Theophylline Induced Variations in Cyclic AMP Content of the Superovulated Preimplantation Mouse Embryo1

In order to investigate the role of cyclic AMP (cAMP) during early mammalian embryogenesis, the endogenous cAMP levels were determined on preimplantation mouse embryos using Gilman’s assay procedure and compared with levels of embryos cultivated in defined medium containing various concentrations of theophylline. Embryos were obtained by superovulation and oviductal flushing at day 2 of development. The LD50 (50 percent mortality corrected for natural mortality) level of embryo cultivation in theophylline for 48 h was 0.91 ± 0.06 mM. The LD50 for 72 h cultivation in theophylline was 0.84 ± 0.10 mM. At the conclusion of the 48 h cultivation period at 1.0 mM, the embryos appeared retarded in development and cAMP levels were raised significantly from the control level of 12.8 ± 4.1 p moles/1000 embryos to 419.3 ± 93.2 p moles/1000 embryos. If the embryos, which were cultured in various amounts of theophylline, were washed and cultured in control medium for an additional 24 h, the LD50 significantly changed to 1.36 ± 0.14 mM theophylline and the cAMP level dropped to normal at a measured 12.5 ± 6.3 p moles/1000 embryos. The interrelationship of theophylline effects and elevated cAMP levels are discussed.