Age-related changes in circulating INSL3 concentrations and their associations with ovarian conditions in Japanese Black beef cattle

• Published in: Theriogenology 2023-11, Vol.211, p.97-104
• Main Authors: Wimalarathne, H.D.A., Nakamura, Y., Ishizaka, K., Silva, B.D.K., Sasakura, K., Shimada, M., Kibushi, M., Sakase, M., Kawate, N.
• Format: Article
• Language: English
• Subjects: Female beef cattle; INSL3; Ovarian follicle; Sandwich TRFIA; Testosterone; Ultrasonography
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2023.08.007

Information on circulating levels of insulin-like peptide 3 (INSL3) in female domesticated animals is limited, as their concentrations are significantly lower than in males. The objectives of the present study were to 1) develop a sandwich time-resolved fluorescence immunoassay (TRFIA) with higher detectability to measure blood INSL3 concentrations in female cattle, 2) determine INSL3 concentrations in female cattle among age groups and reproductive conditions, and 3) explore associations between INSL3 levels and ultrasonographic ovarian measurements. Blood was collected repeatedly from Japanese Black beef female calves (n = 12; 0－8 mo), heifers (n = 10; 10－26 mo), and cows (n = 20; 27－200 mo). Blood was taken from the cows (n = 13) at follicular, post-ovulatory, and luteal phases, and from cows with follicular cysts (n = 12). Ultrasonography of ovaries was conducted in the calves (n = 12) and the cows without ovarian diseases (n = 9). The ovarian area, as well as the number and diameters of antral follicles ≥ 2 mm, were determined in each ovary. The proposed method detected a difference in plasma INSL3 between calves (0.01 ng/mL) and heifers (0.18 ng/mL). However, the conventional assay showed similar levels for calves and heifers (1.82 vs 2.07 ng/mL). Plasma INSL3 and testosterone concentrations increased from calves to heifers (P