Premium
Involvement of cannabinoid receptor‐1 activation in mitochondrial depolarizing effect of lipopolysaccharide in human spermatozoa
Author(s) -
Barbonetti A.,
Vassallo M. R. C.,
Costanzo M.,
Battista N.,
Maccarrone M.,
Francavilla S.,
Francavilla F.
Publication year - 2014
Publication title -
andrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.947
H-Index - 43
eISSN - 2047-2927
pISSN - 2047-2919
DOI - 10.1111/j.2047-2927.2014.00210.x
Subject(s) - endocannabinoid system , cannabinoid receptor , tlr4 , cannabinoid , lipopolysaccharide , biology , sperm , receptor , flow cytometry , microbiology and biotechnology , pharmacology , chemistry , biochemistry , endocrinology , antagonist , botany
Summary Gram‐negative bacteria frequently involved in urogenital tract infections release the endotoxin lipopolysaccharide ( LPS ); its receptor, toll‐like receptor‐4 ( TLR 4), has been recently identified in human spermatozoa, and its direct activation has been suggested in mediating adverse effects of LPS on human spermatozoa. However, the underlying signal transduction remains to be clarified. In other cell types, LPS induces the generation of endocannabinoids, which are involved in mediating endotoxin effects. In human spermatozoa, which exhibit a completely functional endocannabinoid system, the activation of cannabinoid receptor‐1 ( CB 1) inhibited sperm mitochondrial membrane potential (ΔΨm). In this study, we tested the hypothesis of a contribution of CB 1 activation by sperm‐generated endocannabinoids in the adverse effects exerted by LPS on human spermatozoa. The exposure of motile sperm suspensions to E. coli LPS produced a significant decrease in sperm ΔΨm, assessed at flow cytometry with JC ‐1, similar to that induced by Metanandamide (Met‐ AEA ), a non‐hydrolyzable analogue of the endocannabinoid AEA . The LPS ‐induced inhibition of ΔΨm was prevented by the selective CB 1 cannabinoid receptor antagonist, SR 141716. However, the inhibition of ΔΨm induced by either LPS or Met‐ AEA did not affect sperm motility. Consistent with this finding, the CB 1‐mediated inhibition of ΔΨm was neither associated to mitochondrial generation of reactive oxygen species as evaluated by flow cytometry with MytoSox Red nor to apoptosis pathway activation as evaluated with cytoflorimetric assay for activated caspase‐9 and caspase‐3. Any oxidative genomic damage was also ruled out with the cytoflorimetric quantification of the oxidized base adduct 8‐hydroxy‐2′‐deoxyguanosine. In conclusion, E. coli LPS inhibited sperm ΔΨm through the activation of CB 1, but this effect was not accompanied to the activation of mitochondrial dysfunction‐related apoptotic/oxidative mechanisms, which could affect sperm motility and genomic integrity.