Expression of mRNA Encoding IGF-I, IGF-II, Type-I, and II IGF-Receptors and IGF-Binding Proteins-1-4 during Ovarian Follicular Development in Buffalo(Bubalus bubalis)

Abstract

The present study was designed to investigate the expression pattern of IGF-I, IGF-II, type-I and II IGF-receptors, and IGFBP-1-4 in different stages of buffalo ovarian preantral follicles (PFs), antral follicles (AFs), ovulatory follicles (OFs), and immature (IM) and in vitro matured (MO) oocytes. Buffalo ovaries were collected from local abattoir, PFs (200-250 µm), AFs (1-3 mm), and OFs (5-8 mm) were isolated by mechanical method. PFs, AFs, OFs, and oocytes were lysed to release mRNA, reverse transcribed, and then subjected to RT-PCR, whereas protein were localized through immunohistochemistry. Relative expression of mRNA transcripts was clearly seen for IGF-II, type-I and II IGF-receptors, and IGFBP-1-4 in all the stages of developing follicles and oocytes. We were unable to detect mRNA and protein expression of IGF-1 in any of the oocytes or follicles at any stage of the development. IGF-II and both IGF receptors mRNA expression were found higher (P < 0.05) in PFs compared to AFs and OFs. Expression of IGFBP-1 and 2 in PFs, as well as IGFBP-3 and 4 in AFs, was found with higher (P < 0.05) levels. The expression results were further confirmed by localization of IGF-II, type-I and II IGF-receptors, and IGFBP-1-4 proteins. In conclusion, IGF-II appears to be the only ligand that is endogenously expressed by all the follicular stages and oocytes, which may act in an autocrine manner through the Type-1 IGF receptor. Expression of IGFBP-1-4 and IGF-II suggests the possible role of these genes in recruitment, growth, proliferation, and steroidogenic responses during developmental phases of buffalo ovarian follicles.

Expression of kit ligand and insulin‐like growth factor binding protein 3 during in vivo or in vitro development of ovarian follicles in sheep

“…Expression of IGFBP3 in the oocytes at all the stages of in vivo grown ovarian follicles in the present study is in agreement with the previous reports (Armstrong, Baxter, Hogg, & Woad, ; Arraztoa et al., ; Dubey et al., ). While Dubey et al.…”

“…Expression of IGFBP3 in the cumulus cells at all the stages of development in in vivo grown ovarian follicles observed in the present study is in agreement with previous reports at different stages of ovarian folliculogenesis in different species (Dubey et al., ; Hastie & Haresign, ; Wandji et al., ). In vitro culture appears to have up regulated the expression of IGFBP3 both in the cumulus cells and oocytes probably by the presence of.…”

“…Expression of IGFBP3 in the oocytes at all the stages of in vivo grown ovarian follicles in the present study is in agreement with the previous reports (Armstrong, Baxter, Hogg, & Woad, 2002;Arraztoa et al, 2002;Dubey et al, 2015). While Dubey et al (2015) observed high levels of IGFBP3 expression in the oocytes in antral follicles in buffaloes, the expression was decreased at the same stage in the present study. This discrepancy might be due to the morphological classification of the follicles and/or species.…”

“…While Dubey et al. () observed high levels of IGFBP3 expression in the oocytes in antral follicles in buffaloes, the expression was decreased at the same stage in the present study. This discrepancy might be due to the morphological classification of the follicles and/or species.…”

“…Although there are random reports on the expression of KL and IGFBP3 at a few stages of development of the ovarian follicles in different mammalian species (Dubey et al., ; Tuck et al., ), stage‐specific expression patterns of KL and IGFBP3 (Figure ) during ovarian folliculogenesis in mammals is reported for the first time.…”