Fig. 9.

Loss of vascular collagen type IV in brain regions with enlarged paravascular spaces in rats at 13 months post-blast exposure. Coronal brain sections of a blast-exposed rat were treated with pepsin to unmask the collagen type IV epitopes and stained with rabbit polyclonal antibodies against collagen type IV (red). a Lack of collagen type IV immunostaining (red) in the piriform cortical region exhibiting large paravascular spaces (arrows). Note the normal collagen IV staining (red) in the adjacent areas (asterisk). The inset in a corresponds to a section from a control animal showing normal collagen type IV staining (arrow) of the vasculature in the piriform cortex and neighboring regions. b Normal vascular collagen type IV staining of the hippocampal vasculature in the same blast-exposed animal (coll IV, red; GFAP, green). c, d Loss of collagen IV immunostaining in small vessels associated with hypothalamic enlarged paravascular spaces. GFAP⁺ perivascular astrocytic endfeet remained attached (GFAP, green, arrows). e Loss of collagen type IV in the arterial adventitia in regions with enlarged paravascular spaces (α-SMA, green). Arrows in e show arterial regions devoid of collagen IV (red) around a vascular stricture (*). Also note the loss of smooth muscle (α-SMA⁺, green) around the stricture. f Loss of adventitial collagen IV (arrows) in hippocampal arterioles (coll IV, red; α-SMA, green). DAPI, blue. Scale bar, 140 µm a; 20 µm for b–f