Basic Research

Colostrum Oxytocin Modulates Cellular Stress Response, Inflammation, and Autophagy Markers in Newborn Rat Gut Villi

The presence of the neuropeptide oxytocin (OT) in milk and its role in milk letdown are well known. Less known is the role of OT delivered in mothers' milk on newborn gut development.

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Prairie Vole Pups Show Potentiated Isolation-Induced Vocalizations Following Isolation From Their Mother, But Not Their Father

Vocalizations can be markers of emotional social communication. Maternal potentiation was originally described as an increased rate of vocalization by isolated rat pups following an interaction with their mothers, but not with other social companions. Here we asked if potentiation in prairie voles, a species with pair-bonding and bi-parental rearing, is parent-specific.

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Oxytocin Modulates Markers of the Unfolded Protein Response in Caco2BB Gut Cells

We have shown that oxytocin receptor (OTR) expression in neonatal rat enterocytes is robust from birth to weaning, but OTR function during this period is unknown. We previously reported that oxytocin (OT) stimulation of Caco2BB cells (enterocytes in vitro) inhibits the mammalian target of rapamycin complex 1 (mTORC1) signaling. The unfolded protein response (UPR) is known to protectively reduce translation during endoplasmic reticulum (ER) stress. Because the mTORC1 pathway is linked to cellular stress, we investigated markers of UPR in OT-stimulated Caco2BB cells. We report that OT modulates several factors involved in sensing and translation of ER stress.

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Oxytocin Modulates mTORC1 Pathway in the Gut

Our recent findings of a weaning-related pattern of oxytocin (OT) and oxytocin receptor (OTR) expression in the rat enteric nervous system and in villus-crypt enterocytes, together with the known high level and stability of OT in breast milk support that OT may play a role in gut function and development. Here, we use automated Western blotting to explore OT-elicited changes in Akt and pAktT308, as well as in downstream substrates p70 S6 kinase-1 (S6K1) and eIF-4E binding protein 1 (4E-BP1). Relative to fresh growth medium (FGM) alone, our results showed OT in FGM reduced the abundance and phosphorylation of S6K1 and the phosphorylation of 4E-BP1, both substrates of mammalian target of rapamycin complex 1 (mTORC1). Phosphorylation of mTORC1 regulator, RaptorS792 was increased by high and low OT concentrations with predicted inhibitory effects on mTORC1. OT thus down-regulates anabolic effects induced by FGM activity catalyzed by mTORC1. OT is a regulator of the PI3K/Akt/ mTORC1 pathway in Caco2BB cells and may modulate translation in gut cells.