An alkaline follicular fluid fraction induces capacitation and limited release of oviduct epithelium-bound stallion sperm.
Reproduction
; 150(3): 193-208, 2015 Sep.
Article
em En
| MEDLINE
| ID: mdl-26242588
ABSTRACT
Induction of hyperactivated motility is considered essential for triggering the release of oviduct-bound mammalian spermatozoa in preparation for fertilization. In this study, oviduct-bound stallion spermatozoa were exposed for 2 h to i) pre-ovulatory and ii) post-ovulatory oviductal fluid; iii) 100% and iv) 10% follicular fluid (FF); v) cumulus cells, vi) mature equine oocytes, vii) capacitating and viii) non-capacitating medium. None of these triggered sperm release or hyperactivated motility. Interestingly, native FF was detrimental to sperm viability, an effect that was negated by heat inactivation, charcoal treatment and 30 kDa filtration alone or in combination. Moreover, sperm suspensions exposed to treated FF at pH 7.9 but not pH 7.4 showed Ca(2+)-dependent hypermotility. Fluo-4 AM staining of sperm showed elevated cytoplasmic Ca(2+) in hyperactivated stallion spermatozoa exposed to treated FF at pH 7.9 compared to a modest response in defined capacitating conditions at pH 7.9 and no response in treated FF at pH 7.4. Moreover, 1 h incubation in alkaline, treated FF induced protein tyrosine phosphorylation in 20% of spermatozoa. None of the conditions tested induced widespread release of sperm pre-bound to oviduct epithelium. However, the hyperactivating conditions did induce release of 70-120 spermatozoa per oviduct explant, of which 48% showed protein tyrosine phosphorylation and all were acrosome-intact, but capable of acrosomal exocytosis in response to calcium ionophore. We conclude that, in the presence of elevated pH and extracellular Ca(2+), a heat-resistant, hydrophilic, <30 kDa component of FF can trigger protein tyrosine phosphorylation, elevated cytoplasmic Ca(2+) and hyperactivated motility in stallion sperm, but infrequent release of sperm pre-bound to oviduct epithelium.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Oviductos
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Capacitação Espermática
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Motilidade dos Espermatozoides
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Espermatozoides
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Líquido Folicular
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Adesão Celular
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Células Epiteliais
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Cavalos
Limite:
Animals
Idioma:
En
Revista:
Reproduction
Assunto da revista:
MEDICINA REPRODUTIVA
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Holanda