Effects of the pine needle abortifacient, isocupressic acid, on bovine oocyte maturation and preimplantation embryo development

Isocupressic acid (ICA) [15-hydroxylabda-8 (17), 13E-dien-19-oic acid], a labdane diterpene acid, isolated from ponderosa pine (Pinus ponderosa), Lodgepole pine (Pinus contorta), common juniper (Juniperus communis) and Monterey cypress (Cupressus macrocarpa), induces abortion in pregnant cows when ingested primarily during the last trimester. The objective of this study was to investigate the effects of isocupressic acid on bovine oocyte maturation (in vitro maturation (IVM)—Experiment I) and preimplantation embryo development (in vitro culture (IVC)—Experiment II) using in vitro embryo production techniques and to subsequently evaluate viability and developmental competence of ICA-cultured embryos via embryo transfer to recipient heifers (Experiment III). A complete randomized block experimental design was used. In Experiment I and II, isocupressic acid was added to IVM or IVC media at 0 (TRT1, control), 1.3 (TRT2), and 2.6 μg/ml (TRT3) Results from Experiment I and II indicated that ICA did not inhibit oocyte maturation and did not adversely affect preinpiantation embryo development. Furthermore, results from Experiment II demonstrated that isocupressic acid enhanced bovine preimplantation embryo development in vitro in a dose dependent manner. Subsequently, Day 8 (Day 0 = IVF) blastocysts cultured in vitro in the medium containing 2.6 μg/ml ICA were transferred to recipient heifers and resulted in normal pregnancies as determined by ultrasound imaging. Subsequently, all but two births were normal as evaluated by post natal veterinary examination. In conclusion, ICA showed no adverse effects on oocyte maturation and preimplantation embryo development in vitro or subsequent viability in vivo using the ICA concentrations and in vitro culture parameters of this study.