Maternal Care and Hippocampal Plasticity: Evidence for Experience-Dependent Structural Plasticity, Altered Synaptic Functioning, and Differential Responsiveness to Glucocorticoids and Stress

Abstract

Maternal licking and grooming (LG) in infancy influences stress responsiveness and cognitive performance in the offspring. We examined the effects of variation in the frequency of pup LG on morphological, electrophysiological, and behavioral aspects of hippocampal synaptic plasticity under basal and stress-like conditions. We found shorter dendritic branch length and lower spine density in CA1 cells from the adult offspring of low compared with high LG offspring. We also observed dramatic effects on long-term potentiation (LTP) depending on corticosterone treatment. Low LG offspring, in contrast to those of high LG mothers, displayed significantly impaired LTP under basal conditions but surprisingly a significantly enhanced LTP in response to high corticosterone in vitro. This enhanced plasticity under conditions that mimic those of a stressful event was apparent in vivo. Adult low LG offspring displayed enhanced memory relative to high LG offspring when tested in a hippocampal-dependent, contextual fear-conditioning paradigm. Hippocampal levels of glucocorticoid and mineralocorticoid receptors were reduced in low compared with high LG offspring. Such effects, as well as the differences in dendritic morphology, likely contribute to LTP differences under resting conditions, as well as to the maternal effects on synaptic plasticity and behavior in response to elevated corticosterone levels. These results suggest that maternal effects may modulate optimal cognitive functioning in environments varying in demand in later life, with offspring of high and low LG mothers showing enhanced learning under contexts of low and high stress, respectively.

Sex-related long-term behavioral and hippocampal cellular alterations after nociceptive stimulation throughout postnatal development in rats

“…One could hypothesize that the abovementioned outcomes of the neonatal stressful event could be preparatory for possible future adverse events. In fact, there is evidence in favor of such hypothesis, stemming from studies in human beings (Boyce and Chesterman, 1990;Edge et al, 2009), squirrel monkeys (reviewed in Parker et al (2006)) and rodents (Champagne et al, 2008;Hays et al, 2012;Oomen et al, 2009). Alterations in multiple pathways in the central nervous system may contribute to alter the behavioral repertoire in adulthood following neonatal nociceptive stimuli.…”

Hormonal mechanisms of cooperative behaviour

“…Weaver et al 2004). Mothering behaviour also has strong effects on other aspects of hippocampal organization, such as dendrite and spine lengths, affecting memory and cognitive abilities of her offspring in adulthood (Champagne et al 2008). Finally, the degree of maternal care can also determine the density of OT and oestrogen receptors in the medial preoptic area in females, and of AVP receptors in males (Champagne et al 2003).…”

Influence of housing variables on the development of stress-sensitive behaviors in the rat

“…For example, alterations in early post-natal maternal care in the laboratory rat can program the developing HPA-neuroendocrine pathways and behavioral fearfulness when rodents reach adulthood [26][27][28][29]. These effects persist throughout the life of the animal and alter risk for stress-related disease [2,4,30].…”