Capacitation-like changes in equine spermatozoa following cryopreservation

A. D. Thomas, S. A. Meyers, B. A. Ball

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


The primary objective of this study was to assess plasma membrane characteristics and activation of signal transduction pathways in equine spermatozoa during both in vitro capacitation and cryopreservation. Significant plasma membrane restructuring, as assessed by measurement of plasma membrane lipid disorder and phospholipid scrambling, was not observed until after cryopreservation and subsequent thawing (P < 0.05). Although in vitro capacitated cells also displayed increased plasma membrane lipid disorder and phospholipid scrambling (P < 0.05), it appeared that regulation of these events in in vitro capacitated versus cryopreserved equine spermatozoa was not identical. Addition of 5 μM staurosporine to the capacitation media reduced plasma membrane phospholipid scrambling (P < 0.05), but supplementation to the freezing extender prior to cryopreservation did not. Furthermore, progesterone was able to induce a greater degree of acrosomal exocytosis in in vitro capacitated versus frozen/thawed spermatozoa. Expression of phospholipid scramblase, a protein thought to be important in plasma membrane phospholipid scrambling, did not differ between treatments. Comparison of protein tyrosine phosphorylation patterns between in vitro capacitated and cryopreserved cells demonstrated a divergence in signal transduction. Cellular signaling in in vitro capacitated equine spermatozoa appeared to be in part dependent on activation of the cAMP/PKA pathway, whereas signaling in cryopreserved cells seemed to proceed predominantly through alternative pathways. Taken together, these data support the idea that capacitation and "cryocapacitation" are not equivalent processes.

Original languageEnglish
Pages (from-to)1531-1550
Number of pages20
Issue number8
StatePublished - May 2006

Bibliographical note

Funding Information:
This project was supported by the USDA-CSREES No. 2002 – 02074 as well as the Center for Equine Health, UC Davis, with funds provided by the Oak Tree Racing Association, the State of California pari-mutuel fund, and contributions by private donors. The experiments utilizing flow cytometry were conducted in a facility constructed with support from Research Facilities Improvement Program Grant Number C06 RR-12088-01 from the National Center for Research Resources, National Institutes of Health. The authors would also like to thank Barbara Stewart and Dr. Wynne Collins of the School of Veterinary Medicine and Jennifer Linfor, Andrea Brum, Latisha Burnaugh and Josh Boone for their assistance with semen collections.


  • Capacitation
  • Cryocapacitation
  • Cryopreservation
  • Equine
  • Sperm

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine


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