Changes in Insulin-Like Growth Factor-Binding Proteins in Swamp Buffalo Uterus during Estrous Cycle

Insulin-like growth factor-binding proteins (IGFBPs) play a role in regulating insulin-like growth factor (IGFs) action in a wide variety of cell types. The present study characterized the changes in concentration of IGF binding protein-2 (IGFBP-2) and IGF binding protein-3 (IGFBP-3) in uterine obtained from swamp buffalo during the estrous cycle. The uteri of 36 slaughtered swamp buffaloes were collected, the stages of estrous cycle were considered by macroscopic examination of the ovaries and were classified to be early, mid, late luteal and follicular phase. Western blot analysis of endometrial tissue showed that IGFBP-2 was affected by the stage of estrous cycle. The concentration of endometrial IGFBP-2 protein was increased at early and peak at mid luteal phase of the cycle. However, endometrial IGFBP-3 protein was faintly detectable and did not change significantly. Plasma progesterone by radioimmunoassay was also harmonized with endometrial IGFBP-2 protein. Results suggest that increased in endometrial IGFBP-2 at the early and mid luteal phase of the estrous cycle may regulate the activity of the IGFs which may be required to promote the development of the uterus at this stage.