ABSTRACT:Objective To observe the anesthetic effects of xylazine and dexmedetomidine in establishing the model of spinal cord injury in beagle dogs.Methods Thirty female beagle dogs were randomly divided into 3 groups with 1 0 in each:xylazine group (group S ), dexmedetomidine group (group D ), and xylazine +dexmedetomidine group (group S+D).Basal anesthesia with ketamine was performed in all the dogs.Then group S was intramuscularly injected with xylazine discontinuously, group D was intravenously injected with dexmedetomidine 2μg/(kg·h)continuously,but group S+D was injected with xylazine and dexmedetomidine in combination.The heart rate (HR),respiratory frequency (RR),Ramsay score and spasm index (SI)were observed at the time of skin incision (T1),after the beginning of the operation 30 min (T2),before the end of the operation 30 min (T3),and the end of the operation(T4);and the usage of anesthetics was recorded.Results Compared with that in groups S and D,the usage of xylazine and dexmedetomidine in group S+D was decreased by 1/2 and 1/4,respectively (P<0.01),but HR and RR did not change significantly;the sedative effect was superior to that in S.No obvious increase in muscular tensility in the foreleg was observed before operation.Conclusion Xylazine and dexmedetomidine used in combination to establish the model of spinal cord injury in beagle dogs have advantages of better sedative effect,less respiratory depression and lower dosage of anesthetic drugs.

Objective To investigate the effect of minocycline on development of diabetic neuropathic pain in rats and its mechanism.Methods Forty male Sprague-Dawley rats aged 6-8 weeks,weighting 180-220 g,were randomly assigned into 4 groups,with 10 rats in each group:normal control group (group C),normal+minocycline group (group C+M),diabetes mellitus group (group DM),diabetes+minocycline group (group DM+M).Diabetes models of rats in group DM and group DM+M were established by single intraperitoneal injection of streptozotocin (STZ,65 mg/kg),and equal volume of normal saline was injected instead of STZ into group C and group C+M;the fasting blood glucose level was tested every week,and the rats of blood glucose level ≥ 16.6 mmol/L were selected otherwise by additional injection of STZ.Two weeks after that,the intervention treatment of rats was given by single intraperitoneal injection ofminocycline (40 mg/kg) in group DM+M and group C+M.The thermal tail flick latency (TFL),thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) were detected one day prior to the injection of STZ (T0),and one (T1),2 (T2),4 (T3) and 8 (T4) weeks after the injection of STZ.Eight weeks after that,the expressions of malondialdehyde (MDA) and superoxide dismutase (SOD) in the spinal dorsal ofthe rats were detected by principles ofphysical chemistry with enzyme standard instrument,and apoptotic cells in dorsal hom was detected by immunohistochemistry.Results As compared with those in group C and group C+M,TFL,TWL and MWT in group DM and group DM+M were significantly decreased at T2,T3 and T4 (P＜0.05);TFL,TWL and MWT in group DM+M were significantly increased as compared with those in group DM,reaching their peak levels at T4,with significant differences (P＜0.05).SOD level in group D and group DM was significantly lower than that in group C (P＜0.05),and MDA level in group D and group DM was significantly higher than that in group C (P＜0.05);as compared with group DM,group DM+M had higher SOD level and lower MDA level,with significant differences (P＜0.05).The number of apoptotic cells in spinal dorsal of the rats in group DM was significantly larger than that in group C (P＜0.05).Conclusion Minocycline can relieve diabetic neuropathy pain,and the underlying of mechanisms may be through anti-inflammatory,anti-oxidant stress,anti-apoptosis,and reducing the microglia activation in the spinal cord.