Estradiol modulation of central monoamine activity in female mountain spiny lizards

Although estradiol (E2) mediates many behaviors in females, relatively litt le is known about its role in female aggression. Previous studies in female mountain spiny lizards indicated that female aggression is modulated by ov ariectomy and sex steroid hormone replacement and that expression of aggres sive behavior is accompanied by changes in serotonin activity. This study e xamines if E2 modulates the activity of serotonin and other central monoami nes. Free-living females were caught and housed in the laboratory and recei ved one of 3 treatments: sham surgery (SHAM), ovariectomy plus empty implan t (OVEX), or sham surgery plus a long lasting E2 implant (E2-IMP). After 3 weeks of treatment, selected brain areas were examined for levels of monoam ines and their metabolites. Changes in monoamine activity were most pronoun ced in the septum where levels of serotonin (5-HT), 5-hydroxyindoleacetic a cid (5-HIAA), and norepinephrine (NE) were higher in E2-IMP females relativ e to SHAM, and levels of 5-HIAA were higher in OVEX females relative to SHA M. Changes in dopamine (DA) activity were also found, with increased DA con centration and decreased ratio of forebrain:brainstem HVA concentrations in E2-IMP relative to SHAM females. These results suggest that the actions of E2 on aggression might be mediated, in part, by dose-dependent effects on 5-HT activity in the septum. Copyright (C) 2000 S. Karger AG, Basel.