Abstract # 2217 Event # 4:

Scheduled for Thursday, June 21, 2007 10:00 AM-10:15 AM: Session 1 (North Main Hall C/D) Oral Presentation

A rhesus monkey (Macaca mulatta) model of behavioral inhibition: Heritability but no effect of the serotonin transporter polymorphism

J. Rogers1,2, S. E. Shelton3, W. Shelledy1, R. Garcia IV1 and N. H. Kalin3
1Southwest Foundation for Biomedical Research, Dept. of Genetics, 7620 N.W. Loop 410, San Antonio, Texas 78227, USA, 2Southwest National Primate Research Center, 3Univ. of Wisconsin
     One aspect of primate behavior that differs among individuals within species is boldness, or conversely, shyness or behavioral inhibition. Furthermore, among humans, a person’s risk for anxiety disorders or depression is correlated with behavioral inhibition during childhood. This study was designed to determine whether extreme behavioral inhibition shows significant heritability in rhesus monkeys, and if so, to test for an effect of the serotonin transporter gene on variation in those behaviors. This gene has been associated with variation in behavior among rhesus monkeys and psychopathology in humans. We used the Human Intruder paradigm to test 285 rhesus (Macaca mulatta) of known genealogy (mean age 19.3 months). We then calculated the heritability of three behaviors, and examined the effect of the promoter repeat unit polymorphism in the serotonin transporter locus. Two behavioral measures of anxiety (extreme behavioral inhibition as indexed by freezing, and vigilance or orienting to the intruder) show significant heritability [h2=0.38, p=0.012; h2=0.91, p=0.00001, respectively]. Locomotion during testing does not exhibit significant heritability, and neither of the heritable behaviors is statistically related to serotonin transporter genotype. We conclude that young rhesus monkeys are excellent models for genetic analyses of behavioral inhibition and related traits, and that these genetic effects are attributable to molecular variation other than the promoter repeat polymorphism in the serotonin transporter gene.