Abstract # 97:

Scheduled for Friday, June 18, 2010 07:00 PM-09:00 PM: Session 18 (Medallion Ballroom C/D/E/F) Poster Presentation


EFFECTS OF OVARIAN STEROID REMOVAL ON THE SEROTONERGIC SYSTEM AND BEHAVIOR OF FEMALE JAPANESE MACAQUES

N. A. DeBolt Robertson, K. Coleman and C. L. Bethea
Oregon National Primate Research Center, 505 NW 185th Ave., Beaverton, OR 97006, USA
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Endogenous levels of ovarian steroids (e.g., estrogen and progesterone) fluctuate naturally during a woman’s life cycle. After menopause, ovarian steroid secretion is lost, which may result in inadequate serotonin system function and dysregulation of mood and anxiety. We examined whether long-term ovariectomy, as a model of surgical menopause, alters the serotonergic system, resulting in anxious behavior. Group-housed female Japanese macaques (Macaca fuscata) were either ovariectomized [OVX; N=5] or tubally ligated [TL; N=5] at puberty, and returned to their semi-free ranging troop. After 3 years, they were moved to small group housing. We measured anxious behavior using a Human Intruder Test (assesses response to a potentially threatening social stimulus) and a Novel Object Test (assesses reaction to a rubber snake). We assessed activity of the central serotonergic system by measuring prolactin secretion in response to a fenfluramine challenge (5mg/kg IV) under propofol anesthesia. OVX monkeys spent more time in anxious behavior such as freezing [Mann-Whitney U=20.0, P=0.05] in the Human Intruder test compared to TL monkeys. They were also more likely to sleep [U=22.5, P=0.02] and less likely to explore [U=5.0, P=0.05] the snake in the Novel Object test, further indications of anxiety. Prolactin release was significantly less in OVX compared to TL monkeys [F(1,7)=11.0, P<0.01]. These results indicate that removal of ovarian hormones reduces serotonergic function, which in turn causes an increase in anxiety.