Endocannabinoid System in Frog and Rodent Testis: Type-1 Cannabinoid Receptor and Fatty Acid Amide Hydrolase Activity in Male Germ Cells

• Published in: Biology of reproduction 2006-07, Vol.75 (1), p.82-89
• Main Authors: COBELLIS, Gilda, CACCIOLA, Giovanna, SCARPA, Donatella, MECCARIELLO, Rosaria, CHIANESE, Rosanna, FRANZONI, Maria Fosca, MACKIE, Ken, PIERANTONI, Riccardo, FASANO, Silvia
• Format: Article
• Language: English
• Subjects: Amidohydrolases - antagonists & inhibitors; Amidohydrolases - genetics; Amidohydrolases - metabolism; Animals; Arachidonic Acids - pharmacology; Biological and medical sciences; Biological Evolution; Cannabinoid Receptor Modulators - metabolism; Endocannabinoids; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Male; Mammalian male genital system; Mice; Morphology. Physiology; Polyunsaturated Alkamides; Rana esculenta; Rats; Rats, Sprague-Dawley; Receptors, Cannabinoid - genetics; Receptors, Cannabinoid - metabolism; Spermatozoa - drug effects; Spermatozoa - enzymology; Spermatozoa - metabolism; Testis - metabolism; Vertebrates: reproduction
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.106.051730

N-arachidonoylethanolamide (anandamide [AEA]) is the main endocannabinoid described to date in the testis. It exerts its effects through the activation of G-protein coupled cannabinoid receptors (CNR). However, the activity of AEA in controlling male reproduction is still poorly known. Here we provide direct evidence on the presence of the “endocannabinoid system,” constituted by type-1 cannabinoid receptor (CNR1) and fatty acid amide hydrolase (FAAH), in the frog Rana esculenta testis demonstrating its expression in tubular compartment. In fact, during the annual reproductive cycle, both proteins increase in September, when the appearance of spermatids (SPT) occurs. Immunocytochemistry confirms their localization in germ cells and, in particular, in elongated SPT. Signals are still present in spermatozoa (SPZ), as demonstrated by Western blot analysis. Furthermore, the activation of CNR1 reduces sperm motility. Comparative research, carried out using mouse and rat SPZ, definitely indicates that the endocannabinoid system operates in SPZ of phylogenetically distant species. A conserved physiological role of endocannabinoid system in controlling the inhibition of sperm motility is suggested. Abstract CNR1 and FAAH are present in germinal compartment of frog testis and in isolated spermatozoa.