Human sperm anatomy: ultrastructural localization of the cannabinoid1 receptor and a potential role of anandamide in sperm survival and acrosome reaction.
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'-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 microM 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.
Aquila
Saveria
S
Department of Pharmaco-Biology, University of Calabria, Arcavacata di Rende, Cosenza, Italy.
Guido
Carmela
C
Santoro
Antonietta
A
Perrotta
Ida
I
Laezza
Chiara
C
Bifulco
Maurizio
M
Sebastiano
Andò
A
D000176:Acrosin / Q000378:metabolism; D020101:Acrosome Reaction / Q000187:drug effects; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids; D006801:Humans; D007150:Immunohistochemistry; D008024:Ligands; D008297:Male; D046529:Microscopy, Electron, Transmission; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000187:drug effects / Q000378:metabolism*; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D000077285:Rimonabant; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*
C443759:2-methylarachidonyl-2'-fluoroethylamide; D001095:Arachidonic Acids; D063388:Endocannabinoids; D008024:Ligands; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D000176:Acrosin; D000077285:Rimonabant; C078814:anandamide