Changes in burying behavior during the estrous cycle: effect of estrogen and progesterone.

This study demonstrates changes in cumulative burying behavior during various phases of the rat estrous cycle. Low levels of burying behavior were observed during late proestrus. Similar burying behavior levels among females tested in early proestrus, metestrus or diestrus and ovariectomized females were found. In ovariectomized females, treatment with estrogen (E) produced a slight, non-significant reduction in burying behavior. In contrast, progesterone (P) treatment resulted in a dose-dependent, statistically significant decrease in time spent burying. The combined treatment of E and P produced no effect. These data are discussed from the standpoint of the putative anxiolytic effect of P.