title: A reevaluation of the relation between estrogen and emotionality in female rats.
abstract: It has been hypothesized that the emotionality of the female rat is reduced at estrus. In confirmation of previous research, it was found that administration of estradiol benzoate (EB;20 mug/kg) to female rats of the Maudsley Reactive (MR) strain increased open-field activity and decreased open-field defecation. In addition, ovariectomy increased open-field defecation in MR females. Supporting the generality of these findings, hormone administration reduced open-field defecation and increased open-field activity in intact females of a genetically heterogeneous background. Additional studies suggested that the decrease in open-field defecation at estrus is dependent on estrogenic suppression of food intake. Hormone replacement decreased food intake in the period preceding the open-field test, and colonic contents were also lower in rats treated with EB+P (progesterone) immediately after the completion of the open-field test. These changes were seen in both MR and genetically heterogeneous females. It was concluded that the decrease in open-field defecation at estrus may be mediated by a reduction in food intake and a consequent decrease in colonic contents and that the validity of the defecation response as a measure of emotionality may be seriously questioned under these circumstances.
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002369:Castration; D003672:Defecation; D004435:Eating / Q000187:drug effects; D004644:Emotions / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects*; D005260:Female; D009043:Motor Activity / Q000187:drug effects; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D013045:Species Specificity
chemical_list: D011374:Progesterone; D004958:Estradiol