Ghrelin对PI3K/Akt抑制剂预处理大鼠中枢血压调节及NADPH表达的影响

摘要

目的 研究食欲刺激素(ghrelin)对PI3K/Akt抑制剂预处理大鼠中枢血压调节及血管烟酰胺腺嘌呤二核苷酸磷酸(NADPH)表达的影响.方法 选取10~12周龄雄性SD大鼠18只,腹腔内注射麻醉,股动、静脉插管,侧脑室内插管.随机分为3组,人工脑脊液(aCSF)对照组,ghrelin组,PI3K抑制剂(wortmannin)预处理组,每组6只.aCSF组侧脑室内注射aCSF(10 μL);ghrelin组侧脑室内注射aCSF(10 μL),10 min后侧脑室内注射食欲刺激素(50 pmol/10 μL);wortmannin预处理组侧脑室内注射wortmannin (20 nmol/10 μL),10 min后侧脑室内注射食欲刺激素(50 pmol/10 μL).观察各组血压、心率的变化.用酶联免疫吸附法,实验结束后测定NADPH浓度.结果 Ghrelin组平均动脉压(MAP)最大下降幅度(-12.3±2.6)mmHg,心率(HR)最大下降幅度(-29.5±13.4) bpm,与aCSF组相比,差异具有统计学意义(P<0.01, P<0.05).wortmannin预处理组侧脑室内注射食欲刺激素后MAP最大下降幅度(-4.0±2.7)mmHg,与ghrelin组相比,差异具有统计学意义(P<0.01);与aCSF组比较,差异无统计学意义.在延髓和下丘脑中,ghrelin组NADPH浓度为(67.3±8.2)μmol/L和(67.5±7.2) μmol/L,均明显高于aCSF组(P<0.01);wortmannin预处理组与aCSF对照组及ghrelin组比较,差异均无统计学意义.结论 ghrelin通过PI3K/Akt信号传导通路引起降压作用并上调NADPH表达.%Objective To investigate the effect of phosphatidylinositol 3 kinase (PI3K) inhibitor wortmannin on antihypertensive action of ghrelin and dihydronicotinamide adenine dinucleotide phosphate (NADPH).Methods Eighteen male SD rats were divided into three groups (n=6): aCSF (artificial cerebrospinal fluid) control group, ghrelin group, wortmannin pretreatment group.The aCSF (10 μL), aCSF (10 μL) and ghrelin (50 pmol/10 μL) in ten minutes later, and wortmannin (20 nmol/10 μL) and ghrelin (50 pmol/10 μL) in ten minutes later were given by intracerebroventricular injection, respectively, in aCSF control group, ghrelin group, and wortmannin pretreatment group.Mean arterial pressure (MAP) and hart rate (HR) were measured in all rats.The NADPH concentration was measured by Elisa.Results The maximal MAP decreasing (-12.3±2.6) mmHg and HR (-29.5±13.4) bpm in ghrelin group were significantly higher than those in aCSF group (P<0.01, P<0.05).The maximal MAP decreasing (-4.0±2.7) mmHg in wortmannin pretreatment group was significantly lower than that in ghrelin group (P<0.01), while no significant difference compared with aCSF group.NADPH concentration in the hypothalamus (67.3±8.2) μmol/L and medulla oblongata (67.5±7.2) μmol/L in ghrelin group were significantly higher than those in aCSF group (P<0.01).NADPH concentration in wortmannin pretreatment group was no significant difference compared with aCSF and ghrelin group.Conclusion Ghrelin-induced hypotensive effect could be mediated by PI3K/Akt pathway and NADPH.