The cortisol response to ACTH in pigs, heritability and influence of corticosteroid-binding globulin

Abstract

In the search for biological basis of robustness, this study aimed (i) at the determination of the heritability of the cortisol response to ACTH in juvenile pigs, using restricted maximum likelihood methodology applied to a multiple trait animal model, and (ii) at the study of the relationships between basal and stimulated cortisol levels with corticosteroid-binding globulin (CBG), IGF-I and haptoglobin, all important players in glucose metabolism and production traits. At 6 weeks of age, 298 intact male and female piglets from 30 litters (30 dams and 30 boars) were injected with 250 µg ACTH(1-24) (Synacthen). Blood was taken before ACTH injection to measure basal levels of cortisol, glucose, CBG, IGF-I and haptoglobin, and 60 min later to measure stimulated cortisol levels and glucose. Cortisol increased 2.8-fold after ACTH injection, with a high correlation between basal and stimulated levels (phenotypic correlation, r p = 0.539; genetic correlation, r g = 0.938). Post-ACTH cortisol levels were highly heritable ( h 2 = 0.684) and could therefore be used for genetic selection of animals with a more reactive hypothalamic-pituitary-adrenocortical axis. CBG binding capacity correlated with cortisol levels measured in basal conditions in males only. No correlation was found between CBG binding capacity and post-ACTH cortisol levels. Basal IGF-I concentration was positively correlated with BW at birth and weaning, and showed a high correlation with CBG binding capacity with a strong sexual dimorphism, the correlation being much higher in males than in females. Basal haptoglobin concentrations were negatively correlated with CBG binding capacity and IGF-I concentrations. Complex relationships were also found between circulating glucose levels and these different variables that have been shown to be related to glucose resistance in humans. These data are therefore valuable for the genetic selection of animals to explore the consequences on production and robustness traits, but also point at pigs as a relevant model to explore the underlying mechanisms of the metabolic syndrome including the contribution of genetic factors.

Genetic parameters and associated genomic regions for global immunocompetence and other health-related traits in pigs

“…To the best of our knowledge, this is the first study reporting a heritability for the cortisol measured in hair, suggesting the existence of genetic determinism in the susceptibility of animals to chronic stress. In line with our results, some studies in humans determined low-to-medium heritabilities for acute plasma and saliva cortisol levels 42 , and post-ACTH cortisol levels in blood were reported to be highly heritable in pigs 43 .…”

ACTH-induced stress in weaned sows impairs LH receptor expression and steroidogenesis capacity in the ovary

“…ACTH administration has been reported to simulate the stress response, which is reflected by the plasma cortisol response, and influenced reproduction in pigs [8, 9, 11, 13, 23, 24]. In the present study, we administered sows with repeated ACTH injections to mimic stress; this resulted in an increase in the plasma cortisol concentration in the sows that were treated with ACTH but not in the untreated control sows, indicating successful establishment of a stress model.…”

Seasonal effects on plasma cortisol concentrations in the Bedouin buck: circadian studies and response to ACTH

“…Blood samples were collected in refrigerated tubes at −15, 0, 3, 8, 15, 30, 45, 60, 90 and 120 min, and then at 24 and 48 h after each ACTH injection. The goal was to obtain a maximal response of the adrenal glands, a phenotype that we have shown to be highly heritable in pigs (Larzul et al, 2015).…”