title: Alterations in enterocyte mitochondrial respiratory function and enzyme activities in gastrointestinal dysfunction following brain injury.
abstract: OBJECTIVE
  To determine the alterations in rat enterocyte mitochondrial respiratory function and enzyme activities following traumatic brain injury (TBI).
  
  
  METHODS
  Fifty-six male SD rats were randomly divided into seven groups (8 rats in each group): a control group (rats with sham operation) and traumatic brain injury groups at 6, 12, 24 h, days 2, 3, and 7 after operation. TBI models were induced by Feendy's free-falling method. Mitochondrial respiratory function (respiratory control ratio and ADP/O ratio) was measured with a Clark oxygen electrode. The activities of respiratory chain complex I-IV and related enzymes were determined by spectrophotometry.
  
  
  RESULTS
  Compared with the control group, the mitochondrial respiratory control ratio (RCR) declined at 6 h and remained at a low level until day 7 after TBI (control, 5.42 ± 0.46; 6 h, 5.20 ± 0.18; 12 h, 4.55 ± 0.35; 24 h, 3.75 ± 0.22; 2 d, 4.12 ± 0.53; 3 d, 3.45 ± 0.41; 7 d, 5.23 ± 0.24, P < 0.01). The value of phosphate-to-oxygen (P/O) significantly decreased at 12, 24 h, day 2 and day 3, respectively (12 h, 3.30 ± 0.10; 24 h, 2.61 ± 0.21; 2 d, 2.95 ± 0.18; 3 d, 2.76 ± 0.09, P < 0.01) compared with the control group (3.46 ± 0.12). Two troughs of mitochondrial respiratory function were seen at 24 h and day 3 after TBI. The activities of mitochondrial complex I (6 h: 110 ± 10, 12 h: 115 ± 12, 24 h: 85 ± 9, day 2: 80 ± 15, day 3: 65 ± 16, P < 0.01) and complex II (6 h: 105 ± 8, 12 h: 110 ± 92, 24 h: 80 ± 10, day 2: 76 ± 8, day 3: 68 ± 12, P < 0.01) were increased at 6 h and 12 h following TBI, and then significantly decreased at 24 h, day 2 and day 3, respectively. However, there were no differences in complex I and II activities between the control and TBI groups. Furthermore, pyruvate dehydrogenase (PDH) activity was significantly decreased at 6 h and continued up to 7 d after TBI compared with the control group (6 h: 90 ± 8, 12 h: 85 ± 10, 24 h: 65 ± 12, day 2: 60 ± 9, day 3: 55 ± 6, day 7: 88 ± 11, P < 0.01). The changes in α-ketoglutaric dehydrogenase (KGDH) activity were similar to PDH, except that the decrease in KGDH activity began at 12 h after TBI (12 h: 90 ± 12, 24 h: 80 ± 9, day 2: 76 ± 15, day 3: 68 ± 7, day 7: 90 ± 13, P < 0.01). No significant change in malate dehydrogenase (MDH) activity was observed.
  
  
  CONCLUSIONS
  Rat enterocyte mitochondrial respiratory function and enzyme activities are inhibited following TBI. Mitochondrial dysfunction may play an important role in TBI-induced gastrointestinal dysfunction.
authors: Ke-Jun Zhu, Shi-Ming Zhang, Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China.
authors: Ke-Jun
authors: KJ
authors: Zhu
authors: Ke-Jun Zhu, Shi-Ming Zhang, Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China.
authors: Hong
authors: H
authors: Huang
authors: Ke-Jun Zhu, Shi-Ming Zhang, Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China.
authors: Hui
authors: H
authors: Chu
authors: Ke-Jun Zhu, Shi-Ming Zhang, Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China.
authors: Hang
authors: H
authors: Yu
authors: Ke-Jun Zhu, Shi-Ming Zhang, Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China.
authors: Shi-Ming
authors: SM
authors: Zhang
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001930:Brain Injuries / Q000150:complications*; D019069:Cell Respiration; D004195:Disease Models, Animal; D015536:Down-Regulation; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism*; D004734:Energy Metabolism; D020895:Enterocytes / Q000201:enzymology*; D005767:Gastrointestinal Diseases / Q000201:enzymology / Q000209:etiology* / Q000503:physiopathology; D007421:Intestine, Small / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D010100:Oxygen / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D045222:Electron Transport Chain Complex Proteins; D000244:Adenosine Diphosphate; D010100:Oxygen
keywords: Brain injury; Enterocyte; Malate dehydrogenase; Mitochondria; Rats