Characteristics of Intestinal Myoelectrical and Motor Activities in Diet-Induced Obese Rats: Obesity and Motility

The posterior insular cortex is necessary for feeding-induced jejunal myoelectrical activity in male rats

The gastrointestinal tract exhibits coordinated muscle motility in response to food digestion, which is regulated by the central nervous system through autonomic control. The insular cortex is one of the brain regions that may regulate the muscle motility. In this study, we examined whether, and how, the insular cortex, especially the posterior part, regulates gastrointestinal motility by recording jejunal myoelectrical signals in response to feeding in freely moving male rats. Feeding was found to induce increases in jejunal myoelectrical signal amplitudes. This increase in the jejunal myoelectrical signals was abolished by vagotomy and pharmacological inhibition of the posterior insular cortex. Additionally, feeding induced a decrease and increase in sympathetic and parasympathetic nervous activities, respectively, both of which were eliminated by posterior insular cortical inhibition. These results suggest that the posterior insular cortex regulates jejunal motility in response to feeding by modulating autonomic tone.

The therapeutic effects of traditional Chinese medicine on insulin resistance in obese mice by modulating intestinal functions

Introduction

Obesity, mainly caused by excessive accumulation of visceral fat, excessive fat metabolism will cause hormone secretion imbalance and inflammation and other diseases. is extremely detrimental to human health. Although many treatments are available for obesity, most treatments fail to exert a radical effect or are associated with several side effects. Traditional Chinese medicine (TCM) for regulating the intestinal flora, lipid content and inflammation is considered effective. Based on previous studies, Artemisia capillaris, Astragalus propinquus, Phellodendron amurense, Salvia miltiorrhiza, Poria cocos, and Anemarrhena asphodeloides were selected to prepare an innovative herbal formula.

Methods

TCM was characterized by UHPLC-Q-Orbitrap-MS. The anti-inflammatory and lipid-lowering effects of the TCM formula prepared were evaluated in a high-fat diet-fed obese mouse model. The effects of the TCM formula on the intestinal flora were also investigated.

Results

Weights and insulin resistance, as well as inflammation, decreased in the mice after treatment. At the same time, lipid metabolism increased after the mice were gavaged with the TCM formula for 2 weeks. The intestinal motility of the drug administration group was enhanced, with partial restoration of the intestinal flora.

Conclusion

In summary, our innovative Chinese herbal formula significantly reduced weight, reduced intestinal inflammation, improved intestinal motility, and improved lipid metabolism in obese mice. Furthermore, the innovative formula effectively prevented relevant obesity-induced metastatic diseases in the mice.

Intestinal Electrical Stimulation Synchronized With Intestinal Slow Wave Ameliorates Glucagon-Induced Hyperglycemia in Rats

BACKGROUND

Synchronized intestinal electrical stimulation (SIES), in which intestinal electrical stimulation (IES) is delivered in synchronization with the intrinsic slow wave of small intestine, was previously reported to be more potent in accelerating small intestine transit than IES delivered at fixed frequency and phase. We hypothesized that SIES is more potent in suppressing postprandial blood glucose by enhancing the release of glucagon-like peptide-1 (GLP-1) and insulin.

MATERIALS AND METHODS

Rats underwent long-term implant of two pairs of electrodes at the duodenum for IES and SIES, respectively. Acute hyperglycemia was induced with glucagon, and the oral glucose tolerance test was performed on separate days with IES, SIES, or sham (no stimulation).

RESULTS

1. Glucagon reduced the percentage of normal slow wave in sham (70.9% ± 4.1%) from (84.9% ± 2.6%, p = 0.006) of control, which was ameliorated by SIES (82.5% ± 3.3%, p = 0.031). 2. IES and SIES reduced glucagon-induced increase of blood glucose (192 mg/dl) at 30 minutes by 17% and 20%, respectively. SIES showed a further inhibitory effect at 60 minutes (147 vs 171 mg/dl, p = 0.003, vs sham). 3. Compared with sham (139 pg/ml), GLP-1 at 30 minutes was increased in both IES (158 pg/ml) and SIES (169 pg/ml). GLP-1 level was still high at 60 minutes in rats with SIES. 4. At 30 minutes, the plasma insulin level was increased by 18.8 μIU/ml with SIES, which was significantly higher than that with sham (7.1 μIU/ml, p < 0.001) and IES (13.2 μIU/ml, p = 0.041).

CONCLUSION

SIES is more effective than IES in reducing glucagon-induced acute hyperglycemia by enhancing the release of GLP-1 and insulin.

Peripheral and central macrophages in obesity

Obesity is associated with chronic, low-grade inflammation. Excessive nutrient intake causes adipose tissue expansion, which may in turn cause cellular stress that triggers infiltration of pro-inflammatory immune cells from the circulation as well as activation of cells that are residing in the adipose tissue. In particular, the adipose tissue macrophages (ATMs) are important in the pathogenesis of obesity. A pro-inflammatory activation is also found in other organs which are important for energy metabolism, such as the liver, muscle and the pancreas, which may stimulate the development of obesity-related co-morbidities, including insulin resistance, type 2 diabetes (T2D), cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD). Interestingly, it is now clear that obesity-induced pro-inflammatory signaling also occurs in the central nervous system (CNS), and that pro-inflammatory activation of immune cells in the brain may be involved in appetite dysregulation and metabolic disturbances in obesity. More recently, it has become evident that microglia, the resident macrophages of the CNS that drive neuroinflammation, may also be activated in obesity and can be relevant for regulation of hypothalamic feeding circuits. In this review, we focus on the action of peripheral and central macrophages and their potential roles in metabolic disease, and how macrophages interact with other immune cells to promote inflammation during obesity.

Mechanisms of Small Intestine Involvement in Obesity-Induced Atherosclerosis

Purpose

Studies have shown that atherosclerotic plaques are associated with changes in the microbial composition of the intestinal flora and obesity, and that the small intestine plays an irreplaceable role in regulating intestinal flora homeostasis, but the role of the small intestine in the development of obesity-related atherosclerosis remains understudied. Therefore, this study explores the role of the small intestine in obesity-induced atherosclerosis and its molecular mechanisms.

Methods

In the GSE59054 data, small intestine tissue samples from 3 normal and 3 obese mice were analyzed using bioinformatics methods. Screening for differentially expressed genes (DEGs) using the GEO2R tool. The DEGs were next processed for bioinformatics analysis. We constructed an obese mouse model and measured aortic arch pulse wave velocity (PWV). Aortic and small intestine tissues were stained with hematoxylin-eosin (HE) to observe pathological changes. Finally, immunohistochemistry was performed to verify the expression of small intestinal proteins.

Results

We identified a total of 122 DEGs. Pathway analysis revealed that BMP4, CDH5, IL1A, NQO1, GSTM1, GSTA3, CAV1 and MGST2 were mainly enriched in the Fluid shear stress and atherosclerosis pathway. In addition, BMP4, NQO1 and GSTM1 are closely related to atherosclerosis. Ultrasound and pathological findings suggest the presence of obesity atherosclerosis. Immunohistochemistry verified high expression of BMP4 and low expression of NQO1 and GSTM1 in obese small intestine tissues.

Conclusion

The altered expression of BMP4, NQO1 and GSTM1 in small intestine tissues during obesity may be related to atherosclerosis, and Fluid shear stress and atherosclerosis pathway may be the molecular mechanism of their role.

Association of Gastric Myoelectric Activity with Dietary Intakes, Substrate Utilization, and Energy Expenditure in Adults with Obesity

Obesity can modulate gastric myoelectric activity (GMA); however, the relationship of GMA with nutrient intakes and substrate utilization in adults with obesity is lacking. We examined the association of dietary intakes, energy expenditure, and substrate utilization with the GMA. Participants (n = 115, 18−60 y) were divided into healthy weight (HW, n = 24), overweight (OW, n = 29), obese (OB, n = 41) and morbidly obese (MO, n = 21). Two-day multi-pass 24 h recalls were conducted. The GMA was measured by multichannel electrogastrography (EGG) with water-load (WL) testing. Resting metabolic rate (RMR) and percentages of substrate utilization were measured by indirect calorimetry. In the HW, protein intake was directly correlated with average dominant frequency (ADF) and with WL volume, while in obese participants and the MO subgroup, WL volume correlated with carbohydrate intake. In participants with obesity, ADF was positively correlated with fiber intake. In participants with obesity and the OB subgroup, RMR was positively correlated with water-load volume (r = 0.39 and 0.37, p < 0.05). The ADF showed negative correlations with percent of fat utilization and positive correlations with percent of CHO utilization in non-obese groups. However, protein utilization showed inverse correlation in all obese groups. In conclusion, these distinctive associations suggest that certain dietary compositions and dieting regimens impact GMA patterns.

High-fat diets on the enteric nervous system: Possible interactions and mechanisms underlying dysmotility

Obesity is a chronic disease that affects various physiological systems. Among them, the gastrointestinal tract appears to be a main target of this disease. High-fat diet (HFD) animal models can help recapitulate the classic signs of obesity and present a series of gastrointestinal alterations, mainly dysmotility. Because intestinal motility is governed by the enteric nervous system (ENS), enteric neurons, and glial cells have been studied in HFD models. Given the importance of the ENS in general gut physiology, this review aims to discuss the relationship between HFD-induced neuroplasticity and gut dysmotility observed in experimental models. Furthermore, we highlight components of the gut environment that might influence enteric neuroplasticity, including gut microbiota, enteric glio-epithelial unit, serotonin release, immune cells, and disturbances such as inflammation and oxidative stress.

Paternal obesity and its transgenerational effects on gastrointestinal function in male rat offspring

The interplay between obesity and gastrointestinal (GI) motility is contradictory, and the transgenerational influence on this parameter is unknown. We aimed to evaluate the GI function in a model of paternal obesity and two subsequent generations of their male offspring. Newborn male rats were treated with monosodium glutamate (MSG) and composed the F1 generation, while control rats (CONT) received saline. At 90 days, male F1 were mated with non-obese females to obtain male offspring (F2), which later mated with non-obese females for obtaining male offspring of F3 generation. Lee Index analysis was adopted to set up the obesity groups. Alternating current biosusceptometry (ACB) technique was employed to calculate GI transit parameters: mean gastric emptying time (MGET), mean cecum arrival time (MCAT), mean small intestinal transit time (MSITT), and gastric frequency and amplitude of contractions. Glucose, insulin, and leptin levels and duodenal morphometry were measured. F1 obese rats showed a decrease in the frequency and amplitude of gastric contractions, while obese rats from the F2 generation showed accelerated MGET and delayed MCAT and MSITT. Glucose and leptin levels were increased in F1 and F2 generations. Insulin levels decreased in F1, F2, and F3 generations. Duodenal morphometry was altered in all three generations. Obesity may have paternal transgenerational transmission, and it provoked disturbances in the gastrointestinal function of three generations.

Characteristics of myoelectrical activities along the small intestine and their responses to test meals of different glycemic index in rats

The purpose of this study was to characterize intestinal myoelectrical activity along the small intestine and investigate its responses to test meals with different glycemic index at different locations. Sixteen rats were implanted with electrodes in the serosal surface of the duodenum, jejunum, and ileum. Intestinal myoelectrical activities were recorded from these electrodes for 30 min in the fasting state and 3 h after four kinds of meals with different glycemic index, together with the assessment of blood glucose. The results were as follows: 1) in the fasting state, the percentage of normal intestinal slow waves (%NISW) showed no difference; however, the dominant frequency (DF), power (DP), and percentage of spike activity superimposed on the intestinal slow wave (NS/M) were progressively decreased along the entire small intestine; 2) regular solid meal and Ensure solicited no changes in any parameters of intestinal myoelectrical activity; whereas glucose and glucose + glucagon significantly altered the %NISW, DF, DP, and NS/M, and the effects on the proximal intestine were opposite to those in the distal intestine; and 3) postprandial blood glucose level was significantly correlated with %NISW along the entire small intestine. We found that that, in addition to the well-known frequency gradient, there is also a gradual decrease in the DP and spikes along the small intestine in the fasting state. Glucose and hyperglycemic meals inhibit myoelectrical activities in the proximal small intestine but result in enhanced but more dysrhythmic intestinal myoelectrical activities. There is a significant negative correlation between the normality of intestinal slow waves and blood glucose.

Dietary fatty acid content influences the expression of genes involved in the lipid turnover and inflammation in mouse colon and spleen

BACKGROUND

Dietary interventions can improve gastrointestinal (GI) symptoms. We determined the effects of fatty acids (FAs) supplementation with medium- and long-chain saturated FAs on mouse GI motility and correlated them with the expression of genes for free FA receptors (FFAR)1-4, FA binding protein 4 (FABP4) and inflammation.

METHODS

Forty-eight BalbC were assigned to: standard diet (STD), diet rich in medium-chain saturated FAs (COCO) and long-chain saturated FAs (HF) (7% by weight). Body weight (BW) and food intake (FI) were monitored for 8-weeks. GI motility was determined by fecal pellet output (FPO) and colon bead expulsion tests. FABP4 inhibitor, BMS309403 (1mg/kg, ip) was injected to half of each group 2 days/week. mRNA expression of FABP4, (FFAR)1-4, and pro-inflammatory cytokines were measured in colonic and splenic tissues using real-time PCR.

RESULTS

COCO and HF decreased FI. COCO accelerated overall GI transit (p<0.05). COCO increased the mRNA expression of FFAR2 (p<0.001) and TNFα (p<0.01); HF increased the expression of FABP4 and FFAR4 (p<0.05), and FFAR2 (p<0.001) in the colon, and decreased FFAR1 and FFAR4 (p<0.001), TNFα (p<0.01) and IL-1β (p<0.05) in splenic tissues. BMS309403 decreased the FI and delayed colonic transit in STD+BMS and COCO+BMS vs. STD (p<0.05). HF+BMS increased colonic expression of FFAR3 (p<0.01), TNFα (p<0.01), IL-6 (p<0.01), and reduced FFAR4 (p<0.05); COCO+BMS decreased TNFα (p<0.01).

CONCLUSION

Diversification in the dietary lipid content affected GI motility in mice and the expression of FFARs and pro-inflammatory cytokines in vivo.