Serotonergic and dopaminergic regulation of aggression in high and low aggressive birds
Abstract
Aggression and cannibalism are serious concerns for the modern production poultry industry. Injury, stress and mortality from these behaviors have severe impacts on animal well-being as well as economic impacts for the producer. Production breeders have recently become interested in selecting for birds with reduced aggressive and cannibalistic behaviors. However, physiological indicators of aggression are severely lacking. A better understanding of heritable variations in the mechanisms underlying aggression would improve the efficiency of such selection practices. Here we investigate heritable differences in the dopaminergic and serotonergic mediation of aggression in high (DXL, LGPS and 72) and low aggressive strains (HGPS and 63) of birds, via the serotonin (5-HT) 1A and 1B and dopamine (DA) D1 and D2 receptors. Aggression regulation through the 5-HT1A receptor is a common pathway for regulating aggression in high aggressive strains, but not in low aggressive strains. In low aggressive birds, antagonism of the 5-HT1B pathway in subordinate hens increased aggressiveness, while decreasing aggression in dominate hens, yet showed no effect on intermale aggression. Antagonism of 5-HT1B had no effect on aggression in high aggressive strains. These data suggest a genetic x environment (social environment) interaction on 5-HT autoreceptor regulation of aggressiveness. Antagonism of the D1 receptor decreased aggression in only high aggressive strains, while agonism of this receptor increased aggression in both high and low aggressive strains. Alternately, antagonism of the D2 receptor decreased aggression in all strains, while D2 receptor agonism increased aggression in only the low aggressive strain. Our data show evidence of heritable differences in dopaminergic regulation of aggression. Taken together, the results indicate that both 5-HT and DA are involved in regulating aggression in chickens in a strain-, pathway- and receptor-dependent manner.
Degree
Ph.D.
Advisors
Cheng, Purdue University.
Subject Area
Neurobiology|Animal sciences
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