Decline of maternal behavior in the virgin and lactating rat.

Abstract

Sensitized virgins and postpartum lactating mothers, both exhibiting maternal behavior, were given donor litters that increased in age by 1 day, for 28 days, starting at the onset of maternal behavior. Each day females were tested for maternal behavior with pups 4-8 days old: Maternal care (i.e., nursing/crouching, retrieving, nest building and licking) and maternal withdrawal, rejection, and prevention of nursing were recorded. After the ninth day, females were also tested with the progressively older pups from 10 to 28 days of age with which they were living. Virgins and lactating mothers showed generally similar patterns of maternal care although some differences were found, and they declined in maternal behavior toward the older pups in a similar manner. Maternal behavior did not decline in tests with younger pups. The results are interpreted as supporting the hypothesis that the decline as well as the maintenance of maternal behavior postpartum is nonhormonally mediated.

Manipulations During the Second, but not the First, Week of Life Increase Susceptibility to Cocaine Self-Administration in Female Rats

“…Natural maternal behavior peaks during the first part of the lactation period (PND 1-7) and tapers off towards weaning (PND 21) (Reisbick et al, 1975;Rosenblatt, 1969;Rosenblatt and Lehrman, 1963). Thus, one would expect that perturbation of the litter during the first week of life would elicit greater maternal care than perturbation during the second week of life.…”

“…As alluded to above, rodent young are not passive recipients of maternal care, but provide cues that elicit mother-pup interactions (Moltz and Leon, 1973;Reisbick et al, 1975;Smotherman et al, 1974). In fact, the rodent dam is sensitive to the changing stimulus qualities of the pups (Meier and Schutzman, 1968;Young, 1965) and shows systematic changes in maternal behavior depending on the nature of the treatment that the offspring have received (Barnett and Burn, 1967;Bell et al, 1974) and the time during lactation in which the manipulations occur (Smotherman et al, 1977a, b).…”

“…For example, manipulations during the first week of life have different effects on maternal behavior and limbic-hypothalamicpituitary-adrenal (LHPA) axis development from manipulations in the second week of life Ader, 1969, 1974;Levine and Lewis, 1959;Meaney and Aitken, 1985;Reisbick et al, 1975). Likewise, we would expect to see differences in drug-taking behavior in animals who were manipulated during week 1 compared to week 2 of life.…”

Increasing the incentive salience of cocaine challenges preference for pup- over cocaine-associated stimuli during early postpartum: place preference and locomotor analyses in the lactating female rat

“…While the present study used age-matched pups to mimic the stimuli present in the dam's natural environment, changing physical characteristics accompanying normal pup development may include properties that elicit less incentive salience and thus evoke less maternal motivation. Pups' increasing size and functional capacity coincides with a dramatic reduction in maternal behavior (Bridges et al 1972;Reisbick et al 1975;Stern and Mackinnon 1978), while young pups increase the frequency and quality of maternal behavior (Noirot 1964a(Noirot , b, 1965Stern and Mackinnon 1978) and activate dopaminergic reward circuits in the brain (Ferris et al 2005). However, maternal behavior and motivation do not covary in the postpartum dam (Hauser and Gandelman 1985;Mattson et al 2003).…”

Comparison of the “Nursing” and Other Parental Behaviors of Nulliparous and Lactating Female Rats

“…Early comparisons between the parental behaviors of sensitized adult virgin female rats and postpartum dams suggested that few differences existed, and those that did were only observable soon after the onset of parenting but not after numerous days of experience with young pups (Fleming and Rosenblatt, 1974;Reisbick, Rosenblatt, and Mayer, 1975). In contrast, subsequent comparisons focusing on retrieval of pups from a runway (Quadagno, DeBold, Gorzalka, and Whalen, 1974) or T-maze (Bridges, Zarrow, Gandelman, and Denenberg (1972); Stern and MacKinnon, 1976) extension of the home cage as a more sensitive measure of maternal motivation revealed both qualitative and quantitative differences between virgins and postpartum mothers.…”