Reactivity of astrocytes in the periaqueductal gray matter of rats treated with monosodium glutamate

Abstract

Introduction. The astrocytic S100b calcium-binding protein performs numerous intra-and extracellular functions, promoting the survival of central nervous system (CNS) structures. Its increased synthesis and release are a manifestation of reactive glial behavior, crucial for the maintenance of proper neuronal function, particularly under the pathological conditions. The periaqueductal gray matter (PAG) is a mindbrain area composed of four parts dorsomedial (dm), dorsolateral (dl), lateral (l) and ventrolateral (vl)) which are involved in pain sensing and defensive reactions of the body. The aim of this study was to evaluate the S100b protein immunoreactive (S100b-IR) astrocytes in adult rats after administration of monosodium glutamate (MSG). Material and methods. The animals were administered the saline solution (group C), 2 g/kg b.w. MSG (group I) and 4 g/kg b.w. MSG (group II). The study was carried out on the brain sections stained by immunohistochemical peroxidase-antiperoxidase method with a primary mouse antibody against the S100b protein.Results. The analyses showed the presence of the S100b-immunoreactive cells in dm, dl, l, vl PAG of all animals. In the C and I group animals, the PAG astrocytes were characterized mainly by the presence of the studied protein in the nucleus and cytoplasm of the cell body. In the group II rats in all parts of PAG, the S100b-IR cells with numerous, thicker and branched processes were observed. A decrease in the number of the S100b-IR cells was found in dm, dl and l PAG in the MSG-treated animals, particularly with the larger dose. The number of cells with the S100b expression was comparable in vl PAG in all rats. Conclusions. MSG administered parenterally to the higher dose to adult rats affects the immunoreactivity of S100b protein in PAG. Phenotypic changes of the studied cells may indicate reactivity of glial cells and increased expression of the studied protein whereas a decrease in their number may result from the increased protein secretion into the extracellular space or cytotoxic death of glial cells.

Reactivity of astrocytes in hippocampal CA1 area in rats after administration of habanero peppers

“…GFAP-IR and S100β-IR astrocytes of CA1 area were observed and photographed under light microscope Olympus BX 51 (Olympus, Tokyo, Japan) with Olympus Color View IIIu digital camera. Based on the immunoreactivity for GFAP and S100β the morphology of the astrocytes and their distribution in the different layers of the hippocampal CA1 area were analysed [17].…”

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

“…При відтворенні тривожно-депресивних розладів поведінки у білих щурів під впливом глутамату натрію відмічено порушення функції серотонінергічної системи [16], емоційних та адаптивних реакцій, а також зменшення активності лабораторних тварин при введенні харчової добавки у дозі 20 мг/кг [17]. Зміни з боку сірої речовини головного мозку, а саме збільшення кількості білку, вірогідно, внаслідок загибелі гліальних клітин описано в експериментальному дослідженні при введенні глутамату натрію підшкірно у дозі 2 г/кг та 4 г/кг маси тіла протягом 3 днів [18]. Пошкодження гіпоталамусу та порушення роботи органівмішеней негативно впливає на нейроендокринну регуляцію [19].…”

Mechanisms of Monosodium Glutamate Impact on Organs and Systems

“…Введення ГН щурам підшкірно в дозі 2 г/кг та 4 г/кг маси тіла протягом 3 днів поспіль викликало морфологічні зміни в астроцитах сірої речовини головного мозку. Зокрема, в міжклітинному просторі реєстрували збільшення кількості білку S100β, вірогідно, внаслідок загибелі гліальних клітин [23].…”