Li Liu-An, Xia Dong, Wei Shi, Li Xiao, Parvizi Nahid, Zhao Ru-Qian
Key Laboratory of Animal Physiology & Biochemistry, Nanjing Agricultural University, Nanjing 210095, PR China.
Domest Anim Endocrinol. 2008 Jul;35(1):1-7. doi: 10.1016/j.domaniend.2007.12.005. Epub 2008 Feb 4.
Previous studies demonstrated significantly lower plasma cortisol level in homozygous halothane-positive (Hal nn) pigs, as compared with homozygous halothane-negative (Hal NN) pigs. To determine whether such difference is attributed to the fundamental alterations in adrenocortical function, F1 offsprings from Pietrain (Hal nn)xErhualian (Hal NN) were intercrossed to produce F2 sibling pigs with segregated genotypes. Adrenocortical cells were isolated from the Hal nn and Hal NN F2 pigs, respectively, and cultured with or without ACTH challenge. Cortisol levels in culture medium, as well as the content of MC2R, cAMP, CREB, phosphorylated CREB (pCREB), StAR and P450scc in adrenocortical cell lysates, were determined. Cortisol, cAMP, StAR and P450scc levels were significantly lower in Hal nn adrenocortical cells under basal condition without ACTH challenge. ACTH significantly increased cortisol level in the medium and the protein content of MC2R, StAR, P450scc in adrenocortical cell lysates, regardless of genotypes. Total CREB protein content was not different between genotypes and treatments, whereas pCREB content exhibited significant effects of genotype and treatment, being higher in Hal NN than in Hal nn under basal condition and in response to ACTH challenge. These results indicate that the compromised cAMP/PKA/pCREB signaling pathway of ACTH and diminished expression of limiting factors in adrenocortical steroidogenesis (StAR and P450scc) may contribute to the significantly lower plasma cortisol levels in Hal nn pigs.
先前的研究表明，与纯合氟烷阴性（Hal NN）猪相比，纯合氟烷阳性（Hal nn）猪的血浆皮质醇水平显著降低。为了确定这种差异是否归因于肾上腺皮质功能的根本改变，将皮特兰猪（Hal nn）与二花脸猪（Hal NN）杂交产生的F1代进行互交，以产生具有分离基因型的F2代同胞猪。分别从Hal nn和Hal NN F2代猪中分离肾上腺皮质细胞，并在有无促肾上腺皮质激素（ACTH）刺激的情况下进行培养。测定培养基中的皮质醇水平，以及肾上腺皮质细胞裂解物中促黑素细胞激素受体（MC2R）、环磷酸腺苷（cAMP）、环磷腺苷效应元件结合蛋白（CREB）、磷酸化CREB（pCREB）、类固醇急性调节蛋白（StAR）和细胞色素P450侧链裂解酶（P450scc）的含量。在无ACTH刺激的基础条件下，Hal nn肾上腺皮质细胞中的皮质醇、cAMP、StAR和P450scc水平显著较低。无论基因型如何，ACTH均显著提高了培养基中的皮质醇水平以及肾上腺皮质细胞裂解物中MC2R、StAR、P450scc的蛋白含量。不同基因型和处理之间的总CREB蛋白含量没有差异，而pCREB含量表现出基因型和处理的显著影响，在基础条件下以及对ACTH刺激的反应中，Hal NN中的pCREB含量高于Hal nn。这些结果表明，ACTH的cAMP/蛋白激酶A/pCREB信号通路受损以及肾上腺皮质类固醇生成中限制因子（StAR和P450scc）的表达减少可能导致Hal nn猪的血浆皮质醇水平显著降低。
