Effects of orexin-monoaminergic interactions on oxytocin secretion in rat neurohypophyseal cell cultures

Genotype-genotype interactions of the OXTR gene polymorphisms are associated with self-reported daytime dysfunction, sleep latency and personal distress

The oxytocin receptors located in the corticotropin-releasing factor neurons of the paraventricular nucleus are stimulated by oxytocin. Oxytocin functions as the regulator of the corticotropin-releasing factor system and in turn promotes sleep quality. The objective of this study was to examine the main and genotype-genotype interactive effects of the oxytocin receptor gene (OXTR) polymorphisms on sleep quality. A total of 324 participants were randomly recruited from a university in Beijing, China. Sleep quality was measured with the Pittsburgh Sleep Quality Index. The OXTR single-nucleotide polymorphisms (rs2254298, rs2268498, rs13316193, rs2268490 and rs2268491) were genotyped. The results showed that gender and age were associated with various empathy traits (all p < 0.001). The Pittsburgh Sleep Quality Index was positively correlated with the Personal Distress subscale of empathy (p < 0.001). Both rs2254298 and rs2268491 interacted with rs13316193 to influence daytime dysfunction and Personal Distress (all p < 0.05), indicating that in individuals with rs13316193 CC/CT genotype, those with rs2254298 AA/AG or rs2268491 TT/TC genotypes displayed higher daytime dysfunction and Personal Distress scores than those with rs2254298 GG or rs2268491 CC genotypes. Conversely, among the individuals with rs2254298 GG or rs2268491 CC genotypes, the rs13316193 C allele carriers had lower daytime dysfunction and Personal Distress scores than rs13316193 TT homozygotes. There was also a significant interaction between rs2268490 and rs2268498 on the sleep latency dimension of the Pittsburgh Sleep Quality Index. Our findings reveal for the first time the genotype-genotype interactions of the OXTR gene on sleep quality, which may open new research avenues for studying psychopathology involving sleep problems.

The influence of mode of delivery, anthropometric indices, and infant's sex on the maternal and cord blood orexin-A levels: A cohort study

BACKGROUND

Orexin as an adipokin hormone plays an important role in appetite regulation, energy metabolism, obesity, diabetes, and cardiovascular disease. The main source of orexin secretion in nonpregnant and pregnant women is adipose tissue and placenta, respectively. This research was conducted to evaluate the association between orexin-A level and the mode of delivery, anthropometric indices, and sex of the infant.

METHODS

This prospective cohort study was conducted on 69 normal pregnant women. The samples of umbilical cord blood were obtained at the time of delivery, and maternal blood was taken within 24 h of delivery. Serum orexin-A levels were measured by using enzyme-linked immunosorbent assay. Statistical analyses were performed using SPSS and p < 0.05 was considered as significant.

RESULTS

We found a significant difference between postpartum maternal and umbilical cord orexin-A level both with the mode of delivery (p < 0.001). Also, a significant positive correlation was seen between maternal and umbilical cord serum orexin-A levels (r = -0.61, p < 0.001). There was no relationship between serum orexin-A levels with anthropometric indices and the sex of the neonate (p > 0.05).

CONCLUSION

Both maternal and umbilical cord serum orexin-A levels were associated with the mode of delivery. Maternal and cord blood orexin-A levels in normal vaginal delivery are higher than cesarean section.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.

Is Oxytocin Application for Autism Spectrum Disorder Evidence-Based?

Autism spectrum disorder (ASD) is characterized by persistent deficits within two core symptom domains: social communication and restricted, repetitive behaviors. Although numerous studies have reported psychopharmacological treatment outcomes for the core symptom domains of ASD, there are not enough studies on fundamental treatments based on the etiological pathology of ASD. Studies on candidate medications related to the pathogenesis of ASD, such as naltrexone and secretin, were conducted, but the results were inconclusive. Oxytocin has been identified as having an important role in maternal behavior and attachment, and it has been recognized as a key factor in the social developmental deficit seen in ASD. Genetic studies have also identified associations between ASD and the oxytocin pathway. As ASD has its onset in infancy, parents are willing to try even experimental or unapproved treatments in an effort to avoid missing the critical period for diagnosis and treatment, which can place their child in an irreversible state. While therapeutic application of oxytocin for ASD is in its early stages, we have concluded that oxytocin would be a promising therapeutic substance via a thorough literature review focusing on the following: the relationship between oxytocin and sociality; single nucleotide polymorphisms as a biological marker of ASD; and validity verification of oxytocin treatment in humans. We also reviewed materials related to the mechanism of oxytocin action that may support its potential application in treating ASD.

Recommendations for the standardisation of oxytocin nasal administration and guidelines for its reporting in human research

A series of studies have reported on the salubrious effects of oxytocin nasal spray on social cognition and behavior in humans, across physiology (e.g., eye gaze, heart rate variability), social cognition (e.g., attention, memory, and appraisal), and behavior (e.g., trust, generosity). Findings suggest the potential of oxytocin nasal spray as a treatment for various psychopathologies, including autism and schizophrenia. There are, however, increasing reports of variability of response to oxytocin nasal spray between experiments and individuals. In this review, we provide a summary of factors that influence transmucosal nasal drug delivery, deposition, and their impact on bioavailability. These include variations in anatomy and resultant airflow dynamic, vascularisation, status of blood vessels, mode of spray application, gallenic formulation (including presence of uptake enhancers, control release formulation), and amount and method of administration. These key variables are generally poorly described and controlled in scientific reports, in spite of their potential to alter the course of treatment outcome studies. Based on this review, it should be of no surprise that differences emerge across individuals and experiments when nasal drug delivery methods are employed. We present recommendations for researchers to use when developing and administering the spray, and guidelines for reporting on peptide nasal spray studies in humans. We hope that these recommendations assist in establishing a scientific standard that can improve the rigor and subsequent reliability of reported effects of oxytocin nasal spray in humans.