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

Abstract

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 corticotrophinreleasing 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 MSGinduced 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. K E Y W O R D S ANS activity, glucose homeostasis, HPA axis, MSG rats, obesity How to cite this article: Torrezan R, Malta A, de Souza Rodrigues WDN, et al. Monosodium l-glutamate-obesity onset is associated with disruption of central control of the hypothalamic-pituitary-adrenal axis and autonomic nervous system. J Neuroendocrinol. 2019;31:e12717. https://doi.

Phenylhydrazine‐induced anaemia reduces subcutaneous white and brown adipose tissues in hypothalamic obese rats

“…Dornfest et al (1992) showed that PHZinduced anaemia could be reversed by corticoids treatment. Indeed, MSG-obese rodents exhibit hypercorticosteronaemia (Torrezan et al, 2019), a condition that is not able to prevent anaemia, as demonstrated in the present study. WAT mass accumulation, particularly in male mice (Alnaeeli et al, 2014;Zhao et al, 2015).…”

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

“…Moreover, excessive expansion of WAT in M-Obese rats was characterized by adipocyte hypertrophy in both visceral and subcutaneous WAT depots. Autonomic unbalance, with higher vagal hyperactivity and lower sympathetic tonus, is an evident phenomena in M-Obese rodents, which contributes to elevated WAT mass (Torrezan et al, 2019). In addition, in this obese rodent model, several hormonal and metabolic abnormalities contribute to elevated WAT mass and adipocyte hypertrophy, such as greater insulin lipogenic action (Kulyte et al, 2017), reduced lipolytic responses, higher cortisol and reduced growth hormone (GH) levels.…”

“…One group (n = 44) received a daily subcutaneous injection of monosodium glutamate (MSG) in a dose of 4 g/Kg of body weight (bw) during five consecutive days according to a previously established protocol (Olney, 1969). Elevated MSG doses to neonates provoke hypothalamic lesions, inducing lifelong obesity (Timper and Brüning, 2017;Torrezan et al, 2019). This group was denominated M-Obese.…”

Peculiaritis of Hypothalamic Nuclei Microstructure of the White Rat Under the Effect of Sodium Glutamate and Its Absence

“…Пошкодження гіпоталамусу та порушення роботи органівмішеней негативно впливає на нейроендокринну регуляцію [19]. Досліджено можливий вплив глутамату натрію на розвиток ожиріння та появу нездорової харчової поведінки [20,21]. Враховуючи, що саме структури сірого горба гіпоталамуса беруть участь в енергетичному обміні [22], було доцільним вивчити макрота мікроструктуру даної ділянки під впливом глутамату натрію та за умов його відміни.…”