Effects of the anticonvulsant drug Dilantin on cell cycle progression in preimplantation mouse embryos

• Main Author: Blosser, Rachel J.
• Other Authors: Chatot, Clare L.
• Format: Others
• Published: 2011
• Subjects: Cell cycle.; Phenytoin.; Embryology.
• Online Access: http://cardinalscholar.bsu.edu/handle/handle/187495; http://liblink.bsu.edu/uhtbin/catkey/1273261

Embryonic exposure to the anticonvulsant drug Dilantin has been shown to have detrimental effects on development. Some of the observed effects include growth retardation, craniofacial defects, and even death. As the drug is metabolized, toxic intermediates form, which could be causing the characteristic abnormalities observed in embryos exposed to Dilantin. Culture of preimplantation mouse embryos in the presence of IOµg/mL or 20µglmL Dilantin show a slowing of development inl9.3% and 19.1% ofembryos respectively at Day 3 of culture. The toxic intermediates could be causing alterations in cyclin expression, cell cycle proteins, or the cell cycle timing itself. Previous research determined an in vivo baseline expression for cyclins B 1, E, D, A and cdk2, which was used to compare the expression of these cyclins and cdks between in vivo and Dilantin cultured embryos. Altered patterns in cultured embryos suggested that an alteration in cell cycle timing, therefore, S phase timing was determined in cultured untreated embryos utilizing 5'-Bromo-2-deoxyuridine (BrdU) incorporation and indirect immunofluorescence staining. The results of the experiment showed the second S phase was at 30 hpf, approximately 9 hours later, and the third S phase was at 54 hpf, approximately 3 hours later than previous in vivo literature reports. S phase timing in NaOH vehicle controls did not appear different from untreated controls. Dilantin showed S phase peaks at 24 and 55 hpf. In the Dilantin treated embryos, the nuclear staining intensity for the second S phase did not decrease as rapidly as had been observed in control embryos. Embryos that developed beyond the 2-cell stage demonstrated two distinct S phase peaks at 45 and 54 hpf, while embryos at the 2-cell stage did pass through the second S phase but not the third S phase. These data suggested that the Dilantin could be causing a delay in G2. Future experiments would be necessary to determine if the expression of G2 cyclins are being altered in Dilantin treated embryos. === Department of Biology