Receptivity, proceptivity and attractivity of pregnant and pseudopregnant rats.

In the present study the effects of pregnancy and of pseudopregnancy on oestrogen-induced receptivity, proceptivity and attractivity in female rats were investigated. Receptivity and proceptivity were determined in heterosexual pair tests. Attractivity was determined using a new method: a residential plus-maze. It was found that during the second half of pregnancy oestrogen treatment did not induce the above-mentioned behaviours. However, during the second half of pseudopregnancy oestrogen treatment resulted in high levels of these behaviours. Also, combined oestrogen plus progesterone treatment showed similar high frequencies of these behaviours in pseudopregnant rats.