|Cheng, Heng Wei|
Submitted to: International Society of Applied Ethology
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2007
Publication Date: 7/30/2007
Citation: Cheng, H., and Dennis, R.L. 2007. Serotonin and Aggressiveness in Chickens [abstract]. International Society of Applied Ethology. p.128. Interpretive Summary:
Technical Abstract: Serotonin (5-HT) regulates aggressive behavior in animals. This study examined if 5-HT regulation of aggressiveness is gene-dependent. Chickens from two divergently selected lines KGB and MBB (Kind Gentle Birds and Mean Bad Birds displaying low and high aggressiveness, respectively) and DXL (Dekalb XL, an aggressive out-group) were used in the study. Hens were paired within the same strain. At 24 wk of age, the subordinate of each pair received an i.p. injection of either NAN-190 (1mg/kg, a 5-HT (1A) receptor antagonist, NAN), GR-127935 (1mg/kg, a 5-HT (1B) receptor antagonist, GR) or saline (control) for 5 days (n = 10 per treatment). Results showed that the frequency of aggressive behaviors was increased in the hens of DXL and MBB treated with NAN (P<0.05) and in the KGB hens treated with GR (P<0.05), respectively. GR treated KGB hens and NAN treated MBB hens also displayed an increase in feather pecking (FP) (P<0.05), respectively; but neither antagonist had an effect on FP of DXL hens (P>0.05). Among the controls, MBB hens have higher epinephrine (EP) levels than KGB or DXL hens, indicative of the inferior stress coping ability of MBB hens. Treatment with GR significantly reduced EP levels in MBB hens (P<0.05), but not in DXL or KGB hens, suggesting a role of 5-HT(1B) receptor in stress regulation in MBB hens. Hens of all strains treated with GR but not NAN exhibited reduced weight gain and increased plasma 5-HT concentrations compared to controls (P<0.05), suggesting a negative feedback system altering stress coping ability. The results provide evidence for a genetic basis of different serotonergic mediations of aggression in chickens. The data also indicate that, similar to humans and rodents, 5-HT(1A) receptor and 5-HT(1B) receptor have different functions in the regulation of aggressive behaviors in chickens.