Effects of medial preoptic lesions on placentophagia and on the onset of maternal behavior in the rat.

NOONAN, M. AND M. B. KRJSTAL. Effects (~fmedial preoptic lesions on placentophaRia and on the onset ofmaternal be­ havior in the rat. PHYSJOL. BEHAV. 22(6) 1197-1202, 1979.-Lesions of the medial preoptic area (MPO) were produced through permanently indwelling electrodes 24 hr prior to parturition in pregnant rats, or 24 hr prior to donor-placenta presentation in virgin rats determined in a pretest to be placentophages. The lesions had no disruptive effect on placen­ tophagia in the virgin females. However, MPO lesions did delay the onset of placentophagia, pup-retrieval, and nest­ building in some parturient rats. In others, lesions produced an impairment (in latency and quality) only of nest-building. None showed any impairment of pup-licking, or in the clear tendency to leave excreted waste away from the gathered pups. These results suggest the possibility of at least semi-independent mechanisms for the various components of maternal behavior.