Instituto Boliviano de Biología de Altura, Facultad de Medicina, Universidad Mayor de San Andrés, La Paz, Bolivia.
High Alt Med Biol. 2011 Spring;12(1):79-87. doi: 10.1089/ham.2010.1040.
By combining the chick embryo model with incubation at high altitude, this study tested the hypothesis that development at high altitude is related to a fetal origin of adrenocortical but not adrenomedullary suppression and that hypoxia is the mechanism underlying the relationship. Fertilized eggs from sea-level or high altitude hens were incubated at sea level or high altitude. Fertilized eggs from sea-level hens were also incubated at altitude with oxygen supplementation. At day 20 of incubation, embryonic blood was taken for measurement of plasma corticotropin, corticosterone, and Po(2). Following biometry, the adrenal glands were collected and frozen for measurement of catecholamine content. Development of chick embryos at high altitude led to pronounced adrenocortical blunting, but an increase in adrenal catecholamine content. These effects were similar whether the fertilized eggs were laid by sea-level or high altitude hens. The effects of high altitude on the stress axes were completely prevented by incubation at high altitude with oxygen supplementation. When chick embryos from high altitude hens were incubated at sea level, plasma hormones and adrenal catecholamine content were partially restored toward levels measured in sea-level chick embryos. There was a significant correlation between adrenocortical blunting and elevated adrenal catecholamine content with both asymmetric growth restriction and fetal hypoxia. The data support the hypothesis tested and provide evidence to isolate the direct contribution of developmental hypoxia to alterations in the stress system.
本研究将鸡胚模型与高原孵育相结合，旨在检验以下假设：高原环境下的胚胎发育与肾上腺皮质而非肾上腺髓质抑制有关，且低氧是这种关联的作用机制。来自海平面或高海拔母鸡的受精卵在海平面或高海拔环境下孵育。来自海平面母鸡的受精卵也在高海拔环境下用氧气进行孵育。孵育第 20 天，采集胚胎血样，用于检测血浆促肾上腺皮质激素、皮质酮和 Po(2)。生物测量后，采集肾上腺并冷冻，用于检测儿茶酚胺含量。与海平面相比，高原环境下鸡胚的发育导致明显的肾上腺皮质钝性，同时肾上腺儿茶酚胺含量增加。无论是来自海平面还是高海拔母鸡的受精卵，孵育于高原环境都会产生这些影响。用高海拔加氧孵育完全阻止了高海拔对应激轴的影响。当来自高海拔母鸡的鸡胚在海平面孵育时，其血浆激素和肾上腺儿茶酚胺含量部分恢复到海平面鸡胚的水平。肾上腺皮质钝性和肾上腺儿茶酚胺含量的升高与不对称性生长受限和胎儿缺氧显著相关。这些数据支持了所测试的假设，并提供了证据来分离发育性低氧对应激系统改变的直接贡献。
