Meeting Abstract

P3.181  Sunday, Jan. 6  Correlation between local brain estradiol concentrations and aromatase activity after acute stress or sexual interaction DICKENS, M.J.*; BALTHAZART, J.; CORNIL, C.A.; Univ. of California, Berkeley; Univ. of Liege; Univ. of Liege m.dickens@berkeley.edu

Testosterone aromatization in the brain is known to play a key role in male sexual behavior of Japanese quail. Local brain aromatase activity (AA) can be rapidly regulated in vivo (<5 min) but how these changes correlate to changes in estradiol concentration (E2) in the tissue remains unclear. Here we examine rapid changes of E2 and AA in microdissected nuclei of male and female quail after 5 min of sexual interaction (demonstrated to decrease AA in the preoptic area-hypothalamus, HPOA), 15 min of restraint stress (demonstrated to increase AA in the HPOA) or in control conditions. Individual brains were microdissected to isolate HPOA and medio-basal hypothalamus (MBH), and estradiol was extracted and assayed using an UltraSensitive radioimmunoassay in part of each sample while AA was assayed in the rest. In females, E2 and AA were stable across experimental groups and there was a significant, positive correlation between E2 and AA in both HPOA and MBH suggesting that females rely on local AA rather than ovarian production to maintain nuclei-specific E2. In the male HPOA, sexual interactions tended to decrease AA (as predicted) with a corresponding decrease in E2 and there was a positive, significant correlation between AA and E2. Surprisingly, however, stress increased AA (as predicted) but E2 significantly decreased to nearly half of control concentrations. This suggests that acute stress may initiate a previously unidentified phenomenon to regulate local E2. While these data suggest a new context-dependent regulation of AA and E2 following stress, they also further confirm rapid changes in local E2 that may then mediate rapid behavioral effects.