Expression and Role of Bcl-2 in Rat Blastocysts Exposed to High D-Glucose
- Serge Pampfer,
- Sabine Cordi,
- Ivo Vanderheyden,
- Patrick Van Der Smissen,
- Pierre J. Courtoy,
- Anne Van Cauwenberge,
- Henri Alexandre,
- Isabelle Donnay and
- René De Hertogh
- From the Physiology of Human Reproduction Research Unit (S.P., S.C., I.V., R.D.H.), Université Catholique de Louvain, Brussels; the Cell Biology Unit (P.V.D.S., P.J.C.), Christian de Duve Institute of Cellular Pathology, Brussels, Belgium; the Division of Biology and Embryology (A.V.C., H.A.), Université de Mons-Hainaut, Mons and the Veterinary Unit (I.D.), Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
- Address correspondence and reprint requests to Serge Pampfer, PhD, OBST 5330 Research Unit, University of Louvain Medical School, 53 Avenue Mounier, 1200 Brussels, Belgium. E-mail: pampfer{at}obst.ucl.ac.be .
Abstract
Bcl-2 mRNA expression was detected in rat blastocysts by in situ hybridization. The distribution of mRNA expression was rather heterogenous, with ∼2% of high-expressing cells. In vitro exposure to 28 mmol/l D-glucose for 24 h resulted in a significant increase in the proportion of these cells compared with control embryos in either 6 mmol/l D-glucose or 28 mmol/l D+L-glucose. Heterogeneity in the expression of Bcl-2 was also observed at the protein level by immunocytochemistry. Exposure to 28 mmol/l D-glucose significantly increased the incidence of chromatin degradation (karyolysis) and nuclear fragmentation (karyorhexis), two nuclear markers of apoptosis in rat blastocysts. When two different antisense oligodeoxynucleotides designed to block Bcl-2 expression were added to 28 mmol/l D-glucose, the incidence of karyolysis (but not karyorhexis) was increased compared with embryos in 28 mmol/l D-glucose alone. These data suggest that Bcl-2 is involved in the protective response against the induction of karyolysis in blastocysts on their exposure to high concentrations of D-glucose in vitro, whereas karyorhexis appears to result from the activation of an intracellular pathway that is independent of Bcl-2.
Footnotes
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AS, antisense; BSA, bovine serum albumin; FITC, fluorescein isothiocyanate; ICM, inner cell mass; PBS, phosphate-buffered saline; PBS-T, PBS with Tween; PBS-TR, PBS containing Triton; RT-PCR, reverse transcriptase-polymerase chain reaction; SN, control sense; TE, trophectoderm; TM, transmembrane; TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling.
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- Accepted September 11, 2000.
- Received June 7, 2000.
- by the American Diabetes Association, Inc.
