Glutamato monosódico y suprasistema neuroendocrinoinmune murino

Introducción: El glutamato monosódico se emplea en humanos desde el pasado siglo como potenciador del sabor. Su inoculación parenteral en murinos durante el período neonatal causa lesiones en varios núcleos hipotalámicos. Objetivo: Describir los efectos del glutamato monosódico sobre el sistema neuroendocrinoinmune en murinos. Metodos: Se realizó una revisión de artículos de libre acceso en las bases de datos PubMed y SciELO entre enero de 2013 y julio de 2020. También se examinó el texto básico de la asignatura Sangre y Sistema Inmune de la carrera de medicina. Desarrollo: Con independencia de su efecto adictivo, varios estudios defienden la inocuidad del glutamato monosódico. Sin embargo, este compuesto puede atravesar la barrera hematoencefálica de neonatos de murinos, y ocasionar trastornos metabólicos, reproductivos y del sistema inmune. Conclusiones: El glutamato monosódico en roedores causa alteraciones en los órganos que integran el suprasistema neuroendocrinoinmune y, por tanto, afecta sus funciones homeostáticas. Los mecanismos patogénicos no se conocen con exactitud.

Introduction: Monosodium glutamate has been used in humans since the last century as a flavor enhancer. Its parenteral inoculation in murine during the neonatal period causes lesions in several hypothalamic nuclei. Objective: To describe the effects of monosodium glutamate on the neuroendocrine immune system in murine samples. Methods: A review of open access articles in the PubMed and SciELO databases was conducted between January 2013 and July 2020. The basic text of the Blood and Immune System course of the medical school was also reviewed. Development: Regardless of its addictive effect, several studies defend the safety of monosodium glutamate. However, this compound can cross the blood-brain barrier of murine neonates, causing metabolic, reproductive and immune system disorders. Conclusions: Monosodium glutamate in rodents causes alterations in the organs that make up the neuroendocrine-immune suprasystem and, therefore, affects their homeostatic functions. The pathogenic mechanisms are not known exactly.

Differential benefits of physical training associated or not with l-arginine supplementation in rats with metabolic syndrome: Evaluation of cardiovascular, autonomic and metabolic parameters.

Metabolic syndrome (MetS) is characterized by endocrine-metabolic and cardiac alterations that increase the risk of cardiovascular disease, dyslipidemia, and type-2 diabetes mellitus. Dietary supplementation with l-Arginine (L-Arg) is beneficial for fat loss, while chronic aerobic exercise has several benefits in reversing cardiovascular, autonomic, and metabolic dysfunctions caused by obesity. However, the association between these two approaches has not yet been described. This study aimed to evaluate the possible benefits of physical training, with or without l-Arg-supplementation, on cardiovascular, autonomic, and metabolic parameters in rats with MetS, which was induced by the subcutaneous administration of monosodium glutamate at 4 mg g-1day-1 in rats from the first to fifth day of life. Physical training on a treadmill and supplementation with l-Arg-in adulthood were carried out concomitantly for 8 weeks. After this, the animals underwent femoral artery catheterization to record their cardiovascular parameters and autonomic modulation. Organs and blood were removed to measure levels of nitrite, glucose, and hepatic steatosis. In adult rats with MetS, supplementation with l-Arg-in combination with physical training reduced hypertension, tachycardia, adipose tissue mass, free fatty acids, and hepatic steatosis. Supplementation with l-Arg-and physical training separately was beneficial in reducing several aspects of MetS, but a combination of both was especially effective in reducing adipose tissue and hepatic steatosis. Together, the two therapies can form a good strategy to combat MetS.

An Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to the MSG-Induced Obesity Model.

The model of obesity induced by monosodium glutamate cytotoxicity on the hypothalamic nuclei is widely used in the literature. However, MSG promotes persistent muscle changes and there is a significant lack of studies that seek to elucidate the mechanisms by which damage refractory to reversal is established. This study aimed to investigate the early and chronic effects of MSG induction of obesity upon systemic and muscular parameters of Wistar rats. The animals were exposed to MSG subcutaneously (4 mg·g-1 b.w.) or saline (1.25 mg·g-1 b.w.) daily from PND01 to PND05 (n = 24). Afterwards, in PND15, 12 animals were euthanized to determine the plasma and inflammatory profile and to assess muscle damage. In PND142, the remaining animals were euthanized, and samples for histological and biochemical analyses were obtained. Our results suggest that early exposure to MSG reduced growth, increased adiposity, and inducted hyperinsulinemia and a pro-inflammatory scenario. In adulthood, the following were observed: peripheral insulin resistance, increased fibrosis, oxidative distress, and a reduction in muscle mass, oxidative capacity, and neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty restoring in the muscle profile is related to the metabolic damage established early on.

Variaciones morfológicas de la glándula submandibular en ratas obesas por acción de glutamato monosódico / Morphological variations of the submandibular gland in obese rats by the action of monosodium glutamate

Este estudio tuvo como objetivo demostrar la existencia de variaciones morfológicas en el tejido conectivo de la glándula submandibular de ratas obesas expuestas a glutamato monosódico (GMS). Se utilizaron 12 ratas Sprague Dawley machos recién nacidas (6 ratas para el grupo 1, control; 6 ratas para el grupo 2 (GMS), 4 mg/g de glutamato monosódico de peso (5 dosis) mantenidas por 16 semanas respectivamente con una dieta y agua ad libitum. En el estudio se realizó un análisis estereológico e histológico, demostrándose una variación en el tejido conectivo presentando una disminución del volúmen glandular, mayor fibrosis, y disminución de adipocitos a nivel periférico siendo reemplazado por tejido rico en colágeno. Los vasos sanguíneos observados a nivel estereológico no presentan mayores cambios en cuanto a volumen, superficie y área.

SUMMARY: This study aims to demonstrate the existence of morphological variations in the connective tissue of the submandibular gland of obese rats exposed to MSG. Twelve male newborn Sprague Dawley rats were used (6 rats for group 1, control; 6 rats for group 2 (MSG), 4 mg/g of monosodium glutamate of weight (5 doses) maintained for 16 weeks respectively with a diet and water ad libitum. In the study, a stereological and histological analysis was carried out, demonstrating a variation in the connective tissue, presenting a decrease in the glandular volume, greater fibrosis, and a decrease in adipocytes at the peripheral level, being replaced by tissue rich in collagen. Blood cells observed at the stereological level do not present major changes in terms of volume, surface and area, but in the histological study greater vascularization is observed.

The M1-muscarinic acetylcholine receptor subtype may play a role in learning and memory performance in the hippocampus of neonatal monosodium glutamate-obese rats

Here, we investigate the effects of obesity induced by monosodium glutamate (MSG) on cognitive impairment and whether this model induces any alteration in the affinity, density, and subtypes of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Healthy rats were used as controls, and MSG-obese rats were selected via the Lee index > 0.300. The effects of MSG-induced obesity on hippocampal spatial learning and memory processes were evaluated by using the working memory versions of the Morris’ water maze task and the evaluation of mAChRs by binding assay and their subtypes by immunoprecipitation assays. [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ between control and MSG, indicating that affinity is not affected by obesity induced by MSG. The maximum number of binding sites (Bmax) obtained in MSG subjects was lower than that obtained from control rats, indicating a decrease in the expression of total mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 subtype of MSG when compared with control rats (M2 to M5 subtypes did not differ between control and MSG). We also observed that MSG promotes a disruption of the spatial working memory which was accompanied by a decrease in the M1 mAChR subtype in rat hippocampus, thus suggesting deleterious long-term effects besides the obesity. In conclusion, these findings provide new insights into how obesity can influence spatial learning and memory that is hippocampal-dependent. The data suggest that the M1 mAChR subtype protein expression is a potential therapeutic target.

Ethanolic extract of Lippia graveolens stem reduce biochemical markers in a murine model with metabolic syndrome.

Metabolic Syndrome (MetS) is a risk to develop metabolic-chronic degenerative disease, it is important to find natural alternatives to help decrease the risk. Mexican oregano has a traditional use in Mexican food, moreover, has pharmacologic effects that can help to reduce risk the metabolic syndrome. The aim of this work was to determine the effect of Mexican oregano ethanolic extract in metabolic syndrome in murine model. Ethanolic extract of Mexican oregano (Lippia graveolens) stem (Ext) had a favorable effect on biochemical markers in a murine model of MetS, induced by injection of monosodium glutamate (MSG). From newborn female mice, two groups were formed: control and the MSG groups, which received a dosage of 2 mg/kg of MSG via subcutaneous injection at the second and fourth postnatal day (PD 2,4), and 4 mg/kg at the PD 6, 8, 10 to induce obesity. On week 13, a part of the MSG group received Ext (group MSG + Ext) at 300 mg/kg, administered orally daily from week 13 to week 18. The results indicated that ethanolic extract of Lippia graveolens stem decreases the percentage of body fat, waist circumference, and body weight gain as well as cholesterol, serum triglyceride concentrations and systolic and diastolic pressure. Insulin and leptin hormone values showed a significant effect with the Ext administration. However, hepatic lipoperoxidation levels of MSG and MSG + Ext groups did not show any statistically significant differences between them, both being higher than the control group. Taking in consideration the results obtained in this study, it is concluded that the administration of Ext had a beneficial effect in the murine model with MetS. This is the first study demonstrating the potential of the polar fraction Lippia graveolens stem in MetS.

Vitamin E suppresses aortic ultrastructural alterations induced by toxic doses of monosodium glutamate / La vitamina E suprime las alteraciones ultraestructurales aórticas inducidas por dosis tóxicas de glutamato monosódico

SUMMARY: An association between certain food additives and chronic diseases is reported. Current study determined whether administering toxic doses of the food additive monosodium glutamate (MSG) into rats can induce aortopathy in association with the oxidative stress and inflammatory biomarkers upregulation and whether the effects of MSG overdose can be inhibited by vitamin E. MSG at a dose of (4 mg/kg; orally) that exceeds the average human daily consumption by 1000x was administered daily for 7 days to the rats in the model group. Whereas, rats treated with vitamin E were divided into two groups and given daily doses of MSG plus 100 mg/ kg vitamin E or MSG plus 300 mg/kg vitamin E. On the eighth day, all rats were culled. Using light and electron microscopy examinations, a profound aortic injury in the model group was observed demonstrated by damaged endothelial layer, degenerated smooth muscle cells (SMC) with vacuoles and condensed nuclei, vacuolated cytoplasm, disrupted plasma membrane, interrupted internal elastic lamina, clumped chromatin, and damaged actin and myosin filaments. Vitamin E significantly protected aorta tissue and cells as well as inhibited MSG-induced tissue malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). The highest used vitamin E dosage was more effective. Additionally, a significant correlation was observed between the aortic injury degree and tissue MDA, TNF-α, IL-6, and superoxide dismutase (SOD) levels (p=0.001). Vitamin E effectively protects against aortopathy induced by toxic doses of MSG in rats and inhibits oxidative stress and inflammation.

RESUMEN: Se reporta una asociación entre ciertos aditivos alimentarios y enfermedades crónicas. El objetivo de este estudio fue determinar si la administración de dosis tóxicas del aditivo alimentario glutamato monosódico (MSG) en ratas puede inducir aortopatía en asociación con el estrés oxidativo y la regulación positiva de los biomarcadores inflamatorios y si el efecto de una sobredosis de MSG se puede inhibir con vitamina E. Se administró MSG diariamente durante 7 días una dosis de (4 g/kg; por vía oral) que excede el consumo diario humano promedio, en 1000x a las ratas del grupo modelo. Mientras que las ratas tratadas con vitamina E se dividieron en dos grupos y se administraron dosis diarias de MSG más 100 mg/kg de vitamina E o MSG más 300 mg/kg de vitamina E. Todas las ratas fueron sacrificadas en el octavo día. Usando exámenes de microscopía óptica y electrónica, se observó una lesión aórtica profunda en el grupo modelo demostrada por una capa endotelial dañada, células musculares lisas degeneradas (SMC) con vacuolas y núcleos condensados, citoplasma vacuolado, membrana plasmática rota, lámina elástica interna interrumpida, cromatina agrupada y filamentos de actina y miosina dañados. La vitamina E protegió significativamente el tejido y las células de la aorta, además de inhibir el malondialdehído tisular (MDA) inducido por MSG, la interleucina-6 (IL-6) y el factor de necrosis tumoral alfa (TNF-α). La dosis más alta de vitamina E utilizada fue más efectiva. Además, se observó una correlación significativa entre el grado de lesión aórtica y los niveles tisulares de MDA, TNF-α, IL-6 y superóxido dismutasa (SOD) (p=0,001). La vitamina E efectivamente protege contra la aortopatía inducida por dosis tóxicas de MSG en ratas e inhibe el estrés oxidativo y la inflamación.

The ameliorative potentials of aqueous leaf extract of Amaranthus hybridus on monosodium glutamate-induced testicular damage in Wistar rats.

OBJECTIVE: Amaranthus hybridus (AH) is a food plant commonly eaten in our country known as a good source of vitamins, minerals, and antioxidants. The present study was designed to investigate the ameliorative potentials of aqueous extract of A. hybridus on Monosodium Glutamate (MSG) -induced testicular toxicity in adult Wistar rats. METHODS: Thirty-two male Wistar rats weighing 160-180 g were divided into four groups. Group A served as control; rats in Group B were given 300 mg/kg of body weight (BW) of aqueous leaf extract of AH; rats in Group C were given 4 mg/g (BW) of 40% MSG; and rats in Group D were given 4 mg/g (BW) of 40% MSG and 300 mg/kg (BW) of extract orally for 6 weeks. RESULTS: There was a significant increase in body weight and a significant reduction in testis weight, testis volume, and testis/body weight ratio in the group given only MSG when compared with controls. Histologically, rats in Groups A and B had normal testicular architecture, while the rats given MSG only showed a significant derangement in testicular histoarchitecture and impaired sperm parameters when compared with controls and the rats given AH. However, these derangements were alleviated in the MSG+AH group when compared with controls. CONCLUSIONS: Aqueous leaf extract of AH ameliorated the testicular derangement resulting from MSG administration.

Distinct effects of growth hormone deficiency and disruption of hypothalamic kisspeptin system on reproduction of male mice.

Growth hormone (GH) deficiency is a common cause of late sexual maturation and fertility issues. To determine whether GH-induced effects on reproduction are associated with alterations in hypothalamic kisspeptin system, we studied the male reproduction in two distinct GH deficiency mouse models. In the first model, mice present GH deficiency secondary to arcuate nucleus of the hypothalamus (ARH) lesions induced by posnatal monosodium glutamate (MSG) injections. MSG-induced ARH lesions led to significant reductions in hypothalamic Ghrh mRNA expression and consequently growth. Hypothalamic Kiss1 mRNA expression and Kiss1-expressing cells in the ARH were disrupted in the MSG-treated mice. In contrast, kisspeptin immunoreactivity remained preserved in the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN) of MSG-treated mice. Importantly, ARH lesions caused late sexual maturation and infertility in male mice. In our second mouse model, we studied animals profound GH deficiency due to a loss-of-function mutation in the Ghrhr gene (Ghrhrlit/lit mice). Interestingly, although Ghrhrlit/lit mice exhibited late puberty onset, hypothalamic Kiss1 mRNA expression and hypothalamic kisspeptin fiber density were normal in Ghrhrlit/lit mice. Despite presenting dwarfism, the majority of Ghrhrlit/lit male mice were fertile. These findings suggest that spontaneous GH deficiency during development does not compromise the kisspeptin system. Furthermore, ARH Kiss1-expressing neurons are required for fertility, while AVPV/PeN kisspeptin expression is sufficient to allow maturation of the hypothalamic-pituitary-gonadal axis in male mice.

Evaluación semicuantitativa de los microelementos del esmalte en un modelo de obesidad inducido por glutamato monosódico en ratas / Semi-quantitative evaluation of enamel microelements in an obesity model induced by monosodium glutamate in rats

RESUMEN: En la actualidad, existen múltiples modelos experimentales de obesidad, unos de ellos es la utilización de glutamato monosódico (GMS), un potenciador del sabor ampliamente utilizado en industria alimentaria. Este GMS ha sido relacionado con obesidad, diabetes, insulino resistencia, así como en alteraciones en múltiples órganos, tales como testículos, riñón e hígado, entre otros. Ha sido reportado el efecto del GMS en estructuras orales, tales como las glándulas salivales, alterando su morfología y función. La relación del efecto del GMS frente a tejidos dentarios no ha sido reportada, siendo esto relevantes debido a la información que proporciona a disciplinas tales como arqueología científica, identificación forense, paleoecología y odontología. El objetivo del estudio fue observar la modificación de los elementos en la superficie dental, en un modelo de obesidad inducida por GMS, en ratas. Se utilizaron 12 ratas neonatas Sprague Dawley machos, divididas en dos grupos según exposición a GMS (Grupo Control y Grupo GMS 1: 4 mg/g peso de GMS, 5 dosis, mantenidas 16 semanas. Fue calculado el índice de masa corporal (IMC) e Índice de Lee, además de ser analizados el porcentaje de masa de los elementos C, O, Na, P, Ca, Fe y K en la superficie dental, mediante análisis semicuantitativo. Los resultados indican que GMS indujo obesidad en las ratas, así como alteraciones en los porcentajes de masa de los elementos en la superficie dental, evidenciándose disminución de Ca, P y O, además de aumentos en C y Fe. Según reportes previos, la obesidad inducida por GMS, causa alteraciones en secreción y composición salival, elemento íntimamente relacionado con la composición del esmalte, lo que vendría a explicar nuestros resultados. Entender la composición superficial del esmalte superficial podría ayudarnos a comprender de mejor manera la relación entre caries dentaria y obesidad.

SUMMARY: Monosodium glutamate (MSG) is a flavor enhancer widely used in the food industry. It has been associated with obesity, diabetes, insulin resistance, as well as alterations in multiple organs, such as testicles, kidney, liver, among others. While its effect on oral structures such as the salivary glands has been reported, the impact on dental tissues has not been described. Since this information is also relevant in fields such as forensic identification, palaeoecology and dentistry, the objective of the study was to observe alterations on the tooth surface in a model of obesity in rats induced by MSG. Twelve neonate male Sprague Dawley rats were used, divided into two groups according to MSG exposure (Control Group and MSG1 Group: 4 mg / g weight of MSG, 5 doses were maintained for 16 weeks. Body mass index (BMI) and Lee's index as well as mass percentage of elements C, O, Na, P, Ca, Fe and K on the tooth surface were evaluated by semi-quantitative analysis. In addition to increases in C and Fe, results indicate that MSG induced obesity and alterations in the percentages of mass on the tooth surface in rats, showing a decrease in Ca, P and O, According to previous reports, MSG induced obesity causes alterations in secretion and salivary composition, an aspect closely related to enamel composition, thus explaining our results. Enhanced knowledge of enamel surface composition may help improve our understanding of the relationship between dental caries and obesity.

Indicadores metabólicos y de estrés oxidativo en ratas con obesidad inducida con glutamato monosódico / Metabolic and oxidative stress markers in rats with monosodium glutamate-induced obesity

Introducción: La obesidad, especialmente la visceral, constituye un factor de riesgo principal para múltiples enfermedades tales como: diabetes Mellitus tipo 2, enfermedades cardiovasculares, aterosclerosis, dislipidemias, enfermedad por hígado graso no alcohólico y cáncer. Se plantea que el estrés oxidativo podría ser el factor causal común de las comorbilidades asociadas a la obesidad. Objetivo: Evaluar el balance prooxidante/antioxidante en ratas con obesidad inducida con glutamato monosódico. Material y Métodos: Ratas Wistar hembras recibieron glutamato monosódico (4 mg/g de peso corporal) para inducir obesidad o NaCl 0,9 por ciento (Controles) subcutáneamente en período neonatal. A los 90 días, se confirmó la obesidad. Se les practicó eutanasia a los 180 días para la obtención de sangre e hígado para la determinación de marcadores bioquímicos. Resultados: Las ratas obesas presentaron niveles incrementados de TAG, AU, insulina e índices HOMA y TyG. Se constataron mayores concentraciones de nitratos y nitritos, productos avanzados de la oxidación de proteínas y productos de oxidación de la 2-desoxirribosa en el ADN en las ratas obesas. Conclusiones: Se concluye que la obesidad inducida con glutamato monosódico reproduce las principales alteraciones metabólicas asociadas a la obesidad visceral humana, dentro de las que se incluye el estrés oxidativo. Este modelo podría ser útil en la evaluación de estrategias terapéuticas para prevenir o disminuir complicaciones asociadas a la obesidad(AU)

Introduction: Obesity, especially visceral, is a major risk factor for several diseases such as Type 2 diabetes mellitus, cardiovascular diseases, atherosclerosis, dyslipidemia, non-alcoholic fatty liver disease, and cancer. Oxidative stress may be a unifying mechanism for the development of major obesity-related comorbidities. Objective: To evaluate the prooxidant-antioxidant balance in monosodium glutamate-induced obesity in Wistar rats (MSG- obese rats). Material and Methods: Female Wistar rats received subcutaneous (sc) injections of monosodium glutamate solution (4 mg/g of body weight) or vehicle (NaCl 0,9 percent; control) to induce obesity during the neonatal period. At 90 days of life, obesity was determined. At 180 days of life, rats were anesthetized and killed to obtain blood and liver samples for the determination of biochemical markers. Results: MSG obese rats presented significantly higher triglycerides, uric acid and insulin levels, as well as elevated HOMA and TyG indexes. Increased concentrations of nitrate and nitrite, 2-deoxyribose oxidation products and advanced oxidation protein products levels were observed in obese rats. Conclusions: Obesity induced by monosodium glutamate reproduces the main metabolic alterations associated with human visceral obesity, among which oxidative stress is included. This model may be useful for the evaluation of therapeutic strategies to prevent or decrease complications associated with obesity(AU)

Effect of the food matrix on the capacity of flavor enhancers in intensifying salty taste.

The effect of the flavor enhancers monoammonium glutamate (MAG), monosodium glutamate (MSG), disodium guanylate (GMP), and disodium inosinate (IMP) on intensifying salty taste in food matrices (shoestring potatoes, requeijão cheese, and beef burgers) with a reduction in the amount of sodium chloride (NaCl) present was evaluated. Experiments were conducted using a central composite rotational design with two variables: the concentrations of flavor enhancer and NaCl added in the food matrix. The effect of IMP was not significant (P > 0.05) on the intensity of salty taste in any of the matrices analyzed. GMP presented lower performance compared to MAG and MSG in intensifying the salty taste of the treatments, regardless of the reduction of NaCl. Compared to MSG and GMP, MAG showed greater efficiency in intensifying the salty taste in requeijão cheese and beef burger with a reduction of 25%, 50%, 75%, and 100% of NaCl. MSG presented higher efficiency compared to MAG and GMP when applied in shoestring potatoes for all reductions of NaCl tested (25%, 50%, and 75%). The ability of flavor enhancers to improve the salty taste depends on the effect of the flavor enhancer, the complexity of the food matrix, and the reduction of NaCl in foods. PRACTICAL APPLICATIONS: The complexity of the food matrix plays a significant role in the perception of salty taste in sodium-reduced products. In these products, sodium reduction may affect the taste enhancer's effect of enhancing salty taste. Therefore, this study broadens the knowledge of the effects of flavor enhancers on different foods, as well as the ability to enhance salty taste in food matrices with NaCl reduction. Moreover, it provides information on how to reduce the sodium content in these matrices while maintaining the same perception of salty taste as a conventional matrix.

Whole-body vibration promotes lipid mobilization in hypothalamic obesity rat.

OBJECTIVES: This study aimed to analyze the effect of whole-body vibration (WBV) on metabolic parameters using the monosodium l-glutamate (MSG) model of obesity. METHOD: MSG-obese rats that were exposed to WBV on a vibrating platform with 60 Hz frequency, 2 mm amplitude, three times/week, 10 min/day, during eight weeks (from postnatal day (PN) 80 to PN136). Blood glucose, creatine kinases (CK and CK-MB) and lipid profile through plasma and liver levels of lipids and lipoproteins were evaluated. Morphology and oxidative stress of adipose and hepatic tissues were further evaluated. RESULTS: When performing a WBV exercise, animals showed contrasting metabolic responses. Vibration Control group (CTL-WBV) presented a reduction in CK and liver triacylglycerol, an increase in glucose, lactate, total cholesterol, liver cholesterol, and LDL while MSG Vibration group (MSG-WBV) showed an increase in total triacylglycerol, VLDL, lactate, CK, liver cholesterol, additional liver lipid peroxidation and LDL, total cholesterol and CKMB reduction. CONCLUSION: Even although the MSG is a model of impacting injury, the metabolic demand of WBV exercise was able to induce mobilization of substrates, highlighting the lipid mobilization in obese animals, it should be used as a metabolic rehabilitation tool in patients with metabolic diseases, such as obesity and diabetes.

Vagotomy associated with splenectomy reduces lipid accumulation and causes kidneys histological changes in rats with hypothalamic obesity

Purpose To evaluate the influence of autonomic vagal and splenic activities on renal histomorphometric aspects in obese rats. Methods Thirty male Wistar rats were used, of which, 24 received subcutaneous injections of monosodium glutamate (MSG) during the first 5 days of life (4 g/kg body weight) and six control animals received injections of saline solution (CON). Five experimental groups were organized (n = 6/group): falsely-operated control (CON-FO); falsely-operated obese (MSG-FO); vagotomized obese (MSG-VAG); splenectomized obese (MSG-SPL); vagotomized and splenectomized obese (MSG-VAG-SPL). Results The MSG-FO group animals showed a significant reduction in body weight and nasal-anal length when compared to CON-FO group animals (p 0.05). The MSG-VAG-SPL group showed significant reduced in most biometric parameters associated with obesity. Falsely-operated obese animals showed a significant reduction in renal weight, glomerular diameters, glomerular tuff and capsule areas and Bowmans space compared to CON-FO group animals (p < 0.05). There was a significant reduction in diameter, glomerular tuft and capsule areas, and Bowmans space in MSG-VAG, MSG-SPL, MSG-VAG-SPL groups when compared to the MSG-FO group. Conclusions Vagotomy associated with splenectomy induces a reduction in the adiposity and causes histological changes in the kidney of obese rats.(AU)

Monosodium glutamate administration early in life alters pineal melatonin nocturnal profile in adulthood

The pinealgland synthesizes melatonin exclusively at night, which gives melatonin the characteristic of a temporal synchronizer of the physiological systems. Melatonin is a regulator of insulin activities centrally and also peripherally and its synthesis is reduced in diabetes. Since monosodium glutamate (MSG) is often used to induce the type 2 diabetic and metabolic syndrome in animal models, the purpose of this work is to evaluate the potential effects of MSG given to neonates on the pineal melatonin synthesis in different agedmale and female rats. Wistar rats were subcutaneously injected with MSG (4mg/g/day) or saline solution (0.9%) from the second to eighth post-natal day. The circadian profiles both melatonin levels and AANAT activity were monitored at different ages. Body weight, naso-anal length, adipose tissues weight, GTT, ITT and serum insulin levels were also evaluated. Typical obesity with the neonatal MSG treatment was observed, indicated by a great increase in adipose depots without a concurrent increase in body weight. MSG treatment did not cause hyperglycemia or glucose intolerance, but induced insulin resistance. An increase of melatonin synthesis at ZT 15 with phase advance was observed in in some animals. The AANAT activity was positively parallel to the melatonin circadian profile. It seems that MSG causes hypothalamic obesity which may increase AANAT activity and melatonin production in pineal gland. These effects were not temporally correlated with insulin resistance and hyperinsulinemia indicating the hypothalamic lesions, particularly in arcuate nucleus induced by MSG in early age, as the principal cause of the increase in melatonin production.

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.

Vagotomy associated with splenectomy reduces lipid accumulation and causes kidneys histological changes in rats with hypothalamic obesity

ABSTRACT Purpose To evaluate the influence of autonomic vagal and splenic activities on renal histomorphometric aspects in obese rats. Methods Thirty male Wistar rats were used, of which, 24 received subcutaneous injections of monosodium glutamate (MSG) during the first 5 days of life (4 g/kg body weight) and six control animals received injections of saline solution (CON). Five experimental groups were organized (n = 6/group): falsely-operated control (CON-FO); falsely-operated obese (MSG-FO); vagotomized obese (MSG-VAG); splenectomized obese (MSG-SPL); vagotomized and splenectomized obese (MSG-VAG-SPL). Results The MSG-FO group animals showed a significant reduction in body weight and nasal-anal length when compared to CON-FO group animals (p < 0.05). The MSG-VAG-SPL group showed significant reduced in most biometric parameters associated with obesity. Falsely-operated obese animals showed a significant reduction in renal weight, glomerular diameters, glomerular tuff and capsule areas and Bowman's space compared to CON-FO group animals (p < 0.05). There was a significant reduction in diameter, glomerular tuft and capsule areas, and Bowman's space in MSG-VAG, MSG-SPL, MSG-VAG-SPL groups when compared to the MSG-FO group. Conclusions Vagotomy associated with splenectomy induces a reduction in the adiposity and causes histological changes in the kidney of obese rats.

Exploring Anhedonia in Kennelled Dogs: Could Coping Styles Affect Hedonic Preferences for Sweet and Umami Flavours?

Kennelled dogs are at risk of suffering chronic stress due to long-term spatial, social and feeding restrictions. Chronic stress may decrease the dogs' capacity to feel pleasure when facing hedonic experiences, modifying their perception for palatable ingredients. However, different abilities to cope with environmental stressors could prevent the onset of anhedonia. Fourteen kennelled Beagle dogs were used to study the acceptability and preference for different dilute sucrose and monosodium glutamate (MSG) solutions. Coping style of animals was previously evaluated through a human approach test (HAT) and classified as close dogs (CD; proactive) or distant dogs (DD; reactive) according to whether or not they approached an unfamiliar human when a feeding opportunity was presented. Consumption results were analysed taking into account the sucrose/MSG concentrations, HAT (CD or DD), age, and weight of the animals. DD presented a lower intake of sucrose (p = 0.041) and MSG (p = 0.069) solutions compared with CD. However, DD exhibited a higher consumption of MSG than CD at its highest concentrations, supporting that their intake depends on solution palatability. Finally, DD did not prefer sucrose or MSG solutions over water at any dilute solution offered. Together, these results suggest that dogs that are categorized as reactive animals could diminish their ability to perceive dilute palatable solutions, reflecting depressive-like behaviours as anhedonia.

Juice from leaves of cacti of the genus Pereskia: effect on the physiological parameters of Wistar rats / Suco das folhas de cactáceas do gênero Pereskia: efeito sobre os parâmetros fisiológicos de ratos Wistar

The objective was to evaluate whether the juice from the leaves of cacti of three species of the genus Pereskia promotes changes in the physiological parameters of Wistar rats. The study was divided into stage 1 (obesity induction with a hypercaloric diet, monosodium glutamate, and sucrose solution), and stage 2 (use of cactus juice). The data of body weight, Body Mass and Lee Indexes, feed intake, adipose tissue mass, and Visceral and Epididymal Fat Indexes were compared by the Tukey test at 5%. Monosodium glutamate and sucrose in association with the hypercaloric diet did not increase adipose tissues. No statistical difference was found between the means of body weight, Body Mass Index and Lee Index, liver weight, and Hepatosomatic Index. Pereskia grandifolia juice promoted a lower total weight gain due to the low feed intake. Pereskia aculeata juice increased the visceral adipose tissue mass. Thus, the Pereskia grandifolia juice presented a better effect on weight gain. These cacti are rich in nutrients and bioactive compounds that can improve food quality, and prevent chronic non-communicable diseases.(AU)

O objetivo foi avaliar se o suco das folhas de cactáceas de três espécies do gênero Pereskia promove alterações dos parâmetros fisiológicos de ratos Wistar. O estudo foi dividido na etapa 1 (indução da obesidade com dieta hipercalórica, glutamato monossódico e solução de sacarose) e etapa 2 (utilização do suco das cactáceas). Os dados do peso corporal, Índices de Massa Corporal e de Lee, consumo alimentar, massa dos tecidos adiposos e seus Índices de Gordura Visceral e Epididimal foram comparados pelo Teste de Tukey a 5%. O glutamato monossódico e a sacarose em associação com a dieta hipercalórica não aumentaram os tecidos adiposos. Não houve diferença estatística entre as médias do peso corporal, Índice de Massa Corporal e Índice de Lee, peso hepático e o Índice Hepato-Somático. O suco da Pereskia grandifolia promoveu um menor ganho de peso total como resultado do baixo consumo alimentar. O suco da Pereskia aculeata aumentou a massa do tecido adiposo visceral. Concluiu-se que o suco da Pereskia grandifolia apresentou melhor efeito sobre o ganho de peso. Tais cactáceas são ricas em nutrientes e compostos bioativos que poderão melhorar a qualidade alimentar e prevenir doenças crônicas não transmissíveis.(AU)

Monosodium glutamate alters the function and morphology of the parotid gland in Sprague Dawley rats / Glutamato monosódico altera la función y morfología de la glándula parótida en ratas Sprague Dawley

Monosodium glutamate (MSG) is a flavor enhancer widely used in the food industry, with obesogenic properties, in addition to causing alterations in the oral cavity. The aim of the study was to observe the morphofunctional changes in the parotid gland after the administration of MSG in rats. 18 newborn male Sprague Dawley rats were used, divided into three groups (Control group; MSG1 group: 4 mg/g weight of monosodium glutamate, 5 doses, kept for 8 weeks, and MSG2 group: 4 mg/g weight of MSG, 5 doses, kept for 16 weeks). The body mass index (BMI) was calculated, and the salivary flow, pH, a-amylase activity, Na, Cl, K and Ca were analyzed by quantitative analysis. After euthanasia by ketamine/xylazine overdose, parotid volume was analyzed and stereology was performed. MSG administration caused an increase in BMI and a decrease in parotid volume as well as a reduction in salivary flow and pH and an increase in a-amylase activity, also increasing the salivary sodium and chlorine levels. Alterations in the normal stereological parameters of the gland were observed. Exposure to MSG caused morphofunctional alterations at parotid gland.

El glutamato monosódico (MSG), es un potenciador del sabor ampliamente utilizado en la industria alimentaria. Diversos estudios han propuesto la relación entre éste y el desarrollo de obesidad, además de provocar alteraciones en la cavidad oral. El objetivo del estudio fue observar los cambios morfofuncionales a nivel de la glándula parótida, posterior a la administración de MSG en ratas. Se utilizaron 18 ratas neonatas Sprague Dawley machos, divididas en tres grupos según su tiempo de exposición y dosis a MSG (Grupo Control, Grupo MSG1: 4 mg/g peso de glutamato monosódico, 5 dosis, mantenidas 8 semanas, Grupo MSG2: 4 mg/g peso de MSG, 5 dosis, mantenidas 16 semanas. Fue calculado el índice de masa corporal (BMI), además de ser analizado el flujo salival, pH, actividad de α-amilasa, y Na, Cl, K y Ca mediante análisis semicuantitativo. Luego de la eutanasia por sobredosis de ketamina/xilasina, las glándulas parótidas fueron extraídas y analizado su volumen y fueron procesadas para histología, y estudio estereológico. La administración de MSG causó aumento en BMI y disminución del volumen parotídeo, además de disminución del flujo y pH salival, así como aumento en actividad de la a-amilasa, aumentando además los niveles de sodio y cloro salival. Fueron observadas alteraciones a nivel de los parámetros estereológicos normales de la glándula. La exposición a MSG causó alteraciones morfofuncionales a nivel parotídeo, observándose una disminución del volumen de la glándula, acompañado de alteraciones en el adenómero y conductos estriados de la glándula, implicados en la producción, secreción y modificación de la saliva, la cual se vio alterada, en el flujo, pH, y en sus componentes.