Atrial natriuretic peptide induces acrosomal exocytosis in bovine
spermatozoa.
Zamir, Nadav, Dalit Barkan, Nurit Keynan, Zvi Naor, Haim Breitbart.
Department of Physiology and Pharmacology, Sackler School of
Medicine, Tel Aviv university, Tel Aviv 69978, Israel, Department of
Biochemistry, Faculty of Life Sciences, Tel Aviv University, Tel Aviv
69978, Israel, Department of Life Sciences, Bar Ilan University,
Ramat Gan 52900, Israel
APStracts 2:0061E, 1995.
The induction of acrosomal exocytosis in capacitated bull spermatozoa
by atrial natriuretic peptide (ANP) was studied in vitro. ANP
markedly stimulated acrosomal exocytosis in a calcium-dependent
manner. Typically, ANP exerts its action via activation of the ANP
receptor (ANPR-A), a particulate guanylyl cyclase-linked receptor,
and subsequent formation of cGMP. We found that the ANP-induced
acrosome reaction was inhibited by the competitive ANPR-A receptor
antagonist - anantin, indicating a receptor mediated effect. We could
mimic the effect of ANP on the acrosome reaction by using 8-Bromo
-cGMP, suggesting that cGMP may serve as a signal transducer mediating
the acrosome reaction. Indeed, ANP-induced acrosome reaction was
associated with elevation of cGMP levels. cGMP can also be formed by
activation of the soluble form of guanylyl cyclase. Sodium
nitroprusside (SNP) stimulated cGMP accumulation and acrosome
reaction of capacitated spermatozoa. Thus, ANP and NO-releasing
compound (SNP) via activation of guanylyl cyclase (the former
activating the particulate and the latter activating the soluble form
of the enzyme) may play a significant role in the induction of the
acrosome reaction.
Received 18 January 1995; accepted in final form 29 March 1995.
APS Manuscript Number E19-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.