Monoaminergic dysregulation on diestrus-2 and estrus through high emotional reactivity

Rats with great differences in emotional reactivity, during weighing and handling for vaginal smear screening were examined on diestrus-2 (DE-2), proestrus (PE), and estrus (E). Rats with high emotional reactivity (HR), interpreted as trait anxiety, had different serotonergic and dopaminergic profile in hypothalamus-preoptic area (HY-PA) and striatum (Str) and thymus weight lower than that found in rats with low emotional reactivity (LR). In HY-PA of rats with HR when compared to rats with LR, increased 5-hydroxyindoleacetic acid (5-HIAA), 5-HIAA/serotonin (5-HT) ratio, and 3,4-dihydroxyphenylacetic acid (DOPAC) and in Str increased DOPAC and DOPAC/dopamine (DA) ratio were found only on DE-2, paralleled by increased adrenal weight and decreased thymus weight. In Str, a significant effect of HR on 5-HIAA was found only on E, in parallel with increased 5-HT and decreased DOPAC and DOPAC/DA ratio when compared to rats with LR. The results suggest that activation of 5-HT and DA in HY-PA and DA in Str through HR is apparent only on DE-2 while, conversely, on E suppression of striatal DA it is apparent with 5-HT dysregulation. These findings might have some relevance to the predisposition of women with trait anxiety to premenstrual syndrome.