| Abstract | Recent evidence suggests that early exposure to mild stress promotes the development of
novelty seeking behavior. Here we test this hypothesis in squirrel monkeys and investigate
whether novelty seeking behavior is associated with differences in cerebrospinal fluid
(CSF) levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5HIAA), the dopamine
metabolite homovanillic acid (HVA), the norepinephrine metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), and the neuropeptide corticotrophin-releasing factor
(CRF). Monkeys were randomized early in life to either mild intermittent stress (IS) or no
stress (NS) conditions, and subsequently presented with opportunities to interact with a
familiar or novel object in a test box that was connected to each monkey⿿s home cage. To
further minimize the potentially stressful nature of the test situation, monkeys were
acclimated to the test procedures prior to study initiation. Post-test plasma levels of
cortisol in IS and NS monkeys did not differ significantly from baseline levels measured in
undisturbed conditions. During testing, more IS than NS monkeys voluntarily left the home
cage, and IS monkeys spent more time in the test box compared to NS monkeys. More IS
than NS monkeys engaged in object exploration in the test box, and IS monkeys preferred
to interact with the novel vs. familiar object. Novelty seeking was not associated with
differences in 5HIAA, HVA, MHPG, or CRF, but correlated with differences in object
exploration observed in a different test situation at an earlier age. These trait-like
differences in novelty seeking appear to reflect mild early stress-induced adaptations that
enhance curiosity and resilience. |
