Effects of hypertension and mild hypothermia on infarct volume and blood-brain barrier in rats after transient focal cerebral ischemia

Chuanyu LIU; Surong ZHOU; Chengyan LI; Yuanwu MEI

ABSTRACT

BACKGROUND:

Studies have shown that mild hypertension and hypothermia both offer cerebral protection against focal cerebral ischemia,and their possible synergistic effect may provide even better neuroprotective effects.

OBJECTIVE:

To investigate the mechanism of cerebral protection by induced hypertension combined with mild hypothermia against focal cerebral ischemia and reperfusion, through observation of the changes in the infarct volume and blood-brain barrier(BBB) in rats.

DESIGN:

A randomized controlled experimental study based on experimental animals.

SETTING:

The departments of neurology of two university hospitals and department of dermatology in a municipal hospital.MATERIALS The study was carried out in the Laboratory of Department of Neurology, Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology and Laboratory of Department of Neurology, People' s Hospital of Wuhan University from March to July 2001. Sixty-four Wistar rats weighing 180 to 230 g were purchased from the Experimental Animal Center of People' s Hospital of Wuhan University.

INTERVENTIONS:

Sixty-four rats were randomly divided into control group, hypertension group, mild hypothermia group, and combined therapy group, each group consisting of 16 rats. Reperfusion was initiated after a 3-hour focal cerebral ischemia of the 16 rats, and at 2 hour during the ischemia, the rats in the hypertension and mild hypothermia group were treated with hypertension for 3 hours and mild hypothermia, respectively, and those in the combined therapy group received both treatment. The rats in the control group received no treatments for ischemia and reperfusion. Twenty-four hours later, all rats were killed for examination.MAIN OUTCOME

MEASURES:

The scores of neurological deficits, infarct volume and degree of BBB damage.

RESULTS:

The scores for neurological deficits, infarct size and volume of Even' s blue staining were 2. 12 ±0. 54, (17.65 ±4.78)%, and(56.63± 10.70) mm3, respectively, in hypertension group, and 2. 14 ±0.69,(16. 21 ± 3.79)%, and(53.52 ± 8.44) mm3 in mild hypothermia group,and 1.78 ±0. 61, (11, 31 ±3.64)%, and 38.45 ±5.25 mm3 in combined therapy group, which were all decreased significantly as compared with the control group[2.70 ±0. 64, (28.34 ±4. 13)%, and(94.87 ± 15.34) mm3].The combined therapy group had the smallest infarct size and volume of Even's blue staining among the three treatment groups( P ＜ 0.05).

CONCLUSION:

Hypertension and mild hypothermia may reduce the infarct volume and alleviate BBB damage during focal cerebral ischemia and reperfusion in rats, and the effects of combined treatment are more obvious.