Background Type 2 diabetes (T2D) is a major global health issue. Many Asian individuals with T2D are non-obese, suggesting that factors beyond body mass index (BMI) may be relevant. Design and methods This ecological cross-sectional study examined correlations between diabetes prevalence and lifestyle-related factors using age-standardized, prefecture-level data from the 2021 National Database of Health Insurance Claims and Specific Health Checkups of Japan Open Data. Variables included diabetes prevalence (glycated hemoglobin [HbA1c] ≥ 6.5%), obesity (BMI ≥ 25 kg/m 2 ), other obesity-related indicators, and self-reported dietary habits. Associations were assessed using Spearman’s rank correlation coefficients with Benjamini–Hochberg false discovery rate (FDR) correction. Results After FDR correction, prefecture-level diabetes prevalence was positively correlated with BMI ≥ 25 kg/m 2 , elevated waist circumference, and weight gain in both sexes, and with alanine aminotransferase in women. Among dietary variables, the proportion of individuals with impaired masticatory function was positively correlated with diabetes prevalence in both sexes, whereas daily snacking was inversely correlated only in women; breakfast skipping, late-night dinner, and fast eating were not significantly correlated in either sex. However, after adjustment for BMI ≥ 25 kg/m 2 , none of the dietary habit variables showed a significant association with diabetes prevalence in either sex. Conclusions Prefecture-level diabetes prevalence in Japan correlated with several obesity-related indicators and impaired masticatory function in both sexes, although impaired masticatory function was not robust to BMI adjustment. Sex-specific patterns included a positive correlation with alanine aminotransferase and an inverse correlation with daily snacking in women. These findings warrant future individual-level studies.

BACKGROUND:Type 2 diabetes (T2D) is characterized by insulin resistance and defective insulin secretion. Previously, we found that rats fed soft pellets (SPs) on a 3-h restricted schedule over 14 wk demonstrated glucose intolerance and insulin resistance with disruption of insulin signaling. OBJECTIVES:This study aims to determine 1) the time required for an SP diet to induce insulin resistance, and 2) whether the metabolic derangements in rats fed SPs can be reversed by changing to a standard control diet. METHODS:We performed glucose tolerance tests and calculated the homeostasis model assessment of insulin resistance (HOMA-IR) to evaluate the insulinemic response to glucose and assess insulin resistance in nonobese male rats fed control pellets (CPs) or SPs on a 3-h restricted schedule (10:00-13:00) for 4 and 9 wk. At 11 wk, we switched half of the insulin-resistant SP group to CPs [soft-to-control pellets (SCPs)] and after an additional 11 wk evaluated changes in glucose and lipid metabolism across the 3 groups. RESULTS:The glucose tolerance test results in the SP and CP rats did not differ at 4 or 9 wk. The insulin levels in the SP group were higher than in the CP group at both time points (P < 0.05). The HOMA-IR was significantly higher in the SP rats at 9 wk compared with the controls (P < 0.05). At 22 wk, the HOMA-IR, blood glucose levels at 30 min after initiating feeding, hepatic glucose metabolism, and lipid synthesis in rats fed SPs continuously were significantly greater than in those fed CPs (P < 0.05); however, these values in the SCP rats did not differ from those in the CP rats. CONCLUSIONS:A continuous diet of soft-textured, readily absorbable food may be an important and reversible underlying driver in T2D pathogenesis.

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 β-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.

The hypothalamic regulation of appetite governs whole-body energy balance. Satiety is regulated by endocrine factors including leptin, and impaired leptin signaling is associated with obesity. Despite the anorectic effect of leptin through the regulation of the hypothalamic feeding circuit, a distinct downstream mediator of leptin signaling in neuron remains unclear. Angiopoietin-like growth factor (AGF) is a peripheral activator of energy expenditure and antagonizes obesity. However, the regulation of AGF expression in brain and localization to mediate anorectic signaling is unknown. Here, we demonstrated that AGF is expressed in proopiomelanocortin (POMC)-expressing neurons located in the arcuate nucleus (ARC) of the hypothalamus. Unlike other brain regions, hypothalamic AGF expression is stimulated by leptin-induced signal transducers and activators of transcription 3 (STAT3) phosphorylation. In addition, leptin treatment to hypothalamic N1 cells significantly enhanced the promoter activity of AGF. This induction was abolished by the pretreatment of ruxolitinib, a leptin signaling inhibitor. These results indicate that hypothalamic AGF expression is induced by leptin and colocalized to POMC neurons.

"Common clinicopathological features in late-onset hereditary transthyretin amyloidosis (Ala97Gly, Val94Gly and Val30Met)." Amyloid, 26(sup1), pp. 24–25

Recently, we showed that double-transgenic rats overexpressing guanylin (Gn), a bioactive peptide, and its receptor, guanylyl cyclase-C (GC-C), specifically in macrophages demonstrate an anti-obesity phenotype and low expression levels of proinflammatory cytokines in the mesenteric fat even when fed a high-fat diet.Here, we examined the levels and mechanism of Gn and GC-C transcription following saturated fatty acid and lipopolysaccharide (LPS), an activator of toll-like receptor 4 (TLR4), exposure by using the NR8383 macrophage cell line. In addition, the levels of guanylin and cGMP were increased by addition of either palmitic acid or LPS.Next, we investigated the interaction of the gene transcription and nuclear factor κB (NF-κB) by using an NF-κB inhibitor and chromatin immunoprecipitation assay. We showed that palmitic acid induced Gn gene expression via TLR4 and NF-κB. Moreover, we demonstrated that NF-κB binding to the Gn promoter was responsible for the induction of gene transcription by palmitic acid or LPS.Our results indicate that saturated fatty acids such as palmitic acidactivate Gn gene expression via the NF-κB pathway, raising the possibility that the activated Gn-GC-C system may contribute to the inhibition of high-fat diet-induced proinflammatory cytokines in macrophages.

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. AbstractDietary 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 β‐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.

Guanylyl cyclase C (GC-C) is a member of a family of enzymes that metabolize GTP to cGMP and was first identified as a receptor for heat-stable enterotoxin. Guanylin (GNY) has since been identified as an endogenous ligand for GC-C in the intestine of several mammalian species. The GNY/GC-C system regulates ion transportation and pH in the mucosa. Recently, it was reported that GC-C and GNY are involved in lipid metabolism in rat mesenteric adipose tissue macrophages. To examine the role of GC-C and GNY in lipid metabolism in cattle, we used a bovine mesenteric adipocyte primary culture system and a coculture system for bovine adipocytes and GNY-/GC-C-expressing macrophages: Fat droplets were observed to accumulate in bovine mesenteric adipocytes cultured alone, whereas few fat droplets accumulated in adipocytes indirectly cocultured with macrophages. We also observed that GC-C was present in bovine mesenteric adipose tissue, and that fat droplet accumulation decreased after in vitro GNY administration. Expressions of mRNAs encoding lipogenic factors decreased significantly in adipocytes after either coculture or GNY administration. These results suggest that the GNY/GC-C system is part of the control system for lipid accumulation in bovine mesenteric adipose tissue.

Recently we found that guanylin (Gn) and its receptor, guanylyl cyclase C (GC-C), are uniquely expressed in the mesenteric macrophages of some diet-resistant rats and that double-transgenic (dTg) rats overexpressing Gn and GC-C in macrophages demonstrate reduced fatty acid synthase and fat accumulation in fat tissue even when fed a high-fat diet (HFD). Lipid accumulation and fatty acid synthase mRNA levels in cocultured dTg rat adipocytes and macrophages were reduced compared with those in adipocytes cultured with WT rat macrophages. Here, we investigated whether Interleukin-15 (IL-15) derived from Gn-GC-C-expressing macrophages regulates lipid accumulation in adipocytes. IL-15 inhibited fatty acid synthase and lipid accumulation via STAT5 in cultured adipocytes. IL-15 mRNA and protein levels in the mesenteric fat of HFD-fed dTg rats were significantly higher than those of HFD-fed WT rats. Phosphorylated STAT5 levels in the mesenteric fat of HFD-fed dTg rats were increased compared with those of HFD-fed WT rats. In addition, the mRNA level of fatty acid synthase in the mesenteric fat was lower in HFD-fed dTg rats than in HFD-fed WT rats. These results support the hypothesis that IL-15 secreted from Gn-GC-C-expressing macrophages contributes to the inhibition of fatty acid synthase and lipid accumulation in adipocytes, leading to obesity resistance.

Recent evidence suggests that neural pathways from the hindbrain to the hypothalamus are important for informing the hypothalamus of the body's condition with regard to energy metabolism. Here we examined energy metabolism in rats with transections of the midbrain that severed the neural pathway from the hindbrain to the hypothalamus, and then investigated the levels of various molecules associated with control of energy metabolism in these rats. Food intake and body weight were higher in the midbrain-transected rats than in sham-operated rats. In addition, the midbrain-transected rats showed insulin resistance and hyperleptinemia. Furthermore, the hypothalamic mRNA levels of anorectic proopiomelanocortin and cocaine- and amphetamine-related transcript were significantly lower in midbrain-transected rats than in sham-operated rats. Our findings elucidate the mechanisms of food intake and energy balance from the perspective of multifactorial regulatory systems that underlie functions such as neurohormonal integration.

Guanylin (Gn), a bioactive peptide, and its receptor, guanylyl cyclase-C (GC-C), are primarily present in the intestine and maintain homeostasis in body fluids. Recently, rats whose macrophages overexpress Gn and GC-C were found to be resistant to diet-induced obesity. Considering that obesity is strongly related to a chronic inflammatory state in white adipose tissues, it is possible that Gn-GC-C macrophages contribute to the regulation of inflammation. In the present study, we investigated the inflammatory state of mesenteric fat in rats transgenic for both Gn and GC-C (double-transgenic [dTg] rats) by evaluating the levels of cyclic guanosine monophosphate (cGMP), a second messenger of Gn-GC-C, cGMP-dependent protein kinase (PKG), and phosphorylated vasodilator-stimulated phosphoprotein (VASP), a target protein of PKG. The levels of cGMP in dTg rats was higher than in WT rats fed the same diet. Although there were no significant differences in levels of PKG and phosphorylated VASP between WT and dTg rats fed a standard diet (STD), these levels in dTg rats fed a high fat diet (HFD) were markedly increased compared with levels in HFD WT rats. Furthermore, mRNA levels of proinflammatory factors in mesenteric fat were lower in HFD dTg rats than in HFD WT rats and were similar to levels in STD WT and dTg rats. These results indicate that the Gn-GC-C system in macrophages regulates the cGMP-PKG-VASP pathway and controls obesity through the downregulation of proinflammatory factors.

CCK and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important for elucidating the mechanisms by which energy balance is maintained. We found here that coadministration of subthreshold CCK and leptin, which individually have no effect on feeding, dramatically reduced food intake in rats. Phosphorylation of AMP-activated protein kinase (AMPK) in the hypothalamus significantly decreased after coinjection of CCK and leptin. In addition, coadministration of these hormones significantly increased mRNA levels of anorectic cocaine- and amphetamine-regulated transcript (CART) and thyrotropin-releasing hormone (TRH) in the hypothalamus. The interactive effect of CCK and leptin on food intake was abolished by intracerebroventricular preadministration of the AMPK activator AICAR or anti-CART/anti-TRH antibodies. These findings indicate that coinjection of CCK and leptin reduces food intake via reduced AMPK phosphorylation and increased CART/TRH in the hypothalamus. Furthermore, by using midbrain-transected rats, we investigated the role of the neural pathway from the hindbrain to the hypothalamus in the interaction of CCK and leptin to reduce food intake. Food intake reduction induced by coinjection of CCK and leptin was blocked in midbrain-transected rats. Therefore, the neural pathway from hindbrain to hypothalamus plays an important role in transmitting the anorectic signals provided by coinjection of CCK and leptin. Our findings give further insight into the mechanisms of feeding and energy balance.

Ghrelin, a gastrointestinal hormone originally discovered in human and rat stomach, functions as the only orexigenic signal produced by peripheral tissues. Although ghrelin is considered to affect hypothalamic neurons producing agouti-related protein (AgRP) and neuropeptide Y (NPY) and induce food intake, it is still unclear how peripherally administered ghrelin activates these neurons. The vagal afferent fibers are the major neuroanatomical linkage between the gastrointestinal tract and the nucleus tractus solitarii. Recently, several gastrointestinal hormones have been shown to transmit orexigenic or anorectic signals to the brain at least in part via the vagal afferent system. Indeed, blockade of the vagal afferent pathway abolishes ghrelin-induced feeding, indicating that the vagal afferent system is important to convey orexigenic ghrelin signals to the brain. In this chapter, we mention the role of the vagal afferent system for feeding regulation by gastrointestinal hormones and show the functional linkage in feeding between peripheral ghrelin and the vagal afferent system.

The purpose of the present study was to investigate the short-term effects of a 12-day, soft pellet (SP) diet with a 3-h restricted feeding schedule on caloric intake, body weight, lipid metabolism, and insulin sensitivity. Glucose and insulin levels were measured pre-, mid-, and post-feeding. The SP rats exhibited postprandial hyperglycemia compared to rats fed control pellets (CP). The insulin response of SP rats during a meal was significantly higher than that of CP rats. There were no significant differences in the hepatic triacylglycerol contents and lipogenesis gene mRNA levels of SP and CP rats. However, the hepatocytes of SP rats were slightly hypertrophic. In addition, histological analysis revealed that the pancreases of SP rats had more islet areas than those of CP rats. This study demonstrated that feeding an SP-only diet for 12 days induces glucose intolerance, suggesting that the consumption of absorbable food, like a soft diet, may trigger glucose metabolism insufficiency and lead to life-threatening diseases.

Food texture is known to affect energy metabolism. Although feeding with soft pellets (SP) or via a tube is known to cause increases in body weight, it is unclear how different food textures influence energy metabolism. In this study, we investigated the effects of two different food textures on energy balance and glucose and lipid metabolism in male Wistar rats. The rats were fed SP or control pellets (CP) on a 3-h restricted feeding schedule for 14 weeks and their energy intake, body weight, and energy expenditure were examined. The levels of gastrointestinal hormones, glucose and insulin, were investigated at pre-, mid, and post-feeding. Glucose tolerance and insulin tolerance tests were conducted, and the expressions of molecules involved in the insulin signaling system or lipogenesis in the liver were examined. Histological investigation of pancreatic islets was carried out using anti-insulin and anti-Ki-67 antibodies. Furthermore, the expression in the liver and circulating blood of microRNA-33 (miR-33), which regulates insulin receptor substance 2, was examined. There were no significant differences in energy intake, body weight, or gastrointestinal hormone levels between the SP and CP rats; however, the SP rats showed glucose intolerance and insulin resistance with disruption of insulin signaling. Increases in lipogenic factors and miR-33 expression were also found in the SP rats. The numbers of insulin-positive areas and Ki-67-positive cells of SP rats were significantly increased. This study shows that a soft food texture causes diabetes without obesity, so differences in food texture may be an important factor in type 2 diabetes.

Glucagon-like peptide-1 (GLP1) and leptin are anorectic hormones. Previously, we have shown that i.p. coadministration of subthreshold GLP1 with leptin dramatically reduced food intake in rats. In this study, by using midbrain-transected rats, we investigated the role of the neural pathway from the hindbrain to the hypothalamus in the interaction of GLP1 and leptin in reducing food intake. Food intake reduction induced by coinjection of GLP1 and leptin was blocked in midbrain-transected rats. These findings indicate that the ascending neural pathway from the hindbrain plays an important role in transmitting the anorectic signals provided by coinjection of GLP1 and leptin.

A high-fat diet (HFD) is a well-known contributing factor in the development of obesity. Most rats fed HFDs become obese. Those that avoid obesity when fed HFDs are considered diet resistant (DR). We performed a microarray screen to identify genes specific to the mesenteric fat of DR rats and revealed high expression of guanylin and guanylyl cyclase C (GC-C) in some subjects. Our histologic studies revealed that the cellular source of guanylin and GC-C is macrophages. Therefore, we developed double-transgenic (Tg) rats overexpressing guanylin and GC-C in macrophages and found that they were resistant to the effects of HFDs. In the mesenteric fat of HFD-fed Tg rats, Fas and perilipin mRNAs were downregulated, and those of genes involved in fatty acid oxidation were upregulated, compared with the levels in HFD-fed wild-type rats. In vitro studies demonstrated that lipid accumulation was markedly inhibited in adipocytes cocultured with macrophages expressing guanylin and GC-C and that this inhibition was reduced after treatment with guanylin- and GC-C-specific siRNAs. Our results suggest that the macrophagic guanylin-GC-C system contributes to the altered expression of genes involved in lipid metabolism, leading to resistance to obesity.