Mild diabetes: long-term effects on gastric motility evaluated in rats

Syringic Acid Ameliorates Cardiac, Hepatic, Renal and Neuronal Damage Induced by Chronic Hyperglycaemia in Wistar Rats: A Behavioural, Biochemical and Histological Analysis

This study investigated the effects of syringic acid (SA) on renal, cardiac, hepatic, and neuronal diabetic complications in streptozotocin-induced neonatal (nSTZ) diabetic rats. STZ (110 mg/kg i.p) was injected into Wistar rat neonates as a split dose (second and third postnatal day). Diabetes mellitus was diagnosed in adults by measuring fasting blood glucose levels, urine volume, and food and water intake. The treatment of SA (25 mg/kg, 50 mg/kg p.o) was given from the 8th to 18th postnatal week. To assess the development of diabetic complications and the effect of therapy, biochemical indicators in serum and behavioural parameters were recorded at specific intervals during the study period. SA (25 mg/kg, 50 mg/kg p.o) treatment reduced hyperglycaemia, polydipsia, polyphagia, polyuria, relative organ weight, cardiac hypertrophic indices, inflammatory markers, cell injury markers, glycated haemoglobin, histopathological score, and oxidative stress, and increased Na/K ATPase activity. These findings suggest that SA might significantly alleviate diabetic complications and/or renal, neuronal, cardiac, and hepatic damage in nSTZ diabetic rats.

GASTROINTESTINAL MOTILITY IN ELDERLY PATIENTS WITH WELL-CONTROLLED TYPE 2 DIABETES MELLITUS

BACKGROUND

Gastrointestinal (GI) motility disorders in type 2 diabetes mellitus (T2DM) are common. However, the endpoints in well-controlled T2DM in elderly patients are barely understood.

OBJECTIVE

To evaluate GI transit and gastric myoelectric activity in elderly patients with T2DM who were undergoing treatment with metformin and to compare them with non-diabetic healthy controls.

METHODS

A total of thirty participants were enrolled in this study: young non-diabetic (n=10), elderly non-diabetic controls (n=10), and patients with T2DM managed with metformin (n=10). After fasting overnight, the participants ingested a standard meal and magnetic markers for non-invasive monitoring of GI transit and gastric contractility using the alternating current biosusceptometry and electrogastrography techniques.

RESULTS

Mean gastric emptying time, mean colon arrival time, and mean intestinal transit time were determined. There were no significant differences between the groups and in the parameters evaluated (P>0.05). The frequency and amplitude of gastric myoelectric activity were not different between groups; however, abnormal rhythmic index and the half-bandwidth were slightly higher for both elderly diabetic and non-diabetic groups compared with the young adults (P<0.01 and P<0.05, respectively).

CONCLUSION

Our study showed unaltered gastric emptying and intestinal transit in T2DM patients with good glycemic control, and suggest changes in the gastric electrical activity can be a part of aging.

Disturbed gastric motility in patients with long-standing diabetes mellitus

Purpose: Gastric dysmotility has been reported in patients with long-standing diabetes mellitus (DM). Some patients with DM are diagnosed as diabetes gastroparesis and have several upper gastrointestinal (GI) symptoms such as appetite loss and abdominal pain. This study aimed to identify the relationship between gastric motility and upper GI symptoms in patients with long-standing DM. Method: This study was conducted among 23 patients with DM and 15 healthy controls. All the patients with DM were receiving insulin treatment and had at least one history of incidence of diabetic nephropathy, retinopathy or neuropathy. Gastric motility was evaluated using electrogastrography (EGG) and gastric emptying using the ¹³C-acetic acid breath test. The most severe upper gastrointestinal symptoms were assessed in all patients. Results: Compared to healthy controls, patients with long-standing DM showed a significantly lower percentage of normogastria at the postprandial state with a lower power ratio in EGG. Gastric emptying was significantly delayed in patients with DM in the overall analysis. Sixteen patients with DM (69.6%) demonstrated abnormalities in either gastric myoelectrical activity or gastric emptying. Among patients with abnormal EGG or delayed gastric emptying, 12 had some GI symptoms, compared with 3 patients with normal gastric motility. No significant correlation was observed between the gastric emptying parameters and HbA1c values. Conclusion: Patients with long-standing DM showed gastric dysmotility, including impaired gastric myoelectrical activity and delayed gastric emptying. Gastric dysmotility appears to be closely correlated with upper GI symptoms in patients with long-standing DM.

Congenital Anomalies Programmed by Maternal Diabetes and Obesity on Offspring of Rats

Embryo-fetal exposure to maternal disorders during intrauterine life programs long-term consequences for the health and illness of offspring. In this study, we evaluated whether mild diabetic rats that were given high-fat/high-sugar (HF/HS) diet presented maternal and fetal changes at term pregnancy. Female rats received citrate buffer (non-diabetic-ND) or streptozotocin (diabetic-D) after birth. According to the oral glucose tolerance test (OGTT), the experimental groups (n = 11 animals/group) were composed of non-diabetic and diabetic receiving standard diet (S) or HF/HS diet. High-fat/high-sugar diet (30% kcal of lard) in chow and water containing 5% sucrose and given 1 month before mating and during pregnancy. During and at the end of pregnancy, obesity and diabetes features were determined. After laparotomy, blood samples, periovarian fat, and uterine content were collected. The diabetic rats presented a higher glycemia and percentage of embryonic losses when compared with the NDS group. Rats DHF/HS presented increased obesogenic index, caloric intake, and periovarian fat weight and reduced gravid uterus weight in relation to the other groups. Besides, this association might lead to the inflammatory process, confirmed by leukocytosis. Obese rats (NDHF/HS and DHF/HS) showed higher triglyceride levels and their offspring with lower fetal weight and ossification sites, indicating intrauterine growth restriction. This finding may contribute to vascular alterations related to long-term hypertensive disorders in adult offspring. The fetuses from diabetic dams showed higher percentages of skeletal abnormalities, and DHF/HS dams still had a higher rate of anomalous fetuses. Thus, maternal diabetes and/or obesity induces maternal metabolic disorders that contribute to affect fetal development and growth.

Paternal obesity and its transgenerational effects on gastrointestinal function in male rat offspring

The interplay between obesity and gastrointestinal (GI) motility is contradictory, and the transgenerational influence on this parameter is unknown. We aimed to evaluate the GI function in a model of paternal obesity and two subsequent generations of their male offspring. Newborn male rats were treated with monosodium glutamate (MSG) and composed the F1 generation, while control rats (CONT) received saline. At 90 days, male F1 were mated with non-obese females to obtain male offspring (F2), which later mated with non-obese females for obtaining male offspring of F3 generation. Lee Index analysis was adopted to set up the obesity groups. Alternating current biosusceptometry (ACB) technique was employed to calculate GI transit parameters: mean gastric emptying time (MGET), mean cecum arrival time (MCAT), mean small intestinal transit time (MSITT), and gastric frequency and amplitude of contractions. Glucose, insulin, and leptin levels and duodenal morphometry were measured. F1 obese rats showed a decrease in the frequency and amplitude of gastric contractions, while obese rats from the F2 generation showed accelerated MGET and delayed MCAT and MSITT. Glucose and leptin levels were increased in F1 and F2 generations. Insulin levels decreased in F1, F2, and F3 generations. Duodenal morphometry was altered in all three generations. Obesity may have paternal transgenerational transmission, and it provoked disturbances in the gastrointestinal function of three generations.

Swimming Program on Mildly Diabetic Rats in Pregnancy

The present study aims to confirm if the moderate-intensity swimming has successful glycemic control and non-toxic oxidative stress levels and to verify the influence on pancreatic adaptations, embryo implantation, and placental efficiency. Female Wistar rats were randomly distributed to obtain mildly diabetic by streptozotocin induction at birth and the non-diabetic females given vehicle. At adulthood, pregnant rats were put at random into sedentary non-diabetic rats (ND); exercise non-diabetic rats (NDEx); sedentary diabetic rats (D); and exercise diabetic rats (DEx). The rats of the groups submitted to moderate intensity carried loads equivalent to 4% of body weight. On day 17 of gestational day, all rats were submitted to oral glucose tolerance test (OGTT). Next day (GD18), the rats were anesthetized and killed to count implantation sites and to collect placentas, blood, and muscle samples for biochemical biomarkers and pancreas for immunohistochemical analysis. The moderate exercise used was not sufficient to stimulate the aerobic pathway but presented positive results on glucose metabolism, lower embryo postimplantation loss, and pancreatic morphology compared with the sedentary diabetic group. However, the DEx group showed muscular damage, decreased antioxidant defense, and lipid peroxidation. Thus, the moderate-intensity exercise reduces glycemic levels during OGTT and causes no damage to non-diabetic rats related to other analyzed parameters in this study. The exercised diabetic rats present better glycemic metabolism in OGTT, islet pancreatic morphology, and embryofetal development. However, it is necessary an adjustment in this exercise intensity to improve the effectiveness of aerobic training for reduction of maternal muscular and lipid membrane damages.

Maternal-fetal outcomes of exercise applied in rats with mild hyperglycemia after embryonic implantation

BACKGROUND

Exercise is commonly recommended to control hyperglycemia, including during pregnancy. We conducted this study to understand the potential benefits and risks of exercise during pregnancy of women with diabetes. Specifically, we evaluated the effects of swimming on a diabetic rat during pregnancy and assayed maternal-fetal parameters.

METHODS

Diabetes was induced in the female newborn from Wistar rats by the streptozotocin administration on first postnatal day. At 110 days of life, after confirm mild symptoms of diabetes, the rats were mated and randomly distributed into four experimental groups (minimum of 13 animals/group): Control (C)-nondiabetic animals without swimming; Control and Exercise (CEx)-nondiabetic animals submitted to swimming; Mild Diabetic (MD)-diabetic animals without swimming; Mild Diabetic and Exercise (MDEx)-diabetic animals submitted to swimming. The swimming program was performed from day 7 to 21 of pregnancy. Maternal parameters were evaluated during the pregnancy period. On day 21 of pregnancy, the rats were sacrificed and maternal and fetal parameters analyzed.

RESULTS

There are no alterations in body weight, food consumption, water intake, and reproductive outcomes among the groups. The swimming program did not normalize maternal glycemia and other biochemical biomarkers. The diabetes and exercise combination increased organ weight. The fetuses born to these exercising diabetic rats had reduced fetal weight and increased skeletal anomalies (mainly incomplete ossification of sternebra).

CONCLUSION

The intense swimming exercise imposed on female rats during pregnancy impaired maternal metabolic repercussions, contributing to intrauterine growth restriction and fetal skeletal anomalies.

Severity of prepregnancy diabetes on the fetal malformations and viability associated with early embryos in rats†

Preexisting/pregestational diabetes enhances the risk of birth defects. Several factors have been involved during the implantation process, such as cytokines (granulocyte-macrophage-colony-stimulating factor [GM-CSF]). The objective was to evaluate the effects of two levels of diabetes on the redox status of preimplantation embryos during the implantation process to comprehend how both are involved in embryo and fetal viability against maternal diabetes. Female Sprague-Dawley rats received streptozotocin at birth (mild diabetes [MD]) or at adulthood (severe diabetes [SD]) to obtain two experimental diabetes intensities. After confirming the diabetic status, the nondiabetic and diabetic groups were mated around day 110 of life. At gestational day (GD) 21, fetuses were assessed for viability and malformations and ovaries for embryo loss before implantation. Other pregnant nondiabetic and diabetic rats were sacrificed at GD2-4 for maternal and preimplantation embryo oxidative stress markers, maternal serum insulin, uterine fluid GM-CSF, and preimplantation embryo morphological analysis. MD and SD caused abnormal redox levels, lower GM-CSF and insulin levels during the preimplantation period, and embryonic loss before implantation. SD caused lower fetal viability and higher fetal malformation percentages at GD21. The SD dam-derived preimplantation embryos presented lower glutathione levels and higher thiobarbituric acid reactive substances concentration at GD3 and an increased frequency of abnormal preimplantation embryos at GD4. In conclusion, preexisting diabetes leads to complications in the implantation process. Furthermore, maternal oxidative stress and other metabolic changes alter the redox state and morphological structure of preimplantation embryos, contributing to damaged growth and development in late pregnancy.

Expression of asprosin in rat hepatic, renal, heart, gastric, testicular and brain tissues and its changes in a streptozotocin-induced diabetes mellitus model

In this study, we aimed to investigate the presence of asprosin (ASP) in the liver, kidneys, heart, stomach, testicles and brain and to determine the serum and tissue asprosin levels in diabetic rats. A total of 14 male Wistar Albino rats were divided into two groups, each containing 7 rats: (I) control group and (II) experimental diabetes group. Control rats received no treatment and the rats in the experiment group received single-dose of streptozotocin (STZ) (50 mg/kg) dissolved in 0.1 M sodium citrate buffer (pH: 4.5) intraperitoneally. Serum levels of asprosin were measured using ELISA method. The presence of asprosin in hepatic, renal, cardiac, gastric, testicular and brain tissues was investigated using immunohistochemical staining. Asprosin was detected in hepatocytes in the liver, cortical distal tubule cells in the kidney, cardiomyocytes in heart, surface epithelial cells of stomach fundus, interstitial Leydig cells in testes and cortical neurons of the brain. Compared to control group, it was found that diabetic rats had decreased asprosin levels in liver, kidney and heart tissues, increased levels in gastric and testicular tissues and no significant changes in brain tissue. Serum asprosin levels of diabetic rats were found to be decreased compared to the control group. This is the first study in the literature that reports the presence of asprosin in liver, kidney, heart, stomach, testis and brain tissues in rats. The aim of the study is to determine the presence of ASP, a newly discovered adipokine, in various tissues and to examine tissue and serum level changes in STZ-induced diabetes.

Gastrointestinal motility and morphology in mice: Strain-dependent differences

BACKGROUND

BALB/c and C57BL/6 mice are widely used in biomedical research; however, the differences between strains are still underestimated. Our aims were to develop an experimental protocol to evaluate the duodenal contractility and gastrointestinal transit in mice using the Alternating Current Biosusceptometry (ACB) technique and to compare gastrointestinal motor function and morphology between BALB/c and C57BL/6 strains.

METHODS

Male mice were used in experiments (a) duodenal contractility: animals which had a magnetic marker surgically fixed in the duodenum to determine the frequency and amplitude of contractions and (b) gastrointestinal transit: animals which ingested a magnetically marked chow to calculate the Oro-Anal Transit Time (OATT) and the Fecal Pellet Elimination Rate (FPER). The animals were killed after the experiments for organ collection and morphometric analysis.

KEY RESULTS

BALB/c and C57BL/6 had two different duodenal frequencies (high and low) with similar amplitudes. After 10 hours of monitoring, BALB/c eliminated around 89% of the ingested marker and C57BL/6 eliminated 33%; OATT and FPER were slower for C57BL/6 compared with BALB/c. The OATT and amplitude of low frequency had a strong positive correlation in C57BL/6. For BALB/c, the gastric muscular layer was thicker compared to that measured for C57BL/6.

CONCLUSIONS AND INFERENCES

The experimental protocol to evaluate duodenal contractility and fecal magnetic pellets output using the ACB technique in mice was successfully established. BALB/c strains had higher duodenal frequencies and a shorter time to eliminate the ingested marker. Our results showed differences in both motor function and gastrointestinal morphology between BALB/c and C57BL/6 strains.