POSSIBLE ROLES OF INSULIN AND INSULIN-LIKE GROWTH-FACTORS IN RAT PREIMPLANTATION DEVELOPMENT - INVESTIGATION OF GENE-EXPRESSION BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION

The sensitive mRNA phenotyping technique of reverse transcription-poly merase chain reaction was used to demonstrate that insulin receptor mR NA is present in rat embryos during the preimplantation period. In add ition, mRNA encoding insulin-like growth factor (IGF) type I and type II receptors have also been detected in rat preimplantation embryos. I GF-I mRNA was not detected in preimplantation embryos but was found in oviducts and uteri of prepubertal and early pregnant rats. IGF-II mRN A was present in both embryos and in oviducts and uteri during the pre implantation period. These findings suggest that insulin and IGF-I cou ld influence early embryo development in endocrine or in paracrine fas hions, whereas IGF-II may have an additional autocrine mode of action in affecting preimplantation embryos in rats.