Avaliação de neurônios mioentéricos NADPH-diaforase positivos do íleo de ratos diabéticos suplementados com Acetil-L-Carnitina / Evaluation of positive NADPH-diaphorase myenteric neurons in diabetic rats supplemented with Acetyl-L-Carnitine

Objetivou-se avaliar a suplementação com acetil-L-carnitina (ALC) sobre os neurônios mioentéricos do íleo de ratos após a indução de diabetes. Foram usados animais diabéticos suplementados com ALC (DC), diabéticos (D), normoglicêmicos suplementados com ALC (CC) e normoglicêmicos (C). Neurônios NADPH-d foram quantificados e mensurados. Observou-se redução na glicemia e na ingestão de água no grupo DC. A densidade neuronal em 12,72mm² de íleo foi semelhante nos quatro grupos (p>0,05): DC (558,8 ± 220,2), D (513,4 ± 72,01), CC (645,2 ± 144,9) e C (934 ± 248,5). A área média do corpo celular dos neurônios (µm²) nos animais diabéticos, DC (303,9 ± 114,2) e D (285,4 ± 111,8), foram maiores que nos grupos normoglicêmicos, CC (173,6 ± 53,78) e C (158,4 ± 53,73). A área do íleo (mm²) também mostrou-se maior nos animais dos grupos diabéticos, DC (190,96) e D (171,62) quando comparados aos normoglicêmicos: CC (138,04) e C (130,06). Entretanto no grupo DC, ambas as áreas foram maiores que no D (P<0,05). Assim, pode se inferir discreto incremento na população neuronal. Os dados indicaram que a ALC não interferiu nos mecanismos que promovem aumento na produção de óxido nítrico (NO) pelos neurônios mioentéricos do íleo e que a maior dilatação do íleo no grupo DC poderia ser resultante de efeito colateral da dose de carnitina empregada.

The objective was to evaluate supplementation with acetyl-L-carnitine (ALC) on myenteric neurons of the ileum of rats after induction of diabetes. Diabetic animals supplemented with ALC (DC), diabetic (D), normoglycemic animals supplemented with ALC (CC) and normoglycemic (C) were used. NADPH-d neurons were quantified and measured. There was a reduction in blood glucose and water intake in the DC group. The neuronal density in 12.72mm² of ileum was similar in the four groups (p>0.05): DC (558.8 ± 220.2), D (513.4 ± 72.01), CC (645.2 ± 144.9) and C (934 ± 248.5). The mean cell body area of neurons (µm²) in diabetic animals, DC (303.9 ± 114.2) and D (285.4 ± 111.8), were greater than in the normoglycemic groups, CC (173.6 ± 53.78) and C (158.4 ± 53.73). The ileum area (mm²) was larger in animals of the diabetic groups, CD (190.96) and D (171.62) compared to the normoglycemic groups: CC (138.04) and C (130.04). However, in the DC group, both areas were larger than in D (p<0.05). Thus, a slight increase in neuronal population can be inferred. The data indicated that ALC did not interfere with mechanisms that promote an increase in the production of nitric oxide (NO) by myenteric neurons of the ileum and that the greater dilation of the ileum in the DC group could be the result of a side effect of the dose of carnitine used.

Diabetic neuropathy: an evaluation of the use of quercetin in the cecum of rats.

AIM: To investigate the effect of quercetin supplementation on the myenteric neurons and glia in the cecum of diabetic rats. METHODS: Total preparations of the muscular tunic were prepared from the ceca of twenty-four rats divided into the following groups: control (C), control supplemented with quercetin (200 mg/kg quercetin body weight) (CQ), diabetic (D) and diabetic supplemented with quercetin (DQ). Immunohistochemical double staining technique was performed with HuC/D (general population)/nitric oxide synthase (nNOS), HuC-D/S-100 and VIP. Density analysis of the general neuronal population HuC/D-IR, the nNOS-IR (nitrergic subpopulation) and the enteric glial cells (S-100) was performed, and the morphometry and the reduction in varicosity population (VIP-IR) in these populations were analyzed. RESULTS: Diabetes promoted a significant reduction (25%) in the neuronal density of the HuC/D-IR (general population) and the nNOS-IR (nitrergic subpopulation) compared with the C group. Diabetes also significantly increased the areas of neurons, glial cells and VIP-IR varicosities. Supplementation with quercetin in the DQ group prevented neuronal loss in the general population and increased its area (P < 0.001) and the area of nitrergic subpopulation (P < 0.001), when compared to C group. Quercetin induced a VIP-IR and glial cells areas (P < 0.001) in DQ group when compared to C, CQ and D groups. CONCLUSION: In diabetes, quercetin exhibited a neuroprotective effect by maintaining the density of the general neuronal population but did not affect the density of the nNOS subpopulation.

Neuroprotective effect of quercetin on the duodenum enteric nervous system of streptozotocin-induced diabetic rats.

BACKGROUND: In diabetes mellitus (DM), hyperglycemia promotes changes in biochemical mechanisms that induce oxidative stress. Oxidative stress has been closely linked to adverse consequences that affect the function of the gastrointestinal tract caused by injuries to the enteric nervous system (ENS) that in turn cause neurodegeneration and enteric glial loss. Therapeutic approaches have shown that diet supplementation with antioxidants, such as quercetin, reduce oxidative stress. AIMS: This work sought to evaluate neurons and enteric glial cells in the myenteric and submucosal plexuses of the duodenum in diabetic rats supplemented with quercetin. METHODS: The duodenum of 24 rats, including a control group (C), control quercetin supplementation group (CQ), diabetic group (D), and diabetic quercetin supplementation group (DQ), were used to investigate whole mounts of muscular and submucosal layers subjected to immunohistochemistry to detect vasoactive intestinal peptide in the myenteric layer and double-staining for HuC-D/neuronal nitric oxide synthase (nNOS) and HuC-D/S100. RESULTS: A reduction of the general neuronal population (HuC/D) was found in the myenteric and submucosal plexuses (p < 0.001) in the D and DQ groups. The nitrergic subpopulation (nNOS) decreased only in the myenteric plexus (p < 0.001), and glial cells decreased in both plexuses (p < 0.001) in the D and DQ groups. In diabetic rats, quercetin supplementation reduced neuronal and glial loss. Diabetes promoted an increase in the cell body area of both the general and nitrergic populations. Quercetin supplementation only prevented neuronal hypertrophy in the general population. CONCLUSION: Supplementation with quercetin eased the damage caused by diabetes, promoting a neuroprotective effect and reducing enteric glial loss in the duodenum.

Neuroprotection and neurodegeneration in submucosal VIP-IR neurons in the jejunum of ascorbic acid supplemented aging Wistar rats.

The present work studied the effects of ascorbic acid supplementation (1 mg/ml in water daily) on submucosal vasoactive intestinal polypeptide-immunoreactive (VIP-IR) neurons in the jejunum of aging rats. Twenty-five male rats were divided into the following groups: Y90 (young, 90-day-old rats), A345 (aged, 345-day-old rats), A428 (aged, 428-day-old rats), AA345 (ascorbic acid-supplemented rats, 90-345-day old), and AA428 (ascorbic acid-supplemented rats, 90-428-day old). Whole mounts of the submucosal layer were subjected to immunohistochemistry for determination of VIP-IR. Morphometric analyses were carried out in 100 submucosal VIP-IR neuron cell bodies from each group. At 345 days, neurons from supplemented animals were larger than those of non-supplemented animals of the same age. These results indicate that ascorbic acid neutralized free radicals and played a neuroprotective role. At 428 days, no significant differences between cell body areas were seen with or without ascorbic acid supplementation, indicating that, from a certain age onward, the role of ascorbic acid as a VIP-IR antioxidant was reduced. This supposition is supported by the fact that both supplemented and non-supplemented animals had higher blood concentrations of ascorbic acid on Day 428 compared with Day 345. The possible neuroprotective and neurodegenerative effects of ascorbic acid appear to depend on the age of the animals, dose, and its interaction with other antioxidants.

Aspectos gerais e abordagem terapêutica da quercetina sobre as complicações do diabetes causadas pelo estresse oxidativo / General aspects and therapeutic of quercetin on the complications of diabetes caused by oxidative stress

Os flavonóides pertencem à classe de compostos fenólicos, que diferem entre si pela sua estrutura química e características particulares. Frutas, vegetais, grãos, flores, chá e vinho são exemplos de fontes destes compostos. A quercetina é o principal flavonóide presente na dieta humana, sendo a representante mais característica da subclasse flavonol da família dos flavonóides. Desde a sua descoberta, os estudos publicados na literatura científica apontam para o seu papel crucial no combate ao estresse oxidativo, associado a diversas condições patológicas. No diabetes mellitus (DM), por exemplo, também tem sido relatada sua eficiência na inibição da enzima aldose redutase que participa da via dos polióis. Nesta contextualização e considerando as graves consequências advindas do DM para a saúde e qualidade de vida, propôs-se neste trabalho uma revisão geral da literatura pertinente, a fim de reunir dados sobre aspectos biológicos e funcionais da quercetina, bem como, sua atuação benéfica nas complicações do diabetes causadas pelo estresse oxidativo.

Flavonoids belong to the class of phenolic compounds that differ by their chemical structure and characteristics. Fruits, vegetables, grains, flowers, tea and wine are examples of sources of these compounds. Quercetin is the major flavonoid present in the human diet and it is the most typical representative of the flavonol subclass of the flavonoid family. Since its discovery, studies published in scientific literature point to its crucial role in combating oxidative stress associated with various pathological conditions. In diabetes mellitus (DM), for example, it has been also reported the effectiveness in inhibiting aldose reductase enzyme that participates of polyol pathway. In this context and considering the dire consequences of diabetes to health and quality of life, it was proposed in this paper a general review of relevant literature in order to gather data on biological and functional aspects of quercetin and its beneficial role in the complications diabetes caused by oxidative stress.

Immunohistochemical study of vasoactive intestinal peptide (VIP) enteric neurons in diabetic rats supplemented with L-glutamine.

The purpose of this work was to study the area of the varicosities of nerve fibers of myenteric neurons immunoreactive to vasoactive intestinal peptide (VIP-IR) and of the cell bodies of VIP-IR submucosal neurons of the jejunum of diabetic rats supplemented with 2% L-glutamine. Twenty male rats were divided into the following groups: normoglycemic (N), normoglycemic supplemented with L-glutamine (NG), diabetic (D) and diabetic supplemented with L-glutamine (DG). Whole-mounts of the muscle tunica and the submucosal layer were subjected to the immunohistochemical technique for neurotransmitter VIP identification. Morphometric analyses were carried out in 500 VIP-IR cell bodies of submucosal neurons and 2000 VIP-IR varicosities from each group. L-Glutamine supplementation to the normoglycemic animals caused an increase in the areas of the cell bodies (8.49%) and varicosities (21.3%) relative to the controls (P < 0.05). On the other hand, there was a decrease in the areas of the cell bodies (4.55%) and varicosities (28.9%) of group DG compared to those of group D (P < 0.05). It is concluded that L-glutamine supplementation was positive both to normoglycemic and diabetic animals.

Aspectos morfoquantitativos de neurônios mioentéricos NADPH-diaforase positivos do estômago de ratos diabéticos / Morphoquantitative aspects of the NADPH-diaphorase positive myenteric neurons from the stomach of diabetic rats

O presente estudo teve por objetivo analisar as características morfoquantitativas de neurônios mioentéricos NADPH-diaforase positivos do estômago de ratos diabéticos. O estômago de cinco ratos normoglicêmicos e de cinco ratos diabéticos foi submetido a preparados de membrana corados pela técnica histoquímica da NADPH-diaforase. Verificou-se, nos animais diabéticos, diminuição do peso corporal, aumento do consumo diário de água, da glicemia em jejum e da hemoglobina glicada. Com os dados obtidos, foi observado aumento significante na densidade e nas áreas dos perfis celulares neuronais da região pilórica do estômago dos ratos diabéticos...

Carnitina: aspectos gerais e enfoque na neuropatia diabética / Carnitine: general aspects and focus in the diabetic neuropathy

A carnitina pertence a um grupo de componentes da dieta conhecido como nutrientes não vitamínicos e pode ser produzida pelo corpo e consumida na alimentação. Desde a sua descoberta, os estudos publicados na literatura científica versam desde seu principal papel no organismo que é o transporte de ácidos graxos para o interior da mitocôndria, até a multiplicidade de seus efeitos benéficos no tratamento de várias doenças. No diabetes mellitus (DM), por exemplo, é relatada deficiência dos níveis orgânicos de carnitina. Nesta contextualização e considerando as graves conseqüências advindas do DM para a saúde e qualidade de vida, propôs-se neste trabalho uma revisão geral da literatura pertinente, a fim de reunir dados sobre os tipos de deficiência, aspectos biológicos e funcionais da carnitina, bem como sua relação com a neuropatia diabética

Evaluation of the nitrergic myenteric neurons in the distal colon of diabetic rats treated with acetyl-L-Carnitine

In this work, we evaluated the effect of acetyl-L-carnitine supplmentation on the presence of NADPH-diaphorase positive myenteric neurons in the distal colon of rats with diabetes mellitus induced by streptozotocin. Rats 105 days old were divided into four groups: normoglycemic, normoglycemic supplemented with acetyl-L-carnitine, diabetic and diabetic supplemented with acetyl-L-carnitine. Diabetes was induced by the administration of streptozotocin (35 mg/kg, i. v.). Supplementation with acetyl-L-carnitine was done for 105 days. The neuronal density was similar in all groups. In diabetic rats, the area of neuronal cell body profile was greater (p<0, 05) than in normoglycemic rats, whereas in diabetic rats receiving acetyl-L-carnitine the areas were smaller than in the non-supplemented diabetic rats (p<0, 05). The increase in the colonic area of diabetic rats was greater than in diabetic rats treated with acetyl-L-carnitine (p<0, 05), indicating that the increment in the population of these neurons was higher in treated diabetic rats. These results suggest that the beneficial effect of carnitine is restricted to preventing an excessive increase in neuronal area. The greater dilatation of the distal colon seen in diabetic rats supplemented with acetyl-L-carnitine probably represents and adverse effect of this compound.