Abstract
(1) Background: Preoptic region of hypothalamus is responsible to control maternal behavior, which was hypothesized to be associated with gene expressional changes. (2) Methods: Transcriptome sequencing was first applied in the preoptic region of rat dams in comparison to a control group of mothers whose pups were taken away immediately after parturition and did not exhibit caring behavior 10 days later. (3) Results: Differentially expressed genes were found and validated by quantitative RT-PCR, among them NACHT and WD repeat domain containing 1 (Nwd1) is known to control androgen receptor (AR) protein levels. The distribution of Nwd1 mRNA and AR was similar in the preoptic area. Therefore, we focused on this steroid hormone receptor and found its reduced protein level in rat dams. To establish the function of AR in maternal behavior, its antagonist was administered intracerebroventricularly into mother rats and increased pup-directed behavior of the animals. (4) Conclusions: AR levels are suppressed in the preoptic area of mothers possibly mediated by altered Nwd1 expression in order to allow sustained high-level care for the pups. Thus, our study first implicated the AR in the control of maternal behaviors.
Highlights
Introduction iationsPostpartum behavioral changes are critical parts of reproduction in mammals [1].They may be accompanied with altered gene expression levels in brain areas responsible for their regulations
We examined gene expression 10 days following parturition in the medial preoptic area (MPOA) of rat dams rearing their litter and pup-deprived mothers
Pup-deprived mothers showed significantly decreased pupdirected behavior assessed as its percentage of total time, which was 9.5 ± 2.4% compared to the lactating mothers 24.8 ± 4.9% (p < 0.05) (Figure 1)
Summary
Postpartum behavioral changes are critical parts of reproduction in mammals [1]. They may be accompanied with altered gene expression levels in brain areas responsible for their regulations. Rats represent a very good animal model to study mechanisms of postpartum changes in the brain. Females, which are not maternal, do not take care of pups or might attack the pups, while maternal females show caring behaviors, e.g., building of nest, retrieval of pups to the nest, suckling and reduced anxiety, as well as lactation [2]. Maternal behavior is maintained in the postpartum period, even if the level of reproductive steroid hormones becomes low due to lactational anestrous [2]. Steroid hormonal effects contribute to the initiation, but are not required for maintenance
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