Gene array analysis of adrenal glands in broiler chickens following ACTH treatment

Analysis with 21 K poultry oligo microarrays indicated that ACTH treatment affected the expression of 134 genes. Several transcripts assigned to genes involved in the adrenal ACTH signaling pathway and steroidogenic enzymes were identified as differentially expressed by ACTH treatment. Real-time PCR on 18 selected genes confirmed changes in transcript levels of 11 genes, including MC2R, CREM, Cry, Bmal1, Sqle, Prax1, and StAR. Only 4 genes revealed to be differentially expressed between higher and lower adrenal responders to ACTH treatment.The results from the present study reveal putative candidate genes; their role in regulation of adrenal functions and adaptability to stress should be further investigated.Farm animals are often confronted with various challenging situations that may have a negative impact on their performance [1]. Under stressful conditions, several systems, mainly the hypothalamic-pituitary-adrenal (HPA) axis, the autonomic nervous system (ANS) [2,3], and the immune system [4] are called into action to re-establish homeostastis. This is done by setting up a cascade of regulatory mechanisms [5,6], resulting in a mobilization of energy and a shift in metabolism with detrimental effects on growth performance and efficiency of feed utilization. The large variability across species, breeds and individuals in their responses to stress challenges and variability appears to have a large genetic component [7-12]. In fact, the response of adrenal glands to ACTH seems to be variable in numerous species, including rat [27], pig [11,13-16] and quail [10,17] and difference in adrenal responsiveness may play a role in the variability of the response to stress.For example, in a pioneering series of studies with pigs, Hennessy et al. [18] showed that the adrenal response to ACTH is an individual characteristic, which is heritable and reproducible across successive testing [18,14,19]. In broilers, studies indicated that plasma corticosterone concentration after s