The role of endocannabinoids in the regulation of luteinizing hormone and prolactin release. Differences between the effects of AEA and 2AG

Effective suppression of Ih and INa caused by capsazepine, known to be a blocker of TRPV1 receptor

A synthetic inhibitor of capsaicin-induced TRPV1 channel activation is called capsazepine (CPZ). In this study, we aimed to explore the effects of CPZ on hyperpolarization-activated cationic current (Ih) and voltage-gated Na + current (INa) in pituitary tumor (GH3) cells. Through patch-clamp recordings, we found that CPZ concentration-dependently inhibited Ih amplitude and slowed its activation time course. The IC50 and KD values were 3.1 and 3.16 μM, respectively. CPZ also shifted the steady-state activation curve of Ih towards a more hyperpolarized potential. However, there was no change in the gating charge of the curve. A modified Markovian model predicted the CPZ-induced decrease in the voltage-dependent hysteresis of Ih. CPZ suppressed INa in GH3 cells, without altering its activation or inactivation time course. Additionally, exposure to CPZ reduced spontaneous firing. These findings suggest that CPZ's inhibitory effects on Ih and INa are direct and not dependent on vanilloid receptor binding. This could provide light on an unidentified ionic mechanism influencing the membrane excitability of neurons and endocrine or neuroendocrine cells in vivo.

Hormetic effects of a cannabinoid system component, 2-arachidonoyl glycerol, on cell viability and expression profile of growth factors in cultured mouse Sertoli cells: Friend or foe of male fertility?

The generally undesired effects of exocannabinoids on male reproduction include alterations in testicular cell proliferation and function, as well as apoptosis induction. However, this paradigm has been challenged by the ability of endocannabinoids to regulate reproductive function. The present study addresses these paradoxical facts by investigating the effects of the endocannabinoid 2-arachidonoyl glycerol (2-AG) on mouse Sertoli cells' survival and apoptosis, with a mechanistic insight into Sertoli cell-based growth factors' production. The Mus musculus Sertoli cell line (TM4) was exposed to different concentrations of 2-AG, and cell viability was evaluated using MTT assay. Growth factors' gene and protein expressions were analyzed through RT-PCR and western blotting. 2-AG concentration dependently increased TM4 viability, with a slight increase starting at 0.0001 µM, a peak of 190% of the control level at 1 µM, and a decrease at 3 µM. Moreover, 2-AG paradoxically altered mRNA expression of caspase-3 and growth factors. Caspase-3 mRNA expression was down-regulated, and growth factors mRNA and protein expression were up-regulated when using a low concentration of 2-AG (1 μM). Opposite effects were observed by a higher concentration of 2-AG (3 μM). These paradoxical effects of 2-AG can be explained through the concept of hormesis. The results indicate the pivotal role of 2-AG in mediating Sertoli cell viability and apoptosis, at least in part, through altering growth factors secretion. Furthermore, they suggest the involvement of endocannabinoids in Sertoli cell-based physiological and pathological conditions and reflect the ability of abnormally elevated 2-AG to mimic the actions of exocannabinoids in reproductive dysfunction.

Diverse role of endocannabinoid system in mammalian male reproduction

Endocannabinoid system (ECS) is known for its modulatory role in numerous physiological processes in the body. Endocannabinoids (eCBs) are endogenous lipid molecules which function both centrally and peripherally. The ECS is best studied in the central nervous system (CNS), immune system as well as in the metabolic system. The role of ECS in male reproductive system is emerging and the presence of a complete enzymatic machinery to synthesize and metabolize eCBs has been demonstrated in male reproductive tract. Endocannabinoid concentrations and alterations in their levels have been reported to affect the functioning of spermatozoa. A dysfunctional ECS has also been linked to the development of prostate cancer, the leading cause of cancer related mortality among male population. This review is an attempt to provide an insight into the significant role of endocannabinoids in male reproduction and further summarize recent findings that demonstrate the manner in which the endocannabinoid system impacts male sexual behavior and fertility.

The Impact of Controlled Ovarian Stimulation Hormones on the Metabolic State and Endocannabinoid System of Human Cumulus Cells

Different Follicle Stimulating Hormone (FSH) formulation and Luteinizing Hormone (LH) are used in Assisted Reproductive Technology (ART) to induce follicles development and oocytes maturation, but it is still under debate which protocol is to be preferred. In the present study, the different effects on cumulus cells (CCs) of three controlled ovarian stimulation (COS) protocols, based on urinary FSH, recombinant FSH, or human Menopausal Gonadotropin (hMG) administration, were assessed. CCs were obtained from 42 normal-responders women undergoing COS, randomly divided into three groups according to the used gonadotropin formulation. Differences were found in the expression of genes belonging to the endocannabinoid system (the receptors CNR1, CNR2 and TRPV1, and the enzymes involved in the metabolisms of anandamide, NAPE-PLD and FAAH, and 2-acylglycerol, DAGL and MAGL); consistently, changes in lipid (PPARα, and FASN) and carbohydrate (GLUT1 and GLUT9) metabolisms, in CCs’ macromolecules composition (highlighted by Fourier Transform Infrared Microspectroscopy, FTIRM), and in the number of retrieved oocytes were found. For the first time, statistically significant evidence on the differences related to each COS protocol on the endocannabinoid system, metabolism and macromolecular composition of CCs was found, representing a proof of concept to be further confirmed in a larger cohort of patients.

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.

Artificial Neural Network to Predict Varicocele Impact on Male Fertility through Testicular Endocannabinoid Gene Expression Profiles

The relationship between varicocele and fertility has always been a matter of debate because of the absence of predictive clinical indicators or molecular markers able to define the severity of this disease. Even though accumulated evidence demonstrated that the endocannabinoid system (ECS) plays a central role in male reproductive biology, particularly in the testicular compartment, to date no data point to a role for ECS in the etiopathogenesis of varicocele. Therefore, the present research has been designed to investigate the relationship between testicular ECS gene expression and fertility, using a validated animal model of experimental varicocele (VAR), taking advantage of traditional statistical approaches and artificial neural network (ANN). Experimental induction of VAR led to a clear reduction of spermatogenesis in left testes ranging from a mild (Johnsen score 7: 21%) to a severe (Johnsen score 4: 58%) damage of the germinal epithelium. However, the mean number of new-borns recorded after two sequential matings was quite variable and independent of the Johnsen score. While the gene expression of biosynthetic and degrading enzymes of AEA (NAPE-PLD and FAAH, respectively) and of 2-AG (DAGLα and MAGL, respectively), as well as their binding cannabinoid receptors (CB1 and CB2), did not change between testes and among groups, a significant downregulation of vanilloid (TRPV1) expression was recorded in left testes of VAR rats and positively correlated with animal fertility. Interestingly, an ANN trained by inserting the left and right testicular ECS gene expression profiles (inputs) was able to predict varicocele impact on male fertility in terms of mean number of new-borns delivered (outputs), with a very high accuracy (average prediction error of 1%). The present study provides unprecedented information on testicular ECS gene expression patterns during varicocele, by developing a freely available predictive ANN model that may open new perspectives in the diagnosis of varicocele-associated infertility.

Dysregulated peripheral endocannabinoid system signaling is associated with cognitive deficits in first-episode psychosis

Among etiological explanations for psychosis, several hypotheses involving alterations on the immune/inflammatory system have been proposed. The endocannabinoid system (ECS) is an endogenous neuroprotective, anti-inflammatory system that modulates cognitive processes. Its altered expression has been associated with psychotic disorders. 73 patients with a first episode of psychoses (FEP) and 67 healthy controls were recruited in 5 university centers in Spain. The protein expression of the main peripheral ECS components was determined in peripheral blood mononuclear cells. The cognition function was assessed following the MATRICS consensus. After controlling for potential confounding factors, working memory statistically correlated to the peripheral N-acyl phosphatidylethanolamine phospholipase expression (p = 0.039). The short-term verbal memory correlated to the Diacylglycerol lipase (p = 0.043) and the fatty acid amide hydrolase (p = 0.026) expression. Finally, attention measures correlated to the Monoacylglycerol lipase expression, by means of the CPT-II commissions (p = 0.036) and detectability (p = 0.026) scores. The ECS may regulate the activation of key mediators in immune and inflammatory responses that may be involved in the primary neuronal stress phenomenon that occurs from the onset of psychotic illness. This study points a relationship between the ECS and the cognitive function in early psychosis and suggests the use of some of the ECS elements as biomarkers and/or pharmacological targets for FEP.

Marijuana, phytocannabinoids, the endocannabinoid system, and male fertility

Marijuana has the highest consumption rate among all of the illicit drugs used in the USA, and its popularity as both a recreational and medicinal drug is increasing especially among men of reproductive age. Male factor infertility is on the increase, and the exposure to the cannabinoid compounds released by marijuana could be a contributing cause. The endocannabinoid system (ECS) is deeply involved in the complex regulation of male reproduction through the endogenous release of endocannabinoids and binding to cannabinoid receptors. Disturbing the delicate balance of the ECS due to marijuana use can negatively impact reproductive potential. Various in vivo and in vitro studies have reported on the empirical role that marijuana plays in disrupting the hypothalamus-pituitary-gonadal axis, spermatogenesis, and sperm function such as motility, capacitation, and the acrosome reaction. In this review, we highlight the latest evidence regarding the effect of marijuana use on male fertility and also provide a detailed insight into the ECS and its significance in the male reproductive system.

Intra-testicular signals regulate germ cell progression and production of qualitatively mature spermatozoa in vertebrates

Spermatogenesis, a highly conserved process in vertebrates, is mainly under the hypothalamic-pituitary control, being regulated by the secretion of pituitary gonadotropins, follicle stimulating hormone, and luteinizing hormone, in response to stimulation exerted by gonadotropin releasing hormone from hypothalamic neurons. At testicular level, gonadotropins bind specific receptors located on the somatic cells regulating the production of steroids and factors necessary to ensure a correct spermatogenesis. Indeed, besides the endocrine route, a complex network of cell-to-cell communications regulates germ cell progression, and a combination of endocrine and intra-gonadal signals sustains the production of high quality mature spermatozoa. In this review, we focus on the recent advances in the area of the intra-gonadal signals supporting sperm development.

Updates in reproduction coming from the endocannabinoid system

The endocannabinoid system (ECS) is an evolutionarily conserved master system deeply involved in the central and local control of reproductive functions in both sexes. The tone of these lipid mediators-deeply modulated by the activity of biosynthetic and hydrolyzing machineries-regulates reproductive functions from gonadotropin discharge and steroid biosynthesis to the formation of high quality gametes and successful pregnancy. This review provides an overview on ECS and reproduction and focuses on the insights in the regulation of endocannabinoid production by steroids, in the regulation of male reproductive activity, and in placentation and parturition. Taken all together, evidences emerge that the activity of the ECS is crucial for procreation and may represent a target for the therapeutic exploitation of infertility.

Expression of the cannabinoid receptor type 1 in the pituitary of rabbits and its role in the control of LH secretion

The aim of this study was to elucidate the possible direct regulatory role of the endocannabinoids in the modulation of LH secretion in rabbits, a reflex ovulator species. The cannabinoid receptor type 1 (CB1) was characterized by RT-PCR techniques in the anterior pituitary of intact and ovariectomized does treated with GnRH and primed with estrogen and CB1 antagonist, rimonabant. Cannabinoid receptor type 1 immune reaction was evidenced by immunohistochemistry in the cytoplasm of approximately 10% of the pituitary cells with a density of 8.5 ± 1.9 (per 0.01 mm(2)), both periodic acid-Schiff positive (30%) and negative (70%). All CB1-immunoreactive cells were also immune reactive for estrogen receptor type 1. Ovariectomy, either alone or combined with estrogen priming, did not modify the relative abundances of pituitary CB1 mRNA, but decreased (P < 0.01) the expression of estrogen receptor type 1 mRNA. Treatment with CB1 antagonist (rimonabant) inhibited (P < 0.01) LH secretory capacity by the pituitary after GnRH injection, and estrogen priming had no effect. The present findings indicate that the endocannabinoid system is a potential candidate for the regulation of the hypothalamic-pituitary-ovarian axis in reflex ovulatory species.

The role of endocannabinoids in gonadal function and fertility along the evolutionary axis

Endocannabinoids are natural lipids able to bind to cannabinoid and vanilloid receptors. Their biological actions at the central and peripheral level are under the tight control of the proteins responsible for their synthesis, transport and degradation. In the last few years, several reports have pointed out these lipid mediators as critical signals, together with sex hormones and cytokines, in various aspects of animal and human reproduction. The identification of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in reproductive cells and tissues of invertebrates, vertebrates and mammals highlights the key role played by these endogenous compounds along the evolutionary axis. Here, we review the main actions of endocannabinoids on female and male reproductive events, and discuss the interplay between them, steroid hormones and cytokines in regulating fertility. In addition, we discuss the involvement of endocannabinoid signalling in ensuring a correct chromatin remodeling, and hence a good DNA quality, in sperm cells.

The hypophysial pars tuberalis transduces photoperiodic signals via multiple pathways and messenger molecules

Located between the median eminence, the portal vessels, and the pars distalis (PD) of the hypophysis, the hypophysial pars tuberalis (PT) is an important center for transmission of photoperiodic information to neuroendocrine circuits involved in the control of reproduction, metabolism and behavior. Despite enormous and long lasting efforts, output pathways and messenger molecules from the PT have been unraveled only recently. Most interestingly, the PT sends its signals in two directions: via a "retrograde" pathway to the hypothalamus and via an "anterograde" pathway to the PD. TSH has been identified as a messenger of the "retrograde" pathway. As discovered in Japanese quail, TSH triggers molecular cascades mediating thyroid hormone conversion in the mediobasal hypothalamus (MBH) to activate the gonadal axis. These molecular mechanisms are conserved in photoperiodic mammals, and even in non-photoperiodic laboratory mice. The search for molecules of the "anterograde" pathway was for a long time focused on PT-specific neuropeptides, the so-called "tuberalins". The discovery of a PT-intrinsic endocannabinoid system in hamsters which is regulated by the photoperiod provides strong experimental evidence that the PT also synthesizes lipidergic messengers. To date, 2-arachidonoylglycerol (2-AG) appears as the most important lipidergic messenger from the PT. The primary target of 2-AG, the cannabinoid receptor 1 (CB1) is expressed in the hamster PD. A PT-intrinsic endocannabinoid system also exists in man and CB1 receptors are demonstrated in ACTH-producing cells and folliculo-stellate cells of the human PD. These data lend support to the hypothesis that endocannabinoids function as messengers of the anterograde pathway.

Retrograde endocannabinoid signaling reduces GABAergic synaptic transmission to gonadotropin-releasing hormone neurons

Cannabinoids suppress fertility via reducing hypothalamic GnRH output. γ-Aminobutyric acid (GABA)(A) receptor (GABA(A)-R)-mediated transmission is a major input to GnRH cells that can be excitatory. We hypothesized that cannabinoids act via inhibiting GABAergic input. We performed loose-patch electrophysiological studies of acute slices from adult male GnRH-green fluorescent protein transgenic mice. Bath application of type 1 cannabinoid receptor (CB1) agonist WIN55,212 decreased GnRH neuron firing rate. This action was detectable in presence of the glutamate receptor antagonist kynurenic acid but disappeared when bicuculline was also present, indicating GABA(A)-R involvement. In immunocytochemical experiments, CB1-immunoreactive axons formed contacts with GnRH neurons and a subset established symmetric synapses characteristic of GABAergic neurotransmission. Functional studies were continued with whole-cell patch-clamp electrophysiology in presence of tetrodotoxin. WIN55,212 decreased the frequency of GABA(A)-R-mediated miniature postsynaptic currents (mPSCs) (reflecting spontaneous vesicle fusion), which was prevented with the CB1 antagonist AM251, indicating collectively that activation of presynaptic CB1 inhibits GABA release. AM251 alone increased mPSC frequency, providing evidence that endocannabinoids tonically inhibit GABA(A)-R drive onto GnRH neurons. Increased mPSC frequency was absent when diacylglycerol lipase was blocked intracellularly with tetrahydrolipstatin, showing that tonic inhibition is caused by 2-arachidonoylglycerol production of GnRH neurons. CdCl(2) in extracellular solution can maintain both action potentials and spontaneous vesicle fusion. Under these conditions, when endocannabinoid-mediated blockade of spontaneous vesicle fusion was blocked with AM251, GnRH neuron firing increased, revealing an endogenous endocannabinoid brake on GnRH neuron firing. Retrograde endocannabinoid signaling may represent an important mechanism under physiological and pathological conditions whereby GnRH neurons regulate their excitatory GABAergic inputs.

Endocannabinoids and pregnancy

Acylethanolamides such as anandamide (AEA), and monoacylglycerols like 2-arachidonoylglycerol are endocannabinoids that bind to cannabinoid, vanilloid and peroxisome proliferator-activated receptors. These compounds, their various receptors, the purported membrane transporter(s), and related enzymes that synthesize and degrade them are collectively referred to as the "endocannabinoid system (ECS)". Poorly defined cellular and molecular mechanisms control the biological actions of the ECS. Over the last decade evidence has been emerging to suggest that the ECS plays a significant role in various aspects of human reproduction. In this review, we summarize our current understanding of this role especially the involvement of AEA and related ECS elements in regulating oogenesis, embryo oviductal transport, blastocyst implantation, placental development and pregnancy outcomes, and sperm survival, motility, capacitation and acrosome reaction. Additionally, the possibility that plasma and tissue AEA and other cannabinoids may represent reliable diagnostic markers of natural and assisted reproduction and pregnancy outcomes in women will be discussed.