Oxytocin Involvement in Body Composition Unveils the True Identity of Oxytocin

Cellular and molecular organization of the Drosophila foregut

The animal foregut is the first tissue to encounter ingested food, bacteria, and viruses. We characterized the adult Drosophila foregut using transcriptomics to better understand how it triages consumed items for digestion or immune response and manages resources. Cell types were assigned and validated using GFP-tagged and Gal4 reporter lines. Foregut-associated neuroendocrine cells play a major integrative role by coordinating gut activity with nutrition, the microbiome, and circadian cycles; some express clock genes. Multiple epithelial cell types comprise the proventriculus, the central foregut organ that secretes the peritrophic matrix (PM) lining the gut. Analyzing cell types synthesizing individual PM layers revealed abundant mucin production close to enterocytes, similar to the mammalian intestinal mucosa. The esophagus and salivary gland express secreted proteins likely to line the esophageal surface, some of which may generate a foregut commensal niche housing specific gut microbiome species. Overall, our results imply that the foregut coordinates dietary sensing, hormonal regulation, and immunity in a manner that has been conserved during animal evolution.

Relationship between body temperature and behavior of nonpregnant early-lactation dairy cows

Animal behavior and management factors that influence behavior affect physiology and lactation performance. Circadian rhythms of core body temperature are a primary output of the master clock; however, core body temperature in early-lactation dairy cows showed poor fit to 24-h rhythms. We hypothesized that eating behavior was related to daily body temperature oscillations. The objectives of this study were to determine if oscillations in daily behaviors, specifically feeding behavior, were related to body temperature. The behavior of 11 Holstein cows (34 ± 14 d in milk; mean ± standard deviation) housed in a freestall barn was recorded every 10 min for a 48-h period. Simultaneously, data loggers (iButtons; iButtonLink Technology) recorded the body temperature of cows with the same sampling frequency. The mean temperature of all cows showed a better fit to a 2-component cosinor (R² = 0.54) than to a single cosinor model (R² = 0.26). Logistic regression showed that the probability (Pr) of a cow experiencing an increase in body temperature (increment, I) given that she was milking [Pr(I|milking) = 0.94] was higher than for ruminating [Pr(I|ruminating) = 0.69], lying [Pr(I|lying) = 0.66], feeding [Pr(I|feeding) = 0.16], standing [Pr(I|standing) = 0.54], and mounting [Pr(I|mounting) = 0.62]. The main limitations of this study are the length of the observation period and the sample size. Longer observation windows on core body temperature would allow to isolate the noise and the signal and identify patterns with more clarity. Oscillations in body temperature were not associated with feeding. However, findings indicate that milking, activity associated with walking to the parlor, or the temperature in the parlor may affect secondary rhythms of daily body temperature.

Oxytocin Modulates Osteogenic Commitment in Human Adipose-Derived Stem Cells

Human adipose-derived stem cells (hASCs) are commonly harvested in minimally invasive contexts with few ethical concerns, and exhibit self-renewal, multi-lineage differentiation, and trophic signaling that make them attractive candidates for cell therapy approaches. The identification of natural molecules that can modulate their biological properties is a challenge for many researchers. Oxytocin (OXT) is a neurohypophyseal hormone that plays a pivotal role in the regulation of mammalian behavior, and is involved in health and well-being processes. Here, we investigated the role of OXT on hASC proliferation, migratory ability, senescence, and autophagy after a treatment of 72 h; OXT did not affect hASC proliferation and migratory ability. Moreover, we observed an increase in SA-β-galactosidase activity, probably related to the promotion of the autophagic process. In addition, the effects of OXT were evaluated on the hASC differentiation ability; OXT promoted osteogenic differentiation in a dose-dependent manner, as demonstrated by Alizarin red staining and gene/protein expression analysis, while it did not affect or reduce adipogenic differentiation. We also observed an increase in the expression of autophagy marker genes at the beginning of the osteogenic process in OXT-treated hASCs, leading us to hypothesize that OXT could promote osteogenesis in hASCs by modulating the autophagic process.

Investigation of metal modulation of oxytocin structure receptor-mediated signaling

Oxytocin is a 9-amino acid peptide hormone. Since its discovery in 1954, it has most commonly been studied in relation to its role in stimulating parturition and lactation. However, it is now known that oxytocin has a widely diverse set of functions throughout the body including neuromodulation, bone growth, and inflammation. Previous research has suggested that divalent metal ions may be required for oxytocin activity, but the exact metal species and specific pathways have yet to be fully elucidated. In this work, we focus on characterizing copper and zinc bound forms of oxytocin and related analogs through far-UV circular dichroism. We report that Cu(ii) and Zn(ii) bind uniquely to oxytocin and all analogs investigated. Furthermore, we investigate how these metal bound forms may affect downstream signaling of MAPK activation upon receptor binding. We find that both Cu(ii) and Zn(ii) bound oxytocin attenuates the activation of the MAPK pathway upon receptor binding relative to oxytocin alone. Interestingly, we observed that Zn(ii) bound forms of linear oxytocin facilitate increased MAPK signaling. This study lays the foundation for future work on elucidating the metal effects on oxytocin's diverse bioactivity.

The Long Way of Oxytocin from the Uterus to the Heart in 70 Years from Its Discovery

The research program on oxytocin started in 1895, when Oliver and Schafer reported that a substance extracted from the pituitary gland elevates blood pressure when injected intravenously into dogs. Dale later reported that a neurohypophysial substance triggers uterine contraction, lactation, and antidiuresis. Purification of this pituitary gland extracts revealed that the vasopressor and antidiuretic activity could be attributed to vasopressin, while uterotonic and lactation activity could be attributed to oxytocin. In 1950, the amino-acid sequences of vasopressin and oxytocin were determined and chemically synthesized. Vasopressin (CYFQNCPRG-NH₂) and oxytocin (CYIQNCPLG-NH₂) differ by two amino acids and have a disulfide bridge between the cysteine residues at position one and six conserved in all vasopressin/oxytocin-type peptides. This characterization of oxytocin led to the Nobel Prize awarded in 1955 to Vincent du Vigneaud. Nevertheless, it was only 50 years later when the evidence that mice depleted of oxytocin or its receptor develop late-onset obesity and metabolic syndrome established that oxytocin regulates energy and metabolism. Oxytocin is anorexigenic and regulates the lean/fat mass composition in skeletal muscle. Oxytocin's effect on muscle is mediated by thermogenesis via a pathway initiated in the myocardium. Oxytocin involvement in thermogenesis and muscle contraction is linked to Prader-Willi syndrome in humans, opening exciting therapeutic avenues.

Modulation of the thermosensory system by oxytocin

Oxytocin (OT) is a neurohormone involved early in neurodevelopment and is implicated in multiple functions, including sensory modulation. Evidence of such modulation has been observed for different sensory modalities in both healthy and pathological conditions. This review summarizes the pleiotropic modulation that OT can exercise on an often overlooked sensory system: thermosensation. This system allows us to sense temperature variations and compensate for the variation to maintain a stable core body temperature. Oxytocin modulates autonomic and behavioral mechanisms underlying thermoregulation at both central and peripheral levels. Hyposensitivity or hypersensitivity for different sensory modalities, including thermosensitivity, is a common feature in autism spectrum disorder (ASD), recapitulated in several ASD mouse models. These sensory dysregulations occur early in post-natal development and are correlated with dysregulation of the oxytocinergic system. In this study, we discussed the potential link between thermosensory atypia and the dysregulation of the oxytocinergic system in ASD.