Effects of a hypoproteic diet on myosin-V immunostained myenteric neurons and the proximal colon wall of aging rats

Aqueous Extract of Agaricus blazei Murrill Prevents Age-Related Changes in the Myenteric Plexus of the Jejunum in Rats

This study evaluated the effects of the supplementation with aqueous extract of Agaricus blazei Murrill (ABM) on biometric and blood parameters and quantitative morphology of the myenteric plexus and jejunal wall in aging Wistar rats. The animals were euthanized at 7 (C7), 12 (C12 and CA12), and 23 months of age (C23 and CA23). The CA12 and CA23 groups received a daily dose of ABM extract (26 mg/animal) via gavage, beginning at 7 months of age. A reduction in food intake was observed with aging, with increases in the Lee index, retroperitoneal fat, intestinal length, and levels of total cholesterol and total proteins. Aging led to a reduction of the total wall thickness, mucosa tunic, villus height, crypt depth, and number of goblet cells. In the myenteric plexus, aging quantitatively decreased the population of HuC/D(+) neuronal and S100(+) glial cells, with maintenance of the nNOS(+) nitrergic subpopulation and increase in the cell body area of these populations. Supplementation with the ABM extract preserved the myenteric plexus in old animals, in which no differences were detected in the density and cell body profile of neurons and glial cells in the CA12 and CA23 groups, compared with C7 group. The supplementation with the aqueous extract of ABM efficiently maintained myenteric plexus homeostasis, which positively influenced the physiology and prevented the death of the neurons and glial cells.

High-fat diet promotes neuronal loss in the myenteric plexus of the large intestine in mice

BACKGROUND

Obesity is considered a risk factor for other chronic diseases, and diets rich in lipids can cause alterations in the intestinal functions.

AIM

The aim of this study was to investigate the effects of a high-fat diet (HFD) on the myenteric plexus of the large intestine in mice.

METHODS

Swiss mice were distributed into four groups: Control animals fed standard chow for 8 and 17 weeks (C8 and C17 groups) and hyperlipidic animals fed HFD for 8 and 17 weeks (Ob8 and Ob17 groups). Immunofluorescence was performed in the large intestine for the morphologic and quantitative analysis of neuronal populations.

RESULTS

Animals in the Ob17 group exhibited increased body weight and visceral fat gain compared with the C17 group. The intestinal area was also reduced in the two Ob groups. In the proximal colon, the Ob17 group exhibited 16.1 % reduction of the general neuronal density and 33 % reduction of the VIP-immunoreactive (IR) subpopulation. The general neuronal density in the distal colon was reduced by 45 % in the Ob17 group, and the nNOS-IR density was reduced by 35 %. The morphometry of neuronal cell bodies in the Ob17 group exhibited a reduction of the neuronal area of all of the neuronal populations studied in the proximal colon, with a reduction of the subpopulations of nNOS-IR and VIP-IR neurons in the distal colon.

CONCLUSIONS

The HFD caused neuronal loss in the myenteric plexus, and nitrergic neurons were more resilient. The changes were more pronounced in the distal colon after 17 weeks.

Food restriction beginning at lactation interferes with the cellular dynamics of the mucosa and colonic myenteric innervation in adult rats

The effects of food restriction (FR) on the morphoquantitative aspects of the wall and myenteric neurons of the proximal colon in adult rats were analysed. FR was imposed by duplication of the experimental brood size in relation to the control brood during lactation. The FR group received a 50% reduction of food from weaning until 90 days of age. Samples of the colon underwent histological processing to morphometrically analyze the crypts, muscularis mucosae, tunica mucosa, and muscularis externa. We determined the number of goblet cells and serotoninergic enteroendocrine cells, and morphoquantitatively studied the myenteric neuronal population. FR caused hypertrophy in the tunica mucosa, increase in crypt depth and in the muscular layer of the mucosa, a decrease in the thickness of the tunica muscularis and in the number of goblet cells and an increase in serotoninergic cells. A higher neuronal density in the ganglia and a reduction of the cell profile area were observed in the FR group. FR imposed since lactation led to hypertrophy of the tunica mucosa, a reduction of neutral mucin production, atrophy of the tunica muscularis, and an increase in the survival neuronal in adult rats, attributable to an increase in the number of serotoninergic enteroendocrine cells in mucosa.

Probiotics protect the intestinal wall of morphological changes caused by malnutrition

This study sought to morphometrically analyze the jejunal wall of protein-malnourished rats administered a probiotic supplement. The sample consisted of recently weaned Wistar rats (Rattus norvegicus) distributed among four groups: animals given a commercial diet (G1, n = 4); animals given the same ration as G1 plus a probiotic supplement (G2, n = 4); animals given a 4% protein diet (G3, n = 4); and animals given the same ration as G3 plus a probiotic supplement (G4, n = 4). After 12 weeks, part of the jejunum was harvested and subjected to routine histological processing. Transverse sections with a thickness of 3 µm were stained with HE, and histochemical techniques were used to assay for glycoconjugates, including staining with periodic acid-Schiff (PAS) + diastase, Alcian Blue (AB) solution at pH 2.5, and Alcian Blue solution at pH 1.0. Morphometric analysis of the bowel wall showed that the probiotic culture used in this study induced hypertrophy of several layers of the jejunal wall in well-nourished animals and reduced the bowel wall atrophy usually observed in protein-malnourished animals. Neither malnutrition nor the use of probiotics altered the relationship between the number of goblet cells and the number of enterocytes.

Effect of l-glutamine on myenteric neuron and of the mucous of the ileum of diabetic rats

The objective of this work was to investigate the effect of the L-glutamine supplementation to prevent - diabetes induced changes in myenteric neurons and also to verify the effect on the mucosa of the ileum of Wistar rats. The animals were divided in five groups (n = 5): untreated normoglycaemic (UN), normoglycaemic treated with L-glutamine (NG), untreated diabetics (UD), diabetics treated with L-glutamine, starting on the 4th (DG4) or 45th day following diabetes induction (DG45). The amino acid was added to the diet at 1%. The density and size of neurons, the metaphasic index in the crypt, the height of the villus, the depth of the crypt and the number of globet cells were determined. There was no difference in the neuronal density and in the cellular body area of the myosin-stained myenteric neurons of groups DG4 and DG45 when compared to group D. The metaphase index and the number of goblet cells showed no significant differences when all groups were compared (P > 0.05). The villi height of groups DG4 and DG45 were 45.5% (P < 0.05) and 32.4% (P > 0.05) higher than those in group UD, respectively. The analyzed crypts showed similar depth for all studied groups.

Supplementation with 0.1% and 2% vitamin E in diabetic rats: analysis of myenteric neurons immunostained for myosin-V and nNOS in the jejunum

CONTEXT

Diabetes mellitus is a disease characterized by hyperglycemia that, when allowed to progress long-term untreated, develops vascular and neurological complications, which are responsible for the development of alterations in the enteric nervous system in diabetic patients. In the gastrointestinal tract, diabetes mellitus promotes motor and sensory changes, and in the reflex function of this system, causing gastroparesis, diarrhea, constipation, megacolon, slow gastrointestinal transit, gastric stasis and dilation with decreased or increased peristaltic contractions. Several studies have shown that oxidative stress is the main responsible for the vascular and neurological complications affecting the enteric nervous system of diabetics.

OBJECTIVE

The effects of 0.1% and 2% vitamin E on myosin-V- and nNOS-immunoreactive neurons in the jejunum of diabetic rats were investigated.

METHODS

Thirty rats were divided into the groups: normoglycemic, normoglycemic treated with 0.1% vitamin E, normoglycemic treated with 2% vitamin E, diabetic, diabetic treated with 0.1% vitamin E, and diabetic treated with 2% vitamin E. The neuronal density and areas of neuron cell bodies were determined.

RESULTS

Diabetes (diabetic group) significantly reduced the number of myosin-V-immunoreactive neurons compared with the normoglycemic group. The diabetic treated with 0.1% vitamin E and diabetic treated with 2% vitamin E groups did not exhibit a greater density than the D group (P>0.05). Nitrergic density did not change with diabetes (P>0.05). The areas of myosin-V- and nNOS-immunoreactive neurons significantly increased in the normoglycemic treated with 2% vitamin E and diabetic groups compared with the normoglycemic group.

CONCLUSION

Supplementation with 2% vitamin E had a neurotrophic effect only in the area of myosin-V-immunoreactive neurons compared with the diabetic group.

Histological evaluation of the periodontal ligament from aged wistar rats supplemented with ascorbic acid

Ascorbic acid (AA) is able to neutralize reactive oxygen species and is essential for collagen synthesis. In aging process oxidative stress is elevated. This study aims to investigate the effects of AA supplementation on the periodontal ligament (PL) of rats during aging. Twenty five rats were used and divided into groups: J90 (90-day-old control), E345 (345-day-old control), E428 (428-day-old control), EA345 (345-day-old supplemented with AA from 90-day-old on) and EA428 (428-day-old supplemented with AA from 90-day-old on). We analyzed the thickness, density of fibroblasts and blood vessels and collagen fibers types in the PL. In group J90 there was predominantly type III collagen fibers (87.64%). In animals supplemented with AA, the area filled by type I fibers (group EA345: 65.67%, group EA428: 52.23%) was higher than type III fibers. PL in group EA428 was thicker than the one observed in group E428 (P < 0.05). During natural aging process, AA promoted the maturation of collagen fibers and enhanced angiogenesis in periodontal ligament. One can conclude that the supplementation with AA represented a beneficial factor for the development of PL in aged rats.

Administering ascorbic acid to rats undergoing ageing processes: effects on myosin-V immunoreactive myenteric neurons

During the ageing process the enteric nervous system undergoes morphofunctional changes, such as enteric neurodegeneration. Neuronal death can be attributed to increase radicals free, and ascorbic acid (AA), known antioxidant, could minimize damage cause by oxidative stress. The objective of this study is to analyse the behaviour of morphoquantative myenteric neurons in the duodenum of adult Wistar rats with aged 90 (C90), 345 (E345) and 428 (E428) days, as well as animals of the same age who received ascorbic acid supplementation for 120 days (EA345 and EA428). Whole-mount preparations of muscle layer from the duodenum of the animals were immunostained by the method myosin V. 80 microscopic fields were quantified (14.8 mm2/animal) and measured 100 neuronal cell bodies per animal. During the aging process, there was a reduction in neuronal density in all animals groups, indicating that the effects of age were not attenuated with AA supplementation. The increase in the neuronal area of the cell bodies in 428-day-old animals proved the influence of age on this parameter. There was no observed a neuroprotective effect of AA (1 mL/g body weight) on the neuronal population myenteric myosin V immunoreactive.

Dietary restriction interferes with oxidative status and intrinsic intestinal innervation in aging rats

OBJECTIVES

To evaluate the effects of dietary restriction on oxidative status, the HuC/D-neuronal nitric oxide synthase (nNOS) myenteric neuron population, HuC/D-S100 glial cells, and the morphometry of the small intestine in rats at various ages.

METHODS

Fifteen Wistar rats were divided into 7-and 12-mo-old control groups and a 12-mo-old experimental group subjected to dietary restrictions (50% of normal ration) for 5 mo. At 7 and 12 mo of age, the animals were anesthetized, and blood was collected to assess the biochemical components and oxidative status. Ileum samples were subjected to double-marker (HuC/D-nNOS and HuC/D-S100) immunostaining and histologic processing to morphometrically analyze intestinal wall elements and determine the metaphase index and rate of caliciform cells. The data were subjected to analysis of variance and the Tukey post hoc test with a 5% significance level.

RESULTS

Age affected the oxidative status by increasing lipid peroxidation, with no effect on blood components, intrinsic innervation, and intestinal wall elements. The animals subjected to dietary restriction showed improved levels of total cholesterol, triacylglycerols, and oxidative status, with no changes in the nNOS neuron population. However, the dietary restriction dramatically decreased the glial and HuC/D myenteric populations, led to atrophy of the neuronal cell body, induced glial hypertrophy, and decreased the thickness of the intestinal wall.

CONCLUSION

The high oxidative status of the aging animals was reversed by dietary restriction, which also lowered cholesterol and triacylglycerol levels. The present dietary restriction elicited morpho-quantitative changes in the myenteric plexus and histology of the ileum, with likely effects on intestinal functions.

Probiotics prevent growth deficit of colon wall strata of malnourished rats post-lactation

The objective of this study was to analyze morphometrically the colon wall strata of malnourished rats supplemented with probiotics. Sixteen recently weaned Wistar rats (Rattus norvegicus) were distributed into four groups: animals that received commercial chow (G1, n = 4); animals that received the same feed as G1 and were supplemented with probiotics (G2, n = 4); animals that received chow with 4% of proteins (G3, n = 4); animals that received the same feed as G3 and were supplemented with probiotics (G4, n = 4). After 12 weeks, the proximal colon was collected and submitted to histological processing. Three-µm cuts were stained with H.E., Periodic Acid Schifff (P.A.S.) + diasthasis solution and Alcian Blue (A.B.) pH 2.5 and pH 1.0. The morphometric analysis of the intestinal wall showed that the supplementation with ABT-4 probiotic culture prevents the growth deficit of colon wall strata that normally occurs in malnourished rats right after lactation. Besides, no alteration was observed in the proportion of the number of globet cells in relation to the number of enterocytes in malnourished rats, regardless of the supplementation with probiotics.

Analysis of myosin-V immunoreactive myenteric neurons from arthritic rats

CONTEXT

The inflammatory response itself and the consequent oxidative stress are able to promote neurodegeneration. So, it is possible that enteric nervous system is affected by inflammatory diseases threatening quality of life of patients. However, gastrointestinal symptoms of arthritis are usually attributed to anti-inflammatory drugs rather than neural damage.

OBJECTIVE

To confirm if the general population of myenteric neurons from the ileum and jejunum of rats is affected by arthritis.

METHODS

Twenty Holtzmann rats, 58-day-old male, were used and divided in four groups: control group (C30), arthritic group (Art30), older control group (C60) and older arthritic group (Art60). At 58 days old, the animals in groups Art30 and Art60 received an injection of the complete Freund's adjuvant in order to induce arthritis. The whole-mount preparations of ileum and jejunum were processed for myosin-V immunohistochemistry. Quantitative and morphometric analyses were performed.

RESULTS

Groups Art30 and Art60 presented, respectively, a reduction of 2% and 6% in intestinal area when compared to their control groups. No significant differences were observed in general neuronal density among the four groups (P>0.05). Group C60 presented a reduction of 14.4% and 10.9% in mean neuronal cell body area when compared to group C30 (P<0.05), for the ileum and jejunum, respectively. The other groups had a similar mean neuronal cell body area (P>0.05).

CONCLUSION

Arthritis does not promote quantitative or morphological damages in general myenteric population. However, studies in progress have revealed some significant alterations in myenteric neurons subpopulations (nitrergic and VIP-ergic neurons).

Quantification and morphometry of myenteric neurones in the jejunum of Holtzman rats (Rattus norvegicus)

With 2 figures and 3 tables

SUMMARY

The morphological pattern of the myenteric plexus (MP) is species-specific, and little is known about this pattern in Holtzman rats. The aim of the current experiment was the morphological and quantitative study of myenteric neurones in the Holtzman rat jejunum. Hematoxylin-Eosin and NADH-diaphorase (NADH-dp) staining were used to assess muscular layer thickness, neurone cell body area (CBA) and nuclei area (NA). Muscular layer thickness was found to be 114.77 ± 14.89 μm. Neuronal densities across the subregions of the jejunum were similar: mesenteric, 11.78 ± 2.89/mm(2) ; intermediate, 12.06 ± 2.69/mm(2) ; and antimesenteric, 10.67 ± 1.89/mm(2) . As expected, there was positive correlation between the CBA and NA of 79.19, 79.26 and 78.5% in the mesenteric, intermediate and antimesenteric subregions of the jejunum, respectively. Medium-sized neurones predominated in the ganglionic arrangement of the MP. These results indicate that the NADH-dp myenteric neurones in the jejunum of Holtzman rats are similar in many aspects to those found in the ileum of Holtzman rats and to those found in the small intestine of Wistar rats, including their location, ganglionic disposition and predominance of medium-sized CBA. However, neuronal density in the jejunum is lower than in the ileum. Based on these results showing morphological similarities to the MP of the Wistar rat, the Holtzman strain can be used to investigate the effects of adverse conditions on the morphology of the MP.

Atrophy and neuron loss: effects of a protein-deficient diet on sympathetic neurons

Protein deficiency is one of the biggest public health problems in the world, accounting for about 30-40% of hospital admissions in developing countries. Nutritional deficiencies lead to alterations in the peripheral nervous system and in the digestive system. Most studies have focused on the effects of protein-deficient diets on the enteric neurons, but not on sympathetic ganglia, which supply extrinsic sympathetic input to the digestive system. Hence, in this study, we investigated whether a protein-restricted diet would affect the quantitative structure of rat coeliac ganglion neurons. Five male Wistar rats (undernourished group) were given a pre- and postnatal hypoproteinic diet receiving 5% casein, whereas the nourished group (n = 5) was fed with 20% casein (normoproteinic diet). Blood tests were carried out on the animals, e.g., glucose, leptin, and triglyceride plasma concentrations. The main structural findings in this study were that a protein-deficient diet (5% casein) caused coeliac ganglion (78%) and coeliac ganglion neurons (24%) to atrophy and led to neuron loss (63%). Therefore, the fall in the total number of coeliac ganglion neurons in protein-restricted rats contrasts strongly with no neuron losses previously described for the enteric neurons of animals subjected to similar protein-restriction diets. Discrepancies between our figures and the data for enteric neurons (using very similar protein-restriction protocols) may be attributable to the counting method used. In light of this, further systematic investigations comparing 2-D and 3-D quantitative methods are warranted to provide even more advanced data on the effects that a protein-deficient diet may exert on sympathetic neurons. (c) 2009 Wiley-Liss, Inc.

Alterations of the number and the profile of myenteric neurons of Wistar rats promoted by age

The objective of this study was to analyze the morpho quantitative behaviour of duodenum myenteric neurons of Wistar rats (Rattus norvegicus), aged 21, 60, 90, 210, 345 and 428 days, using wholemount preparations of the muscular tunica obtained by dissecting the intestinal tunica for neuronal revealing, through the Giemsa non-histochemical and Myosin-V immunohistochemical techniques. The neurons were quantified in 80 microscopic fields (14.832 mm(2)) for each animal and neuronal cell body morphometry was carried out on 100 neurons/rat. Duodenal samples were submitted to histological routine processing, stained by hematoxylin-eosin method in order to perform morphometric analysis of the muscular tunica. An increase in the length of the small intestine was observed up to the age of 60 days, which was maintained up to 210 days, with a reduction in this parameter from 345 days. Muscular tunica thickness was maintained independently of the animal age. During the course of the study, there was a reduction in the mean neuron population in both techniques used. However, in all of the ages evaluated, the use of the Myosin-V technique lead to a reduced mean number of neurons compared to the Giemsa method. The cellular profile morphometry revealed, with both techniques, the predominance of smaller neurons in young animals, and bigger neurons in animals from higher age groups. It was concluded that advanced age is a determinant factor in the number reduction of myenteric neurons, with maintenance of the intrinsic intestinal innervation by the remaining neurons and that the use of the Giemsa non-histochemical technique showed itself more adequate to determine the total neuronal population.

Evaluation of the effect of Ginkgo biloba extract (EGb 761) on the myenteric plexus of the small intestine of Wistar rats

BACKGROUND

The aging process causes a reduction in the myenteric neuronal population, related to oxidative stress, resulting in malfunctioning of the digestive tract. The purpose of this study was to evaluate the action of Ginkgo biloba extract (EGb 761), an important antioxidant drug, on the myenteric plexus of the jejunum and ileum of rats after treatment for 120 days.

METHODS

Fragments of the jejunum and ileum were collected from three groups of rats: a 90-day-old group (group Y), a 210-day-old group (group A), and a 210-day-old group treated daily with the extract EGb 761 (50 mg/kg body weight) (group TA). The analysis was carried out by using the myosin-V immunohistochemical technique. Neuronal densities were estimated, and a study of the neuronal profile area of 500 neurons from each group was carried out.

RESULTS

In the jejunum, there was a significant neuronal population reduction of 17% only in group A compared with group Y. In the ileum, there was a significant neuronal reduction of 36% in group A compared with group Y, and a significant reduction in group TA of 20%. The difference in the reduction between groups A and TA in the ileum was also significant. In the jejunum, only group A showed a significant increase in neuronal profile area, but in the ileum, there was a significant increase in both groups A and TA.

CONCLUSIONS

A daily dose of 50 mg/kg body weight of Ginkgo biloba extract has a significant neuroprotector effect on the myenteric plexus of the ileum during the aging process in rats.