Maternal prolactin during late pregnancy is important in generating nurturing behavior in the offspring

Abstract

Although maternal nurturing behavior is extremely important for the preservation of a species, our knowledge of the biological underpinnings of these behaviors is insufficient. Here we show that the degree of a mother's nurturing behavior is regulated by factors present during her own fetal development. We found that Cin85-deficient () mother mice had reduced pituitary hormone prolactin (PRL) secretion as a result of excessive dopamine signaling in the brain. Their offspring matured normally and produced their own pups; however, nurturing behaviors such as pup retrieval and nursing were strongly inhibited. Surprisingly, when WT embryos were transplanted into the fallopian tubes of mice, they also exhibited inhibited nurturing behavior as adults. Conversely, when embryos were transplanted into the fallopian tubes of WT mice, the resultant pups exhibited normal nurturing behaviors as adults. When PRL was administered to mice during late pregnancy, a higher proportion of the resultant pups exhibited nurturing behaviors as adults. This correlates with our findings that neural circuitry associated with nurturing behaviors was less active in pups born to mothers, but PRL administration to mothers restored neural activity to normal levels. These results suggest that the prenatal period is extremely important in determining the expression of nurturing behaviors in the subsequent generation, and that maternal PRL is one of the critical factors for expression. In conclusion, perinatally secreted maternal PRL affects the expression of nurturing behaviors not only in a mother, but also in her pups when they have reached adulthood.

In Utero and Postnatal Propylthiouracil-Induced Mild Hypothyroidism Impairs Maternal Behavior in Mice

“…Responses or behaviors shown by mammalian females are important for the physiological and behavioral development of their offspring ( 38 ). A study of an in utero maternal process showed that the fetal stage is a crucial period for behavioral development ( 15 ). In rodents, maternal behaviors are exhibited in several ways, including pup retrieval, licking, nursing, and crouching over pups to keep them warm ( 39 ).…”

“…In order to assess maternal behavior in F1 mice, we first measured the length of time required to retrieve the pups that had been removed from the nest using a slightly modified protocol from a previous study ( 15 ). The test was performed during the dark phase of F1 at postnatal day 110.…”

“…Maternal behavior is one of the social behaviors between mother and offspring. Several hormones, including estrogen ( 13 , 14 ), prolactin ( 15 ), vasopressin, and oxytocin ( 15 – 17 ), are involved in regulating maternal behavior. In rats, maternal behaviors, particularly licking and grooming, regulate the development of the offspring’s endocrine, emotional, and cognitive responses to stress ( 18 ).…”

Adaptive resetting of tuberoinfundibular dopamine (TIDA) network activity during lactation in mice

“…Blood prolactin levels exhibit a marked dynamic profile, driven primarily by reproductive state (Ronnekleiv and Kelly, 1988). While lactation corresponds to a sustained hyperprolactinemic state, beginning during late pregnancy in rodents (Sairenji et al, 2017), circulating prolactin is low under baseline conditions in females and, even more so, in males (Guillou et al, 2015;Kalyani et al, 2016). A brief, albeit pronounced, peak appears within the estrous cycle in the transition from proestrus to estrus (Butcher et al, 1974), enabling the maintenance of the corpus luteum and successful implantation (Morishige and Rothchild, 1974).…”

Early-life stress and life

“…On the other hand, how these internal factors contribution to is very complicated. Both too low [ 7 ] and too high [ 5 ] concentrations of PRL adversely affect maternal behavior. Therefore, if we are thinking of drug treatment, moderate control is necessary.…”