March 2013 (No. 1)
Transcript abundance and apoptosis in day-7 porcine blastocyst cultured with exogenous insulin-like growth factor-I
Marta Wasielak a, Takashi Fujii b, Tsubasa Ohsaki b, Tsutomu Hashizume b, Marek Bogacki a, Ken Sawai b,*
a Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Olsztyn, Poland;
b Department of Animal Science, Faculty of Agriculture, Iwate University, Ueda, Morioka, Iwate, Japan
Exogenous growth factors may increase the efﬁciency of embryo development in vitro. The aim of the present study was to examine the effects of insulin-like growth factor (IGF)-I on porcine embryo development. Porcine embryos obtained by in vitro fertilization were cultured for seven days in the presence of IGF-I (50, 100 or 150 ng/ml). Subsequently, relative transcript abundance (RA) of IGF-related genes (IGFR1, IGFBP2, and IGFBP3), glucose transporter genes (SLC2A4 and SLC2A8), and apoptosis-related genes (BAX and BCL-XL) was analyzed. No differences were observed in the cleavage rate on day 2 post insemination (pi) and blastocysts rate on day 7 pi between IGF-treated and control embryos. IGF-I treatment did not affect RA of IGFR1, IGFBP3, and SLC2A4 genes, but decreased RA of IGFBP2 and SLC2A8 genes. The percentage of TUNEL-positive nuclei in blastocysts did not differ between the experimental groups. However, RA of BAX and BCL-XL genes decreased in response to all IGF-I concentrations, whereas the BCL-XL/BAX RA ratio was enhanced when embryos were cultured in medium containing 150 ng/ml of IGF-I. These results indicate that IGF-I did not stimulate in vitro development of porcine embryos through the IGF signaling system, nor did IGF-I stimulate RA of glucose transporter genes. However, IGF-I at the highest dose was able to increase the BCL-XL/BAX transcript expression ratio. This may indicate that the primary role of IGF-I during the ﬁrst days of embryo development in the pig is associated with anti-apoptotic actions rather than with growth stimulation.
Reproductive Biology 2013 13 1: 58–65.
* Corresponding author at: Department of Animal Science, Faculty of Agriculture, Iwate University, Ueda 3-18-8, Morioka, Iwate 020-8550, Japan; E-mail address: firstname.lastname@example.org