Vanderpooten A, Janssens W, Buyse J, Leenstra F, Berghman L, Decuypere E, Kühn E R
Laboratory of Comparative Endocrinology, Catholic University of Leuven, Belgium.
Domest Anim Endocrinol. 1993 Jul;10(3):199-206. doi: 10.1016/0739-7240(93)90024-6.
The influence of genetic selection for improved feed conversion (FC) and fast growth (GL) in broiler chickens, on the hepatic growth hormone receptor was investigated as a function of age. Selection for improved feed conversion resulted in lean chickens, whereas selection for fast growth resulted in fat chickens. Growth hormone receptor characteristics were determined in liver microsomal fractions and plasma GH concentrations were measured by radioimmunoassay. Embryos from the FC line showed higher specific GH binding than GL embryos at day 16 of embryonic development only (P < 0.05). On day 18 of embryonic development, the FC line had slightly more GH receptors than the GL line (P < 0.05), whereas simultaneous plasma GH concentrations were greater in the GL line. The effect of selection on hepatic growth hormone binding was greatest in 4 week old growing chicks at which age the GL line showed a 2- to 3-fold higher % of specific binding than the FC line (P < 0.001). The difference at this stage is probably due to down regulation of the receptor by the significantly higher GH concentrations in the FC line. The adult GL chickens also showed higher specific binding than FC, but the difference was less pronounced than in the growing stage (P < 0.05). This was due to a higher number of GH receptors, while receptor affinity was unchanged. Because no line difference in plasma GH concentrations was found in adult hens, other unknown mechanisms probably play a role in determining differences in GH receptor binding between these selected lines at older ages.
研究了肉鸡遗传选择对肝脏生长激素受体的影响，该选择旨在改善饲料转化率（FC）和实现快速生长（GL），并将其作为年龄的函数进行研究。选择改善饲料转化率会培育出瘦型鸡，而选择快速生长则会培育出胖型鸡。在肝微粒体部分测定生长激素受体特征，并通过放射免疫测定法测量血浆生长激素浓度。仅在胚胎发育第16天时，FC系胚胎显示出比GL系胚胎更高的特异性生长激素结合（P < 0.05）。在胚胎发育第18天时，FC系的生长激素受体略多于GL系（P < 0.05），而同时GL系的血浆生长激素浓度更高。选择对肝脏生长激素结合的影响在4周龄的生长鸡中最为显著，此时GL系的特异性结合百分比比FC系高2至3倍（P < 0.001）。这个阶段的差异可能是由于FC系中显著更高的生长激素浓度导致受体下调。成年GL鸡也显示出比FC鸡更高的特异性结合，但差异不如生长阶段明显（P < 0.05）。这是由于生长激素受体数量较多，而受体亲和力不变。由于在成年母鸡中未发现血浆生长激素浓度的品系差异，其他未知机制可能在决定这些选定品系在较老龄时生长激素受体结合差异方面发挥作用。
