Angiogenic effect of leptin in the quail chorioallantoic membrane

Leptin, the product of ob gene, beside its key role in the control of body weight and food consumption, can be involved in the control of embryonic development. Leptin administration in ovo accelerated the embryonic and post-embryonic development in Japanese quail. Although the mechanisms of leptin effects on growth and development acceleration are not clear, stimulation of angiogenesis represents one of plausible explanations. Therefore, the aim of the present study was to investigate the pro-angiogenic effect of leptin in vivo in the quail chorioallantoic membrane (CAM). The recombinant murine leptin (10, 100, and 1,000 ng) was applied either ex ovo on the CAM surface of ex ovo incubated embryos at embryonic day 7 or in ovo into the egg albumen at ED5. Changes in blood vessels were quantified by the fractal analysis providing the fractal dimension estimate. Leptin administered in ovo was more efficient in stimulation of angiogenesis than the ex ovo treatment, since 10 ng dose elicited significantly higher stimulation of vessel development of the CAM under the air cell than it did after ex ovo cultivation. Our study confirmed that exogenously applied leptin was able to stimulate angiogenesis in CAM. Leptin-mediated stimulation of angiogenesis may improve nutrient utilization from the yolk and explain at least partially the accelerating effect of leptin on avian embryo growth and development.