Salivary peptide tyrosine-tyrosine 3-36 modulates ingestive behavior without inducing taste aversion

Promising applications of human-derived saliva biomarker testing in clinical diagnostics

Saliva testing is a vital method for clinical applications, for its noninvasive features, richness in substances, and the huge amount. Due to its direct anatomical connection with oral, digestive, and endocrine systems, clinical usage of saliva testing for these diseases is promising. Furthermore, for other diseases that seeming to have no correlations with saliva, such as neurodegenerative diseases and psychological diseases, researchers also reckon saliva informative. Tremendous papers are being produced in this field. Updated summaries of recent literature give newcomers a shortcut to have a grasp of this topic. Here, we focused on recent research about saliva biomarkers that are derived from humans, not from other organisms. The review mostly addresses the proceedings from 2016 to 2022, to shed light on the promising usage of saliva testing in clinical diagnostics. We recap the recent advances following the category of different types of biomarkers, such as intracellular DNA, RNA, proteins and intercellular exosomes, cell-free DNA, to give a comprehensive impression of saliva biomarker testing.

Y1 receptors modulate taste-related behavioral responsiveness in male mice to prototypical gustatory stimuli

Mammalian taste bud cells express receptors for numerous peptides implicated elsewhere in the body in the regulation of metabolism, nutrient assimilation, and satiety. The perturbation of several peptide signaling pathways in the gustatory periphery results in changes in behavioral and/or physiological responsiveness to subsets of taste stimuli. We previously showed that Peptide YY (PYY) - which is present in both saliva and in subsets of taste cells - can affect behavioral taste responsiveness and reduce food intake and body weight. Here, we investigated the contributions of taste bud-localized receptors for PYY and the related Neuropeptide Y (NPY) on behavioral taste responsiveness. Y1R, but not Y2R, null mice show reduced responsiveness to sweet, bitter, and salty taste stimuli in brief-access taste tests; similar results were seen when wildtype mice were exposed to Y receptor antagonists in the taste stimuli. Finally, mice in which the gene encoding the NPY propeptide was deleted also showed reduced taste responsiveness to sweet and bitter taste stimuli. Collectively, these results suggest that Y1R signaling, likely through its interactions with NPY, can modulate peripheral taste responsiveness in mice.

The effect of smell and taste of milk during tube feeding of preterm infants (the Taste trial): a protocol for a randomised controlled trial

INTRODUCTION

Smell and taste of milk are not generally considered when tube feeding preterm infants. Preterm infants have rapid growth, particularly of the brain, and high caloric needs. Enteral feeding is often poorly tolerated which may lead to growth failure and long-term neurodevelopmental impairment. Smell and taste are strong stimulators of digestion and metabolism. We hypothesise that regular smell and taste during tube feeding will improve weight z-scores of very preterm infants at discharge from hospital.

METHODS AND ANALYSIS

Taste is a randomised, unblinded two-centre trial. Infants born at <29 weeks' gestation and/or <1250 g at birth and admitted to a participating neonatal intensive care unit are eligible. Randomisation occurs before infants receive two hourly feeds for 24 hours. Infants are randomised to either smell and taste of milk with each tube feed or tube feeding without the provision of smell and taste. The primary outcome is weight z-score at discharge. Secondary outcomes include: days to full enteral feeds, duration of parenteral nutrition, rate of late-onset sepsis, post menstrual age at removal of nasogastric tube and at discharge from hospital, anthropometric data and neurodevelopmental outcomes at 2 years of corrected age.

ETHICS AND DISSEMINATION

Human Research Ethics Committees of Mater Misericordiae (trial reference number: HREC/16/MHS/112) and the Royal Women's Hospital (trial reference number: 17/21) last approved the trial protocol (version 4.2; Date: 18 December 2018) and recruitment commenced in May 2017 and November 2017, respectively. The trial results will be published in a peer-reviewed journal and will be presented at national and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12617000583347.

Anorectic response to the trichothecene T-2 toxin correspond to plasma elevations of the satiety hormone glucose-dependent insulinotropic polypeptide and peptide YY3-36

T-2 toxin, a potent type A trichothecene mycotoxin, is produced by various Fusarium species and can negatively impact animal and human health. Although anorexia induction is a common hallmark of T-2 toxin-induced toxicity, the underlying mechanisms for this adverse effect are not fully understood. The goal of this study was to determine the roles of two gut satiety hormones, glucose-dependent insulinotropic polypeptide (GIP) and Peptide YY_3-36 (PYY_3-36) in anorexia induction by T-2 toxin. Elevations of plasma GIP and PYY_3-36 markedly corresponded to anorexia induction following oral exposure to T-2 toxin using a nocturnal mouse anorexia model. Direct administration of exogenous GIP and PYY_3-36 similarly induced anorectic responses. Furthermore, the GIP receptor antagonist Pro3GIP dose-dependently attenuated both GIP- and T-2 toxin-induced anorectic responses. Pretreatment with NPY2 receptor antagonist JNJ-31020028 induced a dose-dependent attenuation of both PYY_3-36- and T-2 toxin-induced anorectic responses. To summarize, these findings suggest that both GIP and PYY_3-36 might be critical mediators of anorexia induction by T-2 toxin.

Peptide hormones and lipopeptides: from self-assembly to therapeutic applications

This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions. The self-assembly of these types of molecules is outlined, and how this can impact on bioactivity. Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

Advances in salivary gland gene therapy - oral and systemic implications

INTRODUCTION

Much research demonstrates the feasibility and efficacy of gene transfer to salivary glands. Recently, the first clinical trial targeting a salivary gland was completed, yielding positive safety and efficacy results.

AREAS COVERED

There are two major disorders affecting salivary glands: radiation damage following treatment for head and neck cancers and Sjögren's syndrome (SS). Salivary gland gene transfer has also been employed in preclinical studies using transgenic secretory proteins for exocrine (upper gastrointestinal tract) and endocrine (systemic) applications.

EXPERT OPINION

Salivary gland gene transfer is safe and can be beneficial in humans. Applications to treat and prevent radiation damage show considerable promise. A first-in-human clinical trial for the former was recently successfully completed. Studies on SS suffer from an inadequate understanding of its etiology. Proof of concept in animal models has been shown for exocrine and endocrine disorders. Currently, the most promising exocrine application is for the management of obesity. Endocrine applications are limited, as it is currently impossible to predict if systemically required transgenic proteins will be efficiently secreted into the bloodstream. This results from not understanding how secretory proteins are sorted. Future studies will likely employ ultrasound-assisted and pseudotyped adeno-associated viral vector-mediated gene transfer.

Regulation of energy homeostasis by the NPY system

Obesity develops when energy intake exceeds energy expenditure over time. Numerous neurotransmitters, hormones, and factors have been implicated to coordinately control energy homeostasis, centrally and peripherally. However, the neuropeptide Y (NPY) system has emerged as the one with the most critical functions in this process. While NPY centrally promotes feeding and reduces energy expenditure, peptide YY (PYY) and pancreatic polypeptide (PP), the other family members, mediate satiety. Importantly, recent research has uncovered additional functions for these peptides that go beyond the simple feeding/satiety circuits and indicate a more extensive function in controlling energy homeostasis. In this review, we will discuss the actions of the NPY system in the regulation of energy balance, with a particular focus on energy expenditure.

Modulation of hunger and satiety: hormones and diet

PURPOSE OF REVIEW

To highlight recent research developments relating to the effects of, and interactions between, hormones and diet, as well as underlying mechanisms, on appetite, energy intake and body weight. For this purpose, clinically relevant English language articles were reviewed from October 2012 to April 2014.

RECENT FINDINGS

The mechanisms underlying nutrient-induced energy intake suppression differ between dietary protein and lipid. High-fat, energy-dense diets compromise the satiating effects of gut hormones, and, therefore, promote further overconsumption. These effects are mediated by changes in the signalling in both peripheral and central pathways, and may only be partially reversible by dietary restriction. Additional factors, including probiotics, meal-related factors (e.g., eating speed and frequency), circadian influences and gene polymorphisms, also modify energy intake and eating behaviour.

SUMMARY

Research continues to unravel the pathways and mechanisms underlying the nutrient-induced and diet-induced regulation of energy intake, as well as the changes, both peripherally and in the central nervous system, brought about by the consumption of high-fat, energy-dense diets. Much further work is required to translate this knowledge into novel, and effective, approaches for the management and treatment of obesity and associated metabolic disorders.

Role of cholecystokinin in anorexia induction following oral exposure to the 8-ketotrichothecenes deoxynivalenol, 15-acetyldeoxynivalenol, 3-acetyldeoxynivalenol, fusarenon X, and nivalenol

Cereal grain contamination by trichothecene mycotoxins is known to negatively impact human and animal health with adverse effects on food intake and growth being of particular concern. The head blight fungus Fusarium graminearum elaborates five closely related 8-ketotrichothecene congeners: (1) deoxynivalenol (DON), (2) 3-acetyldeoxynivalenol (3-ADON), (3) 15-acetyldeoxynivalenol (15-ADON), (4) fusarenon X (FX), and (5) nivalenol (NIV). While anorexia induction in mice exposed intraperitoneally to DON has been linked to plasma elevation of the satiety hormones cholecystokinin (CCK) and peptide YY₃₋₃₆ (PYY₃₋₃₆), the effects of oral gavage of DON or of other 8-keotrichothecenes on release of these gut peptides have not been established. The purpose of this study was to (1) compare the anorectic responses to the aforementioned 8-ketotrichothecenes following oral gavage at a common dose (2.5 mg/kg bw) and (2) relate these effects to changes plasma CCK and PYY₃₋₃₆ concentrations. Elevation of plasma CCK markedly corresponded to anorexia induction by DON and all other 8-ketotrichothecenes tested. Furthermore, the CCK1 receptor antagonist SR 27897 and the CCK2 receptor antagonist L-365,260 dose-dependently attenuated both CCK- and DON-induced anorexia, which was consistent with this gut satiety hormone being an important mediator of 8-ketotrichothecene-induced food refusal. In contrast to CCK, PYY₃₋₃₆ was moderately elevated by oral gavage with DON and NIV but not by 3-ADON, 15-ADON, or FX. Taken together, the results suggest that CCK plays a major role in anorexia induction following oral exposure to 8-ketotrichothecenes, whereas PYY₃₋₃₆ might play a lesser, congener-dependent role in this response.