Dissociation between the display of lordosis and soliciting behaviors in female rats with lesions of the dorsomedial pontine tegmentum

Lesions of the dorsomedial tegmentum (DMTL) between the midbrain pontine junction and the middle level of the pons effectively eliminate the induction by estrogen-progesterone of lordosis behavior in ovariectomized rats. However, soliciting behaviors such as ear wiggling and hopping were not inhibited by this type of lesion. The common damaged area in DMTL rats which failed to show lordosis was the medial periventricular gray. The lesions placed in the caudal pontine central gray were not effective in suppressing lordosis response. Lesions of the ventromedial tegmentum (VMTL) were also ineffective in suppressing lordosis. Most of the animals with the VMTL showed soliciting behaviors. In these rats, the incidence of lordosis and lordosis quotient (LQ) were comparable to those of sham operated rats. When bilateral lesions were placed in the lateral tegmentum region, the mean LQ and incidence of soliciting behavior were not significantly different from those of sham operated controls. These results suggest a clear dissociation of the regulatory mechanisms between the display of lordosis and soliciting behaviors at the pontine level.