Abstract:

Objective To observe the dynamic changes of the content of calcitonin gene-related peptide(CGRP) and β-enderphin(β-EP)after experimental cerebral ischemia in rats and the mechanism of hyperbaric oxygen(HBO) therapy.Methods Spragen Dawlay rats were randomly divided into the following groups: ischemia/reperfusion group(I/R), I/R group treated by HBO(HBO) and sham operated group(sham-O) as control. Global brain ischemia was induced using a modified four-vessel occlusion model originally described by Pulsinelli and Buchan. Blood was collected respectively at reperfusion time of 6 h, 24 h, 48 h and 96 h after 20 min of ischemia. The content of CGRP and β-EP was measured by RIA.Results The plasma CGRP level in 6 h HBO group was significantly higher than that of 6 h I/R group( P < 0.001 ) and sham-O group( P <0.05). The plasma CGRP levels of HBO group recovered quicker than I/R group of corresponding time point. The plasma CGRP level in 96 h I/R group was significantly higher than that of sham-O group( P <0.01) and 6 h I/R, 24 h I/R, 48 h I/R group respectively( P < 0.000 01 or P <0.01). The plasma β-EP level in 6 h HBO group was slightly elevated and then decreased gradually. The plasma β-EP level in 96 h HBO group and 96 h I/R group significantly lower than that of sham-O group( P <0.05). There were no statistically significant difference between 96 h HBO group and 96 h I/R group( P >0.05).Conclusion The findings demonstrate that early HBO therapy may reduce ischemia tissue damage by mechanism of increasing level of CGRP and decreasing level of β-EP. The more HBO treatment, the better therapeutic effect.

Key words: hyperbaric oxygen, cerebral ischemia, reperfusion, calcitonin cene-related peptide, &beta, -Enderphin