外周γ-氨基丁酸b受体对慢性应激过程中大鼠血浆儿茶酚胺及皮质醇含量的影响

Effects of peripheral gamma aminobutyric acid b receptor on contents of plasma catecholamine and cortisol of rats with chronic stressing

目的:分析外周γ-氨基丁酸b受体对慢性应激大鼠血浆儿茶酚胺和皮质醇含量变化的作用。方法:实验于2003-07/2004-07在白求恩军医学院军事病理实验室,实验选用雄性健康大鼠100只。随机分为对照组(n=10),应激1,6和15d组,应激组又分为单纯应激组,注射2羟-萨氯酚组和注射氯苯氨丁酸组,每组10只。对照组单独饲养,避免外界干扰;应激组大鼠采用足底电击结合噪声的方法制备应激动物模型,以足底电击建立非条件反射,噪音建立条件反射。同时,注射2羟-萨氯酚组和注射氯苯氨丁酸组分别经腹腔注射γ-氨基丁酸b受体拮抗剂2羟-萨氯酚(100μg/kg)和γ-氨基丁酸b受体激动剂氯苯氨丁酸(4mg/kg)。对照组和应激组均于最后一次应激完成后第2天早8∶00时取血样,采用高效液相-电化学法检测大鼠血浆儿茶酚胺含量,酶联免疫法检测慢性应激过程中血浆皮质醇含量的变化。结果:实验大鼠100只,全部进入结果分析,无脱失值。①在慢性应激1,6,15d过程中单纯应激组大鼠血浆儿茶酚胺含量变化为去甲肾上腺素呈升高趋势[(0.53±0.03),(0.55±0.03),(0.58±0.05)μg/L];肾上腺素呈先升高而后下降趋势[(0.70±0.27),(0.75±0.05),(0.47±0.04)μg/L]。注射2羟-萨氯酚组血浆儿茶酚胺含量变化为去甲肾上腺素呈升高趋势[(0.11±0.02),(0.42±0.10),(0.83±0.02)μg/L];肾上腺素呈先升高后下降趋势[(0.43±0.10),(0.51±0.11),(0.21±0.21)μg/L]。注射氯苯氨丁酸组大鼠血浆儿茶酚胺含量变化为去甲肾上腺素呈升高趋势[(0.11±0.02),(0.20±0.01),(0.47±0.05)μg/L];肾上腺素呈下降趋势[(0.69±0.01),(0.50±0.07),(0.35±0.06)μg/L]。②在慢性应激过程中单纯应激组大鼠血浆皮质醇呈升高趋势[(73±1.5),(83±2.8),(85±5.7)μg/L];注射氯苯氨丁酸组大鼠血浆皮质醇呈明显升高趋势[(22.6±5.8),(76.7±5.7),(88.3±1.4)μg/L],注射2羟-萨氯酚组血浆皮质醇呈明显降低趋势[(85.2±5.4),(75.3±5.6),(65.8±2.6)μg/L]。结论:刺激外周γ-氨基丁酸b受体具有降低慢性应激大鼠血浆儿茶酚胺作用,抑制外周γ-氨基丁酸b受体具有降低慢性应激大鼠血浆皮质醇作用。

AIM： To analyze the effect of peripheral γ aminobutyric acid （GABA） b receptor on content of plasma catecholamine and cortisol of rats with chronic stressing. METHODS： The experiment was conducted at the Military Pathological Laboratory, Norman Bethune Military Medical College of Chinese PLA from July 2003 to July 2004. 100 healthy Wistar male rats were selected and randomly divided into control group （n=10）, 1, 6 and 15 day stress group, each stress group assigned into pure stress group, injected 2OH- Saclofen and injected Baclofen groups with 10 rats in each group. The rats in control group were fed separately in avoidance of outside interference. While those in stress groups were made into models of chronic stress by electric shock at soles and noise. Using electric shock at soles to establish unconditioned reflex; noise establishing conditioned reflex. Meanwhile, The rats in the injected 2OH-Saclofen group and the injected Baclofen group received intraperitoneal injection of GABA b receptor antagonist 2OH- Saclofen（100 μg/kg） and GABA b receptor agonist Baclofen （4 mg/kg）, respectively. Blood samples of the rats in the control group and stress group were gained at 8：00 of the following day after the last stress experiment. Contents of catecholamine and cortisol in plasma were detected by high performance liquid chromatography （HPLC）- Electrochemistry and enzyme-linked imunosorbent assay （ELISA） methods, respectively. RESULTS： 100 experimental rats were all involved in the result analysis, without drop-out. ① During the 1, 6 and 15 days stress, the content of norepinephrine of rats plasma increased in the pure stress group increased gradually [ （0.53±0.03）, （0.55±0.03）, （0.58±0.05）μg/L]. But the content of epinephrine increased at first and then decreased gradually [（0.70±0.27）, （0.75±0.05）, （0.47±0.04）μg/L]. In the injected 2OH-Saclofen group the content of norepinephrine of rat plasma increased gradually [（0.11 ±0.02）, （0.42±0.10）, （0.83±0.02） μg/L]. But the content of epinephrine increased firstly and then decreased gradually [（0.43±0.10）, （0.51±0.11 ）, （0.21＋0.21）μg/L]. In the injected Baclofen group the contents of norepinephrine of rat plasma increased gradually [（0.11±0.02）, （0.20±0.01）, （0.47±0.05）μg/L], and the content of epinephrine decreased [（0.69±0.01 ）, （0.50±0.07）, （0.35±0.06）μg/L]. ② The content of cortisol in plasma of pure stress group increased gradually [（73±1.5）,（83±2.8）,（85±5.7） μ/L]. It increased significantly in the injected Baclofen group [（22.6±5.8）,（76.7±5.7）, （88.3±1.4）μg/L]. It decreased significantly in the injected 2OH-Saclofen group [（85.2±5.4）, （75.3±5.6）, （65.8±2.6）μg/L]. CONCLUSION： The stimulus GABA b receptor has an effect on decreasing the content of catecholamine in plasma of rats with chronic stressing. To inhabit GABA b receptor has an effect on deceasing the content of cortisol in plasma of rats with chronic stressing.