Matrix metalloproteinase inhibitors attenuate neuroinflammation following focal cerebral ischemia in mice

Abstract

The aim of this study was to investigate whether matrix metalloproteinase (MMP) inhibitors attenuate neuroinflammation in an ischemic brain following photothrombotic cortical ischemia in mice. Male C57BL/6 mice were anesthetized, and Rose Bengal was systemically administered. Permanent focal ischemia was induced in the medial frontal and somatosensory cortices by irradiating the skull with cold white light. MMP inhibitors, such as doxycycline, minocycline, and batimastat, significantly reduced the cerebral infarct size, and the expressions of monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and indoleamine 2,3-dioxygenase (IDO). However, they had no effect on the expressions of heme oxygenase-1 and neuroglobin in the ischemic cortex. These results suggest that MMP inhibitors attenuate ischemic brain injury by decreasing the expression levels of MCP-1, TNF-α, and IDO, thereby providing a therapeutic benefit against cerebral ischemia.

Keywords: Indoleamine 2,3-dioxygenase; Matrix metalloproteinase inhibitor; Monocyte chemotactic protein-1; Photothrombotic cortical ischemia; Tumor necrosis factor-α.

Fig. 1

Effects of doxycycline and minocycline on infarct area (left panels) and volume (right panels) in mice. Animals were treated with doxycycline (20 mg/kg, s.c.) or minocycline (45 mg/kg, s.c.) 30 min before and 2 h after ischemic insult, and were sacrificed 24 h after photothrombotic cortical ischemia. The numbers in parentheses indicate the numbers of animals. ^*p<0.05, ^**p<0.01 vs. vehicle group.

Fig. 2

Effect of matrix metalloproteinase (MMP) inhibitors on expression of monocyte chemotactic protein-1 (MCP-1) in ischemic cerebral cortex after photothrombotic cortical ischemia in mice. Doxycycline (20 mg/kg) or minocycline (45 mg/kg) was administered s.c. 30 min before and 2 h after ischemic insult, and batimastat (50 mg/kg) was administered i.p. 30 min before ischemic insult. The animals were sacrificed 24 h after photothrombotic cortical ischemia. Four animals were used in each group. Scale bar=50 µm. ^**p<0.01, ^***p<0.001 vs. vehicle group.

Fig. 3

Effect of MMP inhibitors on expression of tumor necrosis factor-α (TNF-α) in ischemic cerebral cortex after photothrombotic cortical ischemia in mice. Animals were treated with doxycycline (20 mg/kg) or minocycline (45 mg/kg) s.c. 30 min before and 2 h after ischemic insult, or with batimastat (50 mg/kg) i.p. 30 min before ischemic insult, and were sacrificed 24 h after photothrombotic cortical ischemia. Three animals were used in each group. Scale bar=50 µm. ^**p<0.01, ^***p<0.001 vs. vehicle group.

Fig. 4

Effect of MMP inhibitors on expression of indoleamine 2,3-dioxygenase (IDO) in ischemic cerebral cortex after photothrombotic cortical ischemia in mice. Animals were treated with doxycycline (20 mg/kg) or minocycline (45 mg/kg) s.c. 30 min before and 2 h after ischemic insult, or with batimastat (50 mg/kg) i.p. 30 min before ischemic insult, and were sacrificed 24 h after photothrombotic cortical ischemia. Numbers in columns indicate the numbers of animals. Scale bar=50 µm. ^**p<0.01, ^***p<0.001 vs. vehicle group.

Fig. 5

Effect of MMP inhibitors on expression of heme oxygenase-1 (HO-1) in ischemic cerebral cortex after photothrombotic cortical ischemia in mice. Animals were treated with doxycycline (20 mg/kg) or minocycline (45 mg/kg) s.c. 30 min before and 2 h after ischemic insult, or with batimastat (50 mg/kg) i.p. 30 min before ischemic insult, and were sacrificed 24 h after photothrombotic cortical ischemia. Numbers in columns indicate the numbers of animals. Scale bar=50 µm.

Fig. 6

Effect of MMP inhibitors on expression of neuroglobin (Ngb) in the ischemic cerebral cortex after photothrombotic cortical ischemia in mice. Animals were treated with doxycycline (20 mg/kg) or minocycline (45 mg/kg) s.c. 30 min before and 2 h after ischemic insult, or with batimastat (50 mg/kg) i.p. 30 min before ischemic insult, and were sacrificed 24 h after photothrombotic cortical ischemia. Numbers in columns indicate the numbers of animals. Scale bar=50 µm.