| Objective:The purpose of the study was to establish two simple and inexpensive animal models of experimental CVS after SAH and HTEB in rabbits and to investigate the preventive effects of HTEB on CVS following SAH and to study the possible mechanism of the preventive effects .Methods:1. Sixty rabbits with HTEB made successfully were randomly assigned into 6 groups (n = 10,each): the normal 1 day group (N1),the normal 7 day group(N7),SAH 1 day group (S1),SAH 7 day group (S7),HTEB plus SAH 1 day group (HS1),HTEB plus SAH 7 day group (HS7). the normal group (N1,N7): normal saline 0.5 mL/kg was injected into the cisterna magna and 1 mL/h injected through the epidural pipe; SAH group (S1,S7): non-anticoagulant autologous arterial blood 0.5 mL/kg was injected into the cisterna magna and normal saline 1mL/h was injected through the epidural pipe; HTEB plus SAH group (HS1,HS7): non-anticoagulant autologous arterial blood 0.5 mL/kg was injected into the cisterna magna and 1 g·L-1 Ropivacaine 1 mL/h injected through the epidural pipe.2. To establish the HTEB model, T6-7 epidural space was explored, and an epidural pipe was introduced. The 1 g·L-1 ropivacaine was injected continually through the pipe at 1 mL/h to block T1-5 sympathetic nerves.3. SAH models of rabbits were developed by injecting non-anticoagulant autologous arterial blood 0.5 mL/kg into the cisterna magna.4. In-taking food of group N7,S7,HS7 was evaluated every day for 7 days..5. Transcranial Doppler (TCD) ultrasonography was used to detect the basilar artery blood flow velocity changes.6. After taking out the brain by opening skulls, a general observation of specimens was made firstly. Then one-third of basilar arteries were preservinged and fixed by 40 g·L-1 paraformaldehyde, and paraffin-embedded,sected,HE stained. Lastly the basilar artery changes were observed through Optical Microscope. Two-third of basilar arteries were preserved in liquid nitrogen by Eppendof tubes and was used to detect the expressions of preproET-lmRNA and eN0SmRNA by RT-PCR.Results:1. In-taking food was not significant decreased in group N7 except the first day after injecting Sodium Chloride into the cisterna magna. In group S7, it was decreased significantly through the 7 days observative period. It was decreased in the first two days, and returned to normal from the fourth day in group HS7.2. The changes of pathology: By eyes there were blood clots scattering on the basal surface of the brain and around the basilar artery in group HS1,HS7 and S1,S7. But there were no blood clots in group N1,N7.3. Changes of vascular hemodynamic indexes were showed by TCD. Vs and Vm in group S1 and S7 were increased significantly compared with group N1 and N7 (P<0.01); but PI and RI were decreased respectively (P<0.05). Vm and Vs in group HS1 and HS7 were decreased compared with group S1 and S7(P<0.05), but PI and RI were increased respectively(P<0.05). 4. Pathological observation:The structure of the basilar artery in group N1 and N7 were normal. The vessel wall was shrink and the lumina became narrow in group S1 and S7. The pathologic changes in group HS1 and HS7 were slighter than in group S1 and S7.5. The expression of preproET-lmRNA of group S1 and S7 were higher than group N1 and N7(P?0.05),and group HS1 and HS7 higher than group N1 and N7(P?0.05).The expression of eN0SmRNA of group S1 and S7 were decreased significantly compared with N1 and N7 respectively(P?0.05);but there were no significant differences between group N7 and HS7 (P>0.05).Conclusions:1. The HTEB rabbit model can be established successfully by incision T6-7 epidural space and introducing epidural pipe.2. the CVS following SAH rabbit model can be established successfully by injecting non-anticoagulant autologous arterial blood 0.5mL/kg into the cisterna magna.3. HTEB used before SAH can reduce the extent of CVS following SAH, and the longer of the treatment, the better of the effect.4. HTEB used before SAH can inhibit the expressions of preproET-lmRNA and promote the expressions of eNOSmRNA of the vasospasm BA. |
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