title: Effects of selective serotonin antagonism on central neurotransmission.
abstract: Aggression and cannibalism in laying hens can differ in intensity and degree due to many factors, including genetics. Previous behavioral analysis of 2 strains of White Leghorns, DeKalb XL (DXL) and HGPS (a group-selected line for high group productivity and survivability), revealed high and low aggressive phenotypes, respectively. However, the exact genetic mechanisms mediating aggressiveness are currently unknown. Analysis of serotonin (5-HT) mediation of aggression in subordinate hens of these strains revealed increases in aggression in DXL hens following antagonism of the 5-HT1A receptor and in HGPS hens following antagonism of the 5-HT1B receptor. Here, we investigate the different neurotransmitter response in the hypothalamus and raphe nucleus mediating these aggressive responses to receptor antagonism. Elevated aggressive response to 5-HT1B antagonism by HGPS hens was also accompanied by a decrease in raphe nucleus dopamine (DA) and an increase in DA turnover. Increased aggressiveness in DXL hens did not coincide with a reduction in raphe nucleus 5-HT or turnover (as indicated by 5-hydroxyindoleacetic acid levels) following 5-HT1A antagonism. A reduction in 5-hydroxyindoleacetic acid (but not 5-HT) was seen in HGPS hens treated with 5-HT1A antagonist; however, these hens exhibited no change in aggressive behaviors. Our data show evidence of different heritable mechanisms of neurotransmitter regulation of aggressive response, specifically heritable differences in the interaction between 5-HT and catecholamines in regulating aggression.
authors.affiliation: Livestock Behavior Research Unit, USDA-Agricultural Research Service, W. Lafayette, IN 47907, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Dennis
authors.forename: H W
authors.initials: HW
authors.lastname: Cheng
mesh_terms: D000374:Aggression; D000818:Animals; D002645:Chickens / Q000235:genetics / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D005260:Female; D007031:Hypothalamus / Q000502:physiology*; D010069:Oxadiazoles / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011897:Random Allocation; D011903:Raphe Nuclei / Q000502:physiology*; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism; D012641:Selection, Genetic; D012701:Serotonin / Q000378:metabolism*; D058829:Serotonin 5-HT1 Receptor Antagonists / Q000494:pharmacology; D058830:Serotonin 5-HT2 Receptor Antagonists / Q000494:pharmacology; D013045:Species Specificity; D009435:Synaptic Transmission
chemical_list: D010069:Oxadiazoles; D010879:Piperazines; D044302:Receptor, Serotonin, 5-HT1B; D058829:Serotonin 5-HT1 Receptor Antagonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D044282:Receptor, Serotonin, 5-HT1A; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; C090701:GR 127935; D012701:Serotonin