title: Association of HPA axis-related genetic variation with stress reactivity and aggressive behaviour in pigs.
abstract: BACKGROUND
  Stress, elicited for example by aggressive interactions, has negative effects on various biological functions including immune defence, reproduction, growth, and, in livestock, on product quality. Stress response and aggressiveness are mutually interrelated and show large interindividual variation, partly attributable to genetic factors. In the pig little is known about the molecular-genetic background of the variation in stress responsiveness and aggressiveness. To identify candidate genes we analyzed association of DNA markers in each of ten genes (CRH g.233C>T, CRHR1 c.*866_867insA, CRHBP c.51G>A, POMC c.293_298del, MC2R c.306T>G, NR3C1 c.*2122A>G, AVP c.207A>G, AVPR1B c.1084A>G, UCN g.1329T>C, CRHR2 c.*13T>C) related to the hypothalamic-pituitary-adrenocortical (HPA) axis, one of the main stress-response systems, with various stress- and aggression-related parameters at slaughter. These parameters were: physiological measures of the stress response (plasma concentrations of cortisol, creatine kinase, glucose, and lactate), adrenal weight (which is a parameter reflecting activity of the central branch of the HPA axis over time) and aggressive behaviour (measured by means of lesion scoring) in the context of psychosocial stress of mixing individuals with different aggressive temperament.
  
  
  RESULTS
  The SNP NR3C1 c.*2122A>G showed association with cortisol concentration (p = 0.024), adrenal weight (p = 0.003) and aggressive behaviour (front lesion score, p = 0.012; total lesion score p = 0.045). The SNP AVPR1B c.1084A>G showed a highly significant association with aggressive behaviour (middle lesion score, p = 0.007; total lesion score p = 0.003). The SNP UCN g.1329T>C showed association with adrenal weight (p = 0.019) and aggressive behaviour (front lesion score, p = 0.029). The SNP CRH g.233C>T showed a significant association with glucose concentration (p = 0.002), and the polymorphisms POMC c.293_298del and MC2R c.306T>G with adrenal weight (p = 0.027 and p < 0.0001 respectively).
  
  
  CONCLUSIONS
  The multiple and consistent associations shown by SNP in NR3C1 and AVPR1B provide convincing evidence for genuine effects of their DNA sequence variation on stress responsiveness and aggressive behaviour. Identification of the causal functional molecular polymorphisms would not only provide markers useful for pig breeding but also insight into the molecular bases of the stress response and aggressive behaviour in general.
authors.affiliation: Research Unit Molecular Biology, Leibniz Institute for Farm Animal Biology FBN, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany.
authors.forename: Eduard
authors.initials: E
authors.lastname: Muráni
authors.forename: Siriluck
authors.initials: S
authors.lastname: Ponsuksili
authors.forename: Richard B
authors.initials: RB
authors.lastname: D'Eath
authors.forename: Simon P
authors.initials: SP
authors.lastname: Turner
authors.forename: Esra
authors.initials: E
authors.lastname: Kurt
authors.forename: Gary
authors.initials: G
authors.lastname: Evans
authors.forename: Ludger
authors.initials: L
authors.lastname: Thölking
authors.forename: Ronald
authors.initials: R
authors.lastname: Klont
authors.forename: Aline
authors.initials: A
authors.lastname: Foury
authors.forename: Pierre
authors.initials: P
authors.lastname: Mormède
authors.forename: Klaus
authors.initials: K
authors.lastname: Wimmers
mesh_terms: D000374:Aggression; D000483:Alleles; D000818:Animals; D001522:Behavior, Animal; D005819:Genetic Markers; D005838:Genotype; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000502:physiology*; D020641:Polymorphism, Single Nucleotide; D021101:Radiation Hybrid Mapping; D011965:Receptors, Glucocorticoid / Q000235:genetics; D017483:Receptors, Vasopressin / Q000235:genetics; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D013552:Swine / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D011965:Receptors, Glucocorticoid; D017483:Receptors, Vasopressin