Insulin-like growth factor 1 supplementation during in vitro maturation upregulates HRas, Cdc25, and IRS-2 expression...

In vitro maturation (IVM) is an essential assisted reproductive technology that improves oocyte competence and supports the conservation and utilization of valuable livestock genetic resources. The Kacang goat is an indigenous Indonesian breed with important economic and genetic significance. Insulin-like growth factor 1 (IGF-1) has been reported to regulate oocyte maturation through multiple intracellular signaling pathways; however, its molecular effects on maturation-associated genes in Kacang goat oocytes remain poorly characterized. This study evaluated the influence of IGF-1 supplementation during IVM on the expression of Harvey rat sarcoma viral oncogene homolog (HRas), Cell division cycle 25 phosphatase (Cdc25), and insulin receptor substrate-2 (IRS-2), which are associated with meiotic progression and metabolic signaling.

Cumulus-oocyte complexes were collected from Kacang goat ovaries and cultured under IVM conditions either without supplementation (control) or with 100 ng/mL IGF-1. Relative expression of HRas and Cdc25 was quantified using quantitative polymerase chain reaction, while IRS-2 protein expression was assessed by immunocytochemistry. Statistical comparisons between groups were performed using appropriate parametric or non-parametric tests, and correlations among molecular markers were evaluated using Spearman's rank correlation analysis.

IGF-1 supplementation significantly increased the expression of both HRas and Cdc25 compared with the control group (p < 0.05). The relative expression of HRas increased approximately 2.03-fold, whereas Cdc25 expression increased 1.62-fold following IGF-1 treatment. Immunocytochemical analysis demonstrated significantly greater IRS-2 protein expression in IGF-1-treated oocytes than in controls (p < 0.05). Furthermore, strong positive correlations were observed among HRas, Cdc25, and IRS-2 expression levels, with the strongest association detected between HRas and Cdc25 (r = 0.85). These findings indicate coordinated activation of signaling pathways involved in meiotic regulation and cellular metabolism during oocyte maturation.

Supplementation of IVM medium with 100 ng/mL IGF-1 enhanced the expression of HRas, Cdc25, and IRS-2 in Kacang goat oocytes, suggesting activation of molecular pathways associated with meiotic resumption and metabolic regulation. These findings provide mechanistic insights into IGF-1-mediated signaling during oocyte maturation and may help optimize IVM systems for indigenous goat breeds. This improvement in reproductive biotechnology is also relevant to Sustainable Development Goal 2 (Zero Hunger), particularly in supporting sustainable livestock production, conservation of indigenous goat genetic resources, and food security. Nevertheless, further studies evaluating nuclear maturation, fertilization, and embryo developmental competence are required to confirm the functional significance of these molecular responses.