Induced acute hyperglycemia modifies the barrier function of the intestinal epithelium by tissue inflammation and tight junction disruption resulting in hydroelectrolytic secretion in an animal model

Abstract Diabetic-metabolic syndrome (MetS-D) has a high prevalence worldwide, in which an association with the rupture of the intestinal epithelium barrier function (IEBF) has been pointed out, but the functional and morphological properties are still not well understood. This study aimed to evaluate the impact of acute hyperglycemia diabetes on intestinal tight junction proteins, metabolic failure, intestinal ion and water transports, and IEBF parameters. Diabetes was induced in male Rattus norvegicus (200-310 g) with 0.5 mL of streptozotocin (70 mg/kg). Glycemic and clinical parameters were evaluated every 7 days, and intestinal parameters were evaluated on the 14th day. The MetS-D animals showed a clinical pattern of hyperglycemia, with increases in the area of villi and crypts, lactulose:mannitol ratio, myeloperoxidase (MPO) activity, and intestinal tissue concentrations of malondialdehyde (MDA), but showed a reduction in reduced glutathione (GSH) when these parameters were compared to the control. The MetS-D group had increased secretion of Na+, K+, Cl-, and water compared to the control group in ileal tissue. Furthermore, we observed a reduction in mRNA transcript of claudin-2, claudin-15, and NHE3 and increases of SGLT-1 and ZO-1 in the MetS-D group. These results showed that MetS-D triggered intestinal tissue inflammation, oxidative stress, complex alterations in gene regulatory protein transcriptions of intestinal transporters and tight junctions, damaging the IEBF and causing hydroelectrolyte secretion.

Moderate physical exercise and ATP modulate the P2X7 receptor and improve cisplatin-induced gastric emptying delay in rats

Patients undergoing chemotherapy with cisplatin commonly present gastrointestinal effects such as constipation and gastric emptying (GE) delay. Both the purinergic system and physical exercise modulate the gastrointestinal (GI) tract. In the current study, we investigated the role of ATP, physical exercise, and P2X7 receptor blocking on GE delay induced by cisplatin in rats. Male rats were divided into the following groups: control (C), cisplatin (Cis), exercise (Ex), Brilliant Blue G (BBG), ATP, Cis+Ex, Cis+ATP, Cis+BBG, Cis+Ex+BBG, Cis+Ex+BBG+ATP, and Cis+ATP+BBG. GE delay was induced by treatment with 1 mg/kg cisplatin (1 time/week for 5 weeks, ip). The moderate physical exercise was swimming (1 h/day, 5 days/week for 5 weeks). At the end of the treatment or exercise and 30 min before the GE assessment, some groups received BBG (50 mg/kg, sc) or ATP (2 mg/kg, sc). Then, GE was assessed after a 10-min postprandial period. Chronic use of Cis decreased GE delay (P<0.05) compared to the control group. Both exercise and ATP prevented (P<0.05) GE delay compared to Cis. The pretreatment with BBG significantly inhibited (P<0.05) the effect of exercise and ATP. On the other hand, the association between exercise and ATP reversed (P<0.05) the effect of the BBG and prevented GE delay. Therefore, we suggest that both exercise and treatment with ATP activate P2X7 receptors and prevent GE delay induced by cisplatin in rats.

Nandrolone decanoate impairs gastrointestinal motility and duodenal morphometry in moderately exercised rats

The misuse of anabolic androgenic steroid associated or not with physical workouts disrupts gastrointestinal (GI) function homeostasis. Our goal was to investigate the effects of nandrolone decanoate (ND) and moderate swimming on the GI transit of solid meals, GI motor contractility, and intestinal histology in rats. Male Wistar rats were allocated to four groups that received intramuscular injections of ND (5.0 mg/kg) or vehicle (60.0 µL) and were submitted or not to swimming sessions (60 min, 5% body weight overload) for 4 weeks. Gastric emptying, intestinal transit, in vitro GI contractility, intestinal morphometry, and duodenal mucosal mast cells were evaluated in all experimental groups. ND treatment accelerated gastric emptying, slowed small intestine transit time, enhanced gastric carbachol-mediated reactivity, decreased crypt depth and villus height, reduced mucosal thickness, and increased the circular and longitudinal muscle layer thickness of the duodenum in sedentary rats. Moderate exercise accelerated intestinal transit time and reduced submucosa thickness. In vehicle-treated animals, a strong negative correlation was found between intestinal transit and mucosal mast cells, which was reversed by ND treatment. Combining ND treatment and swimming accelerated gastric emptying, increased duodenal cholinergic reactivity, inhibited the sodium nitroprusside relaxing response, increased the number of duodenal mast cells, decreased villus height, and increased the thickness of all muscle layers. ND changed the morphological and functional properties of the GI tract over time, with intense dysmotility, especially in sedentary animals, but moderate exercise seemed to have played a compensatory role in these harmful effects in the gut.

P2X7 receptor antagonist improves gastrointestinal disorders in spontaneously hypertensive rats

The purinergic system participates in the control of blood pressure. Hypertension promotes the occurrence of gastrointestinal disorders such as intestinal inflammation and gastric emptying delay. This study aimed i) to investigate the participation of the P2X7 receptor blocker Brilliant Blue G (BBG) on gastric emptying of solids and changes in oxidative stress in the gastric fundus, duodenum, and colon of spontaneously hypertensive rats (SHR) and ii) to study the putative relationship of this effect with the renin-angiotensin system. Rats were divided into five groups: Control, SHR, SHR+BBG, SHR+BBG+ATP, and SHR+BBG+ANG II. In the gastrointestinal tract, we assessed gastric emptying (GE) and oxidative stress markers (NOx, MPO, GSH, SOD). We observed a decrease in the GE rate (P<0.05) in SHR vs control rats (21.8±2.0% vs 42.8±3.5%). The decrease in GE was returned (P<0.05) to control levels by BBG in SHR rats (21.8±2.0% vs 41.6±3.2%). Co-administration of ATP or ANG II together with BBG bypassed the effect of the P2X7 antagonist on GE in SHR (P<0.05) (21.9±5.0% vs 25.6±3.0% vs 41.6±3.2%). The MPO activity increased (P<0.05) in the gastric fundus of SHR compared to control rats (6.12±2.26 vs 0.077±0.02 UMPO/mg tissue); this effect was prevented (P<0.05) by BBG (0.55±0.15 vs 6.12±2.26 UMPO/mg tissue). Data demonstrated that blockage of P2X7 receptors with BBG can improve the GE delay and oxidative stress biomarkers in SHR animals. This preventive effect of BBG on GE delay was abrogated by ANG II and ATP, thus prompting crosstalk between renin-angiotensin and the purinergic signaling systems underlying this phenomenon.

Plant food resources exploited by Blue-and-Yellow Macaws (Ara ararauna, Linnaeus 1758) at an urban area in Central Brazil / Plantas alimentares exploradas pela Arara Canindé (Ara ararauna, Linnaeus 1758) em uma área urbana do Brasil Central

In this study, we described the food plants available to Blue-and-Yellow Macaws (Ara ararauna), its feeding habits and the relationship between these parameters with feeding niche breadth. We established four transects, each one 12 km long, to sample fruiting plants and the feeding habits of this macaw (monthly 40 h, of observations), at the urban areas of Três Lagoas (Mato Grosso do Sul, Brazil). During all studied months, macaws foraged for palm fruits, mainly Syagrus oleracea and Acrocomia aculeata fruit pulp, both available all year, as well as Caryocar brasiliense and Anacardium occidentale seeds, in the wet season. The year-round feeding activity of macaws suggests Três Lagoas city as an adequate feeding area. The permanent availability of plant food resources, potentially, resulted from the diverse fruiting patterns of exotic and, mainly, native plant species, which provided a variety of suitable fruit patches.

Neste estudo, nós descrevemos as plantas alimentares disponíveis para Arara-Canindé (Ara ararauna), sua atividade alimentar, bem como a relação desses parâmetros com a amplitude do seu nicho alimentar. Para tanto, estabelecemos quatro trajetos, cada um com 12 km, dispersos na área urbana de Três Lagoas (Mato Grosso do Sul, Brasil). A partir deles amostramos, mensalmente durante 40 h, as espécies vegetais que frutificavam e a atividade alimentar dessa ave. As araras exploraram frutos em todos os meses do ano e consumiram principalmente frutos comuns e nutritivos. Entre os itens mais explorados pelas araras estiveram as sementes de Anacardium occidentale e Caryocar brasiliense, cuja frutificação ocorreu durante a estação chuvosa, bem como a polpa dos frutos das palmeiras Syagrus oleracea e Acrocomia aculeata, que frutificaram o ano todo. A presença de araras forrageando todos os meses em Três Lagoas sugere a adequação dessa área urbana como local de alimentação. A disponibilidade de recursos alimentares ao longo do ano, potencialmente, decorreu da combinação da variedade dos padrões de frutificação em espécies vegetais exóticas e, sobretudo, nativas que proporcionaram oferta abundante e variada de recurso alimentar.

Morphocytochemical, immunohistochemical and ultrastructural characterization of the head kidney of fat snook Centropomus parallelus

This study characterized the structure and the morphocytochemical, immunohistochemical and ultrastructural aspects of the head kidney (HK) of the fat snook Centropomus parallelus. The HK is enclosed by a thin capsule of connective tissue, from which fine trabeculae originate and branch into the interior of organ. In the parenchyma, there are aggregates of lymphoid cells containing populations of lymphocytes T immunopositive for CDRO45, in a nodular arrangement, around blood vessels and melano-macrophage centres. Among the cells that constituted these aggregates and surrounded them, were macrophages and monocytes, and their precursors, with strong immunopositivity for CD68, along with cells of the granulocytic lineage in various phases of maturation positive for lysozyme and PAS. Macrophages and chromaffin and interrenal cells are also present. Ultrastructurally, the HK comprises a reticulum-endothelial stroma consisting of endothelial cells, reticulocytes of the fibroblast type and macrophage type and a parenchyma with increased cellularity, principally blood cells of the erythrocytic, granulocytic, lymphocytic, monocytic and thrombocytic series.

Morphological, cytochemical, and ultrastructural observations on the blood cells of the reptile Tupinambis merianae (Squamata)

Tupinambis merianae is a lizard of the Brazilian fauna and belongs to the Squamata order. Blood cell data are scarce. Blood samples from six specimens of adult T. merianae were used to evaluate some hematological parameters. For structural analysis, 2 ml of blood was collected in the presence of EDTA. Part of the blood was used for preparing blood smears which were submitted to the methods of Leishman, Laür, and toluidine blue, and the cytochemical reactions of periodic acid-Schiff, sirius red, sudan black B, and ortho-toluidine-H2 O2. The remainder was centrifuged and the leukocyte buffy coat was fixed in Karnovsky's fluid for electron microscopy examination. The following blood cells were identified: mature and immature erythrocytes, spherical and elliptical thrombocytes, heterophilic granulocytes, eosinophils and basophils types I and II, lymphocytes, monocytes, and azurophilic cells. The more significant results obtained were: the presence of glycogen in the cytoplasm of the thrombocytes, heterophils, and basophils; the presence of basic polyaminoacid-rich proteins in the granules of heterophils and eosinophils and myeloperoxidase in the granules of the heterophils, eosinophils, and azurophilic cells; and sudanophilic small granules in the heterophils, eosinophils, and azurophilic cells. More detailed morphological aspects of the cells were observed by means of ultrastructural analysis.