The faah gene is the first direct target of estrogen in the testis: role of histone demethylase LSD1

A review of cellular and molecular interactions between endocannabinoids and male fertility: Balancing beneficial and detrimental effects

The endocannabinoid system (ECS) has significant potential to influence male reproductive functions by targeting both the central nervous system and peripheral tissues, thereby promoting testicular homeostasis. Endogenous cannabinoids (eCBs) play an important role in regulating reproductive hormones, spermatogenesis, sperm motility, maturation, and function, all crucial for successful fertilization. However, excessive amounts of eCBs disrupt the function of testicular cells, leading to impaired sperm production, reduced motility and capacitation, premature acrosome response, and enhanced apoptosis. Despite these findings, the cellular and molecular mechanisms underlying the implications of eCBs in male reproduction remain unclear. This review is an attempt to provide an insight into the main mechanisms activated by the cross-talk between the ECS and male (in)fertility. The information presented in this report was obtained through an extensive review of scientific literature from various databases, including Web of Science, PubMed, Elsevier, Scopus, and Google Scholar. The reviewed studies suggest that oxidative stress, inflammation, and apoptosis are among the major modulatory mechanisms through which the ECS may contribute to male (in)fertility. This knowledge may lead to the development of potential clinical applications targeting endocannabinoid signaling to address infertility and enhance reproductive health in men.

The Role of the Endocannabinoid System in Human Gametogenesis

The endocannabinoid system (ECS) is a complex endocrine network involved in maintaining body homeostasis. It comprises endocannabinoids, their receptors (CB1 and CB2), and the enzymes and transporters responsible for their synthesis and degradation. While the ECS's role in the nervous system is well established, its functions in other organs and peripheral tissues, including the cardiovascular, gastrointestinal, and reproductive systems, remain incompletely understood. With the increasing use of marijuana, particularly among individuals of reproductive age, concerns have emerged regarding its potential impact on male and female fertility. Phytocannabinoids (∆9tethrahydrocannabinol and cannabidiol), as well as synthetic cannabimimetic drugs, interact with the ECS, influencing sperm and oocyte physiology and reproductive outcomes. Recent research has identified ECS-related biomarkers with potential applications in infertility diagnosis, particularly in assessing male fertility with greater precision. Furthermore, emerging evidence suggests that ECS signaling pathways are involved in epigenetic modifications, which may influence health maintenance, disease susceptibility, and transgenerational inheritance patterns. These findings highlight the therapeutic potential of ECS modulation in reproductive disorders and broader medical applications. This narrative review aims to elucidate the role of the ECS in human reproduction, with a particular focus on the influence of endocannabinoids on gametogenesis. While current research underscores the critical role of the ECS in fertility, further investigations are needed to fully elucidate its underlying mechanisms and its broader implications for reproductive health and therapeutic interventions.

Maternal obesity changes the small intestine endocannabinoid system and fecal metabolites of weanling rats associated with reduced intestinal permeability and impaired glucose homeostasis

The small intestine, including the endocannabinoid system (ECS), regulates the energy homeostasis. If maternal obesity modifies the intestinal ECS of the offspring favoring metabolic disorders throughout life is unexplored. Regardless maternal insults, overaction of the ECS has been related to obesity, mainly via type 1 cannabinoid receptor (CB1) signaling, while type 2 cannabinoid receptor (CB2) signaling and the endocannabinoid-like compounds, such as oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), have been associated with anti-inflammatory effects. We hypothesized that maternal obesity changes the ECS in the small intestine of weanling rat offspring in a sex-specific manner associated with altered fecal metabolites. Female rats received a control diet (C; 9% fat) or an obesogenic diet (OD; 37.2% fat, 11.8% sucrose) 9 weeks before mating, gestation and lactation. Offspring were euthanized at weaning. Maternal obesity increased CB2 protein content and mRNA levels of monocyte chemoattractant protein-1 in the small intestine in male offspring, while decreased fecal content of PEA and OEA in both sexes. Maternal obesity decreased gut permeability, but impaired glycemic homeostasis. Concerning fecal levels of γ-aminobutyric acid, amino acids and hypoxanthine, maternal obesity induced a fecal signature related to inflammatory and glycemic homeostasis impairment and dysbiosis. Maternal obesity induced intestinal inflammation and the signaling of CB2, PEA, and OEA might be part of a counter-regulatory response, contributing to reduced gut permeability, but not enough to avoid overweight and glycemic impairment in the offspring at weaning. Our findings provide molecular insights into the intestinal and fecal biomarkers for metabolic disorders.

The emerging roles of histone demethylases in cancers

Modulation of histone methylation status is regarded as an important mechanism of epigenetic regulation and has substantial clinical potential for the therapy of diseases, including cancer and other disorders. The present study aimed to provide a comprehensive introduction to the enzymology of histone demethylases, as well as their cancerous roles, molecular mechanisms, therapeutic possibilities, and challenges for targeting them, in order to advance drug design for clinical therapy and highlight new insight into the mechanisms of these enzymes in cancer. A series of clinical trials have been performed to explore potential roles of histone demethylases in several cancer types. Numerous targeted inhibitors associated with immunotherapy, chemotherapy, radiotherapy, and targeted therapy have been used to exert anticancer functions. Future studies should evaluate the dynamic transformation of histone demethylases leading to carcinogenesis and explore individual therapy.

Fatty acid amide hydrolase drives adult mammary gland development by promoting luminal cell differentiation

Mammary gland development occurs primarily in adulthood, undergoing extensive expansion during puberty followed by cycles of functional specialization and regression with every round of pregnancy/lactation/involution. This process is ultimately driven by the coordinated proliferation and differentiation of mammary epithelial cells. However, the endogenous molecular factors regulating these developmental dynamics are still poorly defined. Endocannabinoid signaling is known to determine cell fate-related events during the development of different organs in the central nervous system and the periphery. Here, we report that the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH) plays a pivotal role in adult mammary gland development. Specifically, it is required for luminal lineage specification in the mammary gland, and it promotes hormone-driven secretory differentiation of mammary epithelial cells by controlling the endogenous levels of anandamide and the subsequent activation of cannabinoid CB1 receptors. Together, our findings shed light on the role of the endocannabinoid system in breast development and point to FAAH as a therapeutic target in milk-production deficits.

Steroidogenesis and androgen/estrogen signaling pathways are altered in in vitro matured testicular tissues of prepubertal mice

Children undergoing cancer treatments are at risk for impaired fertility. Cryopreserved prepubertal testicular biopsies could theoretically be later matured in vitro to produce spermatozoa for assisted reproductive technology. A complete in vitro spermatogenesis has been obtained from mouse prepubertal testicular tissue, although with low efficiency. Steroid hormones are essential for the progression of spermatogenesis, the aim of this study was to investigate steroidogenesis and steroid signaling in organotypic cultures. Histological, RT-qPCR, western blot analyses, and steroid hormone measurements were performed on in vitro cultured mouse prepubertal testicular tissues and age-matched in vivo controls. Despite a conserved density of Leydig cells after 30 days of culture (D30), transcript levels of adult Leydig cells and steroidogenic markers were decreased. Increased amounts of progesterone and estradiol and reduced androstenedione levels were observed at D30, together with decreased transcript levels of steroid metabolizing genes and steroid target genes. hCG was insufficient to facilitate Leydig cell differentiation, restore steroidogenesis, and improve sperm yield. In conclusion, this study reports the failure of adult Leydig cell development and altered steroid production and signaling in tissue cultures. The organotypic culture system will need to be further improved before it can be translated into clinics for childhood cancer survivors.

Identification of fatty acid amide hydrolase as a metastasis suppressor in breast cancer

Clinical management of breast cancer (BC) metastasis remains an unmet need as it accounts for 90% of BC-associated mortality. Although the luminal subtype, which represents >70% of BC cases, is generally associated with a favorable outcome, it is susceptible to metastatic relapse as late as 15 years after treatment discontinuation. Seeking therapeutic approaches as well as screening tools to properly identify those patients with a higher risk of recurrence is therefore essential. Here, we report that the lipid-degrading enzyme fatty acid amide hydrolase (FAAH) is a predictor of long-term survival in patients with luminal BC, and that it blocks tumor progression and lung metastasis in cell and mouse models of BC. Together, our findings highlight the potential of FAAH as a biomarker with prognostic value in luminal BC and as a therapeutic target in metastatic disease.

Deciphering Complex Interactions in Bioactive Lipid Signaling

Lipids are usually viewed as metabolic fuel and structural membrane components. Yet, in recent years, different families of lipids able to act as authentic messengers between cells and/or intracellularly have been discovered. Such lipid signals have been shown to exert their biological activity via specific receptors that, by triggering distinct signal transduction pathways, regulate manifold pathophysiological processes in our body. Here, endogenous bioactive lipids produced from arachidonic acid (AA) and other poly-unsaturated fatty acids will be presented, in order to put into better perspective the relevance of their mutual interactions for health and disease conditions. To this end, metabolism and signal transduction pathways of classical eicosanoids, endocannabinoids and specialized pro-resolving mediators will be described, and the intersections and commonalities of their metabolic enzymes and binding receptors will be discussed. Moreover, the interactions of AA-derived signals with other bioactive lipids such as shingosine-1-phosphate and steroid hormones will be addressed.

Endocannabinoid system and epigenetics in spermatogenesis and testicular cancer

In mammals, male germ cell development starts during fetal life and is carried out in postnatal life with the formation of sperms. Spermatogenesis is the complex and highly orderly process during which a group of germ stem cells is set at birth, starts to differentiate at puberty. It proceeds through several stages: proliferation, differentiation, and morphogenesis and it is strictly regulated by a complex network of hormonal, autocrine and paracrine factors and it is associated with a unique epigenetic program. Altered epigenetic mechanisms or inability to respond to these factors can impair the correct process of germ development leading to reproductive disorders and/or testicular germ cell cancer. Among factors regulating spermatogenesis an emerging role is played by the endocannabinoid system (ECS). ECS is a complex system comprising endogenous cannabinoids (eCBs), their synthetic and degrading enzymes, and cannabinoid receptors. Mammalian male germ cells have a complete and active ECS which is modulated during spermatogenesis and that crucially regulates processes such as germ cell differentiation and sperm functions. Recently, cannabinoid receptor signaling has been reported to induce epigenetic modifications such as DNA methylation, histone modifications and miRNA expression. Epigenetic modifications may also affect the expression and function of ECS elements, highlighting the establishment of a complex mutual interaction. Here, we describe the developmental origin and differentiation of male germ cells and testicular germ cell tumors (TGCTs) focusing on the interplay between ECS and epigenetic mechanisms involved in these processes.

Phytocannabinoids, the Endocannabinoid System and Male Reproduction

The endocannabinoid system (ECS) is comprised of a set of lipid-derived messengers (the endocannabinoids, ECBs), proteins that control their production and degradation, and cell-surface cannabinoid (CB) receptors that transduce their actions. ECB molecules such as 2-arachidonoyl-sn-glycerol (2-AG) and anandamide (arachidonoyl ethanolamide) are produced on demand and deactivated through enzymatic actions tightly regulated both temporally and spatially, serving homeostatic roles in order to respond to various challenges to the body. Key components of the ECS are present in the hypothalamus-pituitary-gonadal (HPG) axis, which plays critical roles in the development and regulation of the reproductive system in both males and females. ECB signaling controls the action at each stage of the HPG axis through CB receptors expressed in the hypothalamus, pituitary, and reproductive organs such as the testis and ovary. It regulates the secretion of hypothalamic gonadotropin-releasing hormone (GnRH), pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH), estrogen, testosterone, and affects spermatogenesis in males. Δ⁹-tetrahydrocannabinol (THC) and other phytocannabinoids from Cannabis sativa affect a variety of physiological processes by altering, or under certain conditions hijacking, the ECB system. Therefore, phytocannabinoids, in particular THC, may modify the homeostasis of the HPG axis by altering CB receptor signaling and cause deficits in reproductive function. While the ability of phytocannabinoids, THC and/or cannabidiol (CBD), to reduce pain and inflammation provides promising opportunities for therapeutic intervention for genitourinary and degenerative disorders, important questions remain regarding their unwanted long-term effects. It is nevertheless clear that the therapeutic potential of modulating the ECS calls for further scientific and clinical investigation.

Lipid endocannabinoids in energy metabolism, stress and developmental programming

The endocannabinoid system (ECS) regulates brain development and function, energy metabolism and stress in a sex-, age- and tissue-dependent manner. The ECS comprises mainly the bioactive lipid ligands anandamide (AEA) and 2-aracdonoylglycerol (2-AG), cannabinoid receptors 1 and 2 (CB1 and CB2), and several metabolizing enzymes. The endocannabinoid tonus is increased in obesity, stimulating food intake and a preference for fat, reward, and lipid accumulation in peripheral tissues, as well as favoring a positive energy balance. Energy balance and stress responses share adaptive mechanisms regulated by the ECS that seem to underlie the complex relationship between feeding and emotional behavior. The ECS is also a key regulator of development. Environmental insults (diet, toxicants, and stress) in critical periods of developmental plasticity, such as gestation, lactation and adolescence, alter the ECS and may predispose individuals to the development of chronic diseases and behavioral changes in the long term. This review is focused on the ECS and the developmental origins of health and disease (DOHaD).

Quality of Life and a Surveillant Endocannabinoid System

The endocannabinoid system (ECS) is an important brain modulatory network. ECS regulates brain homeostasis throughout development, from progenitor fate decision to neuro- and gliogenesis, synaptogenesis, brain plasticity and circuit repair, up to learning, memory, fear, protection, and death. It is a major player in the hypothalamic-peripheral system-adipose tissue in the regulation of food intake, energy storage, nutritional status, and adipose tissue mass, consequently affecting obesity. Loss of ECS control might affect mood disorders (anxiety, hyperactivity, psychosis, and depression), lead to drug abuse, and impact neurodegenerative (Alzheimer's, Parkinson, Huntington, Multiple, and Amyotrophic Lateral Sclerosis) and neurodevelopmental (autism spectrum) disorders. Practice of regular physical and/or mind-body mindfulness and meditative activities have been shown to modulate endocannabinoid (eCB) levels, in addition to other players as brain-derived neurotrophic factor (BDNF). ECS is involved in pain, inflammation, metabolic and cardiovascular dysfunctions, general immune responses (asthma, allergy, and arthritis) and tumor expansion, both/either in the brain and/or in the periphery. The reason for such a vast impact is the fact that arachidonic acid, a precursor of eCBs, is present in every membrane cell of the body and on demand eCBs synthesis is regulated by electrical activity and calcium shifts. Novel lipid (lipoxins and resolvins) or peptide (hemopressin) players of the ECS also operate as regulators of physiological allostasis. Indeed, the presence of cannabinoid receptors in intracellular organelles as mitochondria or lysosomes, or in nuclear targets as PPARγ might impact energy consumption, metabolism and cell death. To live a better life implies in a vigilant ECS, through healthy diet selection (based on a balanced omega-3 and -6 polyunsaturated fatty acids), weekly exercises and meditation therapy, all of which regulating eCBs levels, surrounded by a constructive social network. Cannabidiol, a diet supplement has been a major player with anti-inflammatory, anxiolytic, antidepressant, and antioxidant activities. Cognitive challenges and emotional intelligence might strengthen the ECS, which is built on a variety of synapses that modify human behavior. As therapeutically concerned, the ECS is essential for maintaining homeostasis and cannabinoids are promising tools to control innumerous targets.

Mechanisms of endocannabinoid control of synaptic plasticity

The endogenous cannabinoid transmitter system regulates synaptic transmission throughout the nervous system. Unlike conventional transmitters, specific stimuli induce synthesis of endocannabinoids (eCBs) in the postsynaptic neuron, and these travel backwards to modulate presynaptic inputs. In doing so, eCBs can induce short-term changes in synaptic strength and longer-term plasticity. While this eCB regulation is near ubiquitous, it displays major regional and synapse specific variations with different synapse specific forms of short-versus long-term plasticity throughout the brain. These differences are due to the plethora of pre- and postsynaptic mechanisms which have been implicated in eCB signalling, the intricacies of which are only just being realised. In this review, we shall describe the current understanding and highlight new advances in this area, with a focus on the retrograde action of eCBs at CB1 receptors (CB₁Rs).

The Complex Interplay between Endocannabinoid System and the Estrogen System in Central Nervous System and Periphery

The endocannabinoid system (ECS) is a lipid cell signaling system involved in the physiology and homeostasis of the brain and peripheral tissues. Synaptic plasticity, neuroendocrine functions, reproduction, and immune response among others all require the activity of functional ECS, with the onset of disease in case of ECS impairment. Estrogens, classically considered as female steroid hormones, regulate growth, differentiation, and many other functions in a broad range of target tissues and both sexes through the activation of nuclear and membrane estrogen receptors (ERs), which leads to genomic and non-genomic cell responses. Since ECS function overlaps or integrates with many other cell signaling systems, this review aims at updating the knowledge about the possible crosstalk between ECS and estrogen system (ES) at both central and peripheral level, with focuses on the central nervous system, reproduction, and cancer.

Tart cherry (Prunus cerasus L.) dietary supplement modulates visceral adipose tissue CB1 mRNA levels along with other adipogenesis-related genes in rat models of diet-induced obesity

PURPOSE

There is increasing evidence for the involvement of dietary bioactive compounds in the cross-talk modulation of endocannabinoid system and some of the key regulators of transcriptional control for adipogenesis.

METHODS

We aimed to characterize the expression of cannabinoid CB1/CB2 receptors and fatty acid amide hydrolase (FAAH) along with selected adipogenesis-related genes (PPARγ, SREBP-1c and PREF-1), adipocyte-secreted factors (leptin and adiponectin), mitochondrial bioenergetic modulators (PGC-1A and UCP-2), and transient receptor potential vanilloid subtype 1 (TRPV1) and 2 (TRPV2) channels in visceral adipose tissue of rats fed with a high-fat diet (HFD) containing either tart cherry seeds alone or tart cherry seeds and juice for 17 weeks. The visceral adipose tissue was weighed and checked the expression of different markers by qRT-PCR, Western blot and immunohistochemistry.

RESULTS

Tart cherry supplements were able to downregulate the HFD-induced mRNA expression of CB1 receptor, SREBP-1c, PPARγ, leptin, TRPV1 and TRPV2 resulting in potential anti-adipogenic effects.

CONCLUSION

The present study points out that the intake of bioactive constituents of tart cherry may attenuate the effect of adipogenesis by acting directly on the adipose tissue and modulating the interplay between CB1, PPARγ and TRPV channel gene transcription.

Epigenetics and the endocannabinoid system signaling: An intricate interplay modulating neurodevelopment

The endocannabinoid (eCB) system is a complex system comprising endogenous cannabinoids (eCBs), their synthesis and degradation enzymes, and cannabinoid receptors. These elements crucially regulate several biological processes during neurodevelopment, such as proliferation, differentiation, and migration. Recently, eCBs were also reported to have an epigenetic action on genes that play key functions in the neurotransmitter signaling, consequently regulating their expression. In turn, epigenetic modifications (e.g. DNA methylation, histone modifications) may also modulate the function of eCB system's elements. For example, the expression of the cnr gene in the central nervous system may be epigenetically regulated (e.g. DNA methylation, histone modifications), thus altering the function of the cannabinoid receptor type-1 (CB1R). Considering the importance of the eCB system during neurodevelopment, it is thus reasonable to expect that alterations in this interaction between the eCB system and epigenetic modifications may give rise to neurodevelopmental disorders. Here, we review key concepts related to the regulation of neuronal function by the eCB system and the different types of epigenetic modifications. In particular, we focus on the mechanisms involved in the intricate interplay between both signaling systems and how they control cell fate during neurodevelopment. Noteworthy, such mechanistic understanding assumes high relevance considering the implications of the dysregulation of key neurogenic processes towards the onset of neurodevelopment-related disorders. Moreover, considering the increasing popularity of cannabis and its synthetic derivatives among young adults, it becomes of utmost importance to understand how exogenous cannabinoids may epigenetically impact neurodevelopment.

Bisphenol A Deranges the Endocannabinoid System of Primary Sertoli Cells with an Impact on Inhibin B Production

Bisphenol A (BPA) is an endocrine disruptor that negatively affects spermatogenesis, a process where Sertoli cells play a central role. Thus, in the present study we sought to ascertain whether BPA could modulate the endocannabinoid (eCB) system in exposed mouse primary Sertoli cells. Under our experimental conditions, BPA turned out to be cytotoxic to Sertoli cells with an half-maximal inhibitory concentration (IC₅₀) of ~6.0 µM. Exposure to a non-cytotoxic dose of BPA (i.e., 0.5 μM for 48 h) increased the expression levels of specific components of the eCB system, namely: type-1 cannabinoid (CB₁) receptor and diacylglycerol lipase-α (DAGL-α), at mRNA level, type-2 cannabinoid (CB₂) receptor, transient receptor potential vanilloid 1 (TRPV1) receptors, and DAGL-β, at protein level. Interestingly, BPA also increased the production of inhibin B, but not that of transferrin, and blockade of either CB₂ receptor or TRPV1 receptor further enhanced the BPA effect. Altogether, our study provides unprecedented evidence that BPA deranges the eCB system of Sertoli cells towards CB₂- and TRPV1-dependent signal transduction, both receptors being engaged in modulating BPA effects on inhibin B production. These findings add CB₂ and TRPV1 receptors, and hence the eCB signaling, to the other molecular targets of BPA already known in mammalian cells.

Cannabinoid signalling and effects of cannabis on the male reproductive system

Marijuana is the most widely consumed recreational drug worldwide, which raises concerns for its potential effects on fertility. Many aspects of human male reproduction can be modulated by cannabis-derived extracts (cannabinoids) and their endogenous counterparts, known as endocannabinoids (eCBs). These latter molecules act as critical signals in a variety of physiological processes through receptors, enzymes and transporters collectively termed the endocannabinoid system (ECS). Increasing evidence suggests a role for eCBs, as well as cannabinoids, in various aspects of male sexual and reproductive health. Although preclinical studies have clearly shown that ECS is involved in negative modulation of testosterone secretion by acting both at central and testicular levels in animal models, the effect of in vivo exposure to cannabinoids on spermatogenesis remains a matter of debate. Furthermore, inconclusive clinical evidence does not seem to support the notion that plant-derived cannabinoids have harmful effects on human sexual and reproductive health. An improved understanding of the complex crosstalk between cannabinoids and eCBs is required before targeting of ECS for modulation of human fertility becomes a reality.

Maternal high-fat diet up-regulates type-1 cannabinoid receptor with estrogen signaling changes in a sex- and depot- specific manner in white adipose tissue of adult rat offspring

PURPOSE

Obesity and high-fat (HF) diet are associated with over activation of the endocannabinoid system (ECS). We have demonstrated that maternal HF diet induces early obesity and modulates cannabinoid signaling in visceral (VIS) and subcutaneous (SUB) white adipose tissue (WAT) in weanling rat offspring. We hypothesized that perinatal maternal HF diet would program the expression of ECS in adipose tissue in a long-term way in parallel to alterations in epigenetic markers and sex hormone signaling.

METHODS

Progenitor female rats received control diet (C, 9% fat) or isocaloric high-fat diet (HF, 28% fat) for 8 weeks before mating, gestation, and lactation. All pups were weaned to C diet and they were euthanized at 180 days old.

RESULTS

Maternal HF diet induced overweight and increased SUB WAT mass of male and female adult offspring. Maternal HF diet induced hypertrophy of VIS and SUB adipocytes only in female offspring associated with increased type 1 cannabinoid receptor protein (CB1) and mRNA (Cnr1) levels. These changes were associated with increased estrogen receptor α binding to Cnr1 promoter in SUB WAT of adult female offspring, which may contribute to higher expression of Cnr1.

CONCLUSION

Increased CB1 signaling in adipose tissue might contribute to higher adiposity programmed by maternal HF diet because endocannabinoids stimulate the accumulation of fat in the adipose tissue. Our findings provide molecular insights into sex-specific targets for anti-obesity therapies based on the endocannabinoid system.

The fundamental role of the endocannabinoid system in endometrium and placenta: implications in pathophysiological aspects of uterine and pregnancy disorders

BACKGROUND

The endocannabinoid system (ECS) consists of the cannabinoid receptors CB1 and CB2, the main endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and their metabolic enzymes N-acylphosphatidylethanolamine-specific phospholipase D, fatty acid amide hydrolase, diacylglycerol lipase and monoacylglycerol lipase. This system is involved in the modulation of essential physiological processes. Its role in the reproductive system has become significantly important in recent years, given its major role in events such as gametogenesis, decidualisation, implantation and placentation.

OBJECTIVE AND RATIONALE

In this paper, we review the literature and summarize the role of the ECS elements in reproduction and their potential as early markers for diagnosis of reproductive disorders or as pharmacological targets for treatment.

SEARCH METHODS

Original research and review papers published from 1964 to June 2019 were selected in terms of relevance, reliability and quality by searching PubMed, MEDLINE and Web of Science, using the following search terms: endocannabinoid system and endometriosis; endocannabinoid system and ectopic pregnancy; endocannabinoid system and miscarriage; endocannabinoid system and pre-eclampsia; endocannabinoid system and endometrial cancer; endocannabinoid system and reproduction; endocannabinoid, endometrium; placenta; N-acylethanolamines; anandamide; 2-arachidonoylglycerol; and cannabinoids.

OUTCOMES

This review demonstrates relevant information concerning ECS alterations in endometriosis, ectopic pregnancy, miscarriage, pre-eclampsia and endometrial cancer. We highlight the importance of the endocannabinoids in endometrial and placental physiology and pathophysiology, from studies in vitro and in vivo and in clinical observations. The most studied of the endogenous cannabinoids is AEA. The levels of AEA were increased in plasma of patients with endometriosis and miscarriage, as well as in the fallopian tube of women with ectopic pregnancy and in endometrial biopsies of endometrial cancer. Changes in the pattern of expression of the cannabinoid receptor CB1 were also observed in endometrial biopsies of endometriosis, fallopian tube and decidua of patients with ectopic pregnancy and pre-eclamptic placenta. Moreover, alterations in CB2 expression have been reported in association with endometrial cancer. In general, studies on the cannabinoid signalling through CB2 and on the biological activities of the other major endocannabinoid, namely 2-AG, as well as its metabolic enzymes are scarce and avidly required.

WIDER IMPLICATIONS

The pathophysiological mechanisms involved in the described endometrial and placental pathologies are still unclear and lack the means for an early diagnosis. Based on current evidence, though alterations in ECS are demonstrated at tissue level, it is difficult to associate plasmatic changes in AEA with specific endometrial and placental diseases. Thus, pairing alterations in AEA levels with 2-AG and/or other endocannabinoid-like molecules may provide more accurate and early diagnoses. In addition, patients may benefit from new therapies that target the ECS and endocannabinoid signalling.

The Epigenetics of the Endocannabinoid System

The endocannabinoid system (ES) is a cell-signalling system widely distributed in biological tissues that includes endogenous ligands, receptors, and biosynthetic and hydrolysing machineries. The impairment of the ES has been associated to several pathological conditions like behavioural, neurological, or metabolic disorders and infertility, suggesting that the modulation of this system may be critical for the maintenance of health status and disease treatment. Lifestyle and environmental factors can exert long-term effects on gene expression without any change in the nucleotide sequence of DNA, affecting health maintenance and influencing both disease load and resistance. This potentially reversible "epigenetic" modulation of gene expression occurs through the chemical modification of DNA and histone protein tails or the specific production of regulatory non-coding RNA (ncRNA). Recent findings demonstrate the epigenetic modulation of the ES in biological tissues; in the same way, endocannabinoids, phytocannabinoids, and cannabinoid receptor agonists and antagonists induce widespread or gene-specific epigenetic changes with the possibility of trans-generational epigenetic inheritance in the offspring explained by the transmission of deregulated epigenetic marks in the gametes. Therefore, this review provides an update on the epigenetics of the ES, with particular attention on the emerging role in reproduction and fertility.

ABHD2 Inhibitor Identified by Activity-Based Protein Profiling Reduces Acrosome Reaction

ABHD2 is a serine hydrolase that belongs to the subgroup of the α,β-hydrolase fold-containing proteins, which is involved in virus propagation, immune response, and fertilization. Chemical tools to selectively modulate the activity of ABHD2 in an acute setting are highly desired to investigate its biological role, but are currently lacking. Here, we report a library-versus-library screening using activity-based protein profiling (ABPP) to evaluate in parallel the selectivity and activity of a focused lipase inhibitor library against ABHD2 and a panel of closely related ABHD proteins. This screen resulted in the rapid identification of novel inhibitors for ABHD2. The selectivity of the inhibitor was further investigated in native mouse testis proteome by competitive ABPP, revealing a highly restricted off-target profile. The progesterone-induced acrosome reaction was reduced in a dose-dependent manner by the newly identified inhibitor, which provides further support for the key-role of ABHD2 in the P4-stimulated acrosome reaction. On this basis, the ABHD2 inhibitor is an excellent starting point for further optimization of ABHD2 inhibitors that can modulate sperm fertility and may lead to novel contraceptives.

HU-671, a Novel Oleoyl Serine Derivative, Exhibits Enhanced Efficacy in Reversing Ovariectomy-Induced Osteoporosis and Bone Marrow Adiposity

Oleoyl serine (OS), an endogenous fatty acyl amide (FAA) found in bone, has been shown to have an anti-osteoporotic effect. OS, being an amide, can be hydrolyzed in the body by amidases. Hindering its amide bond by introducing adjacent substituents has been demonstrated as a successful method for prolonging its skeletal activity. Here, we tested the therapeutic efficacy of two methylated OS derivatives, oleoyl α-methyl serine (HU-671) and 2-methyl-oleoyl serine (HU-681), in an ovariectomized mouse model for osteoporosis by utilizing combined micro-computed tomography, histomorphometry, and cell culture analyses. Our findings indicate that daily treatment for 6 weeks with OS or HU-671 completely rescues bone loss, whereas HU-681 has only a partial effect. The increased bone density was primarily due to enhanced trabecular thickness and number. Moreover, the most effective dose of HU-671 was 0.5 mg/kg/day, an order of magnitude lower than with OS. The reversal of bone loss resulted from increased bone formation and decreased bone resorption, as well as reversal of bone marrow adiposity. These results were further confirmed by determining the serum levels of osteocalcin and type 1 collagen C-terminal crosslinks, as well as demonstrating the enhanced antiadipogenic effect of HU-671. Taken together, these data suggest that methylation interferes with OS’s metabolism, thus enhancing its effects by extending its availability to its target cells.

Effects of Dietary Bisphenol A on the Reproductive Function of Gilthead Sea Bream (Sparus aurata) Testes

Bisphenol A (BPA), a known endocrine disrupting chemical (EDC), was administered by diet to gilthead sea bream (Sparus aurata) in order to study its effects on the endocannabinoid system (ECS) and gonadal steroidogenesis. 2-year-old male gilthead sea bream were fed with two different concentrations of BPA (LOW at 4 and HIGH at 4000 µg/kg body weight for 21 days during the reproductive season. Exposure to 4000 µg BPA/kg bw/day (BPA HIGH) reduced sperm motility and altered the straight-line velocity (VSL) and linearity (LIN). Effects on steroidogenesis were evident, with testosterone (T) being up-regulated by both treatments and 11-ketotestosterone (11-KT) down-regulated by BPA HIGH. Plasma levels of 17β-estradiol (E₂) were not affected. The Gonadosomatic Index (GSI) increased in the BPA HIGH group. Interestingly, the levels of endocannabinoids and endocannabinoid-like compounds were significantly reduced after both treatments. Unpredictably, a few changes were noticed in the expression of genes coding for ECS enzymes, while the receptors were up-regulated depending on the BPA dose. Reproductive markers in testis (leptin receptor (lepr), estrogen receptors (era, erb), progesterone receptors (pr) and the gonadotropin releasing hormone receptor (gnrhr)) were up-regulated. BPA induced the up-regulation of the hepatic genes involved in oogenesis (vitellogenin (vtg) and zona pellucida 1 (zp1)).

Effects of diisononyl phthalate (DiNP) on the endocannabinoid and reproductive systems of male gilthead sea bream (Sparus aurata) during the spawning season

Diisononyl phthalate (DiNP) is a plasticizer used to improve plastic performance in a large variety of items which has been reported as an endocrine-disrupting chemical (EDC) in several organisms. The endocannabinoid system (ECS) is a cellular signaling system, whose functionality is tightly involved with reproductive function. The aim of the present study was the assessment of the effects of DiNP on the gonadal ECS and on the reproductive function of male gilthead sea bream Sparus aurata, an important marine aquacultured species in Europe, during the reproductive season. Fish were fed for 21 days with two diets contaminated with different nominal concentrations of DiNP (DiNP LOW at 15 µg DiNP kg^-1 bw day^-1 and DiNP HIGH at 1500 µg DiNP kg^-1 bw day^-1), based on the tolerable daily intake (TDI) ruled by the European Food Safety Authority for humans. The transcription of several genes related to the ECS was affected by the DiNP. Specifically, DiNP reduced the levels of endocannabinoids and endocannabinoid-like mediators, concomitant with the increase of fatty acid amide hydrolase (FAAH) activity. At the histological level, DiNP LOW induced the highest occurrence of individuals with regressed testes. Steroidogenesis was affected significantly, since plasma 11-ketotestosterone (11-KT), the main active androgen in fish, was significantly decreased by the DiNP HIGH treatment, while plasma 17β-estradiol (E₂) levels were raised, associated with an increase of the gonadosomatic index (GSI). Additionally, the level of testosterone (T) was significantly increased in the DiNP LOW group, however, the same DiNP concentration reduced the levels of 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P). The production of sperm was in general not affected, since spermiation index, sperm density, survival and the duration of forward motility did not exhibit any changes compared to controls. However, computer-assisted sperm analysis (CASA) showed that DiNP reduced the percentage of motile cells. The results clearly suggest a negative effect of DiNP via the diet on the male endocrine system of gilthead sea bream during the reproductive season.

Transcriptional regulation of the endocannabinoid system in a rat model of binge-eating behavior reveals a selective modulation of the hypothalamic fatty acid amide hydrolase gene

OBJECTIVE

Binge-eating episodes are recurrent and are defining features of several eating disorders. Thus binge-eating episodes might influence eating disorder development of which exact underlying mechanisms are still largely unknown.

METHODS

Here we focused on the transcriptional regulation of the endocannabinoid system, a potent regulator of feeding behavior, in relevant rat brain regions, using a rat model in which a history of intermittent food restriction and a frustration stress induce binge-like palatable food consumption.

RESULTS

We observed a selective down-regulation of fatty acid amide hydrolase (faah) gene expression in the hypothalamus of rats showing the binge-eating behavior with a consistent reduction in histone 3 acetylation at lysine 4 of the gene promoter. No relevant changes were detected for any other endocannabinoid system components in any brain regions under study, as well as for the other epigenetic mechanisms investigated (DNA methylation and histone 3 lysine 27 methylation) at the faah gene promoter.

DISCUSSION

Our findings suggest that faah transcriptional regulation is a potential biomarker of binge-eating episodes, with a relevant role in the homeostatic regulation of food intake.

Identification of SEPTIN12 as a novel target of the androgen and estrogen receptors in human testicular cells

SEPTIN12 (SEPT12) is a testis-enriched gene that is downregulated in the testis of infertile men with severe spermatogenic defects. While SEPT12 is involved in spermatogenic failure and sperm motility disorder, SEPT12 transcriptional regulation is still unknown. Here we report the promoter region of SEPT12 as a 245 bp segment upstream of the transcription start site. One androgen receptor (AR) and two estrogen receptor α (ERα) binding sites in this region were initially identified by bioinformatics prediction and confirmed by chromatin immunoprecipitation assay. Truncated ERα or AR binding sites decreased the promoter activity, which indicated that the ERα and AR are essential for the SEPT12 promoter. On the other hand, the promoter activity was enhanced by the treatment with 17β-estradiol (E2) and 5α-dihydrotestosterone (5α-DHT). Thus, one androgen and two estrogen hormone responsive elements located in the promoter of SEPT12 gene can regulate SEPT12 expression. Two single nucleotide polymorphisms (SNPs), rs759992 T > C and rs3827527 C > T, were observed in the SEPT12 gene promoter region and were able to decrease the promoter activity. In conclusion, the current work identified the promoter of the human SEPT12 gene and provided key evidence about its transcriptional regulation via E2 and 5α-DHT. Since SEPT12 has an important role in spermatogenesis, SEPT12 expression analysis can be developed as a potential tool for the assessment of environmental or food pollution by hormones or for the evaluation of the risk of endocrine-disrupting chemicals (EDCs) in general.

Maternal high-fat diet consumption induces sex-dependent alterations of the endocannabinoid system and redox homeostasis in liver of adult rat offspring

Maternal diet plays a critical role in health development. Perinatal overnutrition induces metabolic dysfunctions and obesity in the offspring. Obesity is associated with endocannabinoid system (ECS) over activation and oxidative stress. Liver ECS activation induces hepatic steatosis, inflammation and fibrosis while the antagonism of cannabinoid receptors ameliorates these alterations. Here, we investigated the effect of perinatal maternal high-fat diet (HF, 29% of calories as fat) on the ECS and antioxidant system in liver of male and female adult rat offspring (180 days old). Maternal HF diet increased hepatic cannabinoid receptors, ECS metabolizing enzymes and triglyceride content, with male offspring more affected. ECS changes are likely independent of estradiol serum levels but associated with increased hepatic content of estrogen receptor, which can stimulate the expression of ECS components. Differently, maternal HF diet decreased the activity of the antioxidant enzymes glutathione peroxidase, superoxide dismutase and catalase, and increased oxidative stress markers in both sexes. Alterations in the redox homeostasis were associated with mitochondria damage but not with liver fibrosis. Our data suggest that maternal HF diet induces ECS over activation in adulthood, and that male offspring are at higher risk to develop liver disease compared with female rats.

Disruption of the gonadal endocannabinoid system in zebrafish exposed to diisononyl phthalate

DiNP (Di-isononyl phthalate) has been recently introduced as DEHP (Bis (2-ethylhexyl) phthalate) substitute and due to its chemical properties, DiNP is commonly used in a large variety of plastic items. The endocannabinoid system (ECS) is a lipid signaling system involved in a plethora of physiological pathways including the control of the reproductive and metabolic processes. In this study, the effects of DiNP on the ECS of zebrafish (male and female) gonads were analyzed. Adult zebrafish were chronically exposed for 21 days via water to 3 environmentally relevant concentrations of DiNP (42 μg/L; 4.2 μg/L; 0.42 μg/L). In females, the Gonadosomatic Index (GSI) and the number of fertilized eggs were reduced by the lowest concentration of DiNP tested. The levels of two endocannabinoids, Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG), were not affected, while a reduction of the N-oleoyl-ethanolamine (OEA) level was observed. Transcriptional changes were reported in relation to genes coding for the ECS receptors and the enzymes involved in the ECS pathway. DiNP exposure in males reduced the GSI as well as changed the levels of endocannabinoids. Moreover, DiNP treatment induced significative changes in the genes coding for the ECS receptors and enzymes, and significantly increased the activity of the fatty acid amide hydrolase (FAAH). In summary, in zebrafish, exposure to environmentally relevant concentrations of DiNP disrupted the ECS and affected reproduction in a gender specific manner.

Role of Bisphenol A on the Endocannabinoid System at central and peripheral levels: Effects on adult female zebrafish

Bisphenol A (BPA), a widely used chemical to produce polycarbonate plastics, has become an ubiquitous pollutant due to its extensive use. Its endocrine disrupting properties have been documented in several studies, as well as its potential to induce metabolic and reproductive impairments at environmentally relevant concentrations. Recent insights highlighted the role of the Endocannabinoid System (ECS) in energy homeostasis and lipid metabolism. In fact, disruption of the ECS may induce metabolic alterations among other effects. Thus, the main objective of this study was to investigate the disruptive effects of environmentally relevant concentrations of BPA on the ECS of female zebrafish liver and brain. Adult female zebrafish were exposed for 3 weeks to three different concentrations of BPA (5 μg/L; 10 μg/L; 20 μg/L). We observed changes in the expression of a number of genes involved in the Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG) metabolism in the liver and brain, as well as altered levels of endocannabinoids and endocannabinoid-like mediators. These changes were associated with greater presence of hepatic lipid vacuoles, following exposure to the highest concentration of BPA (20 μg/L) tested, although there were no changes in food intake and in the expression of the molecular markers for appetite. The overall results support the hypothesis that exposure to BPA induced changes in the central and hepatic ECS system of adult female zebrafish causing the increase of the area covered by lipids in the liver at the highest concentration tested, but not via food intake.

2-Arachidonoylglycerol: A signaling lipid with manifold actions in the brain

2-Arachidonoylglycerol (2-AG) is a signaling lipid in the central nervous system that is a key regulator of neurotransmitter release. 2-AG is an endocannabinoid that activates the cannabinoid CB₁ receptor. It is involved in a wide array of (patho)physiological functions, such as emotion, cognition, energy balance, pain sensation and neuroinflammation. In this review, we describe the biosynthetic and metabolic pathways of 2-AG and how chemical and genetic perturbation of these pathways has led to insight in the biological role of this signaling lipid. Finally, we discuss the potential therapeutic benefits of modulating 2-AG levels in the brain.

Perinatal maternal high-fat diet induces early obesity and sex-specific alterations of the endocannabinoid system in white and brown adipose tissue of weanling rat offspring

Perinatal maternal high-fat (HF) diet programmes offspring obesity. Obesity is associated with overactivation of the endocannabinoid system (ECS) in adult subjects, but the role of the ECS in the developmental origins of obesity is mostly unknown. The ECS consists of endocannabinoids, cannabinoid receptors (cannabinoid type-1 receptor (CB1) and cannabinoid type-2 receptor (CB2)) and metabolising enzymes. We hypothesised that perinatal maternal HF diet would alter the ECS in a sex-dependent manner in white and brown adipose tissue of rat offspring at weaning in parallel to obesity development. Female rats received standard diet (9 % energy content from fat) or HF diet (29 % energy content from fat) before mating, during pregnancy and lactation. At weaning, male and female offspring were killed for tissue harvest. Maternal HF diet induced early obesity, white adipocyte hypertrophy and increased lipid accumulation in brown adipose tissue associated with sex-specific changes of the ECS's components in weanling rats. In male pups, maternal HF diet decreased CB1 and CB2 protein in subcutaneous adipose tissue. In female pups, maternal HF diet increased visceral and decreased subcutaneous CB1. In brown adipose tissue, maternal HF diet increased CB1 regardless of pup sex. In addition, maternal HF diet differentially changed oestrogen receptor across the adipose depots in male and female pups. The ECS and oestrogen signalling play an important role in lipogenesis, adipogenesis and thermogenesis, and we observed early changes in their targets in adipose depots of the offspring. The present findings provide insights into the involvement of the ECS in the developmental origins of metabolic disease induced by inadequate maternal nutrition in early life.

Direct regulation of genes involved in sperm release by estrogen and androgen through their receptors and coregulators

Steroid hormones, estrogen and androgen, control transcription in various reproductive and non-reproductive tissues. Both hormones are known to be important for control of sperm release from the seminiferous epithelium (spermiation), a process characterized by extensive remodeling of actin filaments and endocytosis. Earlier studies with an estrogen (E2)-induced rat model of spermiation failure revealed genes involved in actin remodeling (Arpc1b and Evl) and endocytosis (Picalm, Eea1, and Stx5a) to be differentially regulated. Further, among these genes, Arpc1b and Evl were found to be estrogen-responsive whereas Eea1 and Stx5a were androgen-responsive and Picalm was responsive to both hormones in seminiferous tubule cultures. Yet, the mechanism by which these genes are regulated by estrogen and androgen in the testis was unclear. Here, we report the presence of a functional estrogen response element (ERE) upstream of Arpc1b and Evl genes and androgen response element (ARE) upstream of Picalm, Eea1, and Stx5a genes. Chromatin immunoprecipitation in control versus E2-treated testes revealed significant changes in estrogen receptor beta (ERβ) recruitment along with coregulators to the EREs upstream of Arpc1b and Evl genes and androgen receptor (AR) at AREs upstream of Picalm, Eea1, and Stx5a genes. Enrichment patterns of these EREs/AREs with coregulators, activating and repressing histone modifications along with RNA polymerase II recruitment, correlated with the observed expression patterns of these genes upon E2 treatment. Taken together, our results reveal direct targets of estrogen and androgen in the testes and provide insights into transcriptional control of sperm release by the two steroid hormones.

Of Oestrogens and Sperm: A Review of the Roles of Oestrogens and Oestrogen Receptors in Male Reproduction

The crucial role that oestrogens play in male reproduction has been generally accepted; however, the exact mechanism of their action is not entirely clear and there is still much more to be clarified. The oestrogen response is mediated through oestrogen receptors, as well as classical oestrogen receptors’ variants, and their specific co-expression plays a critical role. The importance of oestrogen signalling in male fertility is indicated by the adverse effects of selected oestrogen-like compounds, and their interaction with oestrogen receptors was proven to cause pathologies. The aims of this review are to summarise the current knowledge on oestrogen signalling during spermatogenesis and sperm maturation and discuss the available information on oestrogen receptors and their splice variants. An overview is given of species-specific differences including in humans, along with a detailed summary of the methodology outcome, including all the genetically manipulated models available to date. This review provides coherent information on the recently discovered mechanisms of oestrogens’ and oestrogen receptors’ effects and action in both testicular somatic and germ cells, as well as in mature sperm, available for mammals, including humans.

Effects of Neuroendocrine CB1 Activity on Adult Leydig Cells

Endocannabinoids control male reproduction acting at central and local level via cannabinoid receptors. The cannabinoid receptor CB1 has been characterized in the testis, in somatic and germ cells of mammalian and non-mammalian animal models, and its activity related to Leydig cell differentiation, steroidogenesis, spermiogenesis, sperm quality, and maturation. In this short review, we provide a summary of the insights concerning neuroendocrine CB1 activity in male reproduction focusing on adult Leydig cell ontogenesis and steroid biosynthesis.

Unconventional endocannabinoid signaling governs sperm activation via the sex hormone progesterone

Steroids regulate cell proliferation, tissue development, and cell signaling via two pathways: a nuclear receptor mechanism and genome-independent signaling. Sperm activation, egg maturation, and steroid-induced anesthesia are executed via the latter pathway, the key components of which remain unknown. Here, we present characterization of the human sperm progesterone receptor that is conveyed by the orphan enzyme α/β hydrolase domain-containing protein 2 (ABHD2). We show that ABHD2 is highly expressed in spermatozoa, binds progesterone, and acts as a progesterone-dependent lipid hydrolase by depleting the endocannabinoid 2-arachidonoylglycerol (2AG) from plasma membrane. The 2AG inhibits the sperm calcium channel (CatSper), and its removal leads to calcium influx via CatSper and ensures sperm activation. This study reveals that progesterone-activated endocannabinoid depletion by ABHD2 is a general mechanism by which progesterone exerts its genome-independent action and primes sperm for fertilization.

Anandamide acts via kisspeptin in the regulation of testicular activity of the frog, Pelophylax esculentus

In the frog Pelophylax esculentus, the endocannabinoid anandamide (AEA) modulates Gonadotropin Releasing Hormone (GnRH) system in vitro and down-regulates steroidogenic enzymes in vivo. Thus, male frogs were injected with AEA ± SR141716A, a cannabinoid receptor 1 (CB1) antagonist, to evaluate possible effects on GnRH and Kiss1/Gpr54 systems, gonadotropin receptors and steroid levels. In frog diencephalons, AEA negatively affected both GnRH and Kiss1/Gpr54 systems. In testis, AEA induced the expression of gonadotropin receptors, cb1, gnrh2 and gnrhr3 meanwhile reducing gnrhr2 mRNA and Kiss1/Gpr54 proteins. Furthermore, aromatase (Cyp19) expression increased in parallel to testosterone decrease and estradiol increase. In vitro treatment of testis with AEA revealed direct effects on Cyp19 and induced the expression of the AEA-degrading enzyme Faah. Lastly, AEA effects on Faah were counteracted by the antiestrogen ICI182780, indicating estradiol mediated effect. In conclusion, for the first time we show in a vertebrate that AEA regulates testicular activity through kisspeptin system.

The Endocannabinoid Signaling System in the CNS: A Primer

The purpose of this chapter is to provide an introduction to the mechanisms for the regulation of endocannabinoid signaling through CB1 cannabinoid receptors in the central nervous system. The processes involved in the synthesis and degradation of the two most well-studied endocannabinoids, 2-arachidonoylglycerol and N-arachidonylethanolamine are outlined along with information regarding the regulation of the proteins involved. Signaling mechanisms and pharmacology of the CB1 cannabinoid receptor are outlined, as is the paradigm of endocannabinoid/CB1 receptor regulation of neurotransmitter release. The reader is encouraged to appreciate the importance of the endocannabinoid/CB1 receptor signaling system in the regulation of synaptic activity in the brain.

LSD1-Mediated Demethylation of H3K4me2 Is Required for the Transition from Late Progenitor to Differentiated Mouse Rod Photoreceptor

Epigenetic modifiers can work in concert with transcription factors to control the transition of cells from proliferating progenitors into quiescent terminally differentiated cells. This transition involves changes in histone methylation and one of the key regulators of this is the H3K4me2/1 histone demethylase LSD1. Here, we show that the highest expression of LSD1 occurs in postmitotic retinal cells during the peak period of rod photoreceptor differentiation. Pharmacological inhibition of LSD1 in retinal explants cultured from PN1 to PN8 had three major effects. It prevented the normal decrease in expression of genes associated with progenitor function, it blocked rod photoreceptor development, and it increased expression of genes associated with other retinal cell types. The maintained expression of progenitor genes was associated with a maintained level of H3K4me2 over the gene and its promoter. Among the genes whose expression was maintained was Hes1, a repressor known to block rod photoreceptor development. The inhibition of rod photoreceptor gene expression occurred in spite of the normal expression of transcription factors CRX and NRL, and the normal accumulation of H3K4me2 marks over the promoter and gene body. We suggest that LSD1 acts in concert with a series of nuclear receptors to modify chromatin structure and repress progenitor genes as well as to inhibit ectopic patterns of gene expression in the differentiating postmitotic retinal cells.

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.

Behavioral effects and mechanisms of migraine pathogenesis following estradiol exposure in a multibehavioral model of migraine in rat

Migraine is one of the most common neurological disorders, leading to more than 1% of total disability reported and over 68 million visits to emergency rooms or physician's offices each year in the United States. Three times as many women as men have migraine, and while the mechanism behind this is not well understood, 17β-estradiol (estradiol) has been implicated to play a role. Studies have demonstrated that exposure to estrogen can lead to activation of inflammatory pathways, changes in sodium gated channel activity, as well as enhanced vasodilation and allodynia. Estradiol receptors are found in trigeminal nociceptors, which are involved in signaling during a migraine attack. The purpose of this study was to investigate the role of estradiol in migraine pathogenesis utilizing a multibehavioral model of migraine in rat. Animals were surgically implanted with a cannula system to induce migraine and behavior was assessed following exposure to a proestrus level of estradiol for total locomotor activity, light and noise sensitivity, evoked grooming patterns, and enhanced acoustic startle response. Results demonstrated decreased locomotor activity, increased light and noise sensitivity, altered facial grooming indicative of allodynia and enhanced acoustic startle. Further examination of tissue samples revealed increased expression of genes associated with inflammation and vasodilation. Overall, this study demonstrates exacerbation of migraine-like behaviors following exposure to estradiol and helps further explain the underlying mechanisms behind sex differences found in this common neurological disorder.

Expression of histone H3 lysine 4 methylation and its demethylases in the developing mouse testis

Histone H3 lysine 4 methylation (H3K4me) is an epigenetic modification associated with gene activation and is dynamically regulated by histone methylases and demethylases. To date, the expression patterns of H3K4me and its demethylases in the developing testis remain unclear. The present study was designed to detect the expression of H3K4me1/2/3 and its demethylases LSD1, RBP2 and SMCX in 21-, 40- and 60-day-old mouse testes by using immunohistochemistry, quantitative real-time polymerase chain reaction (PCR) and Western blot. The immunohistochemical results demonstrated that the expression patterns of the same protein were similar in testes at different ages and that the positive staining cell types were mainly Leydig cells, type A and B spermatogonia, leptotene spermatocytes and spermatids for H3K4me1/2/3, Leydig cells, type A spermatogonia, zygotene and pachytene spermatocytes, spermatids, and Sertoli cells for LSD1 and type A and B spermatogonia for RBP2. Immunostaining for SMCX was not detected in testes. Quantitative real-time PCR and Western blot showed that the amounts of LSD1, RPB2 and SMCX mRNA and protein were age-dependent, were significantly reduced with increasing age and exhibited a negative correlation with the protein levels of H3K4me1/2/3. Thus, H3K4me, which is modified by its demethylases, probably plays a role in male spermatogenesis and testis development.

Environmentally induced epigenetic transgenerational inheritance of male infertility

Decreasing male fertility has been observed for the past fifty years. Examples of affected reproductive parameters include decreases in sperm count and sperm quality and increases in testicular cancer, cryptorchidism and hypospadias. Exposures to environmental toxicants during fetal development and early postnatal life have been shown to promote infertility. Environmental exposures inducing epigenetic changes related to male infertility range from life style, occupational exposures, environmental toxicants and nutrition. Exposures during fetal gonadal sex determination have been shown to alter the epigenetic programming of the germline that then can transmit this altered epigenetic information to subsequent generations in the absence of any exposures. This environmentally induced epigenetic transgenerational inheritance of disease will be a component of the etiology of male infertility.

Receptors and signaling pathways involved in proliferation and differentiation of Sertoli cells

The identification of the hormones and other factors regulating Sertoli cell survival, proliferation, and maturation in neonatal, peripubertal, and pubertal life remains one of the most critical questions in testicular biology. The regulation of Sertoli cell proliferation and differentiation is thought to be controlled by cell-cell junctions and a set of circulating and local hormones and growth factors. In this review, we will focus on receptors and intracellular signaling pathways activated by androgen, follicle-stimulating hormone, thyroid hormone, activin, retinoids, insulin, insulin-like growth factor, relaxin, and estrogen, with special emphasis on estrogen receptors. Estrogen receptors activate intracellular signaling pathways that converge on cell cycle and transcription factors and play a role in the regulation of Sertoli cell proliferation and differentiation.

Endocannabinoids are Involved in Male Vertebrate Reproduction: Regulatory Mechanisms at Central and Gonadal Level

Endocannabinoids (eCBs) are natural lipids regulating a large array of physiological functions and behaviors in vertebrates. The eCB system is highly conserved in evolution and comprises several specific receptors (type-1 and type-2 cannabinoid receptors), their endogenous ligands (e.g., anandamide and 2-arachidonoylglycerol), and a number of biosynthetic and degradative enzymes. In the last few years, eCBs have been described as critical signals in the control of male and female reproduction at multiple levels: centrally, by targeting hypothalamic gonadotropin-releasing-hormone-secreting neurons and pituitary, and locally, with direct effects on the gonads. These functions are supported by the extensive localization of cannabinoid receptors and eCB metabolic enzymes at different levels of the hypothalamic-pituitary-gonadal axis in mammals, as well as bonyfish and amphibians. In vivo and in vitro studies indicate that eCBs centrally regulate gonadal functions by modulating the gonadotropin-releasing hormone-gonadotropin-steroid network through direct and indirect mechanisms. Several proofs of local eCB regulation have been found in the testis and male genital tracts, since eCBs control Sertoli and Leydig cells activity, germ cell progression, as well as the acquisition of sperm functions. A comparative approach usually is a key step in the study of physiological events leading to the building of a general model. Thus, in this review, we summarize the action of eCBs at different levels of the male reproductive axis, with special emphasis, where appropriate, on data from non-mammalian vertebrates.

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.

Environmental epigenetics and effects on male fertility

Environmental exposures to factors such as toxicants or nutrition can have impacts on testis biology and male fertility. The ability of these factors to influence epigenetic mechanisms in early life exposures or from ancestral exposures will be reviewed. A growing number of examples suggest environmental epigenetics will be a critical factor to consider in male reproduction.