丙泊酚对新生小鼠下丘脑室旁核神经元及下丘脑小胶质细胞的影响

目的 研究丙泊酚对新生小鼠下丘脑区域神经元激活及小胶质细胞活化水平的影响,并探讨与丙泊酚神经毒性的相关性.方法 15只同窝7d龄(postnatal day 7,P7) C57小鼠按随机数字表法分为3组(n=5):对照组、丙泊酚低剂量组、丙泊酚高剂量组.P7时,丙泊酚低、高剂量组小鼠分别接受丙泊酚30、60 mg/kg腹腔注射,对照组注射同等体积的脂肪乳溶剂.24 h后(P8)处死小鼠收取脑标本,采用免疫组织化学方法检测下丘脑C-Fos、精氨酸加压素(arginine vasopressin,AVP)、糖皮质激素受体(glucocorticoid receptor,GR)及小胶质细胞标志物离子钙接头分子蛋白1(ionized calcium binding adapter molecule 1,Iba1)的表达,Western blot测定AVP及GR的表达.结果 与对照组(9.95±1.51)相比,丙泊酚低剂量组(14.75±1.39)、丙泊酚高剂量组(24.00 ±5.25)室旁核C-Fos阳性细胞数量均明显增多(P ＜0.05,P＜0.01),且高剂量组相对低剂量组增多(P＜0.01);对照组(14.94 ±3.39)与低剂量组(19.63 ±3.70)室旁核表达AVP阳性细胞数量无明显差异,而高剂量组(23.38 ±2.29)中AVP阳性细胞数量对比对照组明显增加(P＜0.01),且蛋白表达上调;高剂量组(37.38 ±3.17)下丘脑室旁核GR表达相对对照组(27.38 ±2.17)及低剂量组(31.38 ±2.39)均明显上调(P ＜0.01,P＜0.05),对照组和低剂量组间无差异;与对照组相比,低剂量组、高剂量组下丘脑背内侧区、腹内侧区、外侧区Iba1标记的小胶质细胞数量均明显减少.结论 丙泊酚激活新生小鼠下丘脑室旁核神经元,致下丘脑精氨酸加压素和糖皮质激素受体表达上调,并抑制小胶质细胞活化水平,影响程度与剂量相关.

Effect of propofol on hypothalamic paraventricular nucleus neurons and microglia in neonatal mice

Objective To investigate the effects of propofol on neuronal and microglia activation in the hypothalamus of neonatal mice and the impact of the neurotoxicity of propofol on the neurons and microglia.Methods Fifteen healthy neonatal (7-day-old) C57 mice from the same litter were randomly divided into control group,low-dose propofol group and high-dose propofol group (n =5).On postnatal day 7,the mice in the low-and high-dose propofol treatment groups received intraperitoneal injection of propofol at 30 mg/kg and 60 mg/kg,respectively,and the control mice were treated with 10％ intralipid of the same volume.Twenty-four hours after the injections,the mice were sacrificed and the cerebrum was collected for immunohistochemistry to detect the expression of C-Fos,arginine vasopressin (AVP),glucocorticoid receptor (GR) and ionized calcium binding adapter molecule 1 (Iba1) in the hypothalamus,and Western blotting was used for quantitative analysis of AVP and GR expressions.Results The C-Fos-positive cells in the paraventricular nucleus (PVN) were significantly increased in both the low-dose propofol group (14.75 ±1.39,P ＜ 0.05)and high-dose propofol group (24.00 ± 5.25,P ＜ 0.01) as compared with the control group (9.95 ± 1.51),and the cell number was significantly greater in the high-dose group than in the low-dose group (P ＜ 0.01).The number of AVP-positive cells in the hypothalamus did not differ significantly between the control group (14.94 ±3.39) and the low-dose group (19.63 ± 3.70) but increased significantly in the high-dose group (23.38 ±2.29,P ＜0.01 vs control),which also showed an up-regulated expression of AVP protein.GR expression was significantly higher in high-dose propofol group (37.38 ± 3.17) than in the control group (27.38 ± 2.17,P ＜ 0.01) and low-dose group (31.38 ± 2.39,P ＜ 0.05).Compared with those in the control group,the numbers of Iba1-positive microglia in the dorsomedial,ventromedial and lateral areas of the hypothalamus were all decreased in the 2 propofol treatment groups.ConcluSion Propofol exposure in early life causes neuronal activation in the PVN,up-regulation of AVP and GR in the hypothalamus and inhibition of microglia activation,and these effects are related with the level of the exposure doses.