Human Sperm Anatomy: Ultrastructural Localization of the Cannabinoid1 Receptor and a Potential Role of Anandamide in Sperm Survival and Acrosome Reaction

Abstract

Recently, the endocannabinoid (EC) system and the presence of CB1 receptor (CB1-R), have been identified in human sperm. However, the effects of EC receptor ligands such as anandamide (N-arachidonoylethanolamine) and the role of EC system in male fertility is still largely unexplored. In the present study, we investigated the ultrastructural compartmentalization of CB1-R and analyzed the effects of its stimulation by using a stable analog of anandamide, 2-methylarachidonyl-2 0 -fluoro-ethylamide (MET-F-AEA). We focused particularly on sperm survival and acrosin activity. The study of human sperm anatomy by transmission electron microscopy with immunogold analysis revealed the location of the CB1-R prevalently in the sperm membranes of the head and interestingly on the mitochondria. The effect of different concentrations of MET-F-AEA from 100 nM to 1 lM evidenced a significant decrease of sperm survival. Interestingly, we analyzed this negative effect at molecular level, testing the EC action on different known sperm survival targets. MET-F-AEA-treatment decreased both pBCL2 and pAkt, two prosurvival proteins, and increased pPTEN expression which is the main regulator of the PI3K/Akt pathway. Moreover, a biphasic effect was observed with increasing MET-F-AEA concentrations on the acrosin activity. The blockage of the CB1-R by using its selective antagonist SR141716 (rimonabant) induced an opposite action on sperm survival supporting a role for this receptor in the biology of the male gamete. Anat Rec,[293][294][295][296][297][298][299][300][301][302][303][304][305][306][307][308][309]

Marijuana, phytocannabinoids, the endocannabinoid system, and male fertility

“…Met AEA (stable form of AEA) was shown to decrease human sperm motility and viability via its action through CB1 [69]. Several other in vitro studies on human spermatozoa are in agreement with these findings [46,47,64,107]. Whan et al [108] exposed human spermatozoa to both therapeutic and recreational levels of THC and showed clearly that it reduced the percentage of motile and progressively motile spermatozoa, while the kinematic parameters such as straight line velocity and average path velocity were also decreased.…”

“…CB1 has been localized to the plasma membrane of the acrosomal region, midpiece, and tail of the spermatozoon, while CB2 receptors are mostly localized in the postacrosomal region as well as midpiece and tail [46,47,64]. The transporters as well as enzymes responsible for synthesis and hydrolysis of endocannabinoids have also been identified in the male gametes of various species, including humans.…”

Cannabinoid CB1 Receptors Are Localized in Striated Muscle Mitochondria and Regulate Mitochondrial Respiration

“…As the functional significance, the activation of CB 1 receptors localized in different body tissues (brain, liver, skeletal muscle, pancreas, adipose tissue) participates in cellular and metabolic functions of the organism (Piomelli, 2003; Silvestri and Di Marzo, 2013; Iannotti et al, 2014; Mazier et al, 2015; Palomba et al, 2015) and regulates the mitochondrial biogenesis in non-neuronal peripheral tissues (Aquila et al, 2010; Tedesco et al, 2010). There are pieces of evidence indicating that mitochondria contain G proteins (Lyssand and Bajjalieh, 2007; Andreeva et al, 2008) and their effector signaling molecules such as soluble adenyl cyclase (Zippin et al, 2003), phosphodiesterase (Acin-Perez et al, 2011) and protein kinase A (PKA) (Ryu et al, 2005).…”

Multigenerational and transgenerational inheritance of drug exposure: The effects of alcohol, opiates, cocaine, marijuana, and nicotine

“…Endocannabinoid signaling has been implicated in oocyte maturation, ovulation, and fertility signals (Battista et al, 2012). In addition, cannabinoid receptor localization has been characterized in testes (Schuel et al, 2002) and sperm (Aquila et al, 2010). Furthermore, anandamide analog administration alters the PI3K/Akt cell survival pathway in sperm (Aquila et al, 2010).…”

“…In addition, cannabinoid receptor localization has been characterized in testes (Schuel et al, 2002) and sperm (Aquila et al, 2010). Furthermore, anandamide analog administration alters the PI3K/Akt cell survival pathway in sperm (Aquila et al, 2010). Further research is required to identify the direct or indirect epigenetic changes caused by marijuana administration in gametes.…”