Maternal alterations induced by exposure to an unfamiliar home cage in early underfed dams

The expression of different behavioral components in the adult rat depends on a number of early influences, including age, hormones, manipulations of sensory cues, and perinatal undernutrition, all of which impact the development of brain areas underlying adaptive processes, maternal behavior, and the response to novelty. The current study investigates the effects of pre- and neonatal undernutrition on various components of maternal behavior of dams exposed to the challenge of an unfamiliar home cage on days 4, 8, and 12 of lactation. Food restriction was initiated from gestational day (G) G6 to G19 when dams received 50-70% of the normal balanced diet, followed by 100% from G20 to G21. After birth, pups were underfed by alternating every 12 h between two lactating dams, one of which, had ligated nipples. Weaning was at 25 days of age followed by an ad libitum diet until postpartum day 90, when females were mated, and subsequently tested for maternal behavior in an unfamiliar cage. The results indicated that in early underfed mothers the frequency of handling wood shavings and of, approaching, licking, crouching, and grasping pups for retrieval was significantly reduced. Moreover, self-grooming increased substantially in the underfed dams, but the frequency of rearing was reduced. Additionally, the body weight of pups nursed by early underfed dams was significantly lower than that of control pups. These findings suggest a relation between early food restriction and the deficient maternal care observed when these dams were challenged by exposure to an unfamiliar home cage.