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Effect of buserelin treatment on pregnancy rate after transfer of microinjected IVF-derived embryos
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Theriogenology EFFECT OF BUSERELIN TREATMENT ON PREGNANCY RATE AFTER TRANSFER OF MICROINJECTED IVF-DERIVED EMBRYOS M. Salaheddine, K.P.E. Spoelder, F. de Loos and A. Garcia Gene Pharming Europe B.V. Niels Bohrweg ll-13,2333 CA Leiden, The Netherlands
Low pregnancy rate due to low embryo viability is reported following transfer of microinjected bovine embryos. This could be either due to detrimental mutagenesis following DNA incorporation or simply to the invasive nature of the microinjection technique resulting in retarded embryonic development. In such schemes where low embryo viability is thought to be a major contributor to the low pregnancy rate, there is a lack of information on means to improve embryo survival. In this experiment recipients receiving microinjected IVF-derived (MIVF) embryos were used to investigate the effect on pregnancy rate of an injection of the GnRH analogue Buserelin. Twelve to twenty hours post-fertilization, slaughterhouse-derived zygotes and zygotes derived from ultrasound-guided oocyte aspiration were microinjected with a DNA construct for human lactoferrin. Embryos were co-cultured for 7-8 days with BOEC in TCM 199 +lO% fetal calf serum at 39’C in an atmosphere of 5% CO2 and humidified air. One hundred and eighty embryos were transfened to 18 months-old Holstein, Maas Rijn IJssel or Piemontese heifers. Five days after transfer (12 days after estrus, day of estrus = 0), heifers were assigned to an IM injection of either 0.02mg Buserelin (2Sml Receptala, Hoechst) or 2Sml saline. Pregnancy diagnosis was carried out 4 weeks after transfer using a B-mode scanner (Aloka SSD500 Dx; Aloka, Co. Ltd., Tokyo, Japan) equipped with a 7.5MHz linnear array transducer. In addition 55 animals were scanned two weeks after transfer for presence of an accessory corpus luteum (CL). Results are shown in the following table: Table 1: Pregnancy rate in Buserelin- vs saline-treated heifers
Buserelin did not improve the pregnancy rate significantly following transfer of MIVF embryos. Similarly, when data was analysed for different embryo stages (expanded blastocysts, blastocysts, morula or embryos cultured for 7 or 8 days), no difference in pregnancy rate was found between Buserelin- and saline-treated groups. The presence of an accessory CL was found in 13/30 (43%) heifers scanned from the Buserelin group, and none of the heifers scanned from the control group formed an accessory CL (n=22). Buserelintreated heifers that did not conceive did not have a longer cycle than control open heifers (28.4f8 vs 29.3f8 days respectively). It is concluded that IM injections of Buserelin 5 days after transfer do not improve pregnancy rates in recipients with microinjected IVF-derived embryos.
Theriogenology EFFECT OF BUSERELIN TREATMENT ON PREGNANCY RATE AFTER TRANSFER OF MICROINJECTED IVF-DERIVED EMBRYOS M. Salaheddine, K.P.E. Spoelder, F. de Loos and A. Garcia Gene Pharming Europe B.V. Niels Bohrweg ll-13,2333 CA Leiden, The Netherlands
Low pregnancy rate due to low embryo viability is reported following transfer of microinjected bovine embryos. This could be either due to detrimental mutagenesis following DNA incorporation or simply to the invasive nature of the microinjection technique resulting in retarded embryonic development. In such schemes where low embryo viability is thought to be a major contributor to the low pregnancy rate, there is a lack of information on means to improve embryo survival. In this experiment recipients receiving microinjected IVF-derived (MIVF) embryos were used to investigate the effect on pregnancy rate of an injection of the GnRH analogue Buserelin. Twelve to twenty hours post-fertilization, slaughterhouse-derived zygotes and zygotes derived from ultrasound-guided oocyte aspiration were microinjected with a DNA construct for human lactoferrin. Embryos were co-cultured for 7-8 days with BOEC in TCM 199 +lO% fetal calf serum at 39’C in an atmosphere of 5% CO2 and humidified air. One hundred and eighty embryos were transfened to 18 months-old Holstein, Maas Rijn IJssel or Piemontese heifers. Five days after transfer (12 days after estrus, day of estrus = 0), heifers were assigned to an IM injection of either 0.02mg Buserelin (2Sml Receptala, Hoechst) or 2Sml saline. Pregnancy diagnosis was carried out 4 weeks after transfer using a B-mode scanner (Aloka SSD500 Dx; Aloka, Co. Ltd., Tokyo, Japan) equipped with a 7.5MHz linnear array transducer. In addition 55 animals were scanned two weeks after transfer for presence of an accessory corpus luteum (CL). Results are shown in the following table: Table 1: Pregnancy rate in Buserelin- vs saline-treated heifers
Buserelin did not improve the pregnancy rate significantly following transfer of MIVF embryos. Similarly, when data was analysed for different embryo stages (expanded blastocysts, blastocysts, morula or embryos cultured for 7 or 8 days), no difference in pregnancy rate was found between Buserelin- and saline-treated groups. The presence of an accessory CL was found in 13/30 (43%) heifers scanned from the Buserelin group, and none of the heifers scanned from the control group formed an accessory CL (n=22). Buserelintreated heifers that did not conceive did not have a longer cycle than control open heifers (28.4f8 vs 29.3f8 days respectively). It is concluded that IM injections of Buserelin 5 days after transfer do not improve pregnancy rates in recipients with microinjected IVF-derived embryos.