Neonatal exposure to monosodium glutamate induces morphological alterations in suprachiasmatic nucleus of adult rat

Abstract

Summary Neonatal exposure to monosodium glutamate (MSG) induces circadian disorders in several physiological and behavioural processes regulated by the suprachiasmatic nucleus (SCN). The objective of this study was to evaluate the effects of neonatal exposure to MSG on locomotor activity, and on morphology, cellular density and expression of proteins, as evaluated by optical density (OD), of vasopressin (VP)‐, vasoactive intestinal polypeptide (VIP)‐ and glial fibrillary acidic protein (GFAP)‐immunoreactive cells in the SCN. Male Wistar rats were used: the MSG group was subcutaneously treated from 3 to 10 days of age with 3.5 mg/g/day. Locomotor activity was evaluated at 90 days of age using ‘open‐field’ test, and the brains were processed for immunohistochemical studies. MSG exposure induced a significant decrease in locomotor activity. VP‐ and VIP‐immunoreactive neuronal densities showed a significant decrease, while the somatic OD showed an increase. Major axes and somatic area were significantly increased in VIP neurons. The cellular and optical densities of GFAP‐immunoreactive sections of SCN were significantly increased. These results demonstrated that newborn exposure to MSG induced morphological alterations in SCN cells, an alteration that could be the basis for behavioural disorders observed in the animals.

A systematic review of the neuropathology and memory decline induced by monosodium glutamate in the Alzheimer’s disease-like animal model

“…The neurobehavioral changes that were studied were mainly the escape latency of animals, locomotor and exploratory behavior, grooming, rearing, cognitive function, anxiety behavior, spatial working memory, memory reconsolidation, and motor coordination. Various neurobehavioral tests were employed in the studies to analyze the cognitive and motor activities, including an open-field test in 20.6% of studies ( n = 6) for locomotor and exploratory behaviors ( Dubovicky et al, 1997 ; Onaolapo et al, 2015 ; Onaolapo et al, 2016a ; Rojas-Castañeda et al, 2016 ; Onaolapo et al, 2017 ; Hassaan et al, 2019 ). The Morris water maze was used to calculate the escape latency of animals in 17.2% of studies ( n = 5) ( Wong et al, 1997 ; Olvera-Cortés et al, 2005 ; Abu-Taweel et al, 2014 ; Jin et al, 2018 ; López-Vázquez et al, 2019 ).…”

Drogas Imunossupressoras Afetam Os Núcleos Hipotalâmicos Envolvidos Na Ingestão Alimentar ? Estudo Experimental

“…Além disso, com base em modelos experimentais, por meio da injeção de glutamato monossódico em altas concentrações em camundongos, foi relatado o rápido ganho de peso dos animais devido à alta toxicidade causada nas células dos núcleos hipotalâmicos envolvidos com a ingestão de alimentos 24,28 .…”

“…Furthermore, based on experimental models, through the injection of high concentrations of monosodium glutamate in mice, the rapid gain of animal weight was reported due to the high toxicity caused in the cells of the hypothalamic nuclei involved with food intake 24 , 28 .…”

Fetal and Postnatal Nicotine Exposure Modifies Maturation of Gonocytes to Spermatogonia in Mice

“…For each of the cells, two background OD measurements were determined in nearby regions without immunoreactive profiles. The mean background OD value calculated was subtracted from the cellular OD value measured to obtain the final OD value [ 30 ].…”