Lateral habenula neurons are necessary for the hormonal onset of maternal behavior and for the display of postpartum estrus in naturally parturient female rats.

In 16-day pregnant, hysterectomized-ovariectomized and estradiol benzoate-treated rats, cytotoxic lesions of the lateral habenula (Lhb) produced severe deficits in maternal behavior (K.P. Corodimas, J.S. Rosenblatt, M.E. Canfield, & J.I. Morrell, 1993). To determine if deficits could be found in parturient rats, females were bilaterally injected with kainic acid (KA) to produce cytotoxic lesions of the Lhb. Controls either received bilateral KA-induced lesions to the hippocampus or were unoperated. All females maintained their pregnancies, underwent parturition, and were tested for maternal behavior (pup retrieval, nursing, and nestbuilding), general activity, and oromotor carrying. Females with lesions of the Lhb had severe disruptions of all components of maternal behavior and postpartum estrus. These results extend previous findings that the Lhb is involved in the hormonal onset of maternal behavior and also demonstrate that the Lhb supports the display of postpartum estrus.