Association between p75 neurotrophin receptor gene expression and cell apoptosis in tissues surrounding hematomas in rat models of intracerebral hemorrhage

Abstract

Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 neurotrophin receptor. p75 neurotrophin receptor protein was detected by immunohistochemistry. p75 neurotrophin receptor mRNA was examined by quantitative real-time polymerase chain reactions. At 24 hours after modeling, cellular apoptosis occured around hematoma with upregulation of p75 neurotrophin receptor protein and mRNA was observed, which directly correlated to apoptosis. This observation indicated that p75 neurotrophin receptor upregulation was associated with cell apoptosis around hematomas after intracerebral hemorrhage.

Keywords: apoptosis; intracerebral hemorrhage; neural regeneration; p75 neurotrophin receptor.

Figure 1

Percentage of apoptosis at 6, 24, 72 hours, and 10 days after intracerebral hemorrhage, respectively as determined by flow cytometry. The apoptosis rate is presented in the tables in the lower right quadrants. FITC: Fluorescein isothiocyanate; PI: propidium iodide. (A–D) Left lower quadrant, annexin V-FITC^-/PI^- is the live cell population; lower right quadrant, annexin V-FITC⁺/PI^- is the apoptotic cell population; upper right quadrant, annexin V-FITC⁺/PI⁺ is the necrotic cell population; left upper quadrant, annexin V-FITC^-/PI⁺ is cell debris.

Figure 2

Hematoxylin-eosin (HE) and immunohistochemical staining of brain tissue surrounding hematomas after intracerebral hemorrhage (ICH). (A) The yellow arrow indicates neuronal apoptosis as shown by darkly stained cytoplasm and chromatin margination around the hematoma. The blue arrow shows the infiltration of neutrophils, suggesting that inflammation occurs around the hematoma after ICH (HE staining, × 400). (B) After ICH, brain tissue edema around the hematoma occurs as indicated by light staining and cell numbers decrease close to the hematoma, (HE staining, × 200). (C) Perivascular edema, suggesting vascular edema after ICH (HE staining, × 400). (D) p75 neurotrophin receptor is mainly expressed in the cytoplasm of neurons in the control (HE staining, × 400). (E–H) Immunohistochemical staining at 6, 24, 72 hours, and 10 days after ICH, respectively (× 400).