The effect of leptin on luteal angiogenic factors during the luteal phase of the estrous cycle in goats

Fibroblast growth factor 2 (FGF2), angiopoietin 1 (Ang1), and vascular endothelial growth factor (VEGF) are angiogenic factors implicated in the vascular development of the corpus luteum (CL). Each factor is regulated or influenced by leptin in non-ovarian tissues. Moreover, leptin and its receptor, ObRb, have been identified in luteal tissue throughout the luteal phase. Therefore, leptin is hypothesized to influence luteal vasculature through the regulation of FGF2, Ang1, and VEGF. Multiparous, cycling crossbred female goats (does) were allocated to early (n = 12), mid (n = 8), and late (n = 11) stages of the luteal phase for CL collection. Luteal tissue was harvested and either snap frozen in liquid N2, paraffin embedded, or cultured with leptin (0, 10−12, 10−11, 10−10, 10−9, 10−8 M). Tissue was analyzed for FGF2, Ang1, VEGF, ObRb, and leptin expression. Angiopoietin 1, FGF2, VEGF expression was higher (P ≤ 0.001) in the mid-luteal stage than the early stage. Expression decreased (P ≤ 0.001) during the late luteal stage with the exception of VEGF, which remained elevated. In contrast, leptin and ObRb were lowest (P ≤ 0.003) during the mid-luteal stage compared to the early and late stages. All factors were detected in and/or around vessels in early stage tissue compared to mid and late stages. Leptin stimulated (P ≤ 0.02) Ang1, FGF2, and VEGF expression only in early stage luteal cultures. Collectively, these data provide evidence that leptin may be involved in the luteal angiogenic process during the early stage of CL formation.