Effects of angiotensin II on the acrosome reaction in equine spermatozoa.
Abstract: 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.
Publication Date: 2000-09-28 PubMed ID: 11006155
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The paper focuses on how the hormone angiotensin II, can trigger a particular reaction called the “acrosome reaction” in horse sperm that have been capacitated (made capable of successfully fusing with an egg) in a lab setting. It suggests this reaction is associated with an increase in the levels of calcium within the cells of the sperm.
Understanding the Role of Angiotensin II in Acrosome Reaction of Equine Spermatozoa
- The study discusses the important role that the hormone angiotensin II plays in initiating what is known as the ‘acrosome reaction’ in horse sperm that have undergone capacitation – a process which prepares the sperm for successful fusion with an egg, under laboratory conditions.
- Angiotensin II is typically known to have varied physiological effects, which are accomplished by interacting with two major types of receptors. The researchers have focused their study on understanding how this hormone influences the sperm cell’s acrosome reaction.
Finding Correlation between Acrosome Reaction and Sperm Viability
- The study has assessed the viability of the sperm and the acrosome reaction using specific markers like fluorescein isothiocyanate-Pisum sativum agglutinin (FITC-PSA) and Hoechst 33258.
- The acrosome reaction was found to be initiated by angiotensin II and this initiation was strongly inhibited by losartan, which specifically antagonizes one of the receptors of angiotensin II, the angiotensin II type 1 receptor.
Lack of Synergistic Effect of Angiotensin II with Progesterone
- While angiotensin II and progesterone both induced the acrosome reaction in equine sperm, the research found no synergistic, or enhanced effect when both were added together. This implies that both hormones trigger the reaction independently.
Role of Calcium and Inhibition by Losartan
- The acrosome reaction was found to be accompanied by a short, sharp increase in calcium inside the sperm cells.
- The study also found that the calcium influx caused by angiotensin II was inhibited if the sperm were pre-treated with losartan, reinforcing losartan’s role in blocking the action of angiotensin II.
Localisation of Angiotensin II type 1 Receptor in Equine Spermatozoa
- Additionally, using Western blotting and indirect immunofluorescence, the study managed to map the locations of the angiotensin II type 1 receptor on the sperm cells, both before and after capacitation.
Conclusion
- The research concludes that angiotensin II stimulates the acrosome reaction in equine sperm that have been capacitated. This effect comes through the angiotensin II type 1 receptor and is also accompanied with a raise in the sperm cell’s intracellular calcium levels.
Cite This Article
APA
Sabeur K, Vo AT, Ball BA.
(2000).
Effects of angiotensin II on the acrosome reaction in equine spermatozoa.
J Reprod Fertil, 120(1), 135-142.
Publication
Researcher Affiliations
- Department of Population Health and Reproduction, Room 1114 Tupper Hall, University of California, Davis, CA 95616, USA.
MeSH Terms
- Acrosome Reaction / drug effects
- Analysis of Variance
- Angiotensin II / pharmacology
- Angiotensin Receptor Antagonists
- Animals
- Calcium / metabolism
- Cells, Cultured
- Drug Synergism
- Horses / metabolism
- Immunoblotting
- Immunohistochemistry
- Intracellular Fluid / chemistry
- Intracellular Fluid / metabolism
- Losartan / pharmacology
- Male
- Progesterone / pharmacology
- Receptor, Angiotensin, Type 1
- Receptors, Angiotensin / analysis
- Sperm Capacitation
- Spermatozoa / chemistry
- Spermatozoa / metabolism
Citations
This article has been cited 6 times.- Corda PO, Santiago J, Fardilha M. G-Protein Coupled Receptors in Human Sperm: An In Silico Approach to Identify Potential Modulatory Targets.. Molecules 2022 Oct 1;27(19).
- Aparicio Prieto MV, Rodríguez Gallego MV, Valdivia Palacín A, Franco Iriarte Y, Hervás Barbara G, Echevarría Orella E, Casis Saenz L. Local renin angiotensin system and sperm DNA fragmentation.. Asian J Androl 2022 Mar-Apr;24(2):139-146.
- Aykan DA, Yaylali A, Eser N, Seyithanoglu M, Yaman S, Aykan AC. The effects of sacubitril/valsartan and ramipril on the male fertility in hypertensive rats.. North Clin Istanb 2020;7(5):425-432.
- Gianzo M, Subirán N. Regulation of Male Fertility by the Renin-Angiotensin System.. Int J Mol Sci 2020 Oct 26;21(21).
- Pascolo L, Zito G, Zupin L, Luppi S, Giolo E, Martinelli M, De Rocco D, Crovella S, Ricci G. Renin Angiotensin System, COVID-19 and Male Fertility: Any Risk for Conceiving?. Microorganisms 2020 Sep 28;8(10).
- Vedantam S, Rani R, Garg M, Atreja SK. Localization of angiotensin-II type 1(AT1) receptors on buffalo spermatozoa: AT1 receptor activation during capacitation triggers rise in cyclic AMP and calcium.. Mol Biol Rep 2014;41(4):1959-65.
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