Experimental anxiety in the black and white model in cycling, pregnant and lactating rats

This study demonstrates changes in experimental anxiety assessed in the black and white paradigm during various reproductive states of female rats. Low levels of experimental anxiety were observed during late proestrus and on day 17 of gestation, stages related to high progesterone (P) levels. In estrus, metestrus, diestrus and on day 21 of gestation, stages characterized by low P concentrations, high levels of experimental anxiety, similar to those exhibited by ovariectomized females, were found. No changes in experimental anxiety were observed on day 8 of lactation compared to ovariectomized females. These data are discussed from the standpoint of the putative anxiolytic-like effect of progestins.