Maternal care is the newborn’s first experience of social interaction, which influences infant survival, development and social competences throughout life. We recently found that postpartum blocking of the endocannabinoid receptor (CB1R) altered maternal behavior. In the current study, maternal care was assessed by time to retrieve pups, pups’ ultrasonic vocalizations (USVs) and pup body weight, comparing CB1R deleted (CB1R KO) vs. wild type (WT) mice. After culling on postpartum day 8, hippocampal expression of oxytocin receptor (OXTR), brain-derived neurotrophic factor (BDNF) and stress-mediating factors were evaluated in CB1R KO and WT dams. Comparisons were also performed with nulliparous (NP) CB1R KO and WT mice. Compared to WT, CB1R KO dams were slower to retrieve their pups. While the body weight of the KO pups did not differ from the weight of WT pups, they emitted fewer USVs. This impairment of the dam-pup relationship correlated with a significant reduction of OXTR mRNA and protein levels among CB1R KO dams in comparison to WT dams. Furthermore, WT dams exhibited elevated OXTR mRNA expression, as well as increased levels of mineralocorticoid (MR) and glucocorticoid (GR) receptors, in comparison to WT NP mice. In contrast, CB1R KO dams showed no such elevation of OXTR expression, alongside lower BDNF and MR as well as elevated corticotropin-releasing hormone (CRH) mRNA levels when compared to CB1R KO NP. Thus, it appears that the disruption of endocannabinoid signaling by CB1R deletion alters expression of the OXTR, apparently leading to deleterious effects upon maternal behavior. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.

PMID:

 

23895426

 

[PubMed – as supplied by publisher]