title: Hatching and distribution of actin filaments in mouse blastocysts whose activities of protein kinase A were suppressed by H-89.
abstract: The role of actin filaments and contractions in hatching was determined in mouse blastocysts whose actin filament bundling abilities had been suppressed by H-89, an inhibitor of protein kinase A. The hatching rate of blastocysts developed from morulae in a medium containing H-89 at a concentration of 4.0 microM was 17.2%, which was significantly lower than the 76.7% of the control blastocysts developed from morulae in a medium without H-89. The rates of blastocysts starting hatching and forming a slit in the zona pellucida were significantly lower in H-89-treated blastocysts (84.4 and 21.9%) than in control blastocysts (100.0 and 90.6%). The lengths of time needed for slit formation in the zona pellucida and for completion of hatching were significantly longer in the H-89-treated blastocysts (27.4 and 43.3 h) than in the control blastocysts (6.5 and 18.8 h). Over the course of 32 h after blastocoel formation, the number of strong contractions was similar in the H-89-treated and control blastocysts, but the number of weak contractions was significantly fewer in the H-89-treated blastocysts (2.41 times) than in the control blastocysts (4.19 times). Although the distribution of actin filaments was similar in the H-89-treated and control blastocysts in the pre-hatching, hatching and post-hatching periods, the rate of H-89-treated blastocysts in which most trophectoderm cells possessed the fluorescence of actin filaments (12.7%) was significantly lower than the 95.0% of the control blastocysts in the pre-hatching period. These results suggest that actin filament-mediated movements of trophectoderm cells contribute to hatching by facilitating the protrusion of trophectoderm cells from a small hole in the zona pellucida and by enlarging the protrusion. We also suggest that the low hatching ability of the treated blastocysts is related to weak contractions with a low frequency and to strong contractions requiring a longer time for re-expansion.
authors.affiliation: Graduate School of Science and Technology, Niigata University, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Suzuki
authors.forename: Sueo
authors.initials: S
authors.lastname: Niimura
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002465:Cell Movement; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D005260:Female; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D009028:Morula / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D015044:Zona Pellucida / Q000187:drug effects / Q000201:enzymology
chemical_list: D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide