PMID- 23406974
OWN - NLM
STAT- MEDLINE
DCOM- 20130926
LR  - 20220321
IS  - 1460-2350 (Electronic)
IS  - 0268-1161 (Print)
IS  - 0268-1161 (Linking)
VI  - 28
IP  - 4
DP  - 2013 Apr
TI  - The clinical significance of calcium-signalling pathways mediating human sperm 
      hyperactivation.
PG  - 866-76
LID - 10.1093/humrep/des467 [doi]
AB  - STUDY QUESTION: What is the prevalence of defects in the Ca(2+)-signalling 
      pathways mediating hyperactivation (calcium influx and store mobilization) among 
      donors and sub-fertile patients and are they functionally significant, i.e. 
      related to fertilization success at IVF? SUMMARY ANSWER: This study identifies, 
      for the first time, the prevalence of Ca(2+) store defects in sperm from research 
      donors, IVF and ICSI patients. It highlights the biological role and importance 
      of Ca(2+) signalling (Ca(2+) store mobilization) for fertilization at IVF. WHAT 
      IS KNOWN ALREADY: Sperm motility and hyperactivation (HA) are important for 
      fertility, mice with sperm incapable of HA are sterile. Recently, there has been 
      significant progress in our knowledge of the factors controlling these events, in 
      particular the generation and regulation of calcium signals. Both pH-regulated 
      membrane Ca(2+) channels (CatSper) and Ca(2+) stores (potentially activating 
      store-operated Ca(2+) channels) have been implicated in controlling HA. STUDY 
      DESIGN, SIZE, AND DURATION: This was a prospective study examining a panel of 68 
      donors and 181 sub-fertile patients attending the Assisted Conception Unit, 
      Ninewells Hospital Dundee for IVF and ICSI. Twenty-five of the donors gave a 
      second sample ( approximately 4 weeks later) to confirm consistency/reliability of the recorded 
      responses. Ca(2+) signalling was manipulated using three agonists, NH4Cl 
      (activates CatSper via pH), progesterone (direct activation of CatSper channels, 
      potentially enhancing mobilization of stored Ca(2+) by CICR) and 4-aminopyridine 
      (4-AP) (effect on pH equivalent to NH4Cl and mobilizes stored Ca(2+)). The 
      broad-spectrum phosphodiesterase inhibitor 3-isobutyl-1-methyxanthine (IBMX), a 
      potent activator of HA was also used for comparison. For patient samples, an 
      aliquot surplus to requirements for IVF/ICSI treatment was examined, allowing 
      direct comparison of Ca(2+) signalling and motility data with functional 
      competence of the sperm. MATERIALS, SETTING, METHODS: The donors and sub-fertile 
      patients were screened for HA (using CASA) and changes in intracellular Ca(2+) 
      were assessed by loading with Fura-2 and measuring fluorescence using a plate 
      reader (FluoStar). MAIN RESULTS AND THE ROLE OF CHANCE: The relative efficacy of 
      the stimuli in inducing HA was 4-AP >> IBMX > progesterone. NH4Cl increased 
      [Ca(2+)]i similarly to 4-AP and progesterone but did not induce a significant 
      increase in HA. Failure of samples to generate HA (no significant increase in 
      response to stimulation with 4-AP) was seen in just 2% of research donors but 
      occurred in 10% of IVF patients (P = 0.025). All donor samples generated a 
      significant [Ca(2+)]i increase when stimulated with 4-AP but 3.3% of IVF and 
      28.6% of ICSI patients failed to respond. Amplitudes of HA and [Ca(2+)]i 
      responses to 4-AP were correlated with fertilization rate at IVF (P= 0.029; P = 
      0.031, respectively). Progesterone reliably induced [Ca(2+)]i responses (97% of 
      donors, 100% of IVF patients) but was significantly less effective than 4-AP in 
      inducing HA. Twenty seven per cent of ICSI patients failed to generate a 
      [Ca(2+)]i response to progesterone (P= 0.035). Progesterone-induced [Ca(2+)]i 
      responses were correlated with fertilization rate at IVF (P= 0.037) but induction 
      of HA was not. In donor samples examined on more than one occasion consistent 
      responses for 4-AP-induced [Ca(2+)]i (R(2) = 0.97) and HA (R(2) = 0.579) were 
      obtained. In summary, the data indicate that defects in Ca(2+) signalling leading 
      to poor HA do occur and that ability to undergo Ca(2+) -induced HA affects IVF 
      fertilizing capacity. The data also confirm that release of stored Ca(2+) is the 
      crucial component of Ca(2+) signals leading to HA and that Ca(2+) store defects 
      may therefore underlie HA failure. LIMITATIONS, REASONS FOR CAUTION: This is an 
      in vitro study of sperm function. While the repeatability of the [Ca(2+)]i and HA 
      responses in samples from the same donor were confirmed, data for patients were 
      from 1 assessment and thus the robustness of the failed responses in patients' 
      needs to be established. The focus of this study was on using 4AP, which 
      mobilizes stored Ca(2+) and is a potent inducer of HA. The n values for other 
      agonists, especially calcium assessments, are smaller. WIDER IMPLICATIONS OF THE 
      FINDINGS: Previous studies have shown a significant relationship between basal 
      levels of HA, calcium responses to progesterone and IVF fertilization rates. 
      Here, we have systematically investigated the ability/failure of human sperm to 
      generate Ca(2+) signals and HA in response to targeted pharmacological challenge 
      and, related defects in these responses to IVF success. [Ca(2+)]i signalling is 
      fundamental for sperm motility and data from this study will lead to assessment 
      of the nature of these defects using techniques such as single-cell imaging and 
      patch clamping. STUDY FUNDING/COMPETING INTEREST(S): Resources from a Wellcome 
      Trust Project Grant (#086470, Publicover and Barratt PI) primarily funded the 
      study. The authors have no competing interests.
FAU - Alasmari, Wardah
AU  - Alasmari W
AD  - Reproductive and Developmental Biology, Medical School, Ninewells Hospital, 
      University of Dundee, Dundee DD1 9SY, UK.
FAU - Barratt, Christopher L R
AU  - Barratt CL
FAU - Publicover, Stephen J
AU  - Publicover SJ
FAU - Whalley, Katherine M
AU  - Whalley KM
FAU - Foster, Erica
AU  - Foster E
FAU - Kay, Vanessa
AU  - Kay V
FAU - Martins da Silva, Sarah
AU  - Martins da Silva S
FAU - Oxenham, Senga K
AU  - Oxenham SK
LA  - eng
GR  - 086470/Wellcome Trust/United Kingdom
GR  - MRC_/Medical Research Council/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130212
PL  - England
TA  - Hum Reprod
JT  - Human reproduction (Oxford, England)
JID - 8701199
RN  - 01Q9PC255D (Ammonium Chloride)
RN  - 4G7DS2Q64Y (Progesterone)
RN  - BH3B64OKL9 (4-Aminopyridine)
SB  - IM
MH  - 4-Aminopyridine/pharmacology
MH  - Ammonium Chloride/pharmacology
MH  - Calcium Signaling/drug effects/*physiology
MH  - Fertilization/physiology
MH  - Fertilization in Vitro
MH  - Humans
MH  - Infertility, Male/*metabolism
MH  - Male
MH  - Progesterone/pharmacology
MH  - Sperm Motility/drug effects
MH  - Spermatozoa/drug effects/metabolism/*physiology
PMC - PMC3600839
MID - EMS51993
OID - NLM: EMS51993
EDAT- 2013/02/15 06:00
MHDA- 2013/09/27 06:00
PMCR- 2013/02/12
CRDT- 2013/02/15 06:00
PHST- 2013/02/15 06:00 [entrez]
PHST- 2013/02/15 06:00 [pubmed]
PHST- 2013/09/27 06:00 [medline]
PHST- 2013/02/12 00:00 [pmc-release]
AID - des467 [pii]
AID - 10.1093/humrep/des467 [doi]
PST - ppublish
SO  - Hum Reprod. 2013 Apr;28(4):866-76. doi: 10.1093/humrep/des467. Epub 2013 Feb 12.