Effects of angiotensin II on the acrosome reaction in equine spermatozoa
Angiotensin II is a hormone with a wide array of physiological effects that exerts its effect via interaction with two major subtypes of receptor. The results of this study show that angiotensin II (from 1 to 100 nmol l(-1)) initiates acrosomal exocytosis in equine spermatozoa that have undergone ca...
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Published in | Journal of reproduction & fertility Vol. 120; no. 1; pp. 135 - 142 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
England
Society for Reproduction and Fertility
01.09.2000
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Subjects | |
Online Access | Get full text |
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Summary: | Angiotensin II is a hormone with a wide array of physiological effects that exerts its effect via interaction with two major
subtypes of receptor. The results of this study show that angiotensin II (from 1 to 100 nmol l(-1)) initiates acrosomal exocytosis
in equine spermatozoa that have undergone capacitation in vitro in a TALP-TEST (Tyrode's albumin lactate pyruvate; 188.7 mmol
TES l(-1), 84.8 mmol Tris l(-1)) buffer with cAMP. The acrosome reaction and sperm viability were assessed with fluorescein
isothiocyanate-Pisum sativum agglutinin (FITC-PSA) and Hoechst 33258, respectively. The initiation of the acrosome reaction
by angiotensin II was strongly inhibited by losartan, a specific angiotensin II type 1 receptor antagonist. Although angiotensin
II as well as progesterone both initiated the acrosome reaction in equine spermatozoa, there was no synergistic effect when
both agonists were added simultaneously. Initiation of acrosomal exocytosis by angiotensin II was accompanied by a rapid and
transient calcium influx that was assessed in capacitated spermatozoa loaded with Fura-2AM. In addition, the angiotensin II-mediated
calcium influx was inhibited when spermatozoa were preincubated with losartan. Western blotting with an antibody against angiotensin
II type 1 receptor detected a major sperm protein of 60 kDa. Indirect immunofluorescence of non-capacitated spermatozoa with
the angiotensin II type 1 receptor antibody revealed labelling in the midpiece and tail. In capacitated spermatozoa, the angiotensin
II type 1 receptor was localized mainly over the anterior region of the sperm head, the equatorial segment and occasionally
on the postacrosomal region in addition to the sperm tail. In conclusion, this study demonstrated the ability of angiotensin
II to stimulate the acrosome reaction in capacitated equine spermatozoa. This effect is mediated via the angiotensin II type
1 receptor and is accompanied by an increase in intracellular calcium. |
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ISSN: | 1470-1626 0022-4251 1741-7899 |
DOI: | 10.1530/jrf.0.1200135 |