Soy isoflavones recover pancreatic islet function and prevent metabolic dysfunction in male rats.

We tested whether chronic supplementation with soy isoflavones could modulate insulin secretion levels and subsequent recovery of pancreatic islet function as well as prevent metabolic dysfunction induced by early overfeeding in adult male rats. Wistar rats raised in small litters (SL, three pups/dam) and normal litters (NL, nine pups/dam) were used as models of early overfeeding and normal feeding, respectively. At 30 to 90 days old, animals in the SL and NL groups received either soy isoflavones extract (ISO) or water (W) gavage serving as controls. At 90 days old, body weight, visceral fat deposits, glycemia, insulinemia were evaluated. Glucose-insulin homeostasis and pancreatic-islet insulinotropic response were also determined. The early life overnutrition induced by small litter displayed metabolic dysfunction, glucose, and insulin homeostasis disruption in adult rats. However, adult SL rats treated with soy isoflavones showed improvement in glucose tolerance, insulin sensitivity, insulinemia, fat tissue accretion, and body weight gain, compared with the SL-W group. Pancreatic-islet response to cholinergic, adrenergic, and glucose stimuli was improved in both isoflavone-treated groups. In addition, different isoflavone concentrations increased glucose-stimulated insulin secretion in islets of all groups with higher magnitude in both NL and SL isoflavone-treated groups. These results indicate that long-term treatment with soy isoflavones inhibits early overfeeding-induced metabolic dysfunction in adult rats and modulated the process of insulin secretion in pancreatic islets.

Monosodium l-glutamate-obesity onset is associated with disruption of central control of the hypothalamic-pituitary-adrenal axis and autonomic nervous system.

The hypothalamic-pituitary-adrenal axis (HPA) exerts important catabolic peripheral effects and influences autonomic nervous system (ANS)-mediated processes. Impaired negative-feedback control or reduced HPA axis sensitivity and altered ANS activity appear to be associated with the development and maintenance of obesity. In the present study, we examined the hypothesis that the central HPA axis is dysregulated favouring ANS disbalance in monosodium l-glutamate (MSG)-induced rat obesity. Glucose homeostasis, corticosterone, leptin and ANS electrical activity were evaluated. Adult MSG-induced obese rats exhibited fasting hyperinsulinaemia, insulin resistance, glucose intolerance, hypercorticosteronaemia, hyperleptinaemia and altered ANS activity. A decrease in food intake was observed during corticotrophin-releasing hormone (CRH) treatment in both control and MSG-treated rats. By contrast, food intake was significantly elevated in control rats treated with dexamethasone (DEXA), whereas no alterations were observed following DEXA treatment in MSG-induced obese rats. After DEXA injection, an increase in fasting insulin and glucose levels, associated with insulin resistance, was seen in both groups. As expected, there was a decrease of parasympathetic activity and an increase of sympathetic nervous activity in CRH-treated control animals and the opposite effect was seen after DEXA treatment. By contrast, there was no effect on ANS activity in MSG-rats treated with CRH or DEXA. In conclusion, impairment of the HPA axis can lead to disbalance of ANS activity in MSG-treated rats, contributing to the establishment and maintenance of obesity.

Treatment with soy isoflavones during early adulthood improves metabolism in early postnatally overfed rats.

PURPOSE: The incidences of obesity and related diseases have reached epidemic proportions, and new therapeutic approaches are needed. Soy isoflavones have been identified as an important dietary factor for preventing and treating metabolic dysfunction. This study examined the effects of high doses of isoflavone on glucose and fat metabolism in a model of programmed obesity and evaluated its effects on the autonomic nervous system. METHODS: Litters of Wistar rats were standardized at nine pups per dam in normal litters (NL) or reduced to three pups per dam at the third day of life (P3) in small litters (SL) to induce postnatal overfeeding. Gavage with a soy bean isoflavone mixture (1 g/day) diluted in water was started at P60 and continued for 30 days. The control animals received vehicle gavage. At P90, biometric and metabolic parameters as well as direct autonomic nerve activity were measured. RESULTS: Increases in glycaemia and insulinaemia observed in SL rats were reduced by isoflavone treatment, which also caused lower glucose-induced insulin secretion by pancreatic islets. Sympathetic activity in the major splanchnic nerve was increased, while vagus nerve activity was reduced by isoflavone treatment. The dyslipidaemia induced by overfeeding in SL rats was restored by isoflavone treatment. CONCLUSION: The present study shows that treatment with isoflavone reduces adiposity and improves glucose and lipid metabolism. Collectively, these effects may depend on autonomic changes.

Sympathetic innervation is essential for metabolic homeostasis and pancreatic beta cell function in adult rats.

Obesity is associated with an imbalance in the activity of the autonomic nervous system (ANS), specifically in the organs involved in energy metabolism. The pancreatic islets are richly innervated by the ANS, which tunes the insulin release due to changes in energy demand. Therefore, changes in the sympathetic input that reach the pancreas can lead to metabolic dysfunctions. To evaluate the role of the sympathetic ends that innervate the pancreas, 60-day-old male Wistar rats were subjected to sympathectomy (SYM) or were sham-operated (SO). At 120 day-old SYM rats exhibited an increase in body weight, fat pads and metabolic dysfunctions. Decreases in the HOMA-IR and reductions in insulin release were observed both in vivo and in vitro. Furthermore, the SYM rats exhibited altered pancreatic islet function in both muscarinic and adrenergic assays and exhibited high protein expression of the alpha-2 adrenergic receptor (α2AR). Because α2AR has been linked to type 2 diabetes, these findings demonstrate the clinical implications of this study.

Altered behavior of adult obese rats by monosodium l-glutamate neonatal treatment is related to hypercorticosteronemia and activation of hypothalamic ERK1 and ERK2.

OBJECTIVES: Obesity is a metabolic and hormonal disorder with serious social and psychological impacts. There is a close relationship among obesity, neuroendocrine homeostasis and behavioral patterns. However, few data are available in the literature regarding this subject. This study assessed behavior and memory of adult obese rats by monosodium l-glutamate (MSG) neonatal treatment or highly palatable dietary treatment. METHODS: MSG obesity was induced by subcutaneous injections of MSG (4 mg/g) during the first 5 days of life (Ob-MSG); control group (C-MSG), received saline solution equimolar. Both groups were fed with commercial chow. To induce dietary obesity, 21-day-old rats were assigned to two experimental diets: highly palatable diet (Ob-Diet) and control diet (C-Diet) composed of commercial chow. Ninety-day-old animals were submitted to behavioral assessment by the open-field test and short- and long-term memory by the object recognition test. Biometric variables were obtained, the Lee index was calculated and mass of retroperitoneal and perigonadal fat pads was measured. Furthermore, an altered behavioral profile was investigated by quantification of plasmatic corticosterone, expression, and activity of hypothalamic extracellular signal-regulated kinase protein (ERK) 1 and 2. RESULTS: Increased Lee index and fat pads were observed in Ob-MSG and Ob-Diet groups. Ob-MSG presented a higher level of anxiety and impaired long-term memory compared to C-MSG, while there was no difference between Ob-Diet and C-Diet. The Ob-MSG group presented a higher level of plasmatic corticosterone and increased phosphorylation of hypothalamic ERK1 and 2. DISCUSSION: Both treatments induced obesity but only Ob-MSG showed altered behavioral parameters, which is related to increased concentration of corticosterone and hypothalamic ERK1 and 2 activation.

Cross-fostering reduces obesity induced by early exposure to monosodium glutamate in male rats.

Maternal obesity programmes a range of metabolic disturbances for the offspring later in life. Moreover, environmental changes during the suckling period can influence offspring development. Because both periods significantly affect long-term metabolism, we aimed to study whether cross-fostering during the lactation period was sufficient to rescue a programmed obese phenotype in offspring induced by maternal obesity following monosodium L-glutamate (MSG) treatment. Obesity was induced in female Wistar rats by administering subcutaneous MSG (4 mg/g body weight) for the first 5 days of postnatal life. Control and obese female rats were mated in adulthood. The resultant pups were divided into control second generation (F2) (CTLF2), MSG-treated second generation (F2) (MSGF2), which suckled from their CTL and MSG biological dams, respectively, or CTLF2-CR, control offspring suckled by MSG dams and MSGF2-CR, MSG offspring suckled by CTL dams. At 120 days of age, fat tissue accumulation, lipid profile, hypothalamic leptin signalling, glucose tolerance, glucose-induced, and adrenergic inhibition of insulin secretion in isolated pancreatic islets were analysed. Maternal MSG-induced obesity led to an obese phenotype in male offspring, characterized by hyperinsulinaemia, hyperglycaemia, hyperleptinaemia, dyslipidaemia, and impaired leptin signalling, suggesting central leptin resistance, glucose intolerance, impaired glucose-stimulated, and adrenergic inhibition of insulin secretion. Cross-fostering normalized body weight, food intake, leptin signalling, lipid profiles, and insulinaemia, but not glucose homeostasis or insulin secretion from isolated pancreatic islets. Our findings suggest that alterations during the lactation period can mitigate the development of obesity and prevent the programming of adult diseases.

HPA axis and vagus nervous function are involved in impaired insulin secretion of MSG-obese rats.

Neuroendocrine dysfunctions such as the hyperactivity of the vagus nerve and hypothalamus-pituitary-adrenal (HPA) axis greatly contribute to obesity and hyperinsulinemia; however, little is known about these dysfunctions in the pancreatic ß-cells of obese individuals. We used a hypothalamic-obesity model obtained by neonatal treatment with monosodium l-glutamate (MSG) to induce obesity. To assess the role of the HPA axis and vagal tonus in the genesis of hypercorticosteronemia and hyperinsulinemia in an adult MSG-obese rat model, bilateral adrenalectomy (ADX) and subdiaphragmatic vagotomy (VAG) alone or combined surgeries (ADX-VAG) were performed. To study glucose-induced insulin secretion (GIIS) and the cholinergic insulinotropic process, pancreatic islets were incubated with different glucose concentrations with or without oxotremorine-M, a selective agonist of the M3 muscarinic acetylcholine receptor (M3AChR) subtype. Protein expression of M3AChR in pancreatic islets, corticosteronemia, and vagus nerve activity was also evaluated. Surgeries reduced 80% of the body weight gain. Fasting glucose and insulin were reduced both by ADX and ADX-VAG, whereas VAG was only associated with hyperglycemia. The serum insulin post-glucose stimulation was lower in all animals that underwent an operation. Vagal activity was decreased by 50% in ADX rats. In the highest glucose concentration, both surgeries reduced GIIS by 50%, whereas ADX-VAG decreased by 70%. Additionally, M3AChR activity was recovered by the individual surgeries. M3AChR protein expression was reduced by ADX. Both the adrenal gland and vagus nerve contribute to the hyperinsulinemia in the MSG model, although adrenal is more crucial as it appears to modulate parasympathetic activity and M3AChR expression in obesity.

Protein Restriction During the Last Third of Pregnancy Malprograms the Neuroendocrine Axes to Induce Metabolic Syndrome in Adult Male Rat Offspring.

Metabolic malprogramming has been associated with low birth weight; however, the interplay between insulin secretion disruption and adrenal function upon lipid metabolism is unclear in adult offspring from protein-malnourished mothers during the last third of gestation. Thus, we aimed to study the effects of a maternal low-protein diet during the last third of pregnancy on adult offspring metabolism, including pancreatic islet function and morphophysiological aspects of the liver, adrenal gland, white adipose tissue, and pancreas. Virgin female Wistar rats (age 70 d) were mated and fed a protein-restricted diet (4%, intrauterine protein restricted [IUPR]) from day 14 of pregnancy until delivery, whereas control dams were fed a 20.5% protein diet. At age 91 d, their body composition, glucose-insulin homeostasis, ACTH, corticosterone, leptin, adiponectin, lipid profile, pancreatic islet function and liver, adrenal gland, and pancreas morphology were assessed. The birth weights of the IUPR rats were 20% lower than the control rats (P < .001). Adult IUPR rats were heavier, hyperphagic, hyperglycemic, hyperinsulinemic, hyperleptinemic, and hypercorticosteronemic (P < .05) with higher low-density lipoprotein cholesterol and lower high-density lipoprotein cholesterol, adiponectin, ACTH, and insulin sensitivity index levels (P < .01). The insulinotropic action of glucose and acetylcholine as well as muscarinic and adrenergic receptor function were impaired in the IUPR rats (P < .05). Maternal undernutrition during the last third of gestation disrupts the pancreatic islet insulinotropic response and induces obesity-associated complications. Such alterations lead to a high risk of metabolic syndrome, characterized by insulin resistance, visceral obesity, and lower high-density lipoprotein cholesterol.

Protective effect of metformin against walker 256 tumor growth is not dependent on metabolism improvement.

BACKGROUND/AIMS: The objective of the current work was to test the effect of metformin on the tumor growth in rats with metabolic syndrome. METHODS: We obtained pre-diabetic hyperinsulinemic rats by neonatal treatment with monosodium L-glutamate (MSG), which were chronically treated every day, from weaning to 100 day old, with dose of metformin (250 mg/kg body weight). After the end of metformin treatment, the control and MSG rats, treated or untreated with metformin, were grafted with Walker 256 carcinoma cells. Tumor weight was evaluated 14 days after cancer cell inoculation. The blood insulin, glucose levels and glucose-induced insulin secretion were evaluated. RESULTS: Chronic metformin treatment improved the glycemic homeostasis in pre-diabetic MSG-rats, glucose intolerance, tissue insulin resistance, hyperinsulinemia and decreased the fat tissue accretion. Meanwhile, the metformin treatment did not interfere with the glucose insulinotropic effect on isolated pancreatic islets. Chronic treatment with metformin was able to decrease the Walker 256 tumor weight by 37% in control and MSG rats. The data demonstrated that the anticancer effect of metformin is not related to its role in correcting metabolism imbalances, such as hyperinsulinemia. However, in morphological assay to apoptosis, metformin treatment increased programmed cell death. CONCLUSION: Metformin may have a direct effect on cancer growth, and it may programs the rat organism to attenuate the growth of Walker 256 carcinoma.

Insulin oversecretion in MSG-obese rats is related to alterations in cholinergic muscarinic receptor subtypes in pancreatic islets.

BACKGROUND/AIMS: Impaired pancreatic beta cell function and insulin secretion/action are a link between obesity and type 2 diabetes, which are worldwide public health burdens. We aimed to characterize the muscarinic acetylcholine receptor (mAChR) M1-M4 subtypes in isolated pancreatic islets from pre-diabetic obese rats that had been treated neonatally with monosodium L-glutamate (MSG). METHODS: At 90 days of age, both the MSG and the control groups underwent biometric and biochemical evaluation. Anti-muscarinic drugs were used to study mAChR function either in vivo or in vitro. RESULTS: The results demonstrated that atropine treatment reduced insulin secretion in the MSG-treated and control groups, whereas treatment with an M2mAChR-selective antagonist increased secretion. Moreover, the insulinostatic effect of an M3mAChR-selective antagonist was significantly higher in the MSG-treated group. M1mAChR and M3mAChR expression was increased in the MSG-obese group by 55% and 73%, respectively. In contrast, M2mAChR expression decreased by 25% in the MSG group, whereas M4mAChR expression was unchanged. CONCLUSIONS: Functional changes in and altered content of the mAChR (M1-M4) subtypes are pivotal to the demand for high pancreatic beta cell insulin secretion in MSG-obese rats, which is directly associated with vagal hyperactivity and peripheral insulin resistance.

Impaired ß-cell function in the adult offspring of rats fed a protein-restricted diet during lactation is associated with changes in muscarinic acetylcholine receptor subtypes.

Impaired pancreatic ß-cell function, as observed in the cases of early nutrition disturbance, is a major hallmark of metabolic diseases arising in adulthood. In the present study, we aimed to investigate the function/composition of the muscarinic acetylcholine receptor (mAChR) subtypes, M2 and M3, in the pancreatic islets of adult offspring of rats that were protein malnourished during lactation. Neonates were nursed by mothers that were fed either a low-protein (4 %, LP) or a normal-protein (23 %, NP) diet. Adult rats were pre-treated with anti-muscarinic drugs and subjected to the glucose tolerance test; the function and protein expression levels of M2mAChR and M3mAChR were determined. The LP rats were lean and hypoinsulinaemic. The selective M2mAChR antagonist methoctramine increased insulinaemia by 31 % in the NP rats and 155 % in the LP rats, and insulin secretion was increased by 32 % in the islets of the NP rats and 88 % in those of the LP rats. The selective M3mAChR antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide decreased insulinaemia by 63 % in the NP rats and 40 % in the LP rats and reduced insulin release by 41 % in the islets of the NP rats and 28 % in those of the LP rats. The protein expression levels of M2mAChR and M3mAChR were 57 % higher and 53 % lower, respectively, in the islets of the LP rats than in those of the NP rats. The expression and functional compositions of M2mAChR and M3mAChR were altered in the islets of the LP rats, as a result of metabolic programming caused by the protein-restricted diet, which might be another possible effect involved in the weak insulin secretion ability of the islets of the programmed adult rats.

Poor pubertal protein nutrition disturbs glucose-induced insulin secretion process in pancreatic islets and programs rats in adulthood to increase fat accumulation.

Similar to gestation/lactation, puberty is also a critical phase in which neuronal connections are still being produced and during which metabolic changes may occur if nutrition is disturbed. In the present study we aimed to determine whether peripubertal protein restriction induces metabolic programming. Thirty-day-old male rats were fed either a low protein (LP group) diet (4% w/w protein) or a normal protein (NP group) diet (23%) until 60 days of age, when they received the NP diet until they were 120 days old. Body weight (BW), food intake, fat tissue accumulation, glucose tolerance, and insulin secretion were evaluated. The nerve electrical activity was recorded to evaluate autonomous nervous system (ANS) function. Adolescent LP rats presented hypophagia and lower BW gain during the LP diet treatment (P<0.001). However, the food intake and BW gain by the LP rats were increased (P<0.001) after the NP diet was resumed. The LP rats presented mild hyperglycemia, hyperinsulinemia, severe hyperleptinemia upon fasting, peripheral insulin resistance and increased fat tissue accumulation and vagus nerve activity (P<0.05). Glucose-induced insulin secretion was greater in the LP islets than in the NP islets; however, the cholinergic response was decreased (P<0.05). Compared with the islets from the NP rats, the LP islets showed changes in the activity of muscarinic receptors (P<0.05); in addition, the inhibition of glucose-induced insulin secretion by epinephrine was attenuated (P<0.001). Protein restriction during adolescence caused high-fat tissue accumulation in adult rats. Islet dysfunction could be related to an ANS imbalance.

Maternal protein malnutrition does not impair insulin secretion from pancreatic islets of offspring after transplantation into diabetic rats.

Pancreatic islets from adult rats whose mothers were protein restricted during lactation undersecrete insulin. The current work analyzes whether this secretory dysfunction can be improved when the pancreatic islets are grafted into hyperglycemic diabetic rats. Two groups of rats were used: the adult offspring from dams that received a low protein diet (4%) during the initial 2/3 of lactation (LP) and, as a control, the adult offspring from dams that consumed a normal protein diet (23%) during the entire period of lactation (NP). Islets from NP- and LP-rats were transplanted into diabetic recipient rats, which were generated by streptozotocin treatment. The islets were transplanted via the portal vein under anesthesia. The fed blood glucose levels were monitored during the 4 days post-transplantation. Transplanted islets from LP-rats (T LP) decreased the fed glucose levels of diabetic rats 34% (21.37 ± 0.24 mM, p<0.05); however, the levels still remained 2-fold higher than those of the sham-operated controls (6.88 ± 0.39 mM, p<0.05). Grafts with NP-islets (T NP) produced the same effect as the LP-islets in diabetic rats. The high fasting blood glucose levels of diabetic rats were improved by the transplantations. Islet grafts from both rat groups recovered 50% of the retroperitoneal fat mass of the diabetic rats (0.55 ± 0.08 g/100 g of body weight for T NP and 0.56 ± 0.07 g/100 g of body weight for T LP, p<0.05). Because pancreatic islets from both the NP- and LP-rats were able to regulate fasting blood glucose concentrations in hyperglycemic rats, we propose that the altered function of pancreatic islets from LP-rats is not permanent.

Efeito de um programa de exercício físico moderado em ratos de diferentes modelos de obesidade / Effect of moderate exercise program on rats from different models of obesity

A obesidade afeta uma parcela crescente da população mundial, acompanhada de distúrbios como a hipertensão e o diabetes tipo 2. Diversos modelos experimentais de obesidade foram criados para melhor entendê-la. Adicionalmente, o efeito do exercício físico na atenuação da obesidade vem sendo estudado. O objetivo do presente estudo foi avaliar o efeito de um programa de exercício físico moderado sobre a obesidade em três modelos experimentais: ninhada reduzida (NR), L-glutamato monosódico (MSG) e dieta hiperlipídica (DHL). Os ratos programados para a obesidade apresentaram diferenças significativas no peso corporal, no índice de Lee, no consumo de ração, na gordura corporal e na tolerância à glicose, se comparados ao grupo dos magros. O exercício físico foi capaz de impedir a instalação da obesidade e a deterioração do controle glicêmico. Os resultados sugerem que o treinamento físico moderado iniciado precocemente pode ser usado como prevenção ao desenvolvimento da obesidade e da síndrome metabólica.

Obesity has affected a growing part of world wild's population, accompanied by disorders such as hypertension and type 2 diabetes. Several experimental models of obesity have been created to better understand it. In addition, the effects of exercise training on animal obesity onset have been highlighted. The present study aimed to evaluate the effect of an exercise program of moderate intensity on obesity onset from three models: small litters (SL), monosodium L-glutamate (MSG) and high-fat diet (HFD). The sedentary obese rats showed significant differences in body weight, Lee's index, food intake, body fat and glucose tolerance compared with control group. However, exercise was able to inhibit obesity onset and to preserve glycemic homeostasis. We conclude that moderate physical exercise can be a tool to be used to prevent and control obesity and metabolic syndrome.

Impaired sympathoadrenal axis function contributes to enhanced insulin secretion in prediabetic obese rats.

The involvement of sympathoadrenal axis activity in obesity onset was investigated using the experimental model of treating neonatal rats with monosodium L-glutamate. To access general sympathetic nervous system activity, we recorded the firing rates of sympathetic superior cervical ganglion nerves in animals. Catecholamine content and secretion from isolated adrenal medulla were measured. Intravenous glucose tolerance test was performed, and isolated pancreatic islets were stimulated with glucose and adrenergic agonists. The nerve firing rate of obese rats was decreased compared to the rate for lean rats. Basal catecholamine secretion decreased whereas catecholamine secretion induced by carbachol, elevated extracellular potassium, and caffeine in the isolated adrenal medulla were all increased in obese rats compared to control. Both glucose intolerance and hyperinsulinaemia were observed in obese rats. Adrenaline strongly inhibited glucose-induced insulin secretion in obese animals. These findings suggest that low sympathoadrenal activity contributes to impaired glycaemic control in prediabetic obese rats.

Low-Intensity swimming training after weaning improves glucose and lipid homeostasis in MSG hypothalamic obese mice.

Low-intensity swimming training, started at an early age, was undertaken to observe glycemic control in hypothalamic obese mice produced by neonatal monosodium l-glutamate (MSG) treatment. Although swimming exercises by weaning pups inhibited hypothalamic obesity onset and recovered sympathoadrenal axis activity, this event was not observed when exercise training is applied to young adult mice. However, the mechanisms producing this improved metabolism are still not fully understood. Current work verifies whether, besides reducing fat tissue accumulation, low-intensity swimming in MSG-weaned mice also improves glycemic control. Although MSG and control mice swam for 15 min/day, 3 days a week, from the weaning stage up to 90 days old, sedentary MSG and normal mice did not exercise at all. After 14 h of fasting, animals were killed at 90 days of age. Retroperitonial fat accumulation was measured to estimate obesity. Fasting blood glucose and insulin concentrations were also measured. Mice were also submitted to ipGTT. MSG obese mice showed fasting hyperglycemia, hyperinsulinemia, and glucose intolerance and insulin resistance. However, the exercise was able to block MSG treatment effects. Higher total cholesterol and triglycerides observed in MSG mice were normalized by exercise after weaning. Exercised MSG animals had higher HDLc than the sedentary group. Data suggest that early exercise training maintains normoglycemia, insulin tissue sensitivity, and normal lipid profile in mice programmed to develop metabolic syndrome.

Changes in calcium fluxes in mitochondria, microsomes, and plasma membrane vesicles of livers from monosodium L-glutamate-obese rats.

The purpose of this work was to evaluate if the fat liver accumulation interferes with intracellular calcium fluxes and the liver glycogenolytic response to a calcium-mobilizing α(1)-adrenergic agonist, phenylephrine. The animal model of monosodium L-glutamate (MSG)-induced obesity was used. The adult rats develop obesity and steatosis. Calcium fluxes were evaluated through measuring the (45)Ca(2+) uptake by liver microsomes, inside-out plasma membrane, and mitochondria. In the liver, assessments were performed on the calcium-dependent glycogenolytic response to phenylephrine and the glycogen contents. The Ca(2+) uptake by microsomes and plasma membrane vesicles was reduced in livers from obese rats as a result of reduction in the Ca(2+)-ATPase activities. In addition, the plasma membrane Na(+)/K(+)-ATPase was reduced. All these matched effects could contribute to elevated resting intracellular calcium levels in the hepatocytes. Livers from obese rats, albeit smaller and with similar glycogen contents to those of control rats, released higher amounts of glucose in response to phenylephrine infusion, which corroborates these observations. Mitochondria from obese rats exhibited a higher capacity of retaining calcium, a phenomenon that could be attributed to a minor susceptibility of the mitochondrial permeability transition pore opening.

O tratamento com isoflavonas mimetiza a ação do estradiol no acúmulo de gordura em ratas ovariectomizadas / Treatment with isoflavones replaces estradiol effect on the tissue fat accumulation from ovariectomized rats

OBJETIVO: As isoflavonas (ISO) presentes na soja são consideradas fitoestrógenos. A administração de fitoestrógenos tem efeito benéfico nos distúrbios da pós-menopausa que são caracterizados pela suspensão da função ovariana com declínio da secreção de estrogênio e conseqüentes desajustes histomorfológicos e metabólicos. O objetivo do presente estudo foi investigar o efeito da suplementação com ISO sobre a espessura do endométrio uterino, o acúmulo de gordura tecidual, o colesterol HDL e a glicose plasmática de ratas ovariectomizadas (OVX). MÉTODOS: Ratas Wistar com 60 dias de vida sofreram cirurgia bilateral para retirada dos ovários. Após o período de 8 dias de recuperação foram divididas em três grupos: falso operada (GC), OVX não-tratadas com ISO (GI) e as OVX suplementadas com ISO (GII). Foram retirados e pesados o útero, as gorduras uterinas e retroperitoneais. Também foram coletadas amostras de sangue para dosagem da concentração de HDL e glicose. RESULTADOS: A OVX promoveu atrofia do endométrio, diminuição do peso do útero e diminuição do HDL. O tratamento com ISO promoveu diminuição dos estoques de gorduras uterina e retroperitoneal, aumento de HDL e redução da glicemia, porém não teve efeito uterotrófico. CONCLUSÕES: Os dados do presente estudo mostram que o tratamento com ISO promove redução da adiposidade, o que pode estar relacionado à redução da lipogênese e ao aumento da lipólise.

OBJECTIVE: Isoflavones (ISO) present in soybean are named phytoestrogens because they show estrogen effect. The use of isoflavones has beneficial effect in disturbance of post-menopause, which is characterized by ovarian function suppression. Decreasing of estrogen secretion and consequent morphologic and metabolic disarrangements are observed in female hormonal decline. The aim of present work was to investigate the effect of ISO on the fat accretion of uterin endometric tissue, and HDL and glucose blood concentration from ovariectomized rats (OVX). METHODS: Female Wistar rats with 60 days-old were submitted a surgery to remove bilaterally the ovarium. After 8-day recovery period the animals were distributed into three groups: sham operate (GC); OVX ISO untreated (GI) and OVX supplemented with ISO (G II). Total uterus mass, uterus fat and retroperitoneal fat pad, were removed, washed and weighted. Samples of uterus were histological processed to measure endometrium thickness. Blood samples were also collected to analyze the concentration of HDL and glucose. The OVX caused endometric atrophy, decrease of uterus weight and HDL reduction. The treatment with ISO provoked decrease of uterin and retroperitoneal fat pad. HDL increase and glycemia reduction were also observed. However, there was no uterotrophic effect. CONCLUSIONS: ISO treatment causes decrease in tissue fat accretion from ovariectomized rats.

[Treatment with isoflavones replaces estradiol effect on the tissue fat accumulation from ovariectomized rats]. / O tratamento com isoflavonas mimetiza a ação do estradiol no acúmulo de gordura em ratas ovariectomizadas.

OBJECTIVE: Isoflavones (ISO) present in soybean are named phytoestrogens because they show estrogen effect. The use of isoflavones has beneficial effect in disturbance of post-menopause, which is characterized by ovarian function suppression. Decreasing of estrogen secretion and consequent morphologic and metabolic disarrangements are observed in female hormonal decline. The aim of present work was to investigate the effect of ISO on the fat accretion of uterine endometric tissue, and HDL and glucose blood concentration from ovariectomized rats (OVX). METHODS: Female Wistar rats with 60 days-old were submitted a surgery to remove bilaterally the ovarium. After 8-day recovery period the animals were distributed into three groups: sham operate (GC); OVX ISO untreated (GI) and OVX supplemented with ISO (G II). Total uterus mass, uterus fat and retroperitoneal fat pad, were removed, washed and weighted. Samples of uterus were histological processed to measure endometrium thickness. Blood samples were also collected to analyze the concentration of HDL and glucose. The OVX caused endometric atrophy, decrease of uterus weight and HDL reduction. The treatment with ISO provoked decrease of uterine and retroperitoneal fat pad. HDL increase and glycemia reduction were also observed. However, there was no uterotrophic effect. CONCLUSIONS: ISO treatment causes decrease in tissue fat accretion from ovariectomized rats.

Fat storage is partially dependent on vagal activity and insulin secretion of hypothalamic obese rat.

Hypothalamic MSG-obese rats show hyperinsulinemia and tissue insulin resistance, and they display intense parasympathetic activity. Current analysis investigates whether early subdiaphragmatic vagotomy prevents tissue insulin sensitivity impairment in adult obese MSG-rats. Hypothalamic obesity was induced by MSG (4 mg/g BW), daily, from birth up to 5 days. Control animals receiving saline solution. On the 30th day rats underwent bilateral subdiaphragmatic vagotomy or sham surgery. An intravenous glucose tolerance test (i.v.GTT) was performed when rats turned 90 days old. Total white fat tissue (WAT) from rat carcass was extracted and isolated; the interscapular brown fat tissue (IBAT) was weighed. Rather than blocking obesity, vagotomy reduced WAT and IBAT in MSG-obese rats when the latter were compared to sham MSG-rats. High blood fasting insulin and normal glucose levels were also observed in MSG-obese rats. Although glucose intolerance, high insulin secretion, and significant insulin resistance were recorded, vagotomy improved fasting insulinemia, glucose tolerance and insulin tissue sensitivity in MSG-obese rats. Results suggest that increased fat accumulation is caused, at least in part, by high blood insulin concentration, and enhanced parasympathetic activity on MSG-obese rats.