title: Rat dams exposed repeatedly to a daily brief separation from the pups exhibit increased maternal behavior, decreased anxiety and altered levels of receptors for estrogens (ERα, ERβ), oxytocin and serotonin (5-HT1A) in their brain.
abstract: In the present study we investigated the neurobiological mechanisms underlying expression of maternal behavior. Increased maternal behavior was experimentally induced by a brief 15-min separation between the mother and the pups during postnatal days 1 to 22. On postnatal days (PND) 12 and 22, we determined in experimental and control dams levels of anxiety in the elevated plus maze (EPM) as well as the levels of receptors for estrogens (ERα, ERβ), oxytocin (OTR) and serotonin (5-HT1AR) in areas of the limbic system (prefrontal cortex-PFC, hippocampus, lateral septum-SL, medial preoptic area-MPOA, shell of nucleus accumbens-nAc-Sh, central-CeA and basolateral-BLA amygdala), involved in the regulation of maternal behavior. Experimental dams, which showed increased maternal behavior towards their offspring, displayed reduced anxiety in the EPM on both PND12 and PND22. These behavioral differences could be attributed to neurochemical alterations in their brain: On both PND12 and PND22, experimental mothers had higher levels of ERα and OTRs in the PFC, hippocampus, CeA, SL, MPOA and nAc-Sh. The experimental manipulation-induced increase in ERβ levels was less widespread, being localized in PFC, the hippocampal CA2 area, MPOA and nAc-Sh. In addition, 5-HT1ARs were reduced in the PFC, hippocampus, CeA, MPOA and nAc-Sh of the experimental mothers. Our results show that the experience of the daily repeated brief separation from the pups results in increased brain ERs and OTRs, as well as decreased 5-HT1ARs in the dam's brain; these neurochemical changes could underlie the observed increase in maternal behavior and the reduction of anxiety.
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Antonios
authors.initials: A
authors.lastname: Stamatakis
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Theodora
authors.initials: T
authors.lastname: Kalpachidou
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Androniki
authors.initials: A
authors.lastname: Raftogianni
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Efstratia
authors.initials: E
authors.lastname: Zografou
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Athanasia
authors.initials: A
authors.lastname: Tzanou
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece.
authors.forename: Stavroula
authors.initials: S
authors.lastname: Pondiki
authors.affiliation: Biology-Biochemistry Lab, School of Health Sciences, National and Kapodistrian University of Athens, Papadiamantopoulou 123, GR-11527 Athens, Greece. Electronic address: fstilian@nurs.uoa.gr.
authors.forename: Fotini
authors.initials: F
authors.lastname: Stylianopoulou
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000378:metabolism*; D001522:Behavior, Animal / Q000502:physiology*; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism*; D005260:Female; D008032:Limbic System / Q000378:metabolism*; D008297:Male; D008425:Maternal Behavior / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D018045:Receptors, Oxytocin / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D018045:Receptors, Oxytocin; C588222:oxytocin receptor, rat; D044282:Receptor, Serotonin, 5-HT1A
keywords: Amygdala; Anxiety; Estrogen receptors; Hippocampus; Maternal behavior; Medial preoptic area; Nucleus accumbens; Oxytocin receptors; Prefrontal cortex; Serotonergic system