title: ICSI-generated mouse zygotes exhibit altered calcium oscillations, inositol 1,4,5-trisphosphate receptor-1 down-regulation, and embryo development.
abstract: ICSI bypasses not only fusion of the gametes but also a series of signalling events that occur in the sperm prior to and during interaction with the oocyte's vestments. The effect of this altered encounter of the gametes on the fertilization-associated intracellular calcium ([Ca2+]i) oscillations has not been thoroughly investigated. Here, ICSI and IVF were performed using gametes from two mouse strains, B6D2F1 and CD1, and in-vitro development, pattern of [Ca2+]i oscillations and down-regulation of inositol 1,4,5-trisphosphate receptor-1 (IP3R-1) in the produced embryos were compared. ICSI and IVF resulted in comparable rates of activation and pre-implantation development. However, ICSI-generated zygotes cleaved at a slower rate, had lower cell numbers and lower hatching rates. The deleterious effects of ICSI could not be exclusively attributed to the injury by the injection since sham-injected IVF zygotes only exhibited delayed progression to the blastocyst stage. ICSI and IVF induced similar initial [Ca2+]i responses, although ICSI zygotes exhibited shorter durations of [Ca2+]i oscillations and showed diminished degradation of IP3R-1. Importantly, sperm manipulation affected the pattern of oscillations, which further decreased pre-implantation developmental rates. Our results demonstrate that ICSI-induced [Ca2+]i responses are not equivalent to those initiated by IVF and that this may have developmental consequences.
authors.affiliation: Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Manabu
authors.initials: M
authors.lastname: Kurokawa
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Fissore
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000196:embryology* / Q000378:metabolism*; D005314:Embryonic and Fetal Development; D005260:Female; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D051379:Mice; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D020554:Sperm Injections, Intracytoplasmic; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism; D015053:Zygote / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D002118:Calcium