anandamide and Infertility--Male

Epidemiological studies have highlighted the ever growing use of illegal drugs among teenagers. The negative effects of marijuana (a Cannabis sativa extract) on reproductive health are poorly known among young people, although chronic exposure to delta-9-tetrahydrocannabinol, the main psychoactive constituent of marijuana, impairs human reproductive potential by disrupting menstrual cycle, suppressing oogenesis and impairing embryo implantation and development, in women, and by increasing ejaculation problems, reducing sperm count and motility, and generating loss of libido and impotence, in men. Endocannabinoids, their metabolic enzymes and target receptors form the so called "endocannabinoid system" and they have been demonstrated to respond to fertility signals. In addition, they interfere with hormones, cytokines and other signalling molecules in both female and male reproductive events. In this review, we shall summarize the current knowledge on the endocannabinoid system, and on the multifaceted roles played by endocannabinoids in reproduction along the evolutionary axis from invertebrates to mammals. Furthermore, we shall discuss the potential use of distinct elements of the endocannabinoid system for the diagnosis and/or treatment of human infertility.

Topics: Adolescent; Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Embryo Implantation; Endocannabinoids; Female; Fertility; Humans; Infertility, Female; Infertility, Male; Male; Polyunsaturated Alkamides; Pregnancy; Receptors, Cannabinoid; Reproduction; Signal Transduction

What are the levels of anandamide (N-arachidonoylethanolamide, AEA) in human seminal plasma and how are these related to abnormal spermatozoa?. Seminal plasma AEA levels were lower in men with asthenozoospermia and oligoasthenoteratozoospermia compared with normozoospermic men.. AEA, a bioactive lipid, synthesized from membrane phospholipids may signal through cannabinoid receptors (CB1 and CB2) to regulate human sperm functions and male reproduction by modulating sperm motility, capacitation and the acrosome reaction in vitro. Local AEA levels are regulated by the synthetic and degradative enzymes, NAPE-PLD and FAAH, respectively. How the deregulation of this endogenous signalling pathway affects human sperm function(s) is not clear.. This was a cross-sectional study of 86 men presenting at an infertility clinic for semen analysis over a period of 2 years.. AEA was quantified, by ultra-high performance liquid chromatography-tandem mass spectrometry, in seminal plasma from 86 volunteers. Using qRT-PCR, CB1, CB2, NAPE-PLD and FAAH transcript levels were determined in spermatozoa from men with normozoospermia, asthenozoospermia, oligoasthenoteratozoospermia and teratozoospermia. Normal spermatozoa were exposed in vitro to methanadamide (meth-AEA) to determine its effect on sperm motility, viability and mitochondrial activity.. Seminal plasma AEA levels (mean ± SEM) were significantly lower in men with asthenozoospermia (0.080 ± 0.01 nM; P < 0.05) or oligoasthenoteratozoospermia (0.083 ± 0.01 nM; P < 0.05) compared with normozoospermic men (0.198 ± 0.03 nM). In addition, the levels of spermatozoal CB1 mRNA were significantly decreased in men with asthenozoospermia (P < 0.001) or oligoasthenoteratozoospermia (P < 0.001) compared with normozoospermic controls. Supra-physiological levels of meth-AEA decreased sperm motility and viability, probably through CB1-mediated inhibition of mitochondrial activity.. The inhibitory effect of meth-AEA was only shown in vitro and may not reflect what happens in vivo.. As the regulation of the endocannabinoid system appears to be necessary for the preservation of normal sperm function and male fertility, there may be implications for the adverse reproductive consequences of marijuana use. Exocannabinoids, such as Δ(9)-THC, are likely to compete with endocannabinoids at the cannabinoid receptors, upsetting the finely balanced endocannabinoid signalling system. The importance of the endocannabinoid system makes it an attractive target for pharmacological interventions to control male fertility.. This work was funded in part by miscellaneous educational funds from the University Hospitals of Leicester National Health Services Trust to support the Endocannabinoid Research Laboratory of University of Leicester. The authors declare no competing interests.

Topics: Amidohydrolases; Arachidonic Acids; Chromatography, High Pressure Liquid; Cross-Sectional Studies; Endocannabinoids; Flow Cytometry; Humans; Infertility, Male; Male; Membrane Potential, Mitochondrial; Mitochondria; Phospholipase D; Polyunsaturated Alkamides; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; RNA, Messenger; Semen; Sperm Motility; Spermatozoa; Tandem Mass Spectrometry

Marijuana is the most commonly used illicit drug. Although there is some indication that reproductive functions in males are impaired in chronic marijuana users, the genetic evidence and underlying causes remain largely unknown. Herein we show that genetic loss of Faah, which encodes fatty acid amide hydrolase (FAAH), results in elevated levels of anandamide, an endocannabinoid, in the male reproductive system, leading to compromised fertilizing capacity of sperm. This defect is rescued by superimposing deletion of cannabinoid receptor 1 (Cnr1). Retention of Faah(-/-) sperm on the egg zona pellucida provides evidence that the capacity of sperm to penetrate the zona barrier is hampered by elevated anandamide levels. Collectively, the results show that aberrant endocannabinoid signaling via CNR1 impairs normal sperm function. Besides unveiling a new regulatory mechanism of sperm function, this study has clinical significance in male fertility.

Topics: Amidohydrolases; Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Endocannabinoids; Gene Deletion; Genetic Complementation Test; Infertility, Male; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutagenesis, Site-Directed; Polyunsaturated Alkamides; Receptor, Cannabinoid, CB1; Signal Transduction; Sperm Motility; Spermatozoa; Urogenital System

Human spermatozoa express type-1 cannabinoid receptor (CB1), whose activation by anandamide (AEA) affects motility and acrosome reaction (AR). In this study, we extended the characterization of the AEA-related endocannabinoid system in human spermatozoa, and we focused on the involvement of the AEA-binding vanilloid receptor (TRPV1) in their fertilizing ability. Protein expression was revealed for CB1 ( approximately 56 kDa), TRPV1 ( approximately 95 kDa), AEA-synthesizing phospholipase D (NAPE-PLD) ( approximately 46 kDa), and AEA-hydrolyzing enzyme [fatty acid amide hydrolase (FAAH), approximately 66 kDa]. Both AEA-binding receptors (CB1 and TRPV1) exhibited a functional binding activity; enzymatic activity was demonstrated for NAPE-PLD, FAAH, and the purported endocannabinoid membrane transporter (EMT). Immunoreactivity for CB1, NAPE-PLD, and FAAH was localized in the postacrosomal region and in the midpiece, whereas for TRPV1, it was restricted to the postacrosomal region. Capsazepine (CPZ), a selective antagonist of TRPV1, inhibited progesterone (P)-enhanced sperm/oocyte fusion, as evaluated by the hamster egg penetration test. This inhibition was due to a reduction of the P-induced AR rate above the spontaneous AR rate, which was instead increased. The sperm exposure to OMDM-1, a specific inhibitor of EMT, prevented the promoting effect of CPZ on spontaneous AR rate and restored the sperm responsiveness to P. No significant effects could be observed on sperm motility. In conclusion, this study provides unprecedented evidence that human spermatozoa exhibit a completely functional endocannabinoid system related to AEA and that the AEA-binding TRPV1 receptor could be involved in the sperm fertilizing ability.

Topics: Acrosome Reaction; Amidohydrolases; Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Capsaicin; Cricetinae; Endocannabinoids; Humans; Infertility, Male; Male; Phospholipase D; Polyunsaturated Alkamides; Progesterone; Receptor, Cannabinoid, CB1; Spermatozoa; TRPV Cation Channels