“Immunolocalization and effect of low concentrations of Insulin like growth factor‐1 (IGF‐1) in the canine ovary”

Abstract

Insulin like growth factor‐1 (IGF‐1) plays an important role in the regulation of ovarian function. Despite its extensive study in several species, there is a paucity of information about IGF‐1`s function and localization in the canine ovary. The aim of the present study was to assess the effect of IGF‐1 on oocyte nuclear maturation and to immunolocalize the IGF‐1 and its receptor (IGF‐1R) in the ovary. Cumulus‐oocyte complexes (COCs) were obtained from 34 bitches. The COCs from each bitch were incubated in TCM 199‐HEPES in the absence (n = 199) or presence (n = 204) of 100 ng/ml IGF‐1 for 96 hr at 38ºC in 5% CO2, stained and evaluated for nuclear maturation by fluorescence microscopy. The results showed that the addition of IGF‐1 did not have an effect (p ˃ 0.05) on the nuclear maturation under these conditions. The immunohistochemical study revealed nuclear and cytoplasmic staining for IGF‐1 and IGF‐1R, respectively. Both were localized in all ovarian structures including the corpus luteum, but not in the granulosa cells from primordial follicles. In addition, IGF‐1 was not localized in the oocytes in tertiary follicles. The results obtained show the presence of IGF‐1 through the stages of follicular growth and in the corpus luteum of the canine ovary. However, its role on oocyte nuclear maturation could not be demonstrated.

Human Adipose-Derived Stem Cells’ Paracrine Factors in Conditioned Medium Can Enhance Porcine Oocyte Maturation and Subsequent Embryo Development

“…It has already been reported that IGF-1 plays an important role in the regulation of ovarian function. A recent study suggested both IGF-1 and IGFR are localized in all ovarian structures including the corpus luteum [ 59 ], and the IGF activity in the ovarian follicle influences follicle development, steroidogenesis and oocyte quality [ 60 ]. The supplementation of IGF-1 to the IVM culture medium improved the IVM and in vitro fertilization rate in porcine oocytes [ 61 ] and this factor stimulates protein kinase A-dependent intracellular mechanisms that involved both meiosis and completion of oocyte nuclear maturation [ 62 ].…”