Blocking ERK signaling pathway lowers MMP-9 expression to alleviate brain edema after traumatic brain injury in rats / 南方医科大学学报

OBJECTIVE@#To investigate the effects of blocking the activation of ERK pathway on the expression of matrix metalloproteinase-9 (MMP-9) and the formation of cerebral edema in SD rats after brain injury.@*METHODS@#Ninety SD rats were randomly divided into 3 equal groups, including a sham-operated group, modified Feeney's traumatic brain injury model group, and ERK inhibition group where the ERK inhibitor SCH772984 (500 μg/kg) was injected via the femoral vein 15 min before brain trauma. At 2 h and 2 days after brain trauma, the permeability of blood-brain barrier was assessed by Evans blue method, the water content of the brain tissue was determined, and the phosphorylation level of ERK and the expression level of MMP-9 mRNA and protein were measured by RT-PCR and Western blotting.@*RESULTS@#Compared with the sham-operated group, the rats with brain trauma exhibited significantly increased level of ERK phosphorylation at 2 h and significantly increased expression of MMP-9 mRNA and protein 2 days after the injury ( < 0.01). Treatment with the ERK inhibitor significantly decreased the phosphorylation level of ERK after the injury ( < 0.01), suppressed over-expression of MMP-9 mRNA and protein 2 days after the injury ( < 0.01). The permeability of blood-brain barrier increased significantly 2 h after brain trauma ( < 0.05) and increased further at 2 days ( < 0.01); the water content of the brain did not change significantly at 2 h ( > 0.05) but increased significantly 2 d after the injury ( < 0.01). Treatment with the ERK inhibitor significantly lowered the permeability of blood-brain barrier and brain water content after brain trauma ( < 0.01).@*CONCLUSIONS@#Blocking the activation of ERK pathway significantly reduced the over-expression of MMP-9 and alleviates the damage of blood-brain barrier and traumatic brain edema, suggesting that ERK signaling pathway plays an important role in traumatic brain edema by regulating the expression of MMP-9.

Blocking ERK signaling pathway lowers MMP-9 expression to alleviate brain edema after traumatic brain injury in rats / 浙江大学学报·医学版

OBJECTIVE@#To investigate the effects of blocking the activation of ERK pathway on the expression of matrix metalloproteinase-9 (MMP-9) and the formation of cerebral edema in SD rats after brain injury.@*METHODS@#Ninety SD rats were randomly divided into 3 equal groups, including a sham-operated group, modified Feeney's traumatic brain injury model group, and ERK inhibition group where the ERK inhibitor SCH772984 (500 μg/kg) was injected via the femoral vein 15 min before brain trauma. At 2 h and 2 days after brain trauma, the permeability of blood-brain barrier was assessed by Evans blue method, the water content of the brain tissue was determined, and the phosphorylation level of ERK and the expression level of MMP-9 mRNA and protein were measured by RT-PCR and Western blotting.@*RESULTS@#Compared with the sham-operated group, the rats with brain trauma exhibited significantly increased level of ERK phosphorylation at 2 h and significantly increased expression of MMP-9 mRNA and protein 2 days after the injury ( < 0.01). Treatment with the ERK inhibitor significantly decreased the phosphorylation level of ERK after the injury ( < 0.01), suppressed over-expression of MMP-9 mRNA and protein 2 days after the injury ( < 0.01). The permeability of blood-brain barrier increased significantly 2 h after brain trauma ( < 0.05) and increased further at 2 days ( < 0.01); the water content of the brain did not change significantly at 2 h ( > 0.05) but increased significantly 2 d after the injury ( < 0.01). Treatment with the ERK inhibitor significantly lowered the permeability of blood-brain barrier and brain water content after brain trauma ( < 0.01).@*CONCLUSIONS@#Blocking the activation of ERK pathway significantly reduced the over-expression of MMP-9 and alleviates the damage of blood-brain barrier and traumatic brain edema, suggesting that ERK signaling pathway plays an important role in traumatic brain edema by regulating the expression of MMP-9.

Role of P38 signaling pathway in neonatal rat astrocyte swelling and aquaporin-4 expression after oxygen-glucose deprivation and recovery / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of P38 signaling pathway in neonatal rat astrocyte swelling and the expression of aquaporin-4 (AQP4) after oxygen-glucose deprivation (OGD) and recovery (OGD/R).</p><p><b>METHODS</b>Primarily cultured neonatal rat astrocytes were subject to OGD for 5 h followed by oxygen-glucose recovery in the presence or absence of the P38 inhibitor SB203580 (10 µmol/L). The astrocytes were investigated at 0.5, 2, 8 and 24 h after oxygen-glucose recovery for morphological changes and cell injuries using lactate dehydrogenase (LDH) assay. The expressions of P38, P-P38, and AQP4 mRNAs and proteins in the astrocytes were detected using RT-PCR and Western blotting.</p><p><b>RESULTS</b>OGD/R caused significantly enhanced expression of P-P38 protein, and this effect was blocked by SB203580. AQP4 mRNA and protein expression declined transiently at 0.5 h after OGD and increased gradually to reach the peak level at 8 h (P<0.05). Application of the SB203580 significantly lowered OGD-induced AQP4 mRNA and protein up-regulation (P<0.05). Astrocyte swelling occurred after OGD/R but was obviously lessened by SB203580. LDH release increased markedly after OGD/R, and was attenuated by treatment with SB203580 (P<0.01).</p><p><b>CONCLUSION</b>P38 signaling pathway participates in astrocyte swelling after OGD/R, and blocking this pathway can attenuate AQP4 up-regulation and ameliorate the cell swelling.</p>

Blocking p38 signal pathway lowers MMP-9 expression and reduces brain edema in rats with traumatic brain injury / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of p38 signal pathway in regulating matrix metalloproteinase-9 (MMP-9) expression and brain edema formation in a rat model of traumatic brain injury (TBI).</p><p><b>METHODS</b>A total of 130 adult male Sprague Dawley rats were randomly divided into 4 groups, namely the normal group (n=10), sham-operated group (n=40), TBI (induced by Feeney free falling methods) group (n=40), and SB group with intraperitoneal SB203580 treatment (10 µmol/L) 15 min before TBI (n=40). The rats were sacrificed 2 h and 2 days after TBI. The expressions of p38, p-p38, and MMP-9 mRNA and protein were detected by RT-PCR and Western blotting. The blood brain barrier permeability was detected by Evans Blue (EB) test, and the brain water content (BWC) was determined using a gravimetric technique.</p><p><b>RESULTS</b>The expression of p-p38 protein increased markedly 2 h after TBI (P<0.05), and was suppressed by SB203580 treatment (P<0.05). MMP-9 mRNA and protein showed no obvious increase at 2 h after TBI, but significantly increased at 2 days as compared with those in the sham-operated group (P<0.05). MMP-9 mRNA and protein were much lower in SB group than in TBI group 2 days after TBI (P<0.05). The blood brain barrier permeability significantly increased 2 h after TBI (P<0.05) and kept increasing until 2 days (P<0.05), but was reduced significantly by SB203580 (P<0.05). BWC increased obviously 2 days after TBI (P<0.05) and was lessened by SB203580 (P<0.05).</p><p><b>CONCLUSION</b>Blocking p38 signal pathway can attenuate MMP-9 upregulation and brain edema after TBI, suggesting the important role of p38 in regulating MMP-9 expression to affect traumatic brain edema.</p>

Effect of apolipoprotein E polymorphisms on intracellular Ca2+ concentration in the early stage after astrocyte injury / 中华创伤杂志

Objective To investigate the correlation between apolipoprotein E (protein:apoE;gene:APOE) polymorphisms and intracellular Ca2 + concentration in the early stage after astrocyte injury.Methods ( 1 ) The CDS region of three APOE alleles was obtained by using reverse transcription polymerase chain reaction (RT-PCR). Then, the recombinant plasmid pEGFP-N1-APOE was constructed and identified by sequencing. (2) Astrocytes were separated from APOE gene-knockout mice for immunocytochemical identification. The recombinant plasmid was transfected into the astrocytes with liposome-mediated method to screen the cell lines that could stably express APOE information. (3) Cell injury models were set up by scarification. Laser scanning confocal microscope (LCSM) was used to detect the dynamic changes of intracellular Ca2+ at 12, 24, 48 and 72 hours postinjury. Results Compared with the control group ( before injury ), every allele showed significant changes of fluorescence intensity of Ca2 + ( P ＜0.05). At 12 hours after injury, the fluorescence intensity of Ca2+ was weak, with no statistical difference between three groups ( P ＞ 0. 05 ). At 24,48 and 72 hours postinjury, the fluorescence intensity was increased progressively, with significant higher intensity in ε4 group than the other two groups (P ＜0.05 ). Conclusions The concentration of intracellular Ca2+ in the astrocytes carrying APOEε4 allele is higher than that of those carrying APOEε2 and ε3 alleles, indicating that APOEε4 carriers may activate Ca2+ channel and lead to aggravation and poor prognosis of acute injury.