|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: February 25, 2010
Publication Date: July 11, 2010
Citation: Dennis, R.L., Cheng, H. 2010. Effects of Postnatal Serotonin Agonism on Fear Response and Memory [abstract]. Poultry Science. 89:T7(E-Suppl 1). Technical Abstract: The neurotransmitter serotonin (5-HT) also acts as a neurogenic compound in the developing brain. Early administration of a 5-HT agonist could alter the development of the serotonergic circuitry, altering behaviors mediated by 5-HT signaling, such as memory, fear and aggression. White leghorn chicks were given an injection of 5-MT (serotonin agonist) at 2.5mg/kg (low dose), 10mg/kg (high dose) or saline (control) on day of hatch and a second dose 24 h later. Chicks were tested for fear response and memory at 2 weeks of age. Chicks were subjected to a social isolation fear test for 20 minutes, time to first vocalization, numbers of vocalization, time to first leap and numbers of leaps were recorded. Chicks injected with low dose of 5-HT agonist had significantly shorter latency to time of first vocalization and a greater number of vocalizations compared with control birds (P<0.05). A similar pattern of changes, but at a tendency only, was found in high dose of 5-HT agonist treated chicks (P>0.10). No difference was found in time to the first leap or number of leaps. In a memory test, chicks were placed in a running wheel and presented with an imprinted object (white box with a red light) and a similar novel object (blue box with a white light), respectively. The distance traveled in the wheel toward each object was measured. Chicks from all groups traveled a similar distance toward a familiar object. However, control chicks walked the least toward a novel object, low dose chicks tended to walk further toward a novel object (P<0.10), and high dose chicks walked significantly farther for a novel object (P<0.05). No difference was found between treatments in a tonic immobility test of fearfulness (P>0.05). Body weight and fluctuating asymmetry of the shank, and shank length and width did not differ among treatments (P>0.05). Our data show that later behaviors including fear and memory can be altered by early alteration of the 5-HT system without altering growth development, such as body weight, leg size and bilateral symmetry.