, and immune response to maternal-fetal interactions. The advances in mathematical and computational modeling of metabolic network behavior, gene prioritization, the protein-protein interaction network, the genetics of PE, and the PE prediction/classification are discussed. Finally, the potential of these models to enable understanding of PE pathogenesis and to evaluate new preventative and therapeutic approaches in the management of PE are also highlighted. Impact statement This review is important to the field of preeclampsia (PE), because it provides a description of the principal in vitro, in vivo, and in silico models developed for the study of its principal aspects, and to test emerging therapies or biomarkers predicting the syndrome before their evaluation in clinical trials. Despite the current advance, the field still lacking of new methods and original modeling approaches that leads to new knowledge about pathophysiology. The part of in silico models described in this review has not been considered in the previous reports.

The endocannabinoid system expression in the female reproductive tract is modulated by estrogen

The endocannabinoid system (ECS) is involved in several physiological events that resulted in a growing interest in its modulation. Moreover, the uterine levels of anandamide (AEA), the major endocannabinoid, must be tightly regulated to create proper embryo implantation conditions. However, there are no evidences about the regulation of AEA in uterus by estrogen. Thus, the aim of this study is to elucidate whether estradiol benzoate (EB) and tamoxifen (TAM) administration to ovariectomized (OVX) rats can induce changes in the expression of cannabinoid receptors and AEA-metabolic enzymes in uterus by evaluating gene transcription and protein levels by qPCR, Western blot and immunohistochemistry. Moreover, the plasmatic and uterine levels of AEA and of prostaglandin E₂ (PGE₂) and prostaglandin F₂α (PGF_2α), the major cyclooxygenase-2 (COX-2) products, were determined by UPLC-MS/MS. The immunohistochemistry showed that cannabinoid receptors, as well as AEA-metabolic enzymes are mainly located in the epithelial cells of both lumen and glands and, to a lesser extent, in the muscle cells. Moreover, EB administration to OVX rats significantly increased CB1, CB2, NAPE-PLD, FAAH and COX-2 expression and transcription. These effects were absent in TAM and TAM+EB treatments showing that this response is estrogen receptor dependent. Additionally, although uterine levels of AEA remained unchanged in EB or TAM treated animals, they showed a rise with EB treatment in plasma. The latter also produced a decrease in uterine PGE₂ levels. In summary, these data collectively indicate that the expression of ECS components, as well as, the AEA and PGE₂ levels in rat uterus is modulated by EB. Thus, estradiol may have a direct regulatory role in the modulation of ECS in female reproductive tissues.

Endocannabinoid system and pregnancy

The endocannabinoid system (eCS), is a complex system, comprising the main endogenous ligands anandamide and 2-arachidonoyl glycerol, the cannabinoid receptors CB1 and CB2 and the biosynthetic and degrading enzymes. Cumulative evidence shows that the eCS plays an important role in reproduction, from egg fertilization to parturition. Therefore, alterations in this system, either by recreation/therapeutic use of cannabis or deregulation of the endogenous cannabinoids, might lead to adverse pregnancy outcomes, including retardation in embryo development, poor blastocyst implantation, inhibition of decidualization, miscarriage and compromised placentation. Nevertheless, the molecular mechanisms by which the eCS participates in different stages of pregnancy remain poorly understood. In this review, we will examine the evidence from animal and human studies to support the role of the eCS in implantation, early-to-late pregnancy and placentation as well as the difficulties of targeting this system for treatment of female infertility.

Marijuana, the Endocannabinoid System and the Female Reproductive System

Marijuana use among women is highly prevalent, but the societal conversation on marijuana rarely focuses on how marijuana affects female reproduction and endocrinology. This article reviews the current scientific literature regarding marijuana use and hypothalamic-pituitary-ovarian (HPO) axis regulation, ovarian hormone production, the menstrual cycle, and fertility. Evidence suggests that marijuana can reduce female fertility by disrupting hypothalamic release of gonadotropin releasing hormone (GnRH), leading to reduced estrogen and progesterone production and anovulatory menstrual cycles. Tolerance to these effects has been shown in rhesus monkeys, but the effects of chronic marijuana use on human female reproduction are largely unknown. Marijuana-induced analgesia, drug reinforcement properties, tolerance, and dependence are influenced by ovarian hormones, with estrogen generally increasing and progesterone decreasing sensitivity to marijuana. Carefully controlled regulation of the Endocannabinoid System (ECS) is required for successful reproduction, and the exogenous cannabinoids in marijuana may disrupt the delicate balance of the ECS in the female reproductive system.

A role for GPR55 in human placental venous endothelial cells

Endocannabinoids and their G protein-coupled receptors have been suggested to play a key role in human pregnancy, by regulating important aspects such as implantation, decidualization, placentation and labor. G protein-coupled receptor 55 (GPR55) was previously postulated to be another cannabinoid receptor, since specific cannabinoids were shown to act independently of the classical cannabinoid receptors CB1 or CB2. Current knowledge about GPR55 expression and function in human placenta is very limited and motivated us to evaluate human placental GPR55 expression in relation to other human peripheral tissues and to analyze spatiotemporal GPR55 expression in human placenta. Gene expression analysis revealed low GPR55 levels in human placenta, when compared to spleen and lung, the organs showing highest GPR55 expression. Moreover, expression analysis showed 5.8 fold increased placental GPR55 expression at term compared to first trimester. Immunohistochemistry located GPR55 solely at the fetal endothelium of first trimester and term placentas. qPCR and immunocytochemistry consistently confirmed GPR55 expression in isolated primary placental arterial and venous endothelial cells. Incubation with L-α-lysophosphatidylinositol (LPI), the specific and functional ligand for GPR55, at a concentration of 1 µM, significantly enhanced migration of venous, but not arterial endothelial cells. LPI-enhanced migration was inhibited by the GPR55 antagonist O-1918, suggesting a role of the LPI-GPR55 axis in placental venous endothelium function.

Decreased circulating anandamide levels in preeclampsia

The endocannabinoid system has a key role in female reproduction, including implantation, decidualization and placentation. A growing number of studies indicate that placental and peripheral blood anandamide levels correlate closely with both spontaneous miscarriage and ectopic pregnancy. Anandamide has also been implicated in blood pressure regulation. In this study, we aimed to determine circulating anandamide levels in preeclampsia for the first time in the literature. Forty-three preeclamptic patients and 71 healthy pregnant women were involved in this case-control study. Serum anandamide concentrations were determined by high-performance liquid chromatography-mass spectrometry technique. Serum total soluble fms-like tyrosine kinase-1 (sFlt-1) and biologically active placental growth factor (PlGF) levels were measured by electrochemiluminescence immunoassay. For statistical analyses, nonparametric methods were applied. Serum levels of anandamide were significantly lower in preeclamptic patients than in healthy pregnant women (0.75 (0.44-1.03) ng ml(-1) vs. 1.30 (0.76-2.0) ng ml(-1), P<0.001). Preeclamptic patients had significantly higher sFlt-1 levels (12,121 (7963-18,316) pg ml(-1) vs. 2299 (1393-3179) pg ml(-1), P<0.001) and significantly lower PlGF concentrations (71.2 (39.2-86.4) pg ml(-1) vs. 256.8 (181.1-421.0) pg ml(-1), P<0.001) as compared with healthy pregnant women. Serum anandamide concentrations did not correlate with serum levels of sFlt-1 and PlGF in our healthy pregnant and preeclamptic groups. In conclusion, we demonstrated for the first time in the literature that serum anandamide concentrations are decreased in women with preeclampsia. However, the cause and consequence of this observation remain to be determined.

2-Arachidonoylglycerol impairs human cytotrophoblast cells syncytialization: influence of endocannabinoid signalling in placental development

A balanced cytotrophoblast cell turnover is crucial for placental development and anomalies in this process associated with gestational diseases. The endocannabinoid system (ECS) has emerged as a new player in several biological processes. However, its influence during placental development is still unknown. We report here the expression of the endocannabinoid 2-arachidonoylglycerol (2-AG) main metabolic enzymes in human cytotrophoblasts and syncytiotrophoblast. We also showed that 2-AG induced a decrease in placental alkaline phosphatase activity, human chorionic gonadotropin secretion and Leptin mRNA levels. Moreover, 2-AG reduced glial cell missing 1 and syncytin-2 transcription and the number of nuclei in syncytium. These effects were mediated by cannabinoid receptors and may result from 2-AG inhibition of the cAMP/PKA signalling pathway. Our data suggest that 2-AG may interfere with the biochemical and morphological differentiation of human cytotrophoblasts, through a CB receptor-dependent mechanism, shedding light on a role for the ECS in placental development.

Endocannabinoids and Reproductive Events in Health and Disease

The lasting research on the endocannabinoid system (ECS) has now provided solid and convincing evidence that proves the detrimental effects of recreational drug abuse (a growing habit among teenagers) on fertility. Endocannabinoids (eCBs) affect reproductive events from gametogenesis to fertilization, from embryo implantation to the final outcome of pregnancy and, thus, they have been proposed as suitable biomarkers to predict the reproductive potential of male and female gametes in clinical practice. Novel tools for reproductive medicine are highly sought after, and here we report the latest findings on the impact of the ECS on fertility, demonstrating how basic research can be translated into new medical strategies.

Increased placental expression of cannabinoid receptor 1 in preeclampsia: an observational study

BACKGROUND

The endocannabinoid system plays a key role in female reproduction, including implantation, decidualization and placentation. In the present study, we aimed to analyze cannabinoid receptor 1 (CB1), CB2 and fatty acid amid hydrolase (FAAH) expressions and localization in normal and preeclamptic placenta, in order to determine whether placental endocannabinoid expression pattern differs between normal pregnancy and preeclampsia.

METHODS

Eighteen preeclamptic patients and 18 normotensive, healthy pregnant women with uncomplicated pregnancies were involved in our case-control study. We determined CB1, CB2 and FAAH expressions by Western blotting and immunohistochemistry in placental samples collected directly after Cesarean section.

RESULTS

CB1 expression semi-quantified by Western blotting was significantly higher in preeclamptic placenta, and these findings were confirmed by immunohistochemistry. CB1 immunoreactivity was markedly stronger in syncytiotrophoblasts, the mesenchymal core, decidua, villous capillary endothelial and smooth muscle cells, as well as in the amnion in preeclamptic samples compared to normal pregnancies. However, we did not find significant differences between preeclamptic and normal placenta in terms of CB2 and FAAH expressions and immunoreactivity.

CONCLUSIONS

We observed markedly higher expression of CB1 protein in preeclamptic placental tissue. Increased CB1 expression might cause abnormal decidualization and impair trophoblast invasion, thus being involved in the pathogenesis of preeclampsia. Nevertheless, we did not find significant differences between preeclamptic and normal placental tissue regarding CB2 and FAAH expressions. While the detailed pathogenesis of preeclampsia is still unclear, the endocannabinoid system could play a role in the development of the disease.

It's not your mother's marijuana: effects on maternal-fetal health and the developing child

Pro-marijuana advocacy efforts exemplified by the "medical" marijuana movement, coupled with the absence of conspicuous public health messages about the potential dangers of marijuana use during pregnancy, could lead to greater use of today's more potent marijuana, which could have significant short- and long-term consequences. This article reviews the current literature regarding the effects of prenatal marijuana use on the pregnant woman and her offspring.

The endocannabinoid anandamide induces apoptosis in cytotrophoblast cells: involvement of both mitochondrial and death receptor pathways

INTRODUCTION

A balanced proliferation, apoptosis and differentiation in trophoblast cells of the human placenta is crucial for a proper placental development. Alteration in trophoblast apoptosis and differentiation are associated with gestational-related complications, such as preeclampsia, intrauterine growth restriction or miscarriages. The endocannabinoids (eCBs) have been recognized as new interveners in pregnancy events such as implantation and decidualization. However, their importance in placentation is poorly understood. We hypothesise that these novel lipid mediators may intervene in cytotrophoblast apoptosis and, concomitantly, have a role during placental development.

METHODS

primary human cytotrophoblasts (hCTs) and the human trophoblast-like choriocarcinoma cell line BeWo cells were exposed to Anandamide (AEA). It was investigated the cellular pathways involved in cell death, by the assessment of cell morphology, caspases activity, mitochondrial membrane potential (Δψm), reactive oxygen/nitrogen species (ROS/RNS) and western blot of cleaved Poly (ADP-ribose) polymerase 1 (PARP-1), truncated Bid (t-Bid) and IκB-α.

RESULTS

AEA decreased hCTs viability and induced morphological features of apoptosis (chromatin condensation and fragmentation), caspase-3/7 activation and PARP-1 cleavage. In BeWo, AEA also increased the activities of caspase-3/7 and 9, induced loss in Δψm and production of ROS/RNS. These effects were reversed by either CB1 or CB2 antagonists, whereas the increase in caspase-3/7 activity was only reversed with CB2 blockage. AEA-treated cells showed increased caspase-8 activation and formation of t-Bid, suggesting the interplay between intrinsic and extrinsic apoptotic pathways. AEA also increased IκB-α expression, a NF-κB regulatory protein.

CONCLUSION

Our results highlight the importance of eCBs in cytotrophoblast cell apoptosis and indicate that a crosstalk between intrinsic and extrinsic apoptotic pathways is involved in AEA-induced effects.

Increased angiotensin II contraction of the uterine artery at early gestation in a transgenic model of hypertensive pregnancy is reduced by inhibition of endocannabinoid hydrolysis

Increased vascular sensitivity to angiotensin II (Ang II) is a marker of a hypertensive human pregnancy. Recent evidence of interactions between the renin-angiotensin system and the endocannabinoid system suggests that anandamide and 2-arachidonoylglycerol may modulate Ang II contraction. We hypothesized that these interactions may contribute to the enhanced vascular responses in hypertensive pregnancy. We studied Ang II contraction in isolated uterine artery (UA) at early gestation in a rat model that mimics many features of preeclampsia, the transgenic human angiotensinogen×human renin (TgA), and control Sprague-Dawley rats. We determined the role of the cannabinoid receptor 1 by blockade with SR171416A, and the contribution of anandamide and 2-arachidonoylglycerol degradation to Ang II contraction by inhibiting their hydrolyzing enzyme fatty acid amide hydrolase (with URB597) or monoacylglycerol lipase (with JZL184), respectively. TgA UA showed increased maximal contraction and sensitivity to Ang II that was inhibited by indomethacin. Fatty acid amide hydrolase blockade decreased Ang IIMAX in Sprague-Dawley UA, and decreased both Ang IIMAX and sensitivity in TgA UA. Monoacylglycerol lipase blockade had no effect on Sprague-Dawley UA and decreased Ang IIMAX and sensitivity in TgA UA. Blockade of the cannabinoid receptor 1 in TgA UA had no effect. Immunolocalization of fatty acid amide hydrolase and monoacylglycerol lipase showed a similar pattern between groups; fatty acid amide hydrolase predominantly localized in endothelium and monoacylglycerol lipase in smooth muscle cells. We demonstrated an increased Ang II contraction in TgA UA before initiation of the hypertensive phenotype. Anandamide and 2-arachidonoylglycerol reduced Ang II contraction in a cannabinoid receptor 1-independent manner. These renin-angiotensin system-endocannabinoid system interactions may contribute to the enhanced vascular reactivity in early stages of hypertensive pregnancy.