The preference for sugar over sweetener depends on a gut sensor cell

AAV-mediated gene transfer to colon-innervating primary afferent neurons

Investigation of neural circuits underlying visceral pain is hampered by the difficulty in achieving selective manipulations of individual circuit components. In this study, we adapted a dual AAV approach, used for projection-specific transgene expression in the CNS, to explore the potential for targeted delivery of transgenes to primary afferent neurons innervating visceral organs. Focusing on the extrinsic sensory innervation of the mouse colon, we first characterized the extent of dual transduction following intrathecal delivery of one AAV9 vector and intracolonic delivery of a second AAV9 vector. We found that if the two AAV9 vectors were delivered one week apart, dorsal root ganglion (DRG) neuron transduction by the second vector was greatly diminished. Following delivery of the two viruses on the same day, we observed colocalization of the transgenes in DRG neurons, indicating dual transduction. Next, we delivered intrathecally an AAV9 vector encoding the inhibitory chemogenetic actuator hM4D(Gi) in a Cre-recombinase dependent manner, and on the same day injected an AAV9 vector carrying Cre-recombinase in the colon. DRG expression of hM4D(Gi) was demonstrated at the mRNA and protein level. However, we were unable to demonstrate selective inhibition of visceral nociception following hM4D(Gi) activation. Taken together, these results establish a foundation for development of strategies for targeted transduction of primary afferent neurons for neuromodulation of peripheral neural circuits.

In conversation with Diego Bohórquez

As Nature Neuroscience celebrates its 25th anniversary, we are having conversations with both established leaders in the field and those earlier in their careers to discuss how neuroscience has evolved, and where it is heading. This month, we are talking to Diego Bohórquez, an Associate Professor at Duke University School of Medicine. He is a self-described 'gut-brain neuroscientist' and spoke with me about his early life in the Ecuadorian Amazon and how his curiosity has led him to his current research topics.

Cultured Vagal Afferent Neurons as Sensors for Intestinal Effector Molecules

The gut-brain axis embodies the bi-directional communication between the gastrointestinal tract and the central nervous system (CNS), where vagal afferent neurons (VANs) serve as sensors for a variety of gut-derived signals. The gut is colonized by a large and diverse population of microorganisms that communicate via small (effector) molecules, which also act on the VAN terminals situated in the gut viscera and consequently influence many CNS processes. However, the convoluted in vivo environment makes it difficult to study the causative impact of the effector molecules on VAN activation or desensitization. Here, we report on a VAN culture and its proof-of-principle demonstration as a cell-based sensor to monitor the influence of gastrointestinal effector molecules on neuronal behavior. We initially compared the effect of surface coatings (poly-L-lysine vs. Matrigel) and culture media composition (serum vs. growth factor supplement) on neurite growth as a surrogate of VAN regeneration following tissue harvesting, where the Matrigel coating, but not the media composition, played a significant role in the increased neurite growth. We then used both live-cell calcium imaging and extracellular electrophysiological recordings to show that the VANs responded to classical effector molecules of endogenous and exogenous origin (cholecystokinin serotonin and capsaicin) in a complex fashion. We expect this study to enable platforms for screening various effector molecules and their influence on VAN activity, assessed by their information-rich electrophysiological fingerprints.

Asymmetric control of food intake by left and right vagal sensory neurons

We investigated the lateralization of gut-innervating vagal sensory neurons and their roles in feeding behavior. Using genetic, anatomical, and behavioral analyses, we discovered a subset of highly lateralized vagal sensory neurons with distinct sensory responses to intestinal stimuli. Our results demonstrated that left vagal sensory neurons (LNG) are crucial for distension-induced satiety, while right vagal sensory neurons (RNG) mediate preference for nutritive foods. Furthermore, these lateralized neurons engage different central circuits, with LNG neurons recruiting brain regions associated with energy balance and RNG neurons activating areas related to salience, memory, and reward. Altogether, our findings unveil the diverse roles of asymmetrical gut-vagal-brain circuits in feeding behavior, offering new insights for potential therapeutic interventions targeting vagal nerve stimulation in metabolic and neuropsychiatric diseases.

Conditioned preference and avoidance induced in mice by the rare sugars isomaltulose and allulose

Isomaltulose, a slowly digested isocaloric analog of sucrose, and allulose, a noncaloric fructose analog, are promoted as "healthful" sugar alternatives in human food products. Here we investigated the appetite and preference conditioning actions of these sugar analogs in inbred mouse strains. In brief-access lick tests (Experiment 1), C57BL/6 (B6) mice showed similar concentration dependent increases in licking for allulose and fructose, but less pronounced concentration-dependent increases in licking for isomaltulose than sucrose. In Experiment 2, B6 male were given one-bottle training with a CS+ flavor (e.g., grape) mixed with 8% isomaltulose or allulose and a CS- flavor (e.g., cherry) mixed in water followed by two-bottle CS flavor tests. The isomaltulose mice showed only a weak CS+ flavor preference but a strong preference for the sugar over water. The allulose mice strongly preferred the CS- flavor and water over the sugar. The allulose avoidance may be due to gut discomfort as reported in humans consuming high amounts of the sugar. Experiment 3 found that the preference for 8% sucrose over 8% isomaltulose could be reversed or blocked by adding different concentrations of a noncaloric sweetener mixture (sucralose + saccharin, SS) to the isomaltulose. Experiment 4 revealed that the preference of B6 or FVB/N mice for isomaltulose+0.01%SS or sucrose over 0.1%SS increased after separate experience with the sugars and SS. This indicates that isomaltulose, like sucrose, has postoral appetition effects that enhances the appetite for the sugar. In Experiments 5 and 6, the appetition actions of the two sugars were directly compared by giving mice isomaltulose+0.05%SS vs. sucrose choice tests before and after separate experience with the two sugars. In general, the initial preference the mice displayed for isomaltulose+0.05%SS was reduced or reversed after separate experience with the two sugars although some strain and sex differences were obtained. This indicates that isomaltulose has weaker postoral appetition effects than sucrose.

Effects of ultra-processed foods on the microbiota-gut-brain axis: The bread-and-butter issue

The topic of gut microbiota and the microbiota-gut-brain (MGB) axis has become the forefront of research and reports in the past few years. The gut microbiota is a dynamic interface between the environment, food, and the host, reflecting the health status as well as maintaining normal physiological metabolism. Modern ultra-processed foods (UPF) contain large quantities of saturated and trans fat, added sugar, salt, and food additives that seriously affect the gut and physical health. In addition, these unhealthy components directly cause changes in gut microbiota functions and microbial metabolism, subsequently having the potential to impact the neural network. This paper reviews an overview of the link between UPF ingredients and the MGB axis. Considerable studies have examined that high intake of trans fat, added sugar and salt have deleterious effects on gut and brain functions, but relatively less focus has been placed on the impact of food additives on the MGB axis. Data from several studies suggest that food additives might be linked to metabolic diseases and inflammation. They may also alter the gut microbiota composition and microbial metabolites, which potentially affect cognition and behavior. Therefore, we emphasize that food additives including emulsifiers, artificial sweeteners, colorants, and preservatives interact with the gut microbiota and their possible effects on altering the brain and behavior based on the latest research. Future studies should further investigate whether gut dysbiosis mediates the effect of UPF on brain diseases and behavior. This thesis here sheds new light on future research pointing to the potentially detrimental effects of processed food consumption on brain health.

Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEET beverages trial

Project SWEET examined the barriers and facilitators to the use of non-nutritive sweeteners and sweetness enhancers (hereafter "S&SE") alongside potential risks/benefits for health and sustainability. The Beverages trial was a double-blind multi-centre, randomised crossover trial within SWEET evaluating the acute impact of three S&SE blends (plant-based and alternatives) vs. a sucrose control on glycaemic response, food intake, appetite sensations and safety after a carbohydrate-rich breakfast meal. The blends were: mogroside V and stevia RebM; stevia RebA and thaumatin; and sucralose and acesulfame-potassium (ace-K). At each 4 h visit, 60 healthy volunteers (53% male; all with overweight/obesity) consumed a 330 mL beverage with either an S&SE blend (0 kJ) or 8% sucrose (26 g, 442 kJ), shortly followed by a standardised breakfast (∼2600 or 1800 kJ with 77 or 51 g carbohydrates, depending on sex). All blends reduced the 2-h incremental area-under-the-curve (iAUC) for blood insulin (p < 0.001 in mixed-effects models), while the stevia RebA and sucralose blends reduced the glucose iAUC (p < 0.05) compared with sucrose. Post-prandial levels of triglycerides plus hepatic transaminases did not differ across conditions (p > 0.05 for all). Compared with sucrose, there was a 3% increase in LDL-cholesterol after stevia RebA-thaumatin (p < 0.001 in adjusted models); and a 2% decrease in HDL-cholesterol after sucralose-ace-K (p < 0.01). There was an impact of blend on fullness and desire to eat ratings (both p < 0.05) and sucralose-acesulfame K induced higher prospective intake vs sucrose (p < 0.001 in adjusted models), but changes were of a small magnitude and did not translate into energy intake differences over the next 24 h. Gastro-intestinal symptoms for all beverages were mostly mild. In general, responses to a carbohydrate-rich meal following consumption of S&SE blends with stevia or sucralose were similar to sucrose.

The elusive cephalic phase insulin response: triggers, mechanisms, and functions

The cephalic phase insulin response (CPIR) is classically defined as a head receptor-induced early release of insulin during eating that precedes a postabsorptive rise in blood glucose. Here we discuss, first, the various stimuli that elicit the CPIR and the sensory signaling pathways (sensory limb) involved; second, the efferent pathways that control the various endocrine events associated with eating (motor limb); and third, what is known about the central integrative processes linking the sensory and motor limbs. Fourth, in doing so, we identify open questions and problems with respect to the CPIR in general. Specifically, we consider test conditions that allow, or may not allow, the stimulus to reach the potentially relevant taste receptors and to trigger a CPIR. The possible significance of sweetness and palatability as crucial stimulus features and whether conditioning plays a role in the CPIR are also discussed. Moreover, we ponder the utility of the strict classical CPIR definition based on what is known about the effects of vagal motor neuron activation and thereby acetylcholine on the β-cells, together with the difficulties of the accurate assessment of insulin release. Finally, we weigh the evidence of the physiological and clinical relevance of the cephalic contribution to the release of insulin that occurs during and after a meal. These points are critical for the interpretation of the existing data, and they support a sharper focus on the role of head receptors in the overall insulin response to eating rather than relying solely on the classical CPIR definition.

The Vagus Nerve Mediates Gut-Brain Response to Duodenal Nutrient Administration

BACKGROUND

Obesity contributes significant disease burden worldwide, including diabetes, cardiovascular disease, and cancer. While bariatric surgery is the most effective and durable obesity treatment, the mechanisms underlying its effects remain unknown. Although neuro-hormonal mechanisms have been suspected to mediate at least some of the gut-brain axis changes following bariatric surgery, studies examining the intestine and its regionally specific post-gastric alterations to these signals remain unclear.

MATERIALS AND METHODS

Vagus nerve recording was performed following the implantation of duodenal feeding tubes in mice. Testing conditions and measurements were made under anesthesia during baseline, nutrient or vehicle solution delivery, and post-delivery. Solutions tested included water, glucose, glucose with an inhibitor of glucose absorption (phlorizin), and a hydrolyzed protein solution.

RESULTS

Vagus nerve signaling was detectable from the duodenum and exhibited stable baseline activity without responding to osmotic pressure gradients. Duodenal-delivered glucose and protein robustly increased vagus nerve signaling, but increased signaling was abolished during the co-administration of glucose and phlorizin.

DISCUSSION

Gut-brain communication via the vagus nerve emanating from the duodenum is nutrient sensitive and easily measurable in mice. Examination of these signaling pathways may help elucidate how the nutrient signals from the intestine are altered when applied to obesity and bariatric surgery mouse models. Future studies will address quantifying the changes in neuroendocrine nutrient signals in health and obesity, with specific emphasis on identifying the changes associated with bariatric surgery and other gastrointestinal surgery.

Sweetener System Intervention Shifted Neutrophils from Homeostasis to Priming

BACKGROUND

Non-nutritive sweeteners (NNS) are part of personalized nutrition strategies supporting healthy glycemic control. In contrast, the consumption of non-nutritive sweeteners has been related to person-specific and microbiome-dependent glycemic impairments. Reports on the effects of NNS on our highly individual cellular immune system are sparse. The recent identification of taste receptor expression in a variety of immune cells, however, suggested their immune-modulatory relevance.

METHODS

We studied the influence of a beverage-typical NNS system on the transcriptional profiling of sweetener-cognate taste receptors, selected cytokines and their receptors, and on Ca²⁺ signaling in isolated blood neutrophils. We determined plasma concentrations of saccharin, acesulfame-K, and cyclamate by HPLC-MS/MS, upon ingestion of a soft drink-typical sweetener surrogate. In an open-labeled, randomized intervention study, we determined pre- versus post-intervention transcript levels by RT-qPCR of sweetener-cognate taste receptors and immune factors.

RESULTS

Here we show that the consumption of a food-typical sweetener system modulated the gene expression of cognate taste receptors and induced the transcriptional regulation signatures of early homeostasis- and late receptor/signaling- and inflammation-related genes in blood neutrophils, shifting their transcriptional profile from homeostasis to priming. Notably, sweeteners at postprandial plasma concentrations facilitated fMLF (N-formyl-Met-Leu-Phe)-induced Ca²⁺ signaling.

CONCLUSIONS

Our results support the notion of sweeteners priming neutrophils to higher alertness towards their adequate stimuli.

Physiology Reconfigured: How Does Bariatric Surgery Lead to Diabetes Remission?

Bariatric surgery improves glucose homeostasis and glycemic control in patients with type 2 diabetes. Over the past 20 years, a breadth of studies has been conducted in humans and rodents aimed to identify the regulatory nodes responsible for surgical remission of type 2 diabetes. The review herein discusses central mechanisms of type 2 diabetes remission associated with weight loss and surgical modification of the gastrointestinal tract.

Guanylyl cyclase C ameliorates visceral pain: an unsuspected link

Visceral pain associated with irritable bowel syndrome afflicts 15% of the US population. Although treatments are limited, guanylyl cyclase C (GUCY2C) agonists alleviate pain and constipation. Until now, it was assumed that the activation of GUCY2C and production of cGMP in enterocytes stimulated fluid secretion and reduced visceral sensation. The recent discovery that a subtype of enteroendocrine cells (EECs) known as neuropod cells synapse with submucosal neurons unveiled a pathway for communicating gut signals to the nervous system. In this issue of the JCI, Barton et al. report that GUCY2C is enriched in neuropod cells and is involved with sensory nerve firing. Selective deletion of GUCY2C in mouse models suggests that defective GUCY2C neuropod-cell signaling underlies visceral pain. These studies introduce possibilities for dissociating the secretory and analgesic effects of GUCY2C agonism. Although further work remains, unveiling the role of neuropod cells is a major step in understanding visceral pain.

Evaluation of mouse behavioral responses to nutritive versus nonnutritive sugar using a deep learning-based 3D real-time pose estimation system

Animals are able to detect the nutritional content of sugar independently of taste. When given a choice between nutritive sugar and nonnutritive sugar, animals develop a preference for nutritive sugar over nonnutritive sugar during a period of food deprivation (Buchanan et al., 2022; Dus et al., 2011; 2015; Tan et al., 2020; Tellez et al., 2016). To quantify behavioral features during an episode of licking nutritive versus nonnutritive sugar, we implemented a multi-vision, deep learning-based 3D pose estimation system, termed the AI Vision Analysis for Three-dimensional Action in Real-Time (AVATAR)(Kim et al., 2022). Using this method, we found that mice exhibit significantly different approach behavioral responses toward nutritive sugar versus nonnutritive sugar even before licking a sugar solution. Notably, the behavioral sequences during the approach toward nutritive versus nonnutritive sugar became significantly different over time. These results suggest that the nutritional value of sugar not only promotes its consumption but also elicits distinct repertoires of feeding behavior in deprived mice.

Intestinal neuropod cell GUCY2C regulates visceral pain

Visceral pain (VP) is a global problem with complex etiologies and limited therapeutic options. Guanylyl cyclase C (GUCY2C), an intestinal receptor producing cyclic GMP(cGMP), which regulates luminal fluid secretion, has emerged as a therapeutic target for VP. Indeed, FDA-approved GUCY2C agonists ameliorate VP in patients with chronic constipation syndromes, although analgesic mechanisms remain obscure. Here, we revealed that intestinal GUCY2C was selectively enriched in neuropod cells, a type of enteroendocrine cell that synapses with submucosal neurons in mice and humans. GUCY2Chi neuropod cells associated with cocultured dorsal root ganglia neurons and induced hyperexcitability, reducing the rheobase and increasing the resulting number of evoked action potentials. Conversely, the GUCY2C agonist linaclotide eliminated neuronal hyperexcitability produced by GUCY2C-sufficient - but not GUCY2C-deficient - neuropod cells, an effect independent of bulk epithelial cells or extracellular cGMP. Genetic elimination of intestinal GUCY2C amplified nociceptive signaling in VP that was comparable with chemically induced VP but refractory to linaclotide. Importantly, eliminating GUCY2C selectively in neuropod cells also increased nociceptive signaling and VP that was refractory to linaclotide. In the context of loss of GUCY2C hormones in patients with VP, these observations suggest a specific role for neuropod GUCY2C signaling in the pathophysiology and treatment of these pain syndromes.

The neural basis of sugar preference

When it comes to food, one tempting substance is sugar. Although sweetness is detected by the tongue, the desire to consume sugar arises from the gut. Even when sweet taste is impaired, animals can distinguish sugars from non-nutritive sweeteners guided by sensory cues arising from the gut epithelium. Here, we review the molecular receptors, cells, circuits and behavioural consequences associated with sugar sensing in the gut. Recent work demonstrates that some duodenal cells, termed neuropod cells, can detect glucose using sodium-glucose co-transporter 1 and release glutamate onto vagal afferent neurons. Based on these and other data, we propose a model in which specific populations of vagal neurons relay these sensory cues to distinct sets of neurons in the brain, including neurons in the caudal nucleus of the solitary tract, dopaminergic reward circuits in the basal ganglia and homeostatic feeding circuits in the hypothalamus, that alter current and future sugar consumption. This emerging model highlights the critical role of the gut in sensing the chemical properties of ingested nutrients to guide appetitive decisions.

Oral Erythritol Reduces Energy Intake during a Subsequent ad libitum Test Meal: A Randomized, Controlled, Crossover Trial in Healthy Humans

The impact of oral erythritol on subsequent energy intake is unknown. The aim was to assess the effect of oral erythritol compared to sucrose, sucralose, or tap water on energy intake during a subsequent ad libitum test meal and to examine the release of cholecystokinin (CCK) in response to these substances. In this randomized, crossover trial, 20 healthy volunteers received 50 g erythritol, 33.5 g sucrose, or 0.0558 g sucralose dissolved in tap water, or tap water as an oral preload in four different sessions. Fifteen minutes later, a test meal was served and energy intake was assessed. At set time points, blood samples were collected to quantify CCK concentrations. The energy intake (ad libitum test meal) was significantly lower after erythritol compared to sucrose, sucralose, or tap water (p < 0.05). Before the start of the ad libitum test meal, erythritol led to a significant increase in CCK compared to sucrose, sucralose, or tap water (p < 0.001). Oral erythritol given alone induced the release of CCK before the start of the ad libitum test meal and reduced subsequent energy intake compared to sucrose, sucralose, or tap water. These properties make erythritol a useful sugar alternative.

Prolonged Consumption of glucose syrup enhances glucose tolerance in mice

There is debate about the metabolic impact of sugar-sweetened beverages. Here, we tested the hypothesis that ad lib consumption of glucose (Gluc) or high-fructose (HiFruc) syrups improves glucose tolerance in mice. We provided C57BL/6 mice with a control (chow and water) or experimental (chow, water and sugar solution) diet across two consecutive 28-day exposure periods, and monitored changes in body composition, glucose tolerance, cephalic-phase insulin release (CPIR) and insulin sensitivity. The sugar solutions contained 11% concentrations of Gluc or HiFruc syrup; these syrups were derived from either corn starch or cellulose. In Experiment 1, consumption of the Gluc diets reliably enhanced glucose tolerance, while consumption of the HiFruc diets did not. Mice on the Gluc diets exhibited higher CPIR (relative to baseline) by the end of exposure period 1, whereas mice on the control and HiFruc diets did not do so until the end of exposure period 2. Mice on the Gluc diets also exhibited higher insulin sensitivity than control mice at the end of exposure period 2, while mice on the HiFruc diets did not. In Experiment 2, we repeated the previous experiment, but limited testing to the corn-based Gluc and HiFruc syrups. We found, once again, that consumption of the Gluc (but not the HiFruc) diet enhanced glucose tolerance, in part by increasing CPIR and insulin sensitivity. These results show that mice can adapt metabolically to high glucose diets, and that this adaptation process involves upregulating at least two components of the insulin response system.

Taste Receptors beyond Taste Buds

Taste receptors are responsible for detecting their ligands not only in taste receptor cells (TRCs) but also in non-gustatory organs. For several decades, many research groups have accumulated evidence for such “ectopic” expression of taste receptors. More recently, some of the physiologic functions (apart from taste) of these ectopic taste receptors have been identified. Here, we summarize our current understanding of these ectopic taste receptors across multiple organs. With a particular focus on the specialized epithelial cells called tuft cells, which are now considered siblings of type II TRCs, we divide the ectopic expression of taste receptors into two categories: taste receptors in TRC-like cells outside taste buds and taste receptors with surprising ectopic expression in completely different cell types.

Enteroendocrine cell types that drive food reward and aversion

Animals must learn through experience which foods are nutritious and should be consumed, and which are toxic and should be avoided. Enteroendocrine cells (EECs) are the principal chemosensors in the GI tract, but investigation of their role in behavior has been limited by the difficulty of selectively targeting these cells in vivo. Here, we describe an intersectional genetic approach for manipulating EEC subtypes in behaving mice. We show that multiple EEC subtypes inhibit food intake but have different effects on learning. Conditioned flavor preference is driven by release of cholecystokinin whereas conditioned taste aversion is mediated by serotonin and substance P. These positive and negative valence signals are transmitted by vagal and spinal afferents, respectively. These findings establish a cellular basis for how chemosensing in the gut drives learning about food.

Dietary regulation in health and disease

Nutriments have been deemed to impact all physiopathologic processes. Recent evidences in molecular medicine and clinical trials have demonstrated that adequate nutrition treatments are the golden criterion for extending healthspan and delaying ageing in various species such as yeast, drosophila, rodent, primate and human. It emerges to develop the precision-nutrition therapeutics to slow age-related biological processes and treat diverse diseases. However, the nutritive advantages frequently diversify among individuals as well as organs and tissues, which brings challenges in this field. In this review, we summarize the different forms of dietary interventions extensively prescribed for healthspan improvement and disease treatment in pre-clinical or clinical. We discuss the nutrient-mediated mechanisms including metabolic regulators, nutritive metabolism pathways, epigenetic mechanisms and circadian clocks. Comparably, we describe diet-responsive effectors by which dietary interventions influence the endocrinic, immunological, microbial and neural states responsible for improving health and preventing multiple diseases in humans. Furthermore, we expatiate diverse patterns of dietotheroapies, including different fasting, calorie-restricted diet, ketogenic diet, high-fibre diet, plants-based diet, protein restriction diet or diet with specific reduction in amino acids or microelements, potentially affecting the health and morbid states. Altogether, we emphasize the profound nutritional therapy, and highlight the crosstalk among explored mechanisms and critical factors to develop individualized therapeutic approaches and predictors.

hsa_circ_0000518 Facilitates Non-Small-Cell Lung Cancer Progression via Moderating miR-330-3p and Positively Regulating SLC1A5

Background/Aim

Non-small-cell lung cancer (NSCLC) is the principal agent of cancer deaths globally. The goal of this study was to determine how circular RNA_0000518 (circ_0000518) regulates tumor progression. Materials/Methods. circ_0000518 was selected as a study target involved in NSCLC from GEO (Gene Expression Omnibus) database. circ_0000518 level was gauged by qRT-PCR. It was confirmed as circRNA by actinomycin D inhibition and RNase R assay. Subcellular localization of circ_0000518 was identified by FISH. Cell function was determined by CCK-8, Transwell, and western blot. Glutamine metabolic factors were detected by ELISA. The target regulation relationship between genes was clarified by dual-luciferase reporter assay. In vivo models were established to evaluate the impact of circ_0000518 on tumor growth. Immunohistochemical staining for Ki67, vimentin, and E-cadherin was used to detect cell proliferation and metastasis, respectively.

Results

circ_0000518 expression was enhanced in NSCLC. si-circ_0000518 inhibited cell proliferation, invasion, and glutamine metabolism. circ_0000518 functioned as a molecular sponge for miR-330-3p, and inhibition of miR-330-3p in cells markedly reversed circ_0000518 interference-mediated antitumor effects. miR-330-3p interacted with 3′-UTR of SLC1A5. miR-330-3p inhibitor-mediated protumor effect was remarkably reversed in cells after the knockdown of SLC1A5. circ_0000518 knockdown reduced glutamine, glutamate, and α-KG by targeting miR-330-3p. Intertumoral injection of circ_0000518 shRNA adeno-associated virus effectively halted xenograft tumor growth.

Conclusion

The current study revealed that circ_0000518 may have a prooncogenic function in the formation and progression of NSCLC, which might be achieved through moderating the miR-330-3p/SLC1A5 axis.

Nutrient-Based Appetite Regulation

Regulation of appetite is dependent on crosstalk between the gut and the brain, which is a pathway described as the gut-brain axis (GBA). Three primary appetite-regulating hormones that are secreted in the gut as a response to eating a meal are glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), and peptide YY (PYY). When these hormones are secreted, the GBA responds to reduce appetite. However, secretion of these hormones and the response of the GBA can vary depending on the types of nutrients consumed. This narrative review describes how the gut secretes GLP-1, CCK, and PYY in response to proteins, carbohydrates, and fats. In addition, the GBA response based on the quality of the meal is described in the context of which meal types produce greater appetite suppression. Last, the beneficiary role of exercise as a mediator of appetite regulation is highlighted.

The Roles of Optogenetics and Technology in Neurobiology: A Review

Optogenetic is a technique that combines optics and genetics to control specific neurons. This technique usually uses adenoviruses that encode photosensitive protein. The adenovirus may concentrate in a specific neural region. By shining light on the target nerve region, the photosensitive protein encoded by the adenovirus is controlled. Photosensitive proteins controlled by light can selectively allow ions inside and outside the cell membrane to pass through, resulting in inhibition or activation effects. Due to the high precision and minimally invasive, optogenetics has achieved good results in many fields, especially in the field of neuron functions and neural circuits. Significant advances have also been made in the study of many clinical diseases. This review focuses on the research of optogenetics in the field of neurobiology. These include how to use optogenetics to control nerve cells, study neural circuits, and treat diseases by changing the state of neurons. We hoped that this review will give a comprehensive understanding of the progress of optogenetics in the field of neurobiology.

Uts2b is a microbiota-regulated gene expressed in vagal afferent neurons connected to enteroendocrine cells producing cholecystokinin

Enteroendocrine cells (EECs) are the primary sensory cells that sense the gut luminal environment and secret hormones to regulate organ function. Recent studies revealed that vagal afferent neurons are connected to EECs and relay sensory information from EECs to the brain stem. To date, however, the identity of vagal afferent neurons connected to a given EEC subtype and the mode of their gene responses to its intestinal hormone have remained unknown. Hypothesizing that EEC-associated vagal afferent neurons change their gene expression in response to the microbiota-related extracellular stimuli, we conducted comparative gene expression analyses of the nodose-petrosal ganglion complex (NPG) using specific pathogen-free (SPF) and germ-free (GF) mice. We report here that the Uts2b gene, which encodes a functionally unknown neuropeptide, urotensin 2B (UTS2B), is expressed in a microbiota-dependent manner in NPG neurons. In cultured NPG neurons, expression of Uts2b was induced by AR420626, the selective agonist for FFAR3. Moreover, distinct gastrointestinal hormones exerted differential effects on Uts2b expression in NPG neurons, where cholecystokinin (CCK) significantly increased its expression. The majority of Uts2b-expressing NPG neurons expressed CCK-A, the receptor for CCK, which comprised approximately 25% of all CCK-A-expressing NPG neurons. Selective fluorescent labeling of Uts2b-expressing NPG neurons revealed a direct contact of their nerve fibers to CCK-expressing EECs. This study identifies the Uts2b as a microbiota-regulated gene, demonstrates that Uts2b-expressing vagal afferent neurons transduce sensory information from CCK-expressing EECs to the brain, and suggests potential involvement of UTS2B in a modality of CCK actions.

Investigating local and systemic intestinal signalling in health and disease with Drosophila

Whole-body health relies on complex inter-organ signalling networks that enable organisms to adapt to environmental perturbations and to changes in tissue homeostasis. The intestine plays a major role as a signalling centre by producing local and systemic signals that are relayed to the body and that maintain intestinal and organismal homeostasis. Consequently, disruption of intestinal homeostasis and signalling are associated with systemic diseases and multi-organ dysfunction. In recent years, the fruit fly Drosophila melanogaster has emerged as a prime model organism to study tissue-intrinsic and systemic signalling networks of the adult intestine due to its genetic tractability and functional conservation with mammals. In this Review, we highlight Drosophila research that has contributed to our understanding of how the adult intestine interacts with its microenvironment and with distant organs. We discuss the implications of these findings for understanding intestinal and whole-body pathophysiology, and how future Drosophila studies might advance our knowledge of the complex interplay between the intestine and the rest of the body in health and disease.

Summary: We outline work in the fruit fly Drosophila melanogaster that has contributed knowledge on local and whole-body signalling coordinated by the adult intestine, and discuss its implications in intestinal pathophysiology and associated systemic dysfunction.