Ananda Malta

Background: Advanced glycation end-products (AGEs) are linked to the development of oxidative stress, insulin resistance, and impaired insulin secretion. Adverse early life conditions, such as exposure to AGEs and their precursors, may lead offspring to the development of metabolic dysfunction in adulthood. Nonetheless, the early impact in offspring metabolism by maternal intake of AGEs precursors during lactation is not known. Objective: Investigate early life metabolism of the offspring whose breastfeeding dams were orally exposed to AGEs precursor. Methods: Breastfeeding Wistar rats were daily treated with the glycation precursor methylglyoxal (MG—60 mg/kg of bodyweight) by gavage or saline 0.9% control (CO) until weaning. In vivo glycemic homeostasis in male offspring was assessed, followed by euthanasia for tissue sample collection for ex vivo assessments. Results: At weaning, MG offspring presented decreased bodyweight (p < 0.05), perigonadal (p < 0.01) and retroperitoneal (p < 0.01) fat. MG offspring presented decreased glucose tolerance (p < 0.05), lower basal insulinemia (p < 0.001), reduced high-glucose static insulin secretion (p < 0.05), and reduced pancreatic islet area (p < 0.05). Accordingly, MG offspring pancreas showed lower GSH and SOD activity (p < 0.05; p < 0.001, respectively) and increased MPO (p < 0.05) activity. Conclusions: The consumption of AGE precursors by breastfeeding dams impaired offspring pancreatic function and glycemic homeostasis early in life.

Vagus nerve (VN) and spleen dysfunctions are often associated with obesity (Ob). Aim: We evaluated the effects of VN and spleen ablation on adiposity, metabolism, and insulin secretion in hypothalamic obese male rats. Methods: Ob was induced by neonatal subcutaneous injection of monosodium glutamate (4 g/kg). At 60 days of life, Ob animals were randomly distributed into four groups ( n = 16 rats/group): sham operation (SHAM), vagotomy (VAG), splenectomy (SPL), and VAG + SPL. Body weight and food intake were monitored for 8 weeks postsurgery. Intraperitoneal glucose tolerance test (ipGTT) and intraperitoneal pyruvate tolerance test (ipPTT) were performed at 148 days of life, and VN activity was recorded at 150 days. After euthanasia (150 days), adiposity, plasma biochemical parameters, glucose‐induced insulin secretion (GIIS), and cholinergic and adrenergic islet responsiveness were evaluated. The pancreas was submitted for histopathological analysis, and the protein content of OXPHOS and IL‐10 was evaluated in isolated pancreatic islets. Results: Decreased VN activity was confirmed in the Ob‐VAG groups, associated with lower visceral adiposity, triglycerides, and plasma insulin, together with improved insulin sensibility and pyruvate tolerance, compared to Ob‐SHAM rats. Spleen absence reduced VN activity and cholinergic insulinotropic responses, with deleterious effects on the endocrine pancreas. Furthermore, Ob‐VAG + SPL rats presented greater reductions in GIIS and more severe endocrine pancreas histopathology, compared to the Ob‐SHAM group, without altered islet size or number or protein content of OXPHOS or IL‐10. Conclusion: Vagal and splenic interactions contribute to glucose homeostasis control in hypothalamic obese rats, modulating insulin secretion and pancreas histology.

High insulin levels during early life may lead to the late development of obesity and diabetes. We investigated whether attenuation of insulin levels by using an antimuscarinic agent could prevent diet-induced obesity and diabetes. Rats’ early exposure to an antimuscarinic agent reduced insulin levels during the lactation period and promoted protection against obesity and metabolic dysfunctions. Independent of the programming mechanisms, insulin levels during early life may be a defining factor of health or diseases later in life.

Both perinatal malnutrition and elevated glucocorticoids are pivotal triggers of the growing global pandemic of metabolic diseases. Here, we studied the effects of metabolic stress responsiveness on glucose–insulin homeostasis and pancreatic-islet function in male Wistar offspring whose mothers underwent protein restriction during lactation. During the first two weeks after delivery, lactating dams were fed a low-protein (4% protein, LP group) or normal-protein diet (22.5% protein, NP group). At 90 days of age, male rat offspring were challenged with food deprivation (72 h of fasting), intracerebroventricular (icv) injection of dexamethasone (2 µL, 2.115 mmol/L) or chronic intraperitoneal injection of dexamethasone (1 mg/kg body weight/5 days). Body weight, food intake, intravenous glucose tolerance test (ivGTT) results, insulin secretion and biochemical parameters were assessed. LP rats did not display significant metabolic changes after long-term starvation (p > 0.05) or under the central effect of dexamethasone (p = 0.999). Chronic dexamethasone induced rapid hyperglycemia (~1.2-fold, p < 0.001) and hyperinsulinemia (NP: 65%; LP: 216%; p < 0.001), decreased insulin sensitivity (NP: ~2-fold; LP: ~4-fold; p < 0.001), reduced insulinemia (20%) and increased glycemia (35%) only in NP rats under ivGTT conditions (p < 0.001). Glucose and acetylcholine insulinotropic effects, as well as the muscarinic receptor antagonist response, were reduced by chronic dexamethasone only in pancreatic islets from NP rats (p < 0.05). The direct effect of dexamethasone on pancreatic islets reduced insulin secretion (NP: 60.2%, p < 0.001; LP: 33.8%, p < 0.001). Peripheral glucose–insulin dyshomeostasis and functional failure of pancreatic islets in LP rats, as evidenced by an impaired acute and chronic response to metabolic stress, may be due to excessive corticosterone action as a long-term consequence.

Nutritional insults early in life, such as during the suckling phase, are associated with phenotypic alterations and promote adverse permanent effects that impair the capacity to maintain energy balance in adulthood. This study aimed to evaluate the long-term effects of a low-protein (LP) diet during lactation on the metabolism and antioxidant systems of adult female rat offspring. Dams were fed a low-protein diet (4% protein) during the first two weeks of lactation or a normal-protein (NP) diet (20% protein) during the entire lactation period. The female offspring received a standard diet throughout the experiment. At 90 days of age, female LP offspring exhibited decreased body weight, feeding efficiency, and fat pad stores. The adult LP female offspring displayed brown adipose tissue hyperplasia without alterations in glucose homeostasis. The LP diet decreased liver triglyceride content and improved the antioxidant system compared to the NP group. The LP diet during the suckling phase promotes a lean phenotype and improves the hepatocyte antioxidant system in adult female offspring. Thus, the LP diet may play an important role in homeostasis and the prevention of metabolic damage.

The purpose of this study was to examine the impact of fructose consumption during the peri-pubertal period on the later onset of metabolic syndrome in rats. Additionally, the study sought to explore the potential of moderate-intensity physical training as a non-pharmacological approach to mitigate the fructose effects. Male rats, 30 days old, received 10% fructose, and were submitted to concomitant moderate-intensity training until 60 days old. They were divided into 4 groups: sedentary control (SC), sedentary fructose (SF), trained control (TC), and trained fructose (TF). Fructose consumption mainly affected adult animals, resulting in glucose intolerance, increased periepididymal fat, and increased total cholesterol, triglycerides, and insulin levels. Furthermore, these rats exhibited reduced sympathetic nerve activity. The moderate running led to a decrease in periepididymal and retroperitoneal adipose tissue, as well as a reduction in total cholesterol and improved glucose tolerance. Peri-pubertal rats that received combination treatments exhibited lower levels of glucose and insulin during an intraperitoneal glucose tolerance test. The results indicate that 10% fructose supplementation during peripuberty predisposes to metabolic syndrome in adulthood. However, simultaneous moderate-intensity exercise training attenuates these effects and induces positive changes in glycemic homeostasis, lipid metabolism, and autonomic nervous system activity.

Regular consumption of dietary sugars can cause significant damage to the β-cells. Almost a century after the discovery of insulin, it has been suggested that the frequent consumption of certain carbohydrates can damage pancreatic β-cells, causing disturbances in the regulation of insulin secretion. Most noncommunicable diseases, such as diabetes, obesity, and hypertension have a common origin, metabolic dysfunction, which is partly due to β-cell malfunction. In this article, we believed that sugars can lead to an imbalance in cellular metabolism, causing insulin exocytosis to dangerously increase or decrease blood insulin concentrations. In this study, we describe the major mechanism of insulin secretion and discuss the effects of sugar on pancreatic β-cells. Although many environmental factors strongly influence β-cells, occidental diet, including excess sugar, has been found to be the predominant factor that kills or disrupts the functioning of the unique cells that produce, store, and secrete insulin.