Exposure to either bisphenol A or S represents a risk for crucial behaviors for pup survival, such as spontaneous maternal behavior in mice

Abstract

Maternal behavior depends on a multitude of factors, including the environmental ones, such as Endocrine Disrupting Chemicals (EDCs), which are increasingly attracting attention. Bisphenol A (BPA), an EDC present in plastic, is known to exert negative effects on maternal behavior. Bisphenol S (BPS), a BPA-substitute, seems to share some endocrine disrupting properties. In this study we focused on the analysis of the effects of low-dose (i.e., 4µg/kg body weight/day, EFSA TDI for BPA) BPA or BPS exposure throughout pregnancy and lactation in C57BL/6J mice. During the first postnatal week we observed the spontaneous maternal behavior. At the pups' weaning, we sacrificed the dams and analyzed the oxytocin system, involved in the control of the maternal care, in the hypothalamic magnocellular nuclei. At birth, pups from BPA-treated dams tended to have lower male-to-female ratio compared to controls, while the opposite was observed among BPS litters. During the first postnatal week, offspring mortality impacted differentially BPA and BPS litters, with more female dead pups among the BPA litters, while more male dead pups in the BPS litters, sharpening the difference in the sex ratio. BPA and BPS dams spent significantly less time in pup-related behaviors than controls. Oxytocin-ir in paraventricular and supraoptic nuclei was increased only in the BPA-treated dams. Alterations in maternal care, along with the treatment itself, may affect, later in life, the offspring physiology and behavior. The exposure to BPs during sensitive developmental periods represents a risk for both dams and offspring, even at low environmentally-relevant doses, through the functional alteration of neural circuits controlling fundamental behaviors for pup survival, such as maternal behaviors.