Time course of the response to ACTH in pig: biological and transcriptomic study

To explore individual variation in the biological response to cortisol, the main stress hormone, in pigs, we have developed a microarray analysis to study the kinetics of the response to an ACTH injection measured at 4 time points. ACTH is a hormone secreted by the pituitary gland and triggering the release of cortisol by the adrenal glands in response to a stress. The objective was to identify genes up- or down-regulated during the stress response triggered by cortisol in the whole blood. To explore individual variation in the biological response to cortisol, whole blood from 30 juvenile Large White (LW) pigs was collected at 4 time point ( t = 0, +1 h, +4 h, +24 h) for a total of 120 samples. All pigs were females and were raised in two batches. Arrays were designed such that all observations of a sole individual were kept on the same array, with two individuals (one from each batch) on one array. This design secured the kinetics of the response for each individual and prevented confounding effects between batch and array. After quality and control, 120 samples were kept for normalization and analyses (represented here).