Effect of relaxin and IGF-I on the pre-implantation development of Mongolian gerbil (Meriones unguiculatus) embryos in vitro.

Abstract

Both relaxin and insulin-like growth factor (IGF) are members of the insulin super family. This study aimed to investigate the effect of relaxin and IGF-I on the pre-implantation of Mongolian gerbil of blastocyst development in vitro. Blastocysts and eight-cell stage embryos were collected from female gerbils. Eight-cell embryos and blastocysts were cultured in mM16 medium supplemented with or without relaxin or IGF-I for 24 h. Blastocysts were counted for total, inner cell mass (ICM) and trophectoderm (TE) cell numbers, and assessed apoptosis incidence. In addition, to measure incorporation of 3H-methionine, blastocysts were cultured for 3 h with relaxin or IGF-I, washed with trichloroacetic acid and measured by liquid scintiration counter. Relaxin (200 ng/ml) increased total, TE and ICM cell numbers of blastocyst (P < 0.05) when it was compared with the control. IGF-I (150 ng/ml) also has influence on total and ICM cell numbers of blastocyst when compared with control. Apoptosis incidence was relatively low, and a significant difference was not observed between each group. The effect of relaxin on incorporation of 3H-methionine was higher than the control group (P < 0.05). Relaxin increased the developmental rate from the eight-cell stage to blastocyst (P < 0.05). In conclusion, relaxin and IGF-I stimulated protein synthesis and increased cell numbers of blastocysts, promoting development of the gerbil embryo in vitro culture.