No abstract

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 1000 ng) was applied either ex ovo on the CAM surface of ex ovo incubated embryos at embryonic day 7 (ED7) or in ovo into the egg albumen at ED5. Changes in blood vessels were quantified by the fractal analysis providing the fractal dimension (Df) estimate. Leptin administered in ovo was more efficient in stimulation of angiogenesis than the ex ovo treatment, since 10 ng dose elicited significantly higher (P < 0.001) 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.

The goal of this study was to assess the influence of simulated microgravity (hypodynamy) on morphological characteristics and mineral content of the long bones of the right leg of female Japanese quail chicks from 3 to 56 days of age. Femur and tibiotarsus were collected at 14, 28, 42 and 56 days; the variables studied were: weight (g), length and width (mm), bone index (ash weight/bone length in mg·mm -1 ), bone breaking strength (N) and calcium, phosphorus and magnesium content (mg·g -1 dry bone).All variables increased with bird age. However, the effect of hypodynamy on the examined variables was frequently large and significant. The tibiotarsus mean weight was significantly (P < 0.001) reduced by 0.154 g, although the femur mean weight in hypodynamy reared quails was almost identical to that of the age-matched control at 56 days. Similarly, there was significantly decreased tibiotarsus mean length (P < 0.01) by 3.16 mm and tibiotarsus mean width (P < 0.001) by 0.44 mm by 56 days. Similarly, bone index and bone breaking strength of both bones in birds reared under hypodynamy were significantly lower (P < 0.001) than those of control. Moreover, hypodynamy significantly (P < 0.01) decreased the calcium content in femur and tibiotarsus at 42 days; phosphorus content in tibiotarsus was reduced significantly at 14 and 42 days (P < 0.001; P < 0.05, respectively) and magnesium content was decreased at 42 days (P < 0.01). On the contrary, magnesium content in both long bones of test quails was increased significantly (P < 0.01) at 14 days. Other differences in femur and tibiotarsus mineral content between test and control group were not significant. These findings suggest that, although hypodynamy reduce bone growth of test birds, the long bones of the right leg of female Japanese quail were able to develop under conditions of simulated microgravity.