Splenic participation in glycemic homeostasis in obese and non-obese male rats

Maternal periodontitis potentiates monosodium glutamate-obesity damage on Wistar offspring's fast-glycolytic muscle

OBJECTIVE

To evaluate the effects of magnifying the damage caused by obesity induced by monosodium glutamate, using a model of maternal periodontitis, on the structure of the anterior tibialis muscle of the offspring.

MATERIALS AND METHODS

Twenty-four female Wistar rats were divided into four experimental groups: control (n = 6), obese (n = 6), control with periodontitis (n = 6) and obese with periodontitis (n = 6). At 78 days of life, the rats were mated with males without any experimental intervention. The offspring of these rats (n = 1/L), at 120 days of life, were weighed and measured, then euthanized. Plasma was collected for analysis of cytokines IL-6, IL-10, IL-17 and TNF-α. Adipose tissues were collected and weighed, and the anterior tibial muscle was designated for histomorphological analyses (n = 6/group).

RESULTS

Monosodium glutamate offspring showed significant muscle changes, such as a reduction in the size of fibres and neuromuscular junctions, and an increase in the nucleus and capillaries. However, all these changes were more expressed in monosodium glutamate-obese with periodontitis offspring.

CONCLUSION

This leads us to suggest a magnifying effect promoted by periodontitis to the damage already well described by monosodium glutamate-obesity, determined by low-intensity inflammation, causing greater muscle damage.

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.

Whole-Body Vibration Promotes Skeletal Muscle Restructuring and Reduced Obesogenic Effect of MSG in Wistar Rats

The negative changes of obesity to the locomotor system are a major concern in the current scenario, where obesity and metabolic syndrome are recurrent in Western societies. A physical exercise is an important tool as a way to rehabilitate obesity, highlighting whole-body vibration, as it is an easy-access modality with few restrictions. In this sense, we sought to evaluate the effect of whole-body vibration on the extensor digitorum longus muscle on a monosodium glutamate-induced obesity model. The main findings of the present study are related to the ability of the treatment with vibration to reduce the obesogenic characteristics and slow down the dyslipidemic condition of the animals. Likewise, the vibration promoted by the vibrating platform was essential in the recovery of the muscle structure, as well as the recovery of the muscle's oxidative capacity, initially compromised by obesity.

MELATONIN IMPROVES SPLEEN HISTOPHYSIOLOGY OF RATS WITH DIET-INDUCED OBESITY: CHRONOTHERAPY APPROACH

One of the most commoncharacteristics of obesity is the development of a systemic low-grade proinflammatory state in the entire body, including the immune organs. Spleen enlargement during diet-induced obesity contributes to the development of chronic inflammation. Melatonin due to immunomodulatory, antioxidant, and systemic metabolic rolesis proposed to be an effective candidate for anti-obesity therapy. As immune systems demonstrate pronounced circadian rhythmicity and immune cells have different types of melatonin receptors, a chronotherapeutic approach might be used to choose the most effective regimes of melatonin administration for the correction of obesity-provoked damage to the spleen. Thus, the main goal of our research was the analysis of the rats' spleen histophysiology during the development of high-calorie diet-inducedobesity (HCD) after administering melatonin daily at different times (morning or evening). Melatonin was administered by gavage for 7 weeks in the dose of 30 mg/kg 1 h before lights-off (HCD ZT11, M ZT11, evening), or 1 h after lights-on (HCD ZT01, M ZT01, morning). For assessment of the morpho-functional state of the spleen,the histopathological evaluation of red and white pulp in different zones of lymphoid follicles was implemented. It was observed that obesity development wasaccompaniedbyhyperemia and vessel dilatation in the red pulp; while in the white pulp notable deformation of germinal centers and destroyed borders between zones of lymphoid follicles were noticed.The HCD group demonstrated a decrease inthe relative amount of the white pulp, the crosssectional area of germinal centers, and the cross-sectional area of the marginal zone; whilethe increased relative amount of red pulp and marginal zone/germinal centers ratiowere detected compared with control. Melatonin administration to obese rats increases the relative amount of the white pulp (HCD ZT11 group), the cross-sectional area of germinal centers (HCD ZT01 and HCD ZT11 groups), and the cross-sectional area of the marginal zone (HCD ZT11 group), and decreasesmarginal zone/germinal centers ratio (HCD ZT01 group) in comparison with the HCD group.Also,it was demonstrated that a choice between the morning or evening regimes of the melatonin treatment did not affect the histophysiology of the spleen in rats receivingthe standard diet (M ZT01 and M ZT11 groups). These results indicate that melatonin can be considered to be a powerful potential therapeutic agent for the amelioration of obesity-induced changes in the spleen.

In Vivo Hypoglycemic Effects, Potential Mechanisms and LC-MS/MS Analysis of Dendropanax Trifidus Sap Extract

Extracts of medicinal plants have been widely used to benefit human health. Dendropanax morbiferus (DM) has been well-studied for its anti-inflammatory and anti-oxidative effects, while Dendropanax trifidus (DT) is a lesser-known ecotype phylogenetically similar to DM, which has received significantly less attention. Studies thus far have primarily focused on leaf and bark extracts of DM, and not much is yet known about the properties of either DM or DT sap. Therefore, here we performed in vivo toxicity and efficacy studies, in order to assess the biological effects of DT sap. To establish a safe dosage range, single dose or two-week daily administrations of various concentrations were performed for ICR mice. Measurements of survival ratio, body/organ weight, blood chemistry, histochemistry and Western blots were performed. A concentration of ≤0.5 mg/g DT sap was found to be safe for long-term administration. Interestingly, DT sap significantly reduced blood glucose in female mice. In addition, increasing concentrations of DT sap decreased phosphorylated (p) insulin receptor substrate (IRS)-1(ser1101)/IRS-1 in liver tissues, while increasing pAMP-activated protein kinase (AMPK)/AMPK in both the liver and spleen. To analyze its components, liquid chromatography-tandem mass spectrometry of DT sap was performed in comparison with Acer saccharum (AS) sap. Components such as estradiol, trenbolone, farnesol, dienogest, 2-hydroxyestradiol and linoleic acid were found to be highly enriched in DT sap compared to AS sap. Our results indicate DT sap exhibits hypoglycemic effects, which may be due to the abundance of the bioactive components.

The neurotherapeutic role of a selenium-functionalized quinoline in hypothalamic obese rats

RATIONALE

Obesity is considered one of the major global health problems and increases the risk of several medical complications, such as diabetes and mental illnesses.

OBJECTIVE

The present study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) on obesity parameters, behavioral and neurochemical alterations in hypothalamic obese rats.

METHODS

Male Wistar rats received subcutaneous neonatal injections of monosodium glutamate (MSG, 4g/kg) or saline. After the Lee Index evaluation, rats were divided into groups and treated with 4-PSQ (5 mg/kg, intragastric route) or canola oil once a day (post-natal days (PND) 60→76). Open-field, elevated plus-maze, forced swim task, object recognition/location memory, and stepdown inhibitory avoidance tasks were conducted from PND 66 to 74. On PND 76, rats were euthanized and epididymal fat, blood, cerebral cortex, andhippocampus were removed. Blood biochemical parameters and cortical/hippocampal acetylcholinesterase (AChE) and Na /K -ATPase activities were assessed.

RESULTS

MSG increased the Lee Index characterizing the chemically induced hypothalamic obesity model. 4-PSQ reversed the increases of epididymal fat, blood glucose, and triglyceride levels caused by MSG exposure. 4-PSQ attenuated anxiety-like and depression-like behaviors induced by neonatal administrations of MSG. Memory deficits found in MSG-obese rats were reversed by treatment with 4-PSQ. Neurochemical alterations produced by MSG evidenced by stimulation ofNa⁺/K⁺-ATPase and AChE activities in the cerebral cortex and hippocampus of rats were normalized by 4-PSQ treatment.

CONCLUSIONS

In brief, 4-PSQ therapy improved hypothalamic obesity-related parameters, as well as psychiatric symptoms, cognitive impairment, and neurochemical alterations found in obese rats.

The Vagus Nerve and Spleen: Influence on White Adipose Mass and Histology of Obese and Non-obese Rats

The vagus nerve (VN) and spleen represent a complex interface between neural and immunological functions, affecting both energy metabolism and white adipose tissue (WAT) content. Here, we evaluated whether vagal and splenic axis participates in WAT mass regulation in obese and non-obese male Wistar rats. High doses of monosodium glutamate (M; 4 g/Kg) were administered during the neonatal period to induce hypothalamic lesion and obesity (M-Obese rats). Non-obese or Control (CTL) rats received equimolar saline. At 60 days of life, M-Obese and CTL rats were randomly distributed into experimental subgroups according to the following surgical procedures: sham, subdiaphragmatic vagotomy (SV), splenectomy (SPL), and SV + SPL (n = 11 rats/group). At 150 days of life and after 12 h of fasting, rats were euthanized, blood was collected, and the plasma levels of glucose, triglycerides, cholesterol, insulin, and interleukin 10 (IL10) were analyzed. The visceral and subcutaneous WAT depots were excised, weighed, and histologically evaluated for number and size of adipocytes as well as IL10 protein expression. M-Obese rats showed higher adiposity, hyperinsulinemia, hypertriglyceridemia, and insulin resistance when compared with CTL groups (p < 0.05). In CTL and M-Obese rats, SV reduced body weight gain and triglycerides levels, diminishing adipocyte size without changes in IL10 expression in WAT (p< 0.05). The SV procedure resulted in high IL10 plasma levels in CTL rats, but not in the M-Obese group. The splenectomy prevented the SV anti-adiposity effects, as well as blocked the elevation of IL10 levels in plasma of CTL rats. In contrast, neither SV nor SPL surgeries modified the plasma levels of IL10 and IL10 protein expression in WAT from M-Obese rats. In conclusion, vagotomy promotes body weight and adiposity reduction, elevating IL10 plasma levels in non-obese animals, in a spleen-dependent manner. Under hypothalamic obesity conditions, VN ablation also reduces body weight gain and adiposity, improving insulin sensitivity without changes in IL10 protein expression in WAT or IL10 plasma levels, in a spleen-independent manner. Our findings indicate that the vagal-spleen axis influence the WAT mass in a health state, while this mechanism seems to be disturbed in hypothalamic obese animals.

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.