The effects of medial preoptic area and amygdala lesions on maternal behavior in the juvenile rat

Abstract

The present study was designed to determine whether the medial preoptic area (MPOA) and the amygdala (AMYG) are involved in the expression of "maternal" behavior in juvenile rats as they are in the adult. Juveniles show many behaviors that are similar to the maternal behaviors shown by the postpartum female rat. Whether these behaviors are social in function, as opposed to parental, and hence mediated by different mechanisms from those regulating adult maternal behavior is not known. To test the roles of the MPOA and AMYG in mediating these behaviors, 21-day-old female juvenile rats received MPOA, AMYG, or SHAM (MPOA/AMYG) lesions and were tested at 22 days of age for maternal and other responses to pups. Major findings demonstrate that MPOA lesions disrupt components of maternal behavior, including retrieving and nest building, while AMYG lesions facilitate these behaviors. These findings indicate striking similarities between the juvenile and rat brain for parental responding.

Specifying the Neurobiological Basis of Human Attachment: Brain, Hormones, and Behavior in Synchronous and Intrusive Mothers

“…In humans, the maternal behavioral repertoire includes gaze at infant face, 'motherese' highpitched vocalizations, expression of positive affect, affectionate touch, and the synchronous adaptation of these behaviors to moments of infant responsiveness (Barrett and Fleming, 2011;Feldman and Eidelman, 2007). Such human maternal behaviors parallel the licking-and-grooming and arched-back nursing of other mammals, which have been linked with the affiliation-related neuropeptide Oxytocin and the functioning of motivational and affective neural systems Lee et al, 2000;Oxley and Fleming, 2000;Shahrokh et al, 2010;Strathearn et al, 2009;Toscano et al, 2009). However, to date, little research examined the integration of brain circuits, affiliative hormones, and maternal behavior in human mothers.…”

“…Lesions and DA manipulation studies (Li and Fleming, 2003) have demonstrated that the NAcc is critical for maternal behavior, particularly for maternal motivation to nest and retrieve pups Hansen, 1994;Hansen et al, 1991;Keer and Stern, 1999;Li and Fleming, 2003;Vernotica et al, 1999). The amygdala, a central node of the limbic affective system, has similarly been implicated in social affiliation and maternal attachment (Fleming and Korsmit, 1996;Lee et al, 2000;Oxley and Fleming, 2000). Lesions to the amygdala reduce maternal behavior (Toscano et al, 2009) and significant amygdala c-fos changes are observed following mother-pup interaction (Fleming and Korsmit, 1996).…”

“…However, whereas the NAcc is likely to play a role in the reward-related aspects of mothering, the amygdala, which mediates fear processing and vigilance (Cardinal et al, 2002), may be important for the stress-related components. Both the NAcc and amygdala work in concert with several cortical areas, including the medial preoptic area, which integrates infant sensory cues and foster adequate parenting (Insel and Young, 2001;Lee et al, 2000;Oxley and Fleming, 2000), the anterior cingulate (ACC), and the dorso-medial prefrontal cortex (dmPFC) (MacLean et al, 1990;MacLean and Newman, 1988;Murphy et al, 1981;Slotnick, 1967;Stamm, 1955). Some of these cortical areas, particularly the ACC and dmPFC, have been implicated in empathy and 'theory of mind' skills (Assaf et al, 2009;Gallagher and Frith, 2003;Vollm et al, 2006), and may increase the mother's capacity to read and respond to her infant's signals.…”

Brain serotonin determines maternal behavior and offspring survival

“…Commercially available nestlets (NES3600, Ancare, Bellmore, NY, USA) were placed into cages (1 nestlet per cage) containing a dam and her litter on a single occasion between PN0 and PN2. Dams were allowed to shred the nestlet into a nest and thereafter nests were scored using a modified rating scale (Oxley & Fleming ) as follows: 1, nest material untouched; 2, nest material scattered (no nest formed); 3, very rough nest shape (no enclosing walls and gathered loosely); 4, definite nest formed (flat, enclosing walls but no bowl‐shape) and 5, definite spherical nest (enclosing walls and bowl‐shape). For nest construction, the following group sizes were used: 24 TPH2 +/+ and 22 TPH2 −/− dams with their own pups, 12 TPH2 +/+ dams with TPH2 −/− pups, 15 TPH2 −/− dams with TPH2 +/+ pups, 10 TPH2 −/+ and 11 TPH2 −/− dams with mixed litters.…”

Raising overlapping litters: Differential activation of rat maternal neural circuitry after interacting with newborn or juvenile pups

“…Specifically, several studies have shown that lesions in the mPOA or the vBNST, as well as the impairment of the connectivity between the mPOA/vBNST and the mesolimbic dopaminergic system, abolish the expression of maternal behaviour. Based on these and other studies, Numan and Numan and Stolzenberg proposed that mPOA/vBNST efferents to the ventral tegmental area (VTA) facilitate dopaminergic inputs to the NA, which in turn release the ventral pallidum from the inhibitory influence of this nucleus, promoting the expression of voluntary maternal response towards pups .…”