Study Of The Effects Of Aminoguanidine Sulfate In Delayed Cerebral Vasospasm After Subarachnoid Hemorrhage In Rabbits

Objective:To study the effects of Aminoguanidine sulfate in delayed cerebral vasospasm after subarachnoid hemorrhage and its mechanism of action in rabbits.Materials and methods:The subarachnoid hemorrhage animal model were made by tied up one side of the common carotid artery+and twice blood injection into the the cisterna magna.72 healthy adult rabbits were randomly allocated into four groups:The control group (A group), SAH group (B group), SAH animals treated with Aminoguanidine intravenous (C group) and SAH animals treated with Aminoguanidine subarachnoid intervention group (D group).Then the 4 groups were divided into 3 subgroups according to the different time points, each subgroup contains 6 rabbits. The animals of A group corresponding only to sham surgical procedures, then raised under standard rearing for 24h, 72h,7d,without subarachnoid injection of blood; The animals of B group were processed with intrathecal injection of blood twice, then raised under standard rearing for 24h,72h,7d; The animals of C group were raised under standard rearing for 24h,72h,7d after the SAH model had made, respectively, during those days aminoguanidine sulfate was given by intravenous administration; The animals of C group were raised under standard rearing for 24h,72h,7d after the SAH model had made, respectively, during those days aminoguanidine sulfate was given by intrathecal administration. All the animals'brains and basilar artery were removed at the three time points,24h,72h,7d, HE staining and iNOS immunohistochemical staining was made to explore the vascular changes in the basilar artery and endothelial cell iNOS expression, while taking hippocampus processed with HE staining and Bcl-2, Bax immunohistochemical staining to explore Bax and Bcl-2 expression.During the same time the neurobiology score was Implementated once a day, The experimental data were processedwiath SPSS statistical software for statistical analysis.Results:HE staining observed:(1) the basilar artery:The basilar artery endothelial cells, smooth muscle cells of A groups arranged in neat rows, with normal structure, no thickening of the arterial wall smooth; The vascular endothelial cells, smooth muscle cell of B groups degeneration and swelling, disordered blood vessel diameter were significantly thinner than A group, and the artery wall thickening; C, D groups of vascular endothelial cell swelling was not obvious, no wall thickening, reduced diameter than the B group of light. (2) the hippocampal CA1 area:A group of neurons arranged in neat, large, round nucleus, clear nucleolus, occasional apoptotic cells at each time point group differences in neuronal density is not, and the remaining three groups were seen in varying degrees neuronal apoptosis; B group showed significantly reduced number of neurons, neuron shrinkage, nuclei show clear, a large number of pyramidal cells; C, D basic neatly arranged in two groups of neurons, neuronal density at each time point compared with B group. Immunohistochemistry section observation:iNOS, Bcl-2 and Bax positive cells showed cytoplasmic color, see the brown particles. (1) iNOS positive cells in observation:In the A group, iNOS-positive cells in the basilar artery only see a small amount of endothelial expression of group differences at each time point is not, in the other three groups was the expression of the basilar artery endothelial cells; B group and C, D group, iNOS-positive cells expressed many and strong, the strongest in 72 hours, C, D groups not seen this trend. (2) Bcl-2 positive cells observation:In the A group, Bcl-2 positive cells in the hippocampal neurons in a small amount of expression of group differences at each time point is not, and the remaining three groups of hippocampal CAl area compared with the expression of Bcl-2 A group was; where C, D group and B group, at each time point Bcl-2 positive cells and the expression of more than strong; B group the expression of Bcl-2 intensity first decreased with time, then slowly rising trend, C,D groups this trend was not obvious. (3) Bax-positive cells observed results: In group A, Bax-positive cells in the hippocampal neurons in a small amount of expression of group differences at each time point is not, the other three Bax expression in hippocampal CAl area significantly; B group and C,D group, Bax-positive cells and the expression of many strong expression of the highest in 72 hours, then decreased, a trend in the C,D group is not obvious. Neurological score observed:A group:food and water intake were normal, only after two operations in the short-term decline in food intake, no neurological deficit; B,C,D groups were each there after subarachnoid injection of blood reduced consumption of water, transferred with varying degrees of neurological dysfunction, the most important 72 hours -96 hours, B group and duration of symptoms was significantly heavier than C,D groups, C and D groups were similar.Conclusion:1 Incision injury and the side of common carotid artery ligation didn't significantly affected the iNOS expression in rabbit's basilar artery endothelial cells and Bcl-2, Bax expression in the contralateral hippocampus.2 SAH can incressed the iNOS expression of the endothelial cells in basilar artery and the Bcl-2, Bax expression in the hippocampus.3 Aminoguanidine sulfate (Ag) may be preventing a large number of NO-mediated anti-oxidative stress and cell toxicity through the selective inhibition of inducible nitric oxide synthase (iNOS) overexpression, which plays a neuroprotective role.4 The group of animals treated with Aminoguanidine (Ag) on CVS after SAH was observed mild vasodilator effect, but its mechanism is not clear. May be the mechanism is that aminoguanidine selectively inhibited the iNOS, without affecting the endothelial nitric oxide synthase (eNOS),which produces physiological amount of NO to maintain vascular relaxation. The mechanism needs further study.