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.

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.

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.

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.

Efficacy of subconjunctival bevacizumab injection in corneal neovascularisation.

Aim: To evaluate the therapeutic effect of subconjunctival Bevacizumabon corneal neovascularisation Design: A prospective randomized noncomparative study. Method: The charts of 10 consecutive patients with corneal neovascularisation who received single S.C. inj. of Bevacizumab (2.5mg/0.1ml) were reviewed. Digital photographs of the cornea were taken pre & post injection & then at 1 wk,3wk & 2months duration. Digital photographs of the cornea were analyzed to determine the length, density, extent, centricity of corneal neovascularisation and the area of cornea covered by neovascularisation as a percentage of the total corneal area. Results: Subconjunctival injection of Bevacizumab (Avastin) caused significant regression of corneal neovascularisation in 1 pt, partial regression in 6 pts and no effect in 3 pts as measured by length and surface area of neovascularisation. No significant ocular or systemic complications were found. Conclusion: Subconjunctival inj. of Bevacizumab is effective in regressing corneal neovascularisation.

Efeito da metformina no remodelamento miocárdico e renal em ratos obesos com resistência à insulina / Effect of metformin on renal and myocardial remodeling in obese rats with insulin resistance

Diversas evidências comprovam que a obesidade está associada a alterações estruturais e funcionais do coração em modelos humanos e animais. Outros estudos recentes também demonstram que a obesidade humana está associada com alterações na função e na estrutura vascular, especialmente em grandes e médias artérias. Estudos epidemiológicos têm confirmado que a obesidade é um fator de risco significativo para o aparecimento de proteinúria e de doença renal terminal em uma população normal. Com o objetivo de determinar as alterações morfológicas relacionadas ao remodelamento cadíaco, vascular e renal em um modelo experimental de obesidade induzida pelo glutamato monossódico (MSG) e os efeitos da metformina sobre estes achados, foram estudados 25 ratos divididos em cinco grupos: controle com 16 e 22 semanas (CON-16 e CON-22); obeso com 16 e 22 semanas (MSG-16 e MSG-22) e obeso + metformina (MET-22) 300mg/Kg/dia por via oral. A caracterização da resistência à insulina foi feita através da medida da insulina plasmática e cálculo do índice de HOMA-IR. As análises morfológicas e quantificação do colágeno miocárdico foram feitos pelo sistema de imagem Image Pro Plus analysis. A pressão arterial sistólica foi levemente maior no grupo MSG-22, adquirindo significância estatística quando comparada com o grupo MSG-16 (122+-2 vs 108+-2 mmHg, p<0,05). Por outro lado, o grupo MET-22 mostrou níveis mais baixos de pressão arterial (118+-1 mmHg), sem alcançar diferença significativa. No grupo de animais obesos, foi observado aumento na relação média-lumen com 16 semanas (39,9+-3,7 vs 30,2+-2,0 %, p<0,05) e com 22 semanas (39,8+-1,3 vs 29,5+-1,2%, p<0,05), que foi reduzida com o uso da metformina (31,5+-0,9%). O depósito de colágeno na área perivascular no ventrículo esquerdo foi significativamente maior no grupo MSG-22 (1,39+-0,06 vs 0,83+-0,06 % no CON-22, p<0,01), sendo atenuado pela metformina (1,02+-0,04%). No rim, a área seccional transversa das arteríolas intrarrenais ...

Many evidences show that obesity is associated to structural and functional changes in the heart of human and animal models. Recent studies also show that human obesity is associated with vascular structural and functional modifications, specially at large and medium-sized arteries. Epidemiological studies have confirmed that obesity is a significant risk factor for the development of proteinuria and end-stage renal disease in a normal population. With the objective to determinate morphological changes related to cardiac, vascular and renal remodeling in an experimental model of monosodium glutamate (MSG)-induced obesity and the effect of metformin at this finding. Twenty five rats were studied and divided into five groups: control with 16 e 22 weeks (CON-16 and CON-22); obese with 16 and 22 weeks (MSG-16 e MSG-22), and obese + metformin (MET-22) 300mg/Kg/day per oral. The characterization of insulin resistance was done through measurement of plasma insulin and calculation of HOMA-IR index. The morphological analysis and the quantification of myocardial collagen were carried out by Image Pro Plus analysis system. The systolic blood pressure was slightly higher in MSG-22 group, reaching statistical significance when compared to MSG-16 group (122+-2 vs 108+-2 mmHg, p<0.05). On the other hand, the MET-22 group demonstrated lower blood pressure levels (118+-1 mmHg), without reaching statistical difference. The obese animals presented increase in media-to-lumen ratio with 16 weeks (39.9+-3.7 vs 30.2+-2.0 %, p<0.05) and with 22 weeks (39.8+-1.3 vs 29.5+-1.2%, p<0.05), which was reduced with use of metformin (31.5+-0.9%). The collagen deposition in perivascular area of left ventricle was significantly greater in MSG-22 group (1.39+-0.06 vs 0.83+-0.06 % in CON-22, p<0.01), and attenuated by metformin (1.02+-0.04%). In the kidney, the media cross-sectional area of intrarenal arterioles was similar among the groups ...

Effect of the oral administration of monosodium glutamate during pregnancy and breast-feeding in the offspring of pregnant Wistar rats / Efeito da administração de glutamato monossódico durante a gestação e amamentação na prole de ratas Wistar prenhes

PURPOSE: Determine the effects of the MSG (monosodium glutamate) in the offspring of pregnant rats through the comparison of the weight, NAL (nasal-anal length) and IL (Index of Lee) at birth and with 21 days of life. METHODS: Pregnant Wistar rats and their offspring were divided into 3 groups: GC, G10 and G20. Each of the groups received 0 percent, 10 percent and 20 percent of MSG, respectively from coupling until the end of the weaning period. RESULTS: Neither weight nor NAL were different among the groups at birth. The group G20 at birth had an IL lower than the group GC (p<0,05) and with 21 days of life presented weight and NAL lower than the groups G10 and this lower than the GC (p<0,01). Otherwise the G20 at 21 days of life had the IL similar to the other two groups. The weight profit percentage from birth to the 21st day of life was lower in the G20 regarding the other two groups (p<0,01). The G20 had a NAL increase percentage from birth to the 21st day of life lower than the G10 and this lower than the GC (p<0,01). CONCLUSIONS: MSG presented a dose-dependent relation in the variables weight and NAL. It caused a decrease in the growth pattern as well as in the weight gain pattern until the 21st day of life. The IL of the group 20 percent had an increased in relation to the control group after 3 weeks of follow up.

OBJETIVO: Avaliar o efeito do glutamato monossódico (GMS) nos fetos de ratas prenhes por meio da comparação do peso, comprimento nasal-anal (CNA) e índice de Lee (IL) ao nascimento e com 21 dias de vida. MÉTODOS: Foram utilizadas ratas prenhes da linhagem Wistar distribuídas em três grupos: grupo controle (GC), G10 e G20. Estes, respectivamente, foram alimentados com ração contendo 0, 10 e 20 por cento de GMS desde o período de acasalamento até o final da amamentação. RESULTADOS: O peso e o CNA não foram diferentes entre os grupos ao nascimento. O grupo G20, ao nascimento, teve IL menor que o grupo GC (p < 0,05) e, aos 21 dias de vida, apresentou peso e CNA menores que o grupo G10, o qual foi menor que o GC (p < 0,01). O grupo G20, aos 21 dias de vida, teve IL semelhante aos outros dois grupos. O percentual de ganho de peso do nascimento ao 21º dia de vida foi menor no G20 em relação aos outros dois grupos (p < 0,01). O grupo G20 teve percentual de aumento de CNA do nascimento ao 21º dia de vida menor que o grupo G10, e este menor que o grupo GC (p < 0,01). CONCLUSÕES: O GMS nas concentrações de 10 e 20 por cento na ração de ratas prenhes Wistar apresentou uma relação dose-dependente nas variáveis peso e CNA. Houve diminuição no padrão de ganho de peso e de aumento de CNA do nascimento ao 21º dia de vida com uso de GMS. O IL na prole do grupo G20 aumentou em relação ao do grupo GC após 3 semanas de acompanhamento.

Effects of monosodium glutamate on food acceptance and toxicity of selenium in rats.

Food acceptance and toxic effects of feeding sodium selenite (Se) alone and in combination with monosodium glutamate (MSG), a taste enhancer were studied in the laboratory rat. Dose-dependent stimulation of daily food intake was observed with MSG offered in no-choice or bi-choice with the plain food. Consumption of pellets containing 0.05, 0.5 and 1.0% Se was significantly low than the plain or MSG containing pellets but their active ingredient was sufficient to cause mortality of rats. Food pellets containing both MSG and Se in no-choice feeding trial were not preferred by the rats, as their consumption remained low as compared to pellets containing only MSG. However, prior feeding on MSG containing pellets for two days increased the amount of intake of Se-containing pellets. No mortality of rats feeding on pellets containing different concentrations of MSG was recorded. Feeding on Se-containing pellets caused dose-dependent mortality on the third day of the trial. As compared to rats feeding on Se-containing pellets, the mortality rate was reduced in those provided Se in combination with MSG but the intake of active ingredient of Se in both these trials did not differ significantly. Decrease in death rate of rats feeding on Se in combination with MSG containing pellets suggested that addition of MSG to seleniferous food probably provide protection to some extent from the toxic effects of selenium. However, combination of excess doses of MSG and Se in food pellets caused mortality of all experimental animals.

Differential effect of polyherbal, antiobesity preparation, OB-200G in male and female mice and monosodium glutamate-treated rats.

Effect of administration of different doses (0.25, 0.5, 1 and 2 g/kg, twice daily, po) of a polyherbal preparation, OB-200G and fluoxetine (10 mg/kg, ip) for 21 days was studied on food intake and body weight in male and female Laka mice. The study further investigated the effect of administration of 0.5 g/kg dose of OB-200G for 40 days on body weight, fat pad weights, locomotor activity and biochemical parameters in monosodium glutamate (MSG)-treated male and female Wistar rat pups. Administration of OB-200G produced dose dependent decrease in body weight in both male and female mice. On the other hand, fluoxetine decreased body weight only in female mice. The food intake was significantly (P < 0.05) increased in both fasted male and female mice after treatment with the lower dose (0.25 g/kg, po) of OB-200G. However, significant (P < 0.05) decrease in food intake was recorded with the administration of higher doses (0.5, 1 and 2 g/kg, po) of OB-200G and fluoxetine in fasted female mice on day 1, 7, 14 and 21. But in male mice differential effect on food intake was recorded at different doses on day 1, 7, 14 and 21. Further, OB-200G administration significantly (P < 0.05) decreased body weight and fat pad weights, increased serum glucose levels and ambulatory activity in MSG-treated female rats but not in MSG-treated male rats. The results suggest that OB-200G involves gender differences in mediating its antiobesity effect and may supplement the current armamentarium for the treatment of obesity.

Processo de reparo em feridas de extraçäo dental em ratas submetidas à açäo do glutamato monossódico: estudo histológico / Monossodium glutamate effect on the healing of extraction wounds in female rats: histological study

A presente investigaçäo foi efetuada com o objetivo de se analisar histologicamente a evoluçäo do processo de reparo em feridas de extraçäo dental em ratas submetidas à açäo do glutamato monossódico. Setenta ratas receberam por vias subcutânea soluçäo de glutamato monossódico (4 mg/g de peso corporal em 0,1 ml de soluçäo de Nacl) nos períodos de 2, 4, 6, 8 e 10 dias após o nacimentos. Setenta ratas receberam soluçäo de Nacl a 0,9 por cento (0,1 nl/rata) nos mesmos períodos. Decorridos noventa dias do tratamento, os incisivos centrais superiores direitos de todos os animais foram extraídos. Os animais foram sacrificados nos períodos de 1, 3, 6, 9, 15, 21 e 30 dias após a cirurgia. Os resultados obtidos permitiram concluir que as ratas que foram tratadas com glutamato monossódico perderam peso corporal, sugerindo lesöes hipotalâmicas além de um retardo na cronologia do processo de reparo alveolar, com interferência especialmente na fase de organizaçäo do coágulo e na fase de proliferaçäo celular, sendo o tecido ósseo neoformado mais imaturo e a cortical óssea alveolar sofreu extensas áreas de reabsorçäo nos terços médios e cervical, no 3º, 6º e 9º dias pós-operatórios

The effect of adipose cell size on the measurement of GLUT 4 in white adipose tissue of obese mice

Glucose transporter (GLUT 4) was assessed in subcellular membrane fractions of white adipose tissue (WAT) from obese insulin-resistant aurothioglucose (AuTG)- or monosodium glutamate (MSG)-treated mice. Obesitywas demonstrable by increased body weight and/ or Lee index, as well as by the heavier WAT and brown adipose tissue in relation to similar weights of gastrocnemius and heart. In vivo insulin-resistance in obese animals was suggested by moderate hyperglycemia and severe hyperinsulinemia. Morphological analyses of adipose cells showed a > 10-fold increase in cell volume of obese mice. Subcellular fractionation indicated a reduced (P<0.01) protein membrane content in the fat-free extract (FFE) from obese mice. However, the specific activity of 5'nucleotidase, a plasma membrane (PM) marker, in EFE and PM did not differ among groups. In addition, the total PM enzyme activity per unit of cell surface area was also unchanged. The GLUT 4 content, assessed by Western blotting and expressed per µg membrane protein, was reduced by ~50 percent (P<0.01) in all membrane fractions from obese animals. However, the total FFE GLUT 4 content per cell was increased...

Chemical lesion of the circumventricular organs with monosodium glutamate reduces the blood pressure of spontaneously hypertensive but not of one kidney-one clip hypertensive rats

Subcutaneous injection of monosodium glutamate (MSG) on days 1, 5 and 9 of the experiment (5g/kg per day) significantly reduced the blood pressure of a group of 10 spontaneously hypertensive rats (SHR) measured 7 and 14 days after treatment (200 ñ 7 mmHg vs 172 ñ 8 mmHg or 185 ñ 3 mmHg, respectively) without affecting that of 11 age-matched Wistar Kyoto (WKY) rats (127 ñ 7 mmHg and 119 ñ 5 mmHg, respectively). Using autoradiographic methods and 125 I-Sar 1-angiotensin II, receptor binding was shown to be higher in the subfornical organ (SFO) of SHR (332 ñ 31 fmol/mg protein) when compared to WKY rats (240 ñ 30 fmol/mg protein) and similar (222 ñ 21 vs 170 ñ 14 fmol/mg protein) in the paraventricular (PVN). Binding to angiotensin-converting enzyme (ACE) was evaluated using the ACE inhibitor 125 I-35 A as ligand. Binding to ACE was lower in SHR in the PVN and the globus pallidus (GP) of SHR when compared to WKY rats (PVN: 111 ñ 9 vs 172 ñ 13 and GP: 163 ñ 2 vs 213 ñ 7 fmol/mg protein) and similar in the SFO, choroid plexus (ChP) and caudate nucleus (CD) of both strains (SFO: 779 ñ 107 vs 805 ñ 169; ChP: 2, 780 ñ 210 vs 3, 140 ñ 360 and CD: 461 ñ 42 vs 424 ñ 18 fmol/mg protein). No changes in angiotensin II (Ang II) receptor number or binding to ACE were detected in thesebrain areas after MSG treatment of SHR or WKY rats. Similar MSG treatment did not affect the development of one kidney-one clip (1K-1C) experimental hypertension in a group of 10 Wistar rats when compared a group of 8 saline-treated animals. 1K-1C surgery was performed 7 days after MSG treatment and blood pressure measured before (saline 123 ñ 1 mmHg vs MSG 126 ñ 1 mmHg) and both 7 (151 ñ 4 mmHg vs 158 ñ 3 mmHg) and 15 days (163 ñ 4 mmHg vs 172 ñ 6 mmHg) after surgery. The results support the hypothesis of a differential role of central MSG-sensitive mechanisms in genetic and experimental renal forms of hypertension

Inflammatory edema induced by carrageenin in monosodium glutamate-treated rats

Rats treated with monosodium glutamate (MSG) during the neonatal period show hypothalamic lesions and multiple neuroendocrine alterations manifested as a remarkable increase in levels of circulating corticosterone and obesity. Paw edema induced by local injection of carrageenin was significantly reduced in MSG-treated rats compared to normal rats. In contrast, both adrenalectomized rats and adrenalectomized, MSG-treated rats showed an increased response to carrageenin relative to controls. These results suggest that glucocorticoids are important modulators of inflammation in this phase of the process