丙泊酚对吗啡鞘内注射所致瘙痒大鼠脊髓内胃泌素释放肽受体的影响

目的:观察丙泊酚对鞘内注射吗啡所致瘙痒大鼠脊髓膨大中胃泌素释放肽受体（gastrin-releasing peptide receptor，GRPR）的影响，并探讨其缓解瘙痒的可能作用机制。方法:将30只造模成功的大鼠随机分为8、16、24、32、60 min组5组，分别在40 μg/kg吗啡鞘内注射10 min后的第8、16、24、32、60 min处死，行Western blot检测脊髓膨大处GRPR蛋白表达水平。另将48只造模成功的大鼠随机分为对照组、丙泊酚组、生理盐水组和脂肪乳剂组4组，经鞘内注射相同容量生理盐水或吗啡40 μg/kg后10 min，分别经颈内静脉注射相同容量的生理盐水80 μL/kg、丙泊酚0.8 mg/kg、生理盐水80 μL/kg或脂肪乳剂80 μL/kg。每组选择6只大鼠用摄像机记录注射生理盐水或吗啡前30 min和后60 min内的搔抓次数。其余大鼠在给药10 min后的第32 min处死，用于Western blot及免疫荧光检测脊髓膨大处GRPR蛋白的表达情况。结果:Western blot结果显示，32 min组大鼠GRPR蛋白表达量明显减少（P<0.05），其余各组之间差异无统计学意义。与生理盐水组及脂肪乳剂组相比，丙泊酚组搔抓次数减少（P<0.01）；Western blot结果显示，对照组及丙泊酚组的GRPR蛋白表达量较低（P<0.05），生理盐水组与脂肪乳剂组的表达量相近。结论:低剂量丙泊酚静注可缓解大鼠鞘内注射吗啡所致搔抓行为，并减少瘙痒大鼠脊髓膨大中GRPR的表达。

Effects of propofol on spinal cord GRPR of intrathecal morphine-induced pruritus model in rats

AIM: To observe the effects of propofol on intrathecal morphine-induced pruritus in rats and explore the possible mechanism of propofol in treating intrathecal morphine-induced pruritus. METHODS: Thirty rats succeeded with intrathecal morphine-induced pruritus model, were randomly divided into 5 groups: 8 min group, 16 min group, 24 min group, 32 min group and 60 min group. 10 min after intrathecal injection with 40μg/kg morphine , rats were killed at 8 min, 16 min, 24 min, 32 min and 60 min thereafter, respectively to collect the dorsal spinal cord for Western blot. Forty-eightrats succeeded with intrathecal morphine-induced pruritus model, were randomLy divided into 4 groups: control group, propofol group, normal saline group and intralipid group. Same volume of normal saline 80 μL/kg, propofol 0.8 mg/kg, normal saline 80 μL/kg, intralipid 80 μL/kg were administered via the jugular vein to four groups respectively 10 min after intrathecal injection with normal saline or 40μg/kg morphine. Six rats were randomly selected from each group for pruritus behavior observation. The observation started from 30 min before up to 60 min after the intrathecal injection, and the injection scratching responses of the rat were recorded. The remaining rats in each group were executed after the intrathecal injection 42 min to collect the spinal cord for Western blot and immunohistochemistry to detect the protein concentration of GRPR. RESULTS:The peak of scratching frequency was at 10-20 min after morphine intrathecal injection, and almost disappeared at 60min. Compared with normal saline and intralipid groups, the scratching behavior was significantly decreased in propofol group (P<0.01); the expression of GRPR in spinal cord of control group and propofol group was lower (P<0.01). There was no significant difference of the expression of GRPR between normal saline group and intralipid group. CONCLUSION: Intrathecal injection of morphine-induced scratching behavior can be significantly alleviated by low-dose propofol. Propofol may significantly decrease the expression of GRPR in spinal cord in morphine-induced pruritus model.