Glucose-dependent insulinotropic polypeptide counteracts diet-induced obesity along with reduced feeding, elevated plasma leptin and activation of leptin-responsive and proopiomelanocortin neurons in the arcuate nucleus.

AIM: To clarify the effects of glucose-dependent insulinotropic polypeptide (GIP) receptor agonists (GIPRAs) on feeding and body weight. MATERIALS AND METHODS: Acute and subchronic effects of subcutaneous GIPFA-085, a long-acting GIPRA, on blood glucose, food intake, body weight, respiratory exchange ratio and plasma leptin levels were measured in diet-induced obese (DIO) mice and/or functional leptin-deficient ob/ob mice. The effects of GIPFA-085 on the hypothalamic arcuate nucleus (ARC) neurons from lean and DIO mice were studied by measuring cytosolic Ca2+ concentration ([Ca2+ ]i ). RESULTS: Single bolus GIPFA-085 (30, 300 nmol/kg) dose-dependently reduced blood glucose in glucose tolerance tests, elevated plasma leptin levels at 0.5-6 hours and inhibited food intake at 2-24 hours after injection in DIO mice. Daily GIPFA-085 (300 nmol/kg) inhibited food intake and increased fat utilization on day 1, and reduced body weight gain on days 3-12 of treatment in DIO, but not ob/ob, mice. GIPFA-085 increased [Ca2+ ]i in the ARC leptin-responsive and proopiomelanocortin (POMC) neurons. GIPFA-085 and leptin cooperated to increase [Ca2+ ]i in ARC neurons and inhibit food intake. CONCLUSIONS: GIPFA-085 acutely inhibits feeding and increases lipid utilization, and sustainedly lowers body weight in DIO mice via mechanisms involving rises in leptin and activation of ARC leptin-responsive and POMC neurons. This study highlights the therapeutic potential of GIPRAs for treating obesity and diabetes.

D-Allulose cooperates with glucagon-like peptide-1 and activates proopiomelanocortin neurons in the arcuate nucleus and central injection inhibits feeding in mice.

A rare sugar D-Allulose has sweetness without calorie. Previous studies have shown that D-Allulose improves glucose and energy metabolism and ameliorates obesity. However, underlying mechanisms remain elusive. This study explored the effect of central injection of D-Allulose on feeding behavior in mice. We also examined direct effects of D-Allulose on the neurons in the hypothalamic arcuate nucleus (ARC) that regulate feeding, including the anorexigenic glucagon-like peptide-1 (GLP-1)-responsive neurons and proopiomelanocortin (POMC) neurons. Single neurons were isolated from ARC and cytosolic Ca2+ concentration ([Ca2+]i) was measured by fura-2 microfluorometry. Administration of D-Allulose at 5.6, 16.7 and 56 mM concentration-dependently increased [Ca2+]i in ARC neurons. The [Ca2+]i increases took place similarly when the osmolarity of superfusion solution was kept constant. The majority (40%) of the D-Allulose-responsive neurons also responded to GLP-1 with [Ca2+]i increases. D-Allulose increased [Ca2+]i in 33% of POMC neurons in ARC. D-Allulose potentiated the GLP-1 action to increase [Ca2+]i in ARC neurons including POMC neurons. Intracerebroventricular injection of D-Allulose significantly decreased food intake at 1 and 2 h after injection. These results demonstrate that D-Allulose cooperates with glucagon-like peptide-1 and activates the ARC neurons including POMC neurons. Furthermore, central injection of D-Allulose inhibits feeding. These central actions of D-Allulose may underlie the ability of D-Allulose to counteract obesity and diabetes.

First Report of Pectobacterium polaris Causing Aerial Stem Rot of Potato in China.

In July 2020, potato plants (cv. Xisen 6) showing characteristic symptoms of aerial stem rot were observed in a field in Fengning Manchu Autonomous County, Chengde, Hebei Province (northern China). The disease incidence in that field (5 ha in size) was more than 50%. Aerial stem rot of potato has increased in prevalence over recent years in Chengde, it can cause significant yield loss on susceptible cultivars such as Xisen 6 and Huangxin 226. Affected stem (light brown and water-soaked stem sections) pieces ca. 0.5 cm in length were surface-sterilized by dipping them in 75% ethanol for one min and then three successive rinses with sterile distilled water. Then, the tissues were soaked in 200 µl 0.9% saline for 20 min. Aliquots (20 µl) of three tenfold dilutions of the tissue specimen soaking solution were plated onto the crystal violet pectate (CVP) medium. The CVP plates were incubated at 28°C for 48 h. Colonies producing pits were restreaked and purified on Luria-Bertani (LB) agar plates. The bacterial gDNA was extracted using the EasyPure Bacteria Genomic DNA Kit (TransGen Biotech, Beijing, China). The 16S rDNA region was amplified by PCR using the universal primers 27F/1492R (Weisburg et al. 1991) and sequenced. Results of the Blastn analysis of the 16S rDNA amplicons (MZ348607, MZ348608) suggested that the isolates FN20211 and FN20222 belonged to the genus Pectobacterium. Housekeeping genes including acnA, gapA, icdA, mdh, proA and rpoS were also amplified using a set of primers (Ma et al. 2007; Waleron et al. 2008) followed by sequencing (MZ356250-MZ356261). To determine the species of the stem rot Pectobacterium isolates, multi-locus sequence analysis (MLSA) was performed with six housekeeping genes, and phylogenetic tree was reconstructed using RAxML (github.com/stamatak/standard-RAxML). No sequence variation was observed at any MLSA locus between FN20211 and FN20222. The result of phylogenetic analysis showed that the isolates clustered with P. polaris type strain NIBIO1006T, which was isolated from potato (Dees et al. 2017). And the concatenated sequence of the six loci of isolate FN20211/FN20222 is 100% identical to those of the strains PZ1 (CP046377.1) and WBC1 (GCF_011378945.1), which were isolated from potato in South Korea and from Chinese cabbage in China, respectively. Potato seedlings (cv. Xisen 6 and Favorita) were inoculated with the isolates FN20211 and FN20222 by injecting 100 µl of bacterial suspensions (108 CFU·mL-1) into the upper parts of the stems of potato plants, or injected with 100 µl of 0.9% saline as control. The seedlings were grown at 25°C and 50% relative humidity. Three days after inoculation, only the bacteria-inoculated seedlings showed disease symptoms resembling to those observed in the field. Bacterial colonies were obtained from the infected stems and were identified using the same PCR primers as described above. Therefore, P. polaris isolates FN20211 and FN20222 fulfill Koch's postulates for aerial stem rot of potato. P. polaris causing blackleg and soft rot on potato plants has been reported in European countries including Netherlands, Norway (Dees et al. 2017) and Poland (Waleron et al. 2019), and also in Pakistan (Sarfraz et al. 2019) and Russia (Voronina et al. 2021). To our knowledge, this is the first report of P. polaris causing aerial stem rot of potato in China. The stem rot poses a significant threat to the local potato industry, and further research on epidemiology and disease management options is needed.

Influence of food texture on energy metabolism and adiposity in male rats.

NEW FINDINGS: What is the central question of this manuscript? What is the effect of food texture on fat accumulation, lipogenesis and proinflammatory factors in the adipose tissue and on energy balance in male rats? What is the main finding and its importance? Calorie intake and fat accumulation in rats fed soft pellets ad libitum increased, but their body weight did not. The data suggest that, even when BMI is normal, frequent consumption of soft food may contribute to the development of lifestyle-related diseases. ABSTRACT: Dietary factors such as food texture are known to affect feeding behaviour and energy metabolism. We recently found that rats fed soft pellets (SPs) on a 3 h restricted feeding schedule showed glucose intolerance, insulin resistance with disruption of insulin signalling, and hyperplasia of pancreatic ß-cells, even though there were no differences in energy intake and body weight between rats fed control pellets (CPs) and rats fed SPs. We investigated the effect of food texture on fat accumulation, lipogenesis and proinflammatory factors in the mesenteric fat, as well as on energy balance in male rats fed CPs or SPs. We used 7-week-old Wistar rats that were randomly divided into two groups, ad libitum fed either CPs or SPs for 27 weeks. Body weight and calorie intake were monitored once a week throughout the experiment. The calorie intake, lipogenesis and fat accumulation of the rats fed SPs increased, whereas their body weight did not. Additionally, SP rats used their fat mainly as a source of energy and increased their energy expenditure. Our data suggest that the habit of frequently eating soft food causes visceral fat accumulation without an increase in body weight. Further investigations using soft-textured foods could lead to the development of appropriate interventions for non-overweight patients with lifestyle-related diseases.

Mechanism of muscle atrophy in a normal-weight rat model of type 2 diabetes established by using a soft-pellet diet.

Dietary factors such as food texture affect feeding behavior and energy metabolism, potentially causing obesity and type 2 diabetes. We previously found that rats fed soft pellets (SPs) were neither hyperphagic nor overweight but demonstrated glucose intolerance, insulin resistance, and hyperplasia of pancreatic ß-cells. In the present study, we investigated the mechanism of muscle atrophy in rats that had been fed SPs on a 3-h time-restricted feeding schedule for 24 weeks. As expected, the SP rats were normal weight; however, they developed insulin resistance, glucose intolerance, and fat accumulation. In addition, skeletal muscles of SP rats were histologically atrophic and demonstrated disrupted insulin signaling. Furthermore, we learned that the muscle atrophy of the SP rats developed via the IL-6-STAT3-SOCS3 and ubiquitin-proteasome pathways. Our data show that the dietary habit of consuming soft foods can lead to not only glucose intolerance or insulin resistance but also muscle atrophy.

Identification and characterization of opportunistic pathogen Pectobacterium polonicum causing potato blackleg in China.

Blackleg and aerial stem rot of potato (Solanum tuberosum L.), caused by soft rot enterobacteria of the genera Pectobacterium and Dickeya, has recently increased years in Hebei Province, China. Field surveys were performed during the 2021 potato growing season in Hebei to identify and characterize bacterial pathogens. Sixteen potato plants showing blackleg or aerial stem rot were collected from three potato-producing areas, and ten representative pectinolytic bacteria were isolated from symptomatic plants. 16S rDNA sequencing and multilocus sequence analysis were performed to determine the taxonomic position of the bacterial isolates. The isolates belonged to the genus Pectobacterium, including Pectobacterium atrosepticum, Pectobacterium carotovorum, Pectobacterium brasiliense, and Pectobacterium parmentieri. The exceptions were isolates BY21311 and BY21312, which belonged to a new species of Pectobacterium polonicum previously found in groundwater. The taxonomy of isolate BY21311 was confirmed using whole genome-based analysis. P. polonicum has only been identified in potato plants on one farm in Baoding region in China. Isolates BY21311 and BY21312 displayed similar physiological and biochemical traits to the type strain DPMP315T. Artificial inoculation assays revealed that isolate BY21311 fulfilled Koch's postulates for potato blackleg. These findings represent the first time P. polonicum, a water-associated Pectobacterium species may be the cause of blackleg in the field. Interestingly, P. polonicum BY21311 has reduced ability to macerate potato tubers when compared to P. atrosepticum, P. brasiliense, P. versatile, and P. parvum, which is more virulent in tubers than the type strain DPMP315T. The host range of isolate BY21311 was determined by injection method, which can impregnate five plants. Although the genome of isolate BY21311 harbors gene clusters encoding a type III secretion system, it did not elicit a hypersensitive response (HR) in Nicotiana benthamiana or N. tabacum leaves. T3SS effector AvrE and T4SS effector PilN were obtained by predicting isolate BY21311 genome. P. polonicum appears to show significant variations in gene content between two genomes, and gene content varies between isolates BY21311 and DPMP315T, with strain specific-genes involved in many aspects, including lipopolysaccharide biosynthesis, substrate translocation, T4SS and T6SS among others, suggesting that isolates BY21311 and DPMP315T might represent distinct clades within the species.

Oral Semaglutide under Human Protocols and Doses Regulates Food Intake, Body Weight, and Glycemia in Diet-Induced Obese Mice.

The first oral form of the glucagon-like peptide-1 receptor agonist, oral semaglutide, has recently been launched and potently controls glycemia and body weight in subjects with type 2 diabetes. This drug carries the absorption enhancer and requires specific protocols of administration. The mechanism of action of oral semaglutide is not fully understood, for which an appropriate experimental model is required. This study explores the metabolic effects of oral semaglutide in mice under human protocols and doses. Oral semaglutide was bolus and once daily injected into high-fat diet-induced obese (DIO) mice under human protocols, followed by monitoring blood glucose, food intake, and body weight. Oral semaglutide 0.23 mg/kg, a comparable human dose (14 mg) in a small volume of water under human protocols rapidly decreased blood glucose and food intake and continuously reduced food intake and weight gain for 3 days in DIO mice. At 0.7 mg/kg (42 mg), this drug was somewhat more potent. Oral semaglutide with human protocols and doses rapidly reduces blood glucose and food intake and continuously suppresses feeding and weight in DIO mice. This study establishes mice as a model suitable for analyzing the mechanism of anti-obesity/diabetes actions of oral semaglutide.

d-Allulose Inhibits Ghrelin-Responsive, Glucose-Sensitive and Neuropeptide Y Neurons in the Arcuate Nucleus and Central Injection Suppresses Appetite-Associated Food Intake in Mice.

d-allulose, a rare sugar, has sweetness with few calories. d-allulose regulates feeding and glycemia, and ameliorates hyperphagia, obesity and diabetes. All these functions involve the central nervous system. However, central mechanisms underlying these effects of d-allulose remain unknown. We recently reported that d-allulose activates the anorexigenic neurons in the hypothalamic arcuate nucleus (ARC), the neurons that respond to glucagon-like peptide-1 and that express proopiomelanocortin. However, its action on the orexigenic neurons remains unknown. This study investigated the effects of d-allulose on the ARC neurons implicated in hunger, by measuring cytosolic Ca2+ concentration ([Ca2+]i) in single neurons. d-allulose depressed the increases in [Ca2+]i induced by ghrelin and by low glucose in ARC neurons and inhibited spontaneous oscillatory [Ca2+]i increases in neuropeptide Y (NPY) neurons. d-allulose inhibited 10 of 35 (28%) ghrelin-responsive, 18 of 60 (30%) glucose-sensitive and 3 of 8 (37.5%) NPY neurons in ARC. Intracerebroventricular injection of d-allulose inhibited food intake at 20:00 and 22:00, the early dark phase when hunger is promoted. These results indicate that d-allulose suppresses hunger-associated feeding and inhibits hunger-promoting neurons in ARC. These central actions of d-allulose represent the potential of d-allulose to inhibit the hyperphagia with excessive appetite, thereby counteracting obesity and diabetes.

Onion component, isoalliin, stimulates feeding and activates the arcuate nucleus neuropeptide Y, ghrelin- and Ninjin'yoeito-responsive neurons.

Appetite loss or anorexia substantially decreases the quality of life in patients with cancer, depression and gastrointestinal disorders, and can lead to sarcopenia and frailty. Foods that restore appetite have been sought-for but are not currently available. Historically, onion intake was adopted to treat a variety of diseases with reduced appetite including cancer and gastrointestinal disturbances. While isoalliin is a core component of onion, the effects of isoalliin on feeding behavior and feeding centers remain unknown. Neuropeptide Y (NPY) and ghrelin are the most potent central and peripheral inducers of appetite. A Japanese kampo medicine Ninjin'yoeito activates ghrelin-responsive NPY neurons in the hypothalamic arcuate nucleus (ARC) and counteracts anorexia induced by an anti-cancer drug cisplatin. This study explored the effects of isoalliin on feeding behavior and activities of ARC neurons in mice. Isoalliin, injected intraperitoneally, dose-dependently increased food intake during dark phase (DP) and daily without altering light phase (LP) food intake. We measured cytosolic Ca2+ concentration ([Ca2+]i) in single ARC neurons including NPY neurons identified by GFP fluorescence. Isoalliin increased [Ca2+]i in 10 of 18 (55.6%) NPY neurons, a majority of which also responded to ghrelin with [Ca2+]i increases, indicating that the ARC ghrelin-responsive NPY neuron is the major target of isoalliin. Isoalliin also increased [Ca2+]i in the ARC neurons that responded to Ninjin'yoeito. These results indicate that isoalliin enhances feeding at the active period and activates ARC ghrelin-responsive NPY neurons and Ninjin'yoeito-responsive neurons. These abilities of isoalliin to stimulate DP feeding and activate ARC orexigenic neurons provide scientific evidence for the health beneficial effects of onion experienced historically and globally.