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This Article Full Text Full Text (PDF) All Versions of this Article: 68/5/1808    most recent biolreprod.102.010009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hinck, L. Articles by De Hertogh, R. Search for Related Content PubMed PubMed Citation Articles by Hinck, L. Articles by De Hertogh, R. Agricola Articles by Hinck, L. Articles by De Hertogh, R.

Identification of Caspase-6 in Rat Blastocysts and Its Implication in the Induction of Apoptosis by High Glucose¹

Physiology of Human Reproduction Research Unit,³ Université Catholique de Louvain, 1200 Brussels, Belgium Diabetes and Nutrition Unit,⁴ Université Catholique de Louvain, 1200 Brussels, Belgium

Previous investigations have shown that maternal diabetes impairs rodent embryo development during the earliest phase of gestation. Exposure to high concentrations of glucose before implantation results in a decrease in the number of cells per embryo and in a concomitant increase in two nuclear markers of apoptosis: chromatin degradation and nuclear fragmentation. In the present study, we show that caspase-6 is expressed in rat blastocysts, using reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry. Caspase-6 is detected in all cells of the blastocyst and is excluded from the nucleus. To assess the role of caspase-6 in the glucose-induced apoptosis, rat blastocysts were incubated for 24 h in either 6 or 28 mM glucose in the presence or absence of a specific inhibitor of caspase-6 (VEID-CHO, 100 nM). After incubation, blastocysts were examined for the proportion of nuclei showing signs of chromatin degradation and nuclear fragmentation. Addition of VEID-CHO was found to inhibit nuclear fragmentation, but did not prevent the increase in chromatin degradation triggered by excess glucose. Our data indicate that chromatin degradation and nuclear fragmentation are two nuclear damages that are induced separately by high glucose in rat blastocysts. Furthermore, nuclear fragmentation in rat blastocysts is apparently mediated by the activation of caspase-6.

¹ Supported by the Action de Recherche Concertée de la Direction Générale de la Recherche de la Communauté Française de Belgique (grant 96/01-96), by the Juvenile Diabetes Foundation International, and by the European Foundation for the Study of Diabetes (attributed to S.P. and R.D.). L.H. is the holder of a research fellowship from FRIA.

² Correspondence: René De Hertogh, Unité de diabétologie et nutrition, UCL/DIAB 5474, Av. Hippocrate, 54, B-1200 Brussels, Belgium. FAX: 32 2 764 5418; dehertogh{at}obst.ucl.ac.be

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