149 GLUCOSE METABOLISM OF IN VITRO AND IN VIVO PRODUCED BOVINE EMBRYOS
J.F. De La Torre Sanchez A , M. Lane B , J. Gibbons B , D.K. Gardner B and G.E. SeidelA Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO, USA. email: delatorf@lamar.colostate.edu;
B Colorado Center for Reproductive Medicine, Englewood, CO, USA.
Reproduction, Fertility and Development 16(2) 196-197 https://doi.org/10.1071/RDv16n1Ab149
Submitted: 1 August 2003 Accepted: 1 October 2003 Published: 2 January 2004
Abstract
It has been documented that higher glucose metabolism of bovine blastocysts is correlated with higher pregnancy rates following embryo transfer. The aim of this study was to determine the effect of switching embryos between in vivo and in vitro conditions on glucose metabolism. Four types of embryos were produced: Vivo-vivo: embryos were developed entirely in vivo (7.5 days); embryos were collected from superovulated cows at Day 5 following estrus, transferred to a recipient and collected again 2.5 days later to make an appropriate control. Vivo-vitro: embryos developed 5 days in vivo and then were cultured in vitro for 2.5 days. Vitro-vivo: embryos were produced in vitro using slaughterhouse oocytes and frozen semen, cultured until Day 5, and then transferred to recipients and recovered 2.5 days later. Vitro-vitro: embryos were produced entirely in vitro up to Day 7.5. Embryos were cultured in a chemically defined, sequential system (G1/G2), using recombinant human albumin as a protein source, supplemented with hyaluronan and citrate. At Day 7.5, glucose metabolism was measured by determining the amount of 3H2O released when individual embryos (n = 111 for all groups) were placed in a 3-μL hanging drop containing 3H-glucose in a closed chamber for 3 h. Embryos were graded 1 (good quality) or 2 (fair or poor). Data were analyzed by ANOVA using a 4 × 2 factorial design with factors group (vivo-vivo, vivo-vitro, vitro-vivo, vitro-vitro) and quality (1, 2). To validate the vivo-vivo group, 15 embryos produced in vivo (without collection and re-transfer) were analyzed for glucose metabolism, resulting in similar values. Grade 1 embryos metabolized more glucose (P < 0.01) than Grade 2 embryos (16.6 ± 1.2 v. 10.7 ± 2.5 pmol/embryo/h) The vivo-vivo and vitro-vitro embryos metabolized more glucose (P < 0.05) than the vivo-vitro and vitro-vivo embryos (15.4 ± 1.7 and 19.3 ± 2.0 v. 9.0 ± 4.5 and 10.7 ± 1.6 pmol/embryo/h, respectively). There was an interaction (P < 0.05) due to higher glucose metabolism of Grade 1 over Grade 2 embryos in the vitro-vivo and vitro-vitro groups, but no difference between grades for the vivo-vivo and vivo-vitro groups. We conclude that assessment for visual quality was meaningful, and that changing development conditions (vivo to vitro or vitro to vivo) appears to have a detrimental effect on glucose metabolic capabilities of bovine blasocysts lasting up to 2.5 days, and possibly on their developmental competence. Significantly, bovine blastocysts cultured in sequential media G1/G2 had equivalent glucose metabolism to those embryos developed completely in vivo.
