DIFFERENT PATTERN OF INTERLEUKIN-1-BETA-(IL-1-BETA), INTERLEUKIN-1 RECEPTOR ANTAGONIST-(IL-1RA) AND INTERLEUKIN-1 RECEPTOR-TYPE I-(IL-1R TI) MESSENGER-RNA-EXPRESSION IN SINGLE PREIMPLANTATION MOUSE EMBRYOS AT VARIOUS DEVELOPMENTAL STAGES

The interleukin-1 (IL-1) system has been shown to play an important ro le in human and murine embryo implantation. Recent studies have docume nted immunohistochemical evidence of interleukin-1 beta (IL-1 beta), i nterleukin-1 receptor antagonist (IL-1ra) and interleukin-1 receptor t ype I (IL-IR tI) in human preimplantation embryos and protein levels o f interleukin-1 alpha (IL-1 alpha), IL-1 beta and IL1ra in human preim plantation embryo culture fluid have been correlated with successful i mplantation and pregnancy. Our aim in this study was to detect IL-1 be ta, IL-1ra and IL-1R tI mRNA in single preimplantation mouse embryos a nd to describe the frequency of positive mRNA-expression at different developmental stages. B6C3F1-mice, 12 weeks old were pregnant mare ser um gonadotropin (PMSG)/human chorionic gonadotropin (hCG)-stimulated a nd mated. Animals were sacrificed at day 0.5, and zygotes were flushed from the tubes and cultured in HAMs-F10 medium. 2-cell-(2C-), 8-cell- (8C-), morula-(M-), early blastocyst-(EB-) and hatching blastocyst-(HB -) stage embryos were examined by one round of reverse transcriptase ( RT) followed by two rounds of polymerase chain reaction (PCR) carried out on individual mouse embryos for B-actin (internal standard), IL-1 beta, IL-1ra and IL-IR tI-mRNAs. The frequencies of positive mRNA-expr essions were as follows (2C/8C/M/EB/HB); beta-actin: 91/96/100/100/98% ; K-1b: 0/0/2.5/6.25/19; IL-1ra; 0/5/30/41/74% and IL-1R tI: 0/0/10/20 /25%. The incidence of 1L-lra mRNA expression increased with developme ntal stage. IL-1ra mRNA seems to be expressed in a very high percentag e (74%) of embryos near the. time of implantation, whereas the percent age of IL-1 beta-mRNA positive embryos is surprisingly low (19%,). (C) 1997 Elsevier Science Ireland Ltd.