Figure 3.

Glutamate increases MMP-2 and MMP-9 levels, decreases tight junction protein levels, and causes barrier leakage in isolated brain capillaries. A, Western blot showing MMP-2, MMP-9, ZO-1, occludin, claudin-1, and claudin-5 in isolated rat brain capillaries exposed to 0, 50, or 100 μm glutamate (Glu); β-actin was used as protein loading control. B, Western blot showing TIMP-1, TIMP-2, and TIMP-3 protein expression in isolated brain capillaries from control, pilocarpine, and SE rats. C, MMP-2 protein levels in rat brain capillary lysate determined by ELISA from control capillaries and capillaries exposed to 100 μm glutamate. Data are mean ± SEM (n = 3 independent experiments; pooled tissue of n = 10 rats per experiment). Statistical comparison: **t₍₄₎ = 6.65, p = 0.0027 (unpaired t test). D, MMP-9 protein levels in rat brain capillary lysate determined by ELISA from control capillaries and capillaries exposed to 100 μm glutamate. Data are mean ± SEM (n = 3 independent experiments; pooled tissue of n = 10 rats per experiment). Statistical comparison: **t₍₄₎ = 4.63, p = 0.0098 (unpaired t test). E, Texas Red leakage from rat brain capillaries exposed to 100 μm glutamate; high osmotic mannitol was used as positive control for barrier opening. Data are 0–255 AFU and presented as mean ± SEM for n = 7 brain capillaries per time point from one brain capillary isolation with n = 10 rats.