Caspase activation in human spermatozoa in response to physiological and pathological stimuli.
OBJECTIVE
To investigate caspase activation in response to a variety of pathological and physiological stimuli in light of the fact that current research offers no clear consensus about caspase activation pathways in spermatozoa.


METHODS
A prospective, controlled study.


METHODS
Male infertility clinic, Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio.


METHODS
Fifteen healthy volunteers.


METHODS
Spermatozoa were exposed to [1] Fibroblast-associated (Fas) death receptor activation, [2] mitochondrial apoptosis induction using betulinic acid, [3] oxidative stress, and [4] prolonged incubation up to 3 hours without any external stimuli.


METHODS
Active caspases-1, -3, -8, and -9 were examined in human spermatozoa by flow cytometry using carboxyfluorescein derivatives.


RESULTS
Inducing Fas antibody did not result in any caspase activation. Conversely, betulinic acid significantly triggered caspase-9 and -3 activation. The application of oxidative stress and prolonged incubation (3 hours) failed to result in caspase activation.


CONCLUSIONS
These results suggest that Fas has no functional relevance in mediating caspase activation in human ejaculated spermatozoa. Although spermatozoal mitochondria are highly susceptible to specific agonists of apoptosis such as betulinic acid via caspase activation, oxidative stress-induced apoptosis appears to be caspase independent.
Grunewald
Sonja
S
Department of Dermatology/Andrology Unit, University of Leipzig, Leipzig, Germany.
Paasch
Uwe
U
Said
Tamer M
TM
Sharma
Rakesh K
RK
Glander
Hans-Juergen
HJ
Agarwal
Ashok
A
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020170:Caspase 1 / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D053978:Pentacyclic Triterpenes; D011446:Prospective Studies; D013094:Spermatozoa / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D014315:Triterpenes / Q000494:pharmacology; D019014:fas Receptor / Q000378:metabolism; D000094062:Betulinic Acid
D000972:Antineoplastic Agents, Phytogenic; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D019014:fas Receptor; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D020170:Caspase 1; D000094062:Betulinic Acid