Maternal Contact Differentially Modulates Central and Peripheral Oxytocin in Rat Pups During a Brief Regime of Mother–Pup Interaction that Induces a Filial Huddling Preference

Abstract

Central oxytocin mediates the acquisition of a filial preference for maternal odour in rat pups, manifested by their huddling preferences. The present study was designed to examine whether maternal care modulates oxytocin concentrations in rat pups and, if so, how different types of maternal contact are associated with the pups’ oxytocin concentrations. Pairs of 14-day-old littermates were removed from their home cage for 1 h and then placed with a lactating foster mother for 2 h, or they remained isolated at room temperature. Enzyme immunoassays revealed that maternal care and maternal separation can differentially modulate pups’ oxytocin concentrations. Both hypothalamic and serum oxytocin increased during the 1-h separation. Pups placed with a foster mother after the separation maintained the same concentrations in the hypothalamus and serum through the fostering period. By contrast, pups placed with no mother showed a further increase in hypothalamic oxytocin but serum oxytocin decreased. Behavioural analyses revealed that skin-to-skin contact with the mother, but not simple physical contact or maternal licking / grooming, was positively correlated with the pups’ hypothalamic oxytocin concentrations. These neuroendocrine data match previous findings showing that skin-to-skin contact with mother facilitates the acquisition of the pups’ huddling preference for a maternally-associated odour. Taken together, the present study suggests that maternal skin-to-skin contact stimulates pups’ central oxytocin, at the same time as creating the conditions for inducing a preference for maternal odour and establishing a social affiliation in rat pups; the natural schedule of maternal separation and reunion may modulate pups’ oxytocin concentrations, providing scaffolding for the acquisition of their filial huddling preference.

Stress in Neonatal Rats with Different Maternal Care Backgrounds: Monoaminergic and Hormonal Responses

“…On the other hand, OT is known to be involved in the pupmother attachment [2]. Previous works report that maternal care, such as the presence and tactile stimuli from mothers may modulate OT concentrations in rat pups [2,3], similarly to what is seen in our study: pups receiving higher licking frequencies from the mother (HL) showed higher basal plasma OT levels.…”

Stress in Neonatal Rats with Different Maternal Care Backgrounds: Monoaminergic and Hormonal Responses

“…On the other hand, OT is known to be involved in the pup-mother attachment [2]. Previous works report that maternal care, such as the presence and tactile stimuli from mothers may modulate OT concentrations in rat pups [2,3], similarly to what is seen in our study: pups receiving higher licking frequencies from the mother (HL) showed higher basal plasma OT levels.…”

“…Neuroendocrine aspects of this attachment have been reported, such as the participation of the hormone oxytocin (OT), related to affiliative behaviors [2,3]. In humans, disturbances in the mother-infant relationship are a risk factor for psychiatric disorders such as anxiety and depression in adulthood [4,5].…”

Developmental Perspectives on Oxytocin and Vasopressin

“…Hypothesis in which development shines light on the 'Dark Matter of Social Neuroscience', or the unclarified neural mechanisms between social sensory inputs and social behavior outputs (Insel, 2010). (a) During developmental sensitive periods, parental nurturing (Kojima et al, 2012;Weisman et al, 2012) and/or sensory inputs (Zheng et al, 2014) drive the activity of the PVN resulting in increased release of oxytocin. This oxytocin can regulate multi-sensory plasticity in the neocortex.…”

“…Mogi et al (2011) report that oxytocin content is lower in the cingulate cortex of rats at postnatal day 14 when separated from their mother. Oxytocin responds to maternal separation and skin-to-skin contact in pre-weanling rats (Kojima et al, 2012). Oxytocin concentrations were sampled from pre-weanling rat hypothalamus and blood at several time points during a separation and reunion paradigm with a foster mother, which in previous studies elicits a huddling preference in the pups.…”