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Abstract Our aim was to evaluate the effects of cisplatin and dexamethasone alone and combined on gastric contractility and histomorphometry of BALB/c and C57BL/6 mice. BALB/c and C57BL/6 male mice (8-week-old) were randomly separated into: Control; Cisplatin (7.5 mg/Kg); Dexamethasone (2.0 mg/Kg); and Dexamethasone plus Cisplatin (2.0 mg/Kg of dexamethasone 1-hour prior to 7.5 mg/Kg of cisplatin). Drugs were administered intraperitoneally for three days. Body weight and food intake were evaluated on 2nd day. Alternating Current Biosusceptometry technique was employed to measure gastric contractions on 3rd day. Afterward, mice were killed for gastric histomorphometric analysis. Cisplatin decreased food intake and caused bradygastria in BALB/c mice; however, the amplitude of gastric contractions decreased in both BALB/c and C57BL/6. Dexamethasone and cisplatin combined restored the gastric frequency and food intake only in BALB/c, but drug combination reduced the gastric amplitude of contractions in both strains. Dexamethasone alone increased gastric mucosa thickness in C57BL/6 and decreased muscular thickness in BALB/c. In conclusion, the mouse strains presented differences in acute effects of cisplatin and dexamethasone alone and combined on gastric function. This reinforces the importance of choosing the appropriate mouse strain for studying the acute effects of drugs on the gastrointestinal tract.

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The aim of this work was to study the impact of the methodology of in vitro gastric digestion (i.e., in terms of motility exerted and presence of gastric emptying) and gel structure on the degree of intestinal proteolysis and lipolysis of emulsion gels stabilized by whey protein isolate. Emulsions were prepared at pH 4.0 and 7.0 using two homogenization pressures (500 and 1000 bar) and then the emulsions were gelled by heat treatment. These gels were characterized in terms of texture analysis, and then were subjected to one of the following gastric digestion methods: in vitro mechanical gastric system (IMGS) or in vitro gastric digestion in a stirred beaker (SBg). After gastric digestion, the samples were subjected to in vitro intestinal digestion in a stirred beaker (SBi). Hardness, cohesiveness, and chewiness were significantly higher in gels at pH 7.0. The degree of proteolysis was higher in samples digested by IMGS-SBi (7-21%) than SBg-SBi (3-5%), regardless of the gel's pH. For SBg-SBi, the degree of proteolysis was not affected by pH, but when operating the IMGS, higher hydrolysis values were obtained for gels at pH 7.0 (15-21%) than pH 4.0 (7-13%). Additionally, the percentage of free fatty acids (%FFA) released was reduced by 47.9% in samples digested in the IMGS-SBi. For the methodology SBg-SBi, the %FFA was not affected by the pH, but in the IMGS, higher values were obtained for gels at pH 4.0 (28-30%) than pH 7.0 (15-19%). Our findings demonstrate the importance of choosing representative methods to simulate food digestion in the human gastrointestinal tract and their subsequent impact on nutrient bioaccessibility.

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Changes in physiological parameters that are induced by acute exercise on a treadmill in healthy military dogs have not been thoroughly investigated, especially with regard to age. This study investigated the effects of acute exercise on a treadmill on cardiovascular function, biochemical parameters and gastric antral motility in military dogs. Thermography was used to assess variations in superficial hindlimb muscle temperature. Nine healthy dogs were distributed into three groups according to their age (Group I: 25 ± 7 months; Group II: 51 ± 12 months; Group III: 95 ± 10 months) and sequentially subjected to running exercise on a treadmill for 12 min (3.2 km/h at 0° incline for 4 min, 6.4 km/h at 0° incline for 4 min and 6.4 km/h at 10° incline for 4 min). Heart rate, systolic and diastolic arterial pressure (DAP), gastric motility, haematocrit and biochemical analyses were performed at rest and after each session of treadmill exercise. Infrared thermographic images of muscles in the pelvic member were taken. Exercise decreased DAP in Group I, increased systolic arterial pressure in Groups II and III and increased mean arterial pressure in Group III (all p < 0.05). After the exercise protocol, plasma creatine kinase and aspartate aminotransferase levels increased only in Group I (p < 0.05). Exercise increased heart rate and decreased the gastric motility of a solid meal at 180 min in all groups (all p < 0.05). Exercise also elevated temperature in the femoral biceps muscles in Group I compared with the older dogs. The results indicate that acute exercise decreased gastric motility in dogs, regardless of age, and caused more pronounced cardiovascular changes in older dogs than in younger dogs. Acute exercise also altered biochemical parameters and superficial hindlimb muscle temperature in younger military dogs.

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We previously found that acute exercise inhibited the gastric emptying of liquid in awake rats by causing an acid-base imbalance. In the present study, we investigated the involvement of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, vasoactive intestinal peptide (VIP), and corticotropin-releasing factor (CRF) peptide in this phenomenon. Male rats were divided into exercise or sedentary group and were subjected to a 15-min swim session against a load (2.5 or 5% b.w.). The rate of gastric emptying was evaluated after 5, 10, or 20 min postprandially. Separate groups of rats were treated with vehicle (0.9% NaCl, 0.1 mL/100 g, ip) or one of the following agents: atropine (1.0 mg/kg, ip), the NO non-selective inhibitor Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10.0 mg/kg, ip), or the selective cGMP inhibitor 1H-(1,2,4)oxadiazole[4,3-a]quinoxalin-1-one (ODQ; 5.0 mg/kg, ip), the i-NOS non-specific inhibitor (aminoguanidine; 10.0 mg/kg, ip), the corticotropin-releasing factor receptor antagonist (astressin; 100 µg/kg, ip), or the vasoactive intestinal peptide (VIP) receptor antagonist Lys1, Pro2,5, Arg3,4, Tyr6 (100 µg/kg, ip). Compared to sedentary rats, both the 2.5 and 5% exercise groups exhibited higher (P<0.05) values of blood lactate and fractional gastric dye recovery. Corticosterone and NO levels increased (P<0.05) in the 5% exercised rats. Pretreatment with astressin, VIP antagonist, atropine, L-NAME, and ODQ prevented the increase in gastric retention caused by exercise in rats. Acute exercise increased gastric retention, a phenomenon that appears to be mediated by the NO-cGMP pathway, CRF, and VIP receptors.

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A new in vitro mechanical gastric system (IMGS) was fabricated which incorporates: a J-shaped stomach, a mechanical system with realistic peristaltic frequency and force magnitude, and a reproduction of the gastric pH curve. To evaluate the impact of a more realistic gastric peristalsis on the intestinal lipolysis of protein-stabilized O/W emulsions, the emulsions were subjected to two different in vitro digestion methodologies: (i) gastric digestion in the IMGS and intestinal digestion in a stirred beaker (SB), and (ii) gastric and intestinal digestion assays carried out in SBs. At the end of the intestinal digestion, the total amount of free fatty acids released was significantly higher for the first methodology (IMGS-SB) in comparison with the second one (27.5% vs. 23.0%), probably due to the higher physical instability induced by the IMGS in the gastric contents. These results reaffirm that O/W emulsion stability plays a crucial role in controlling the final extent of lipolysis of this kind of food-grade emulsions.

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BACKGROUND: This study proposes an experimental model to assess the consequences of gastric surgeries on gastric motility. We investigated the effects of proximal gastrectomy (PG) using a non-invasive technique (alternate current biosusceptometry [ACB]) on gastric contractility (GC), gastric emptying (GE), and orocecal transit (OCT) after the ingestion of liquids and solids in rats. METHODS: Twenty-four male rats were subjected to gastric motility assessment before and after the PG procedure. The GE and OCT results are expressed as the mean time of gastric emptying (MGET) and cecum arrival (MCAT). The GC recordings are presented as the frequency and amplitude of contractions. KEY RESULTS: Mean time of gastric emptying after solid meals were significantly different (p < 0.001) between control and PG (113 ± 5 to 99 ± 6 min). Mean time of cecum arrival ranged from 265 ± 9 to 223 ± 11 min (p < 0.001) and 164 ± 9 to 136 ± 17 min (p < 0.050) for solid and liquid meals, respectively. The assessment of GC showed that surgery decreased the phasic frequency (4.4 ± 0.4 to 3.0 ± 1.1 cpm, p < 0.050) and increased the amplitude of contractions (3.6 ± 2.7 to 7.2 ± 3.0 V/s, p < 0.050). No significant difference was found in tonic frequency. CONCLUSIONS & INFERENCES: The ACB system was able to assess GE, OCT, and GC in gastrectomized rats. Overall, PG accelerated GE and gastrointestinal transit, likely due to the increase in both intragastric pressure and amplitude contraction. Our data presented an efficient model to investigate functional consequences from gastric surgeries that will allow further studies involving different procedures.

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AIM: To evaluate gastric motility using electrical bio-impedance (EBI) and gastric changes as a result of stress induced by psychological tests. METHODS: A group of 57 healthy women, aged 40-60 years, was recruited, and a clinical history and physical examination were performed. The women were free from severe anxiety, chronic or acute stress, severe depression, mental diseases and conditions that affect gastric activity. The women were evaluated under fasting conditions, and using a four-electrode configuration, the gastric signals were obtained through a BIOPAC MP-150 system. The volunteers were evaluated using the following paradigm: basal state, recording during the Stroop Test, intermediate resting period, recording during the Raven Test, and a final resting period. We analyzed the relative areas of the frequency spectrum: A1 (1-2 cpm), A2 (2-4 cpm), A3 (4-8 cpm), and A4 (8-12 cpm), as well as the median of area A2 + A3. The data were analyzed by an autoregressive method using a Butterworth filter with MatLab and Origin. Analysis of variance (ANOVA) and Friedman ANOVA (for nonparametric variables) were performed; in addition, pairs of groups were compared using the T dependent and Wilcoxon T tests. RESULTS: The results of the main values of area A2 were not significantly different comparing the five steps of the experimental paradigm. Nevertheless, there was a tendency of this A2 region to decrease during the stress tests, with recuperation at the final resting step. When an extended gastric region was considered (1-4 cpm), significant differences with the psychological stress tests were present (F = 3.85, P = 0.005). The A3 region also showed significant changes when the stress psychological tests were administered (F = 7.25, P < 0.001). These differences were influenced by the changes in the adjacent gastric region of A2. The parameter that we proposed in previous studies for the evaluation of gastric motility by electrical bio-impedance (EBI) was the median of the area under the region from 2 to 8 cpm (A2 + A3). The mean values of these frequencies (median of the A2 + A3 area) with the stress test showed significant changes (F = 5.5, P < 0.001). The results of the Wilcoxon T test for the A4 area parameter, which is influenced by the breathing response, changed significantly during the Raven stress test (P < 0.05). CONCLUSION: We confirm that the gastric response to acute psychological stress can be evaluated by short-term EBI.

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