Nitric oxide system parameters in the basal magnocellular nucleus of the rat brain following intracerebroventricular administration of colchicine

Abstract

Background. The basal magnocellular nucleus (BMN) is a brain structure that provides cholinergic innervation of the neocortex. Disruption of BMN functional activity is observed in many neurodegenerative diseases. One of the key regulatory systems of neuronal activity in the brain is the nitric oxide (NO) system, however, the interactions among NO system components during neurodestruction have not yet been fully elucidated. Objective. The aim of the study was to determine L-arginine, nitrites, nitrotyrosine levels, iNOS, and nNOS expression in the rat BMN in a model of colchicine-induced neurodestruction. Methods. The study involved 30 male Wistar rats divided into three groups: intact, sham-operated with intracerebroventricular (ICV) administration of 3 μl of NaCl, and colchicine group with ICV injection of colchicine (15 μg/3 μl NaCl). ICV injections were carried out using a digital stereotaxic apparatus. Two weeks after colchicine administration, the animals developed cognitive deficits evidenced by behavioral testing. Following euthanasia, the brain tissue was rapidly removed for further processing. iNOS and nNOS expression was assessed via immunofluorescence microscopy, nitric oxide metabolites were measured using the Griess method, L-arginine concentration via HPL C-MS, and nitrotyrosine level via EL ISA. Results. Intracerebroventricular administration of colchicine was followed by a decrease in L-arginine level accompanied by a significant increase in NO metabolites and nitrotyrosine levels in the BMN of rats. Immunofluorescent analysis revealed increased density of iNOS-positive and a progressive reduction of nNOS-positive cells in the BMN cell population of colchicine-injected rats. Correlation analysis confirmed that NO-system imbalance plays a significant role in neurodestruction. Conclusions. Colchicine-induced neurodestruction in the rat BMN is associated with imbalance of the nitric oxide system characterized by decreased L-arginine levels, increased NO metabolites and nitrotyrosine content, elevated iNOS expression, and reduced nNOS-positive cell density. These alterations may contribute to neurodegenerative processes in the BMN. Вступ. Базальне магноцелюлярне ядро (BMN) є структурою головного мозку, що забезпечує холінергічну іннервацію неокортексу. Порушення функціональної активності BMN спостерігається під час багатьох нейродегенеративних захворюваннях. Однією з ключових регуляторних систем нейрональної активності в мозку є система оксиду азоту (NO), проте взаємодія між компонентами системи NO в умовах нейродеструкції досі залишається недостатньо з’ясованою. Мета. Метою дослідження було визначити рівні L-аргініну, нітритів, нітротирозину, а також експресію iNOS та nNOS у BMN щурів за моделювання колхіцин-індукованої нейродеструкції.