RESUMEN
We asked whether acute redox signaling from mitochondria exists concomitantly to fatty acid- (FA-) stimulated insulin secretion (FASIS) at low glucose by pancreatic ß-cells. We show that FA ß-oxidation produces superoxide/H2O2, providing: i) mitochondria-to-plasma-membrane redox signaling, closing KATP-channels synergically with elevated ATP (substituting NADPH-oxidase-4-mediated H2O2-signaling upon glucose-stimulated insulin secretion); ii) activation of redox-sensitive phospholipase iPLA2γ/PNPLA8, cleaving mitochondrial FAs, enabling metabotropic GPR40 receptors to amplify insulin secretion (IS). At fasting glucose, palmitic acid stimulated IS in wt mice; palmitic, stearic, lauric, oleic, linoleic, and hexanoic acids also in perifused pancreatic islets (PIs), with suppressed 1st phases in iPLA2γ/PNPLA8-knockout mice/PIs. Extracellular/cytosolic H2O2-monitoring indicated knockout-independent redox signals, blocked by mitochondrial antioxidant SkQ1, etomoxir, CPT1 silencing, and catalase overexpression, all inhibiting FASIS, keeping ATP-sensitive K+-channels open, and diminishing cytosolic [Ca2+]-oscillations. FASIS in mice was a postprandially delayed physiological event. Redox signals of FA ß-oxidation are thus documented, reaching the plasma membrane, essentially co-stimulating IS.
Asunto(s)
Membrana Celular , Ácidos Grasos , Secreción de Insulina , Células Secretoras de Insulina , Mitocondrias , Oxidación-Reducción , Transducción de Señal , Animales , Ratones , Mitocondrias/metabolismo , Ácidos Grasos/metabolismo , Células Secretoras de Insulina/metabolismo , Membrana Celular/metabolismo , Ratones Noqueados , Insulina/metabolismo , Peróxido de Hidrógeno/metabolismo , Fosfolipasas A2 Grupo VI/metabolismo , Fosfolipasas A2 Grupo VI/genética , Glucosa/metabolismo , Receptores Acoplados a Proteínas GRESUMEN
Maternal diabetes may influence glucose metabolism in adult offspring, an area with limited research on underlying mechanisms. Our study explored the impact of maternal hyperglycemia during pregnancy on insulin resistance development. Adult female Sprague-Dawley rats from control and diabetic mothers were mated, and their female offspring were monitored for 150 days. The rats were euthanized for blood and muscle samples. Maternal diabetes led to heightened insulin levels, increased HOMA-IR, elevated triglycerides, and a raised TyG index in adult offspring. Muscle samples showed a decreased protein expression of AMPK, PI3K, MAPK, DRP1, and MFF. These changes induced intergenerational metabolic programming in female pups, resulting in insulin resistance, dyslipidemia, and glucose intolerance by day 150. Findings highlight the offspring's adaptation to maternal hyperglycemia, involving insulin resistance, metabolic alterations, the downregulation of insulin signaling sensors, and disturbed mitochondrial morphology. Maintaining maternal glycemic control emerges as crucial in mitigating diabetes-associated disorders in adult offspring.
Asunto(s)
Diabetes Mellitus Experimental , Diabetes Gestacional , Resistencia a la Insulina , Insulina , Músculo Esquelético , Fenotipo , Efectos Tardíos de la Exposición Prenatal , Ratas Sprague-Dawley , Transducción de Señal , Animales , Femenino , Embarazo , Insulina/metabolismo , Insulina/sangre , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Diabetes Gestacional/metabolismo , Diabetes Gestacional/patología , Efectos Tardíos de la Exposición Prenatal/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patología , Ratas , Mitocondrias/metabolismo , Glucemia/metabolismoRESUMEN
Diabetes mellitus increases the risk of obstetric complications, morbidity, and infant mortality. Controlled nutritional therapy with micronutrients has been employed. However, the effect of calcium (Ca2+) supplementation on diabetic pregnancy is unclear. We aimed to evaluate whether diabetic rats supplemented with Ca2+ during pregnancy present better glucose tolerance, redox status, embryonic and fetal development, newborn weight, and the prooxidant and antioxidant balance of male and female pups. For this, newborn rats received the beta-cytotoxic drug streptozotocin for inducing diabetes on the day of birth. In adulthood, these rats were mated and treated with Ca2+ twice a day from day 0 to day 20 of pregnancy. On day 17, the pregnant rats were submitted to the oral glucose tolerance test (OGTT). At the end of pregnancy, they were anesthetized and killed to collect blood and pancreas samples. The uterine horns were exposed for an evaluation of maternal reproductive outcomes and embryofetal development, and the offspring's liver samples were collected for redox status measurement. Nondiabetic and diabetic rats supplemented with Ca2+ showed no influence on glucose tolerance, redox status, insulin synthesis, serum calcium levels, and embryofetal losses. The reduced rate of newborns classified as adequate for gestational age (AGA) and higher rates of LGA (large) and small (LGA) newborns and higher -SH and GSH-Px antioxidant activities in female pups were observed in diabetic dams, regardless of supplementation. Thus, maternal supplementation caused no improvement in glucose tolerance, oxidative stress biomarkers, embryofetal growth and development, and antioxidants in pups from diabetic mothers.
Asunto(s)
Calcio , Diabetes Mellitus Experimental , Embarazo , Ratas , Animales , Masculino , Femenino , Antioxidantes/farmacología , Diabetes Mellitus Experimental/complicaciones , Ratas Wistar , Estrés Oxidativo , Suplementos Dietéticos , Glucosa/farmacología , GlucemiaRESUMEN
Studies on vitamin D supplementation have been performed in experimental and clinical investigations considering gestational diabetes and/or vitamin D deficiency in pregnancy. However, the results are controversial and few present the effects and mechanisms of this micronutrient on pregestational diabetes. The objective of this study was to evaluate the effect of vitamin D on the pregnancy of rats with pre-existing diabetes and their fetuses. Pregestational diabetes was induced in Sprague-Dawley rats at birth. The adult diabetic and nondiabetic rats were orally administered with vitamin D (cholecalciferol) throughout the pregnancy. The diabetes status was monitored during pregnancy by an oral glucose tolerance test (OGTT). At the end of the pregnancy, pancreas and blood samples were collected for morphological analyses and lipid peroxidation measurements, respectively. The influence of vitamin D treatment on reproductive outcomes, fetal growth, and development were compared to those of untreated diabetic and nondiabetic pregnant rats. P < 0.05 was considered a significant statistical limit. The diabetic rats given vitamin D had a greater number of insulin-positive cells, contributing to reduced blood glucose levels and thiobarbituric acid reactive substance concentrations (TBARS-an indicator of membrane lipid peroxidation), and increased reduced thiol group levels, contributing to suitable intrauterine conditions for better fetal development, which was confirmed by higher fetal viability rates. Thus, this study shows the effects and mechanisms of vitamin D supplementation on pre-existing diabetes in pregnant rats, confirming its beneficial effects on maternal redox status and glycemic control, and the decline of adverse maternal-fetal repercussions.
Asunto(s)
Diabetes Mellitus Experimental , Diabetes Gestacional , Embarazo , Femenino , Humanos , Ratas , Animales , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/tratamiento farmacológico , Ratas Sprague-Dawley , Diabetes Gestacional/tratamiento farmacológico , Vitamina D/uso terapéutico , Suplementos Dietéticos , Resultado del EmbarazoRESUMEN
Animal models are widely used for studying diabetes in translational research. However, methods for induction of diabetes are conflicting with regards to their efficacy, reproducibility and cost. A comparison of outcomes between the diabetic models is still unknown, especially full-term pregnancy.To understand the comparison, we analyzed the streptozotocin (STZ)-induced diabetes at three life-different moments during the neonatal period in Sprague-Dawley female rats: at the first (D1), second (D2) and fifth (D5) day of postnatal life. At adulthood (90 days; D90), the animals were submitted to an oral glucose tolerance test (OGTT) for diabetic status confirmation. The diabetic and control rats were mated and sacrificed at full-term pregnancy for different analyses. Group D1 presented a higher mortality percentage after STZ administration than groups D2 and D5. All diabetic groups presented higher blood glucose levels as compared to those of the control group, while group D5 had higher levels of glycemia compared with other groups during OGTT. The diabetic groups showed impaired reproductive outcomes compared with the control group. Group D1 had lower percentages of mated rats and D5 showed a lower percentage of a full-term pregnancy. Besides that, these two groups also showed the highest percentages of inadequate fetal weight. In summary, although all groups fulfill the diagnosis criteria for diabetes in adult life, in our investigation diabetes induced on D5 presents lower costs and higher efficacy and reproducibility for studies involving diabetes-complicated pregnancy.
Asunto(s)
Diabetes Mellitus Experimental , Animales , Glucemia , Femenino , Insulina , Embarazo , Ratas , Ratas Sprague-Dawley , Reproducibilidad de los Resultados , EstreptozocinaRESUMEN
Fructose consumption has increased worldwide, and it has been associated with the development of metabolic diseases such as insulin resistance (IR) and steatosis. The aim was to evaluate if lower fructose concentrations may cause pancreatic structural abnormalities, leading to a glucose intolerance without steatosis in male rats. Young male rats orally received 7% fructose solution for 12 weeks. Body weight, food, water, and energy intake were measured. An oral glucose tolerance test (OGTT) was performed. After final experimental period, all rats were anaesthetized and killed. Blood samples were collected for biochemical analyses and organs (liver and pancreas) were processed for morphological analyses. Fructose consumption was not associated with lipid accumulation in liver. However, fructose administration was associated with an increased area under curve from OGTT and an increased percentage of insulin-positive cells, high beta cell mass and reduced pancreatic islet area. Fructose supplementation (7%) did not cause steatosis, but it led to abnormal morphology and function of pancreatic islet cells, contributing for glucose intolerance development. Our findings demonstrate that even low fructose concentrations may cause deleterious effects in animals.
Asunto(s)
Glucemia/efectos de los fármacos , Fructosa/administración & dosificación , Animales , Modelos Animales de Enfermedad , Agua Potable , Fructosa/metabolismo , Prueba de Tolerancia a la Glucosa , Resistencia a la Insulina , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Ratas , Ratas WistarRESUMEN
Maternal obesity can cause complications for both women and their offspring for generations. Therefore, we intended to verify the repercussions of induction of transgenerational obesity on biochemical parameters, reproductive performance, and congenital anomaly frequency in Wistar rats. Female rats were used from successive generations. The female rats of parental generation (F0, n=10) were mated to obtain their offspring (F1 generation). F1 female rats received a monosodium glutamate (MSG) solution to induce obesity (n=07) or vehicle (control, n=06) during the neonatal period. These adult female rats were classified as normal or obese using the Lee Index, mated, and delivered offspring (F2 generation), which were also evaluated for obesity using the Lee Index in adult life (F2MSG, n=13, born from obese dams) or non-obesity status (F2Control, n=12, born from control dams), and were mated in adulthood. During pregnancy, glycemia and an oral glucose tolerance test (OGTT) were analyzed. At term pregnancy, the females were sacrificed for serum biochemical profile, maternal reproductive outcomes, and fetal development. In F2MSG rats, body weight gain at early pregnancy, glycemia by OGTT, total cholesterol, high-density-lipoprotein, and alanine transaminase activity were higher compared with those of F2Control rats. F2MSG rats also presented a lower implantation number and gravid uterus weight, increased pre-implantation loss and anomaly frequency in their fetuses (F3 generation) compared with those of F2Control rats. Therefore, even without significant changes in body weight gain, obesity was established at the end of pregnancy of Wistar rats using other biomarkers. Additionally, these rats showed multiple adverse reproductive outcomes, confirming the deleterious effects that lead to obesity.