Variations in maternal behaviour are associated with differences in oxytocin receptor levels in the rat

Female Long-Evans rats exhibit stable individual differences in maternal be haviours such as pup licking/grooming and arched-back nursing posture (LG-A BN). These variations in maternal behaviour are accompanied by differences in lactation-induced increases in oxytocin receptor levels in brain regions known to mediate the expression of maternal care in this species (i.e. the bed nucleus of the stria terminalis, the medial preoptic area and the late ral septum). Oxytocin receptor levels in the central nucleus of the amygdal a were significantly higher in high compared to low LG-ABN females regardle ss of reproductive status. These findings suggest that individual differenc es in maternal behaviour may be directly related to variations in oxytocin receptor expression.