Evidence that nitric oxide synthase is involved in progesterone-induced acrosomal exocytosis in mouse spermatozoa.
In a recent work, we detected nitric oxide synthase (NO synthase) in the acrosome and tail of mouse and human spermatozoa by an immunofluorescence technique. Also, NO-synthase inhibitors added during sperm capacitation in vitro reduced the percentage of oocytes fertilized in vitro, suggesting a role for NO synthase in sperm function. Therefore, in the present study the effect of three NO-synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME), NG-nitro-D-arginine methyl ester (D-NAME) and L-NG-nitro-arginine (NO2-arg), and of a nitric oxide donor, spermine-NONOate, on the progesterone-induced acrosome reaction of mouse sperm was examined. NO-synthase inhibitors were added at 0, 60 or 90 min during capacitation; at 120 min, mouse epididymal spermatozoa were exposed to 15 microM progesterone for another 15 min. In another set of experiments, different concentrations of spermine-NONOate were added to capacitated spermatozoa for 15 min; in these experiments, progesterone was not included. NO2-arg and L-NAME blocked progesterone-induced exocytosis regardless of the time at which these inhibitors were added. Moreover, D-NAME did not inhibit exocytosis. In contrast, spermine-NONOate stimulated the acrosomal exocytosis in vitro directly. These results provide evidence that mouse sperm NO synthase participates in the progesterone-induced acrosome reaction in vitro and that nitric oxide induces this event.
Herrero
M B
MB
Centro de Estudios Farmacológicos y Botánicos, Buenos Aires, Argentina.
Viggiano
J M
JM
Pérez Martínez
S
S
de Gimeno
M F
MF
D000177:Acrosome / Q000187:drug effects*; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology*; D019335:Nitroarginine / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D013094:Spermatozoa / Q000187:drug effects* / Q000648:ultrastructure; D013237:Stereoisomerism; D013268:Stimulation, Chemical
D004791:Enzyme Inhibitors; D019335:Nitroarginine; D011374:Progesterone; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester