COX-2 and NF-κB expression and ultrastructural alterations in the basal magnocellular nucleus of the rat brain following intracerebroventricular colchicine administration

Abstract

Aim. To provide a comprehensive assessment of cyclooxygenase-2 (COX-2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression as well as ultrastructural alterations in the basal magnocellular nucleus (BMN) of the rat brain following intracerebroventricular administration of colchicine.

Materials and methods. The study was conducted on 30 male Wistar rats aged 10–11 months, allocated into three groups (n = 10 per group): intact, sham-operated (intracerebroventricular administration of 0.9 % saline), and colchicine-treated (intracerebroventricular injection of 15 μg colchicine). The expression of COX-2 and NF-κB in the BMN was evaluated using immunofluorescence microscopy and ImageJ software by calculating corrected total cell fluorescence (CTCF), cell area, and cell density. Ultrastructural alterations in brain tissue, including neurodegeneration, gliosis, and myelin sheath damage, were examined using a PEM-100-01 transmission electron microscope. Statistical analysis was performed using one-way analysis of variance (ANOVA) or the Kruskal–Wallis test (applied according to normality test results), Tukey’s or Dunn’s post hoc test, Pearson’s correlation coefficient (r), Kendall’s tau (τ), linear regression analysis, and analysis of covariance (ANCOVA), with a significance level set at p < 0.05.

Results. In the BMN of rats subjected to intracerebroventricular colchicine administration, a significant decrease in the area of COX-2- and NF-κB-positive cells, a marked increase in their density, and substantial alterations in marker expression were observed. COX-2 expression was characterized by an approximately 3-fold increase in the number of immunopositive cells without a concomitant increase in integrated fluorescence intensity, whereas NF-κB demonstrated both an increased density of positive cells and enhanced expression levels. ANCOVA confirmed an independent effect of colchicine-induced injury on the expression of both markers. Ultrastructural examination revealed pronounced neuropil vacuolization, activation of autophagic–lysosomal processes, enhanced phagocytic activity, myelin sheath degeneration, and axonal edema.

Conclusions. Colchicine-induced neurodegeneration is accompanied by the development of a pronounced neuroinflammatory response in the BMN, manifested by activation of the COX-2 and NF-κB signaling pathways, morphometric remodeling of the cellular population, and profound ultrastructural alterations in nervous tissue. These findings indicate an important role of pro-inflammatory mechanisms in the pathogenesis of colchicine-induced neurodegenerative brain injury.