Meeting Abstract

P2.126  Wednesday, Jan. 5  Acute stress alters brain aromatase activity in Japanese quail (Coturnix japonica) in a sex-specific manner DICKENS, M.J.*; CORNIL, C.A.; BALTHAZART, J.; Univ. of Liège; Univ. of Liège; Univ. of Liège molly.dickens@ulg.ac.be

Acute stress is assumed to rapidly and temporarily suppress reproductive behavior, but the mechanisms of suppression are poorly understood. Since activity of brain aromatase, the enzyme that converts testosterone to estradiol to activate reproductive behavior in male quail (C. japonica), can be rapidly and reversibly modified, modulation of aromatase activity (AA) may play a role in mediating these effects of stress. We investigated AA in six aromatase expressing brain nuclei in both male and female quail before, during, and after 30 min of acute restraint stress. In males, a pronounced change in AA was observed within 5 min in the medial preoptic nucleus (POM), the region associated with male reproductive behavior, but not other brain nuclei. Although the direction of effect is opposite to that predicted by the effects of aromatase on behavior, it is consistent with the observation that AA decreases in males following sexual interaction with a female (opposite effects of stress). In females, AA was also increased in the POM but only at 15 min of stress and there was a strong, sustained suppression of AA in the ventromedial and tuberal hypothalamus, regions associated with female reproductive behavior. Although increases in AA were paralleled by stress-induced increases in plasma corticosterone (CORT), individual CORT concentrations (measured in jugular and brachial plasma) were not correlated with changes in AA in males. In females, CORT concentrations were weakly predictive of changes in AA in the POM. These data indicate that stress has rapid, reversible and sex-specific effects on AA in the brain of Japanese quail but whether these enzymatic changes are directly mediated by stress-induced increases in CORT remains to be determined.