c-fos expression in rats with focal cerebral ischemia/reperfusion injury following hyperbaric oxygen intervention

Yizhan CAO; Xing JIN; Qing ZHA; Boliang WANG; Yuexia ZHONG; Guoqiang FU; Baojian HE

ABSTRACT

BACKGROUND:

Hyperbaric oxygen (HBO) can increase oxygen diffusing capacity, thereby, improve hypoxic state of brain edema and brain tissue and promote the recovery of physiological function of brain cells in focal zone, the establishment of bypass circuit, and regeneration and repair of brain cells.

OBJECTIVE:

To observe the effect of hyperbaric oxygen on c-fos oncogene expression of rats at different time points following acute focal cerebral ischemia/reperfusion(I/R) injury.

DESIGN:

Randomized grouping animal experiment.

SETTING:

Department of Emergency, Tangdu Hospital, Fourth Military Medical University of Chinese PLA; Department of Laboratory Medicine, Xi'an Gaoxin Hospital;The General Hospital of the Air Force of Chinese PLA; Hyperbaric Oxygen Treatment Center, Department of Aerospace Medicine, Fourth Military Medical University of Chinese PLA.MATERIALS This experiment was carried out in the Hyperbaric Oxygen Treatment Center, Department of Aerospace Medicine, Fourth Military Medical University of Chinese PLA in April 2002. Sixty-five 2-month-old healthy male SD rats.

METHODS:

The involved rats were randomized into model group (n =20), normal control group (n =5), pure oxygen treatment group (n =20) and HBO treatment group (n =20). In the model group, following the method of Koizumi et al, rat models of middle cerebral artery (MCA) ischemia were developed. In the normal control group, only occlusion of arterial blood flow was omitted; In the pure oxygen treatment group, the operation procedure was the same as that of model group, and embolus being drawn out at ischemia for 1 hour, rats were placed in the hyperbaric cabin at 2,9,21, 45 and 69 hours after embolus being inserted, and they inhaled pure oxygen under the normal pressure; In the HBO treatment group, the operation procedure was the same as that of model group, and rats inhaled pure oxygen for 1 hour under 0.25 MPa pressure. MAIN OUTCOME

MEASURES:

By means of immunohistochemical and pathohistological methods, neutrophilic infiltration,c-fos oncogene protein and positive cell expression in cerebral cortex, preoptic area and corpora striatum of rats in each group were observed at cerebral I/R 5, 12, 24 and 72 hours; Neuronal necrosis degree in cerebral cortex, medial area of corpora striatum and preoptic area, and cerebrovascular leakage area of left cerebral hemisphere of rats were calculated.

RESULTS:

Sixty-five rats were involved in the final analysis. ① c-fos positive products mainly focused in the center of the preoptic area, but they were occasionally seen in the contralateral cortex, slightly expressed in the preoptic area and moderately expressed in the corpora striatum, c-fos positive products began to reduce in the above-mentioned area at ischemia 12 hours, and were obviously reduced at ischemia 24 hours; c-fos positive products in the cerebral cortex and preoptic area were obviously weakened in the HBO treatment group than in the simple ischemia group; At I/R 12 hours,neutrophils in the preoptic area and corpora striatum were significantly lower in the HBO treatment group than in the model group, respectively(P ＜ 0.05); At I/R 24 hours, neutrophils in the cerebral cortex, preoptic area and corpora striatum were significantly lower in the HBO treatment group than in the model group (P ＜ 0.05). ② Cerebrovascular leakage area was more significantly contracted in the HBO treatment group than in the model group (P＜ 0.05); At I/R 72 hours, the number of injured nerve cells in the optic chiasm cortex, medial area of corpora striatum and preoptic area was significantly smaller in the HBO treatment group than in the model group (P＜0.05). Neuronal damage was not found in the sham-operation group.

CONCLUSION:

HBO can markedly contract cerebrovascular leakage area of rats with acute focal cerebral ischemia/reperfusion injury, alleviate the symptoms of nervous system, inhibit neutrophilic infiltration and c-fos oncogene protein expression in the infarct area, and reduce neuronal necrosis in the "penumbral region".