Central Sympathetic Modulation Reverses Microvascular Alterations in a Rat Model of High-Fat Diet-Induced Metabolic Syndrome.

OBJECTIVES: The objective of this study was to investigate the role of the SNS on hemodynamic, metabolic, and microvascular alterations in a rat model of HFD-induced MS with salt supplementation. METHODS: In total, 40 adult male Wistar rats were fed normal chow (n = 10) or a HFD (n = 30) for 20 weeks. Thereafter, the HFD group received the centrally acting sympatho-modulatory drugs clonidine (0.1 mg/kg) or rilmenidine (1 mg/kg) or vehicle (n = 10/group) orally by gavage. FCD was evaluated using intravital video microscopy, and the SCD was evaluated using histochemical analysis. RESULTS: The pharmacological modulation of the SNS induced concomitant reductions in SBP, HR and plasma catecholamine levels. These effects were accompanied by a reversal of functional and structural capillary rarefaction in the skeletal muscle in both treated groups and an increase in SCD in the left ventricle only in the rilmenidine group. Improvement of the lipid profile and of glucose intolerance was also obtained only with rilmenidine treatment. CONCLUSIONS: Modulation of sympathetic overactivity results in the reversal of microvascular rarefaction in the skeletal muscle and left ventricle and improves metabolic parameters in an experimental model of MS in rats.

Commercial Extruded Plant-Based Diet Lowers Circulating Levels of Trimethylamine N-Oxide (TMAO) Precursors in Healthy Dogs: A Pilot Study.

Elevations in circulating trimethylamine N-oxide (TMAO) and its precursors are observed in humans and dogs with heart failure and are associated with adverse outcomes in people. Dietary intervention that reduces or excludes animal ingredients results in rapid reduction of plasma TMAO and TMAO precursors in people, but the impact of diet in dogs has not been studied. The objective of the current study was to determine the effect of diet on plasma TMAO and 2 of its precursors (choline and betaine) in dogs fed a commercial extruded plant-based diet (PBD) or a commercial extruded traditional diet (TD) containing animal and plant ingredients. Sixteen healthy adult mixed breed dogs from a university colony were enrolled in a randomized, 2-treatment, 2-period crossover weight-maintenance study. Mean (SD) age and body weight of the dogs were 2.9 years (± 1.7) and 14.5 kg (± 4.0), respectively. Eight dogs were female (3 intact, 5 spayed) and 8 dogs were male (4 intact, 4 castrated). Plasma choline, betaine and TMAO were quantified by LC-SID-MRM/MS at baseline, and after 4 weeks on each diet. Choline and betaine were also quantified in the diets. Plasma choline levels were significantly lower (P = 0.002) in dogs consuming a PBD (Mean ± SD, 6.8 µM ± 1.2 µM) compared to a TD (Mean ± SD, 7.8 µM ± 1.6 µM). Plasma betaine levels were also significantly lower (P = 0.03) in dogs consuming a PBD (Mean ± SD, 109.1 µM ± 25.3 µM) compared to a TD (Mean ± SD, 132.4 µM ± 32.5 µM). No difference (P = 0.71) in plasma TMAO was detected in dogs consuming a PBD (Median, IQR, 2.4 µM, 2.1 µM) compared to a TD (Median, IQR, 2.3 µM, 1.1 µM). Betaine content was lower in the PBD than in the TD while choline content was similar in the diets. Our findings indicate consumption of a commercial extruded PBD for 4 weeks reduces circulating levels of the TMAO precursors choline and betaine, but not TMAO, in healthy adult dogs.

Short-term amino acid, clinicopathologic, and echocardiographic findings in healthy dogs fed a commercial plant-based diet.

Consumer demand for commercially prepared plant-based (PB) dog food is increasing, but studies evaluating the short- or long-term effects of PB diets on canine health are lacking. The objective of this study was to assess the short-term amino acid (AA), clinicopathologic, and echocardiographic findings in 34 client-owned dogs fed a commercial extruded plant-based diet (PBD) in which pea protein was the primary protein source and 4 control dogs fed a commercial extruded traditional diet (TD). Plasma AA and whole blood taurine concentrations were measured in dogs at baseline and after 4 weeks on the PBD or the TD. Hematologic, serum biochemical, and echocardiographic testing were performed at baseline and after 12 weeks on the PBD or the TD. Four dogs in the PBD group did not complete the study. All essential AAs, except methionine, were higher in dogs after 4 weeks on the PBD compared to baseline. Taurine (plasma and whole blood) was also higher after 4 weeks on the PBD compared to baseline. A meaningful difference was detected in whole blood taurine between the PBD group and the control group at 4 weeks (P = .026) with the PBD group being higher. Median hematologic and biochemical results for the PBD group were within normal limits at baseline and at 12 weeks. In the PBD group, left ventricular internal diastolic dimension (LVIDd, P = < .001) and normalized LVIDd (P = .031) were higher 12 weeks post-PBD compared to baseline. There were no meaningful differences in left ventricular internal systolic dimension (LVIDs), normalized LVIDs, or fractional shortening 12 weeks post-PBD. There was no statistical evidence of difference between the 2 groups of dogs for any of the echocardiographic parameters at baseline or at 12 weeks. Essential AA or taurine deficiency was not observed in this cohort of dogs fed a commercial extruded PBD. Additionally, clinically relevant hematologic, serum biochemical and echocardiographic alterations were not detected. Further research is required to determine if long-term static feeding of PB diets can meet and maintain AA and other nutrient targets in dogs.

Aliskiren improves renal morphophysiology and inflammation in Wistar rats with 2K1C renovascular hypertension.

Hypertension is characterized by persistent elevated blood pressure levels, one of the leading causes of death in the world. Renovascular hypertension represents the most common cause of secondary hypertension, and its progress is associated with overactivation of the renin angiotensin aldosterone system (RAAS), causing systemic and local changes. Aliskiren is a renin-inhibiting drug that optimizes RAAS suppression. In this sense, the objective of the present study was to analyze the morphophysiology of the left kidney in Wistar rats with renovascular hypertension after treatment with Aliskiren. Parameters such as systolic blood pressure, urinary creatinine and protein excretion, renal cortex structure and ultrastructure, fibrosis and tissue inflammation were analyzed. Our results showed that the hypertensive animals treated with Aliskiren presented a reestablishment of blood pressure, expression of renin, and renal function, as well as a remodeling of morphological alterations through the reduction of fibrosis. The treatment regulated the laminin expression and decreased pro-inflammatory cytokines, restoring the integrity of the glomerular filtration barrier. Therefore, our findings suggest that Aliskiren has a renoprotective effect acting on the improvement of the morphology, physiology and pathology of the renal cortex of animals with renovascular hypertension.

Capybara Oil Improves Hepatic Mitochondrial Dysfunction, Steatosis, and Inflammation in a Murine Model of Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is recognized as the most common cause of liver dysfunction worldwide and is commonly associated with obesity. Evidences suggest that NAFLD might be a mitochondrial disease, which contributes to the hepatic steatosis, oxidative stress, cytokine release, and cell death. Capybara oil (CO) is a rich source of polyunsaturated fatty acids (PUFA), which is known to improve inflammation and oxidative stress. In order to determine the effects of CO on NAFLD, C57Bl/6 mice were divided into 3 groups and fed a high-fat diet (HFD) (NAFLD group and NAFLD + CO group) or a control diet (CG group) during 16 weeks. The CO (1.5 g/kg/daily) was administered by gavage during the last 4 weeks of the diet protocol. We evaluated plasma liver enzymes, hepatic steatosis, and cytokine expression in liver as well as hepatocyte ultrastructural morphology and mitochondrial function. CO treatment suppressed hepatic steatosis, attenuated inflammatory response, and decreased plasma alanine aminotransferase (ALT) in mice with NAFLD. CO was also capable of restoring mitochondrial ultrastructure and function as well as balance superoxide dismutase and catalase levels. Our findings indicate that CO treatment has positive effects on NAFLD improving mitochondrial dysfunction, steatosis, acute inflammation, and oxidative stress.

Exercise Training Reverses Structural Microvascular Rarefaction and Improves Endothelium-Dependent Microvascular Reactivity in Rats with Diabetes.

BACKGROUND: We evaluated structural microvascular alterations in the skeletal muscle and left ventricle, as well as endothelium-dependent microvascular reactivity in the skeletal muscle, of diabetic rats subjected to long-term aerobic exercise training. METHODS: Diabetes was experimentally induced by a combination of a high-fat diet with a single low dose of streptozotocin (35 mg/kg, i.p.). Animals with diabetes were divided into sedentary (DM+SED) and training groups (DM+TR) and compared with rats without diabetes (CON). We then measured maximal exercise capacity, fasting glucose and insulin, endothelium-dependent microvascular reactivity in skeletal muscle, and structural alterations of microvasculature in the skeletal and cardiac muscles. RESULTS: Diabetes induced microvascular rarefaction and reduced endothelium-dependent microvascular reactivity. Physical exercise completely reversed microvascular rarefaction in the skeletal muscle (1.85 ± 0.05 vs. 1.17 ± 0.03 capillary/fiber ratio, P < 0.05) and in the left ventricle (0.48 ± 0.66 vs. 0.25 ± 0.01 Vv[cap]/Vv[fib] ratio, P < 0.05) compared with the DM+SED group and normalized the microcirculatory responses to acetylcholine in skeletal muscle (CON 38.76 ± 5.60 vs. DM+TR 30.47% ± 5.77%). As expected, exercise training increased the maximal velocity and exercise tolerance compared with the DM+SED (P < 0.05) and CON (P < 0.05) groups. Exercise training also reduced fasting glucose (P < 0.05) compared with DM+SED and normalized insulin levels compared with CON. CONCLUSIONS: Our results suggest that long-term physical exercise reverses skeletal and cardiac muscle microvascular rarefaction, as well as impaired endothelium-dependent microvascular reactivity, induced by diabetes in rats.

Mangiferin prevents guinea pig tracheal contraction via activation of the nitric oxide-cyclic GMP pathway.

Previous studies have described the antispasmodic effect of mangiferin, a natural glucoside xanthone (2-C-ß-Dgluco-pyranosyl-1,3,6,7-tetrahydroxyxanthone) that is present in mango trees and other plants, but its mechanism of action remains unknown. The aim of this study was to examine the potential contribution of the nitric oxide-cyclic GMP pathway to the antispasmodic effect of mangiferin on isolated tracheal rings preparations. The functional effect of mangiferin on allergic and non-allergic contraction of guinea pig tracheal rings was assessed in conventional organ baths. Cultured tracheal rings were exposed to mangiferin or vehicle, and nitric oxide synthase (NOS) 3 and cyclic GMP (cGMP) levels were quantified using western blotting and enzyme immunoassays, respectively. Mangiferin (0.1-10 µM) inhibited tracheal contractions induced by distinct stimuli, such as allergen, histamine, 5-hydroxytryptamine or carbachol, in a concentration-dependent manner. Mangiferin also caused marked relaxation of tracheal rings that were precontracted by carbachol, suggesting that it has both anti-contraction and relaxant properties that are prevented by removing the epithelium. The effect of mangiferin was inhibited by the nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) (100 µM), and the soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (10 µM), but not the adenylate cyclase inhibitor, 9-(tetrahydro-2-furyl)adenine (SQ22536) (100 µM). The antispasmodic effect of mangiferin was also sensitive to K⁺ channel blockers, such as tetraethylammonium (TEA), glibenclamide and apamin. Furthermore, mangiferin inhibited Ca²âº-induced contractions in K⁺ (60 mM)-depolarised tracheal rings preparations. In addition, mangiferin increased NOS3 protein levels and cGMP intracellular levels in cultured tracheal rings. Finally, mangiferin-induced increase in cGMP levels was abrogated by co-incubation with either ODQ or L-NAME. These data suggest that the antispasmodic effect of mangiferin is mediated by epithelium-nitric oxide- and cGMP-dependent mechanisms.

Avaliação da técnica de esfoliação com escova citológica para coleta de células conjuntivais em gatos sadios: comparação entre a face palpebral da membrana nictitante e a conjuntiva palpebral / Evaluation of the exfoliative cytology technique using cytobrush in healthy cats: Comparison between palpebral surface of nictitating membrane and palpebral conjunctiva

A citologia conjuntival é um importante meio de diagnóstico de afecções da superfície ocular. Buscam-se técnicas que forneçam quantidade e qualidade celular, com uso de instrumentos que provoquem mínimo trauma e que diminuam as chances de danos iatrogênicos ao olho. Existem diversas técnicas de coleta de células, entre elas encontram-se: impressão, esfoliação e punção por agulha fina. Dentre os métodos utilizados para esfoliação, o uso da escova citológica fornece resultados superiores em vários parâmetros, incluindo a qualidade das células. Estudou-se a citologia conjuntival por esfoliação com escova citológica, utilizada para coleta de material da cérvix uterina, tendo como objetivos determinar se tal instrumento se adequaria à coleta de material da face palpebral da membrana nictitante e da conjuntiva palpebral de felinos sadios. Foram avaliados os seguintes parâmetros: facilidade de execução da técnica, possibilidade de ocorrência de danos iatrogênicos e quantidade e qualidade de células coletadas. Cinquenta gatos machos (58%) e fêmeas (42%), com ou sem raça definida, participaram do estudo. Apenas gatos isentos de alterações oculares no exame físico foram incluídos. A escova citológica se mostrou um instrumento de fácil utilização, que fornece células em quantidade satisfatória e com morfologia preservada. Comparada a conjuntiva palpebral, a face palpebral da membrana nictitante se mostrou um local mais adequado à realização da coleta de amostras citológicas, pela maior facilidade de execução da técnica e menor possibilidade de danos iatrogênicos. No que diz respeito à quantidade e qualidade celular, não houve diferença significativa entre os dois locais de coleta. Foi possível observar células provenientes das diferentes camadas do epitélio conjuntival com predomínio de células intermediárias e ausência de células caliciformes.

Conjunctival cytology is an important diagnostic method for ocular superficial diseases. There are several techniques to collect cells, including impression, exfoliation and fine needle aspiration. These techniques have shown individual variations depending on method and instrument used on the collection process. Techniques with instruments that cause low damage and decrease iatrogenic damage risks to the eyes, providing cellular quantity and quality, are wanted. Exfoliative cytology techniques are frequently used in human and veterinary medicine. Among the methods used for exfoliation, cytobrush provides better results on many parameters, including cell quality. The use of conjunctival exfoliation cytology using cytobrush (brush usually used for cervix cytology) was investigated. The aim was to determine if this technique would provide an adequate number and quality of conjunctival third eyelid cells of cats; to compare these samples with those collected by the same way from conjunctival area and to determine a cytologic pattern of this region. This comparison would provide information about technique security, possible damage risks and collected cells characteristics. Cats were evaluated through physical and routine ophthalmic exam. Fifty domestic cats, males (58%) and females (42%), of any breed were accepted. In the study were included only animals free of ocular and systemic changes. Cytobrush showed an easy and usefulness instrument, that provides satisfactory amount of cells with preserved morphology. Compared to palpebral conjunctiva, palpebral surface of nictitating membrane showed a most adequate site to cytological sample collect, greater facility of technical perform and smaller possibility of iatrogenic damage. In respect to quality and quantity of cells there was no significant difference between collect sites. It was possible to observe epithelial cells of conjunctiva from different stratum with predominance of intermediate cells and absence of goblet cells.