An evaluation of the effectiveness of pre-ischemic hyperbaric oxygen and post-ischemic aminoguanidine in experimental cerebral ischemia

OBJECTIVE: To study the effects of pre-ischemic hyperbaric oxygen (HBO) and post-ischemic aminoguanidine (AG) on the infarct volume in permanent middle cerebral artery occlusion.

METHODS: This study was approved by the Animal Experiments Ethics Committee of Gulhane Military Medical Academy, Ankara, Turkey and carried out from March 2006 to August 2006. A total of 28 Sprague-Dawley rats (200-320 g) were divided into 4 groups: control (K) group (n = 7); HBO group (n = 7); HBO + AG group (n = 7); and the AG group (n = 7). All rats underwent middle cerebral artery occlusion (MCAO) by subtemporal craniectomy, and permanent ischemia was created. A 2.8 atmospheric pressure of HBO was first applied to the HBO and HBO + AG groups for 45 minutes, and occlusion was created after 2 hours. In the HBO + AG group, intraperitoneal administration of AG hemisulfate (100 mg/kg) was started 6 hours after MCAO, and was continued twice a day for 3 days.

RESULTS: The rate of infarction was found to be 22.2+/-3.1% in the control group, 16.1+/-2.7% in the HBO group, 15.2+/-1.9% in the HBO+AG group, and 14.4+/-3.3% in the AG groups. The rate of infarctions (therefore the volume of infarct) in the HBO, HBO + AG, and AG groups were found to be significantly decreased compared with the control group (p=0.002, p=0.001, and p=0.001).

CONCLUSION: In permanent MCAO-induced ischemia in rats, HBO and AG were observed to have a lowering effect on the infarct volume, but no additive effect was observed. This situation can be explained by different mechanisms of action.