中脑导水管周围灰质注射鲑鱼降钙素对去势大鼠痛阈的影响

Influence of salmon calcitonin injected in periagueductal gray on the pain threshold in ovariectomized rats

目的观察中脑导水管周围灰质(PAG)注射微量鲑鱼降钙素(sCT)后对去势大鼠痛阈的影响。方法 56只雌性SD大鼠被随机分为正常对照(NC)组、假手术组、切除双侧卵巢(OVX)组、慢性压迫性损伤(CCI)组、sCT低剂量组、sCT中剂量组和sCT高剂量组。OVX术后4周,采用CCI方法制备神经性疼痛大鼠模型,并给予sCT低、中、高剂量组PAG注射相应剂量的sCT,每日1次,共7 d。应用斜板试验评估肌张力和本体感觉功能,热板试验评估热痛阈(TWL),von Frey纤丝测定机械痛阈(MNT)。结果各组间大鼠肌张力和本体感觉比较差异无统计学意义。与NC组比较,假手术组及OVX组TWL及MNT差异无统计学意义,CCI组显著降低(均P<0.05);与CCI组比较,各sCT组TWL和MNT显著提高(均P<0.05),sCT剂量与TWL和MNT呈正相关(r=0.97,r=0.963;均P<0.01)。结论 sCT能够提高去势大鼠的痛阈,且这种效应呈剂量依赖性。

Objective To observe the influence of salmon calcitonin（sCT）injected in periagueductal gray（PAG） on the pain threshold in ovariectomized（OVX） rats.Methods Fifty-six female SD rats were randomized into normal control（NC） group,sham operated group,OVX group,chronic constriction injury（CCI） group,low-dose sCT group,middle-dose sCT group and high-dose sCT group.After OVX operation 4 weeks,rat models of neuropathic pain were prepared by CCI,then the corresponding dosage of sCT was microinjected in PAG of low-dose sCT group,middle-dose sCT group and high-dose sCT group,once a day for 7 d.Muscular strength and proprioception,thermal withdrawal latency（TWL）,mechanical nociceptive threshold（MNT） was measured using inclined-plane test,hot plate test,von Frey monofilaments test respectively.Results Muscular strength and proprioception among different groups was no significant difference.Compared with NC group,the TWL and MNT in sham operated group and OVX group have no change,but decreased significantly in CCI group（all P0.05）.Compared with CCI group,the TWL and MNT were increased significantly in sCT groups（all P0.05）.The sCT dose was positive correlation with TWL and MNT（r=0.97,r=0.963;all P0.01）.Conclusion sCT can increase the pain threshold in ovariectomized rats,and this effect is dose-dependent.