摘要
目的:观察胃电刺激(GES)对大鼠下丘脑腹内侧区(VMH)胃扩张(GD)相关神经元的作用及脑内增食欲素(orexin)表达的影响,初步探讨 GES的中枢作用机制．方法:选用成年Wistar大鼠52只,采用细胞外记录神经元单位放电方法,记录VMH神经元自发放电活动,根据神经元对胃扩张刺激反应的不同,分为胃扩张兴奋性神经元(GD-E) 和胃扩张抑制性神经元(GD-I)．观察3组不同参数的胃电刺激(GES1,GES2,GES3)对VMH 内GD-E和GD-I放电频率的影响:GES1(6 mA, 0．3 ms,40 Hz,2 s-on,3 s-off)为标准参数; GES2的串刺激持续时间减少为0．1 s:GES3的串刺激频率减少至20 Hz,其他参数均同GES1．采用免疫荧光组织化学染色方法和放射免疫分析法观测胃电刺激2 h对大鼠下丘脑外侧区 (LHA)增食欲素-A(orexin-A)阳性神经元和不同脑orexin含量表达的影响．结果:VMH记录的96个神经元中有82个神经元(85．41％)对胃扩张刺激(GD,3-5 mL, 10-30 s)有反应,其中31个(37．8％)为胃扩张兴奋性(GD-E)神经元,51个(62．2％)为胃扩张抑制性(GD-I)神经元．GES1,2,3分别兴奋了 55．0％,17．6％,14．3％的GD-E神经元．GES1对 GD-E神经元的作用明显强于GES2和GES3 (P=0．002,P=0．016)．63．6％,37．9％和51．9％的GD-I神经元分别被GES1,2,3所兴奋,其中 GES2的兴奋作用较弱(P=0．043)．GES1刺激胃窦部2 h,下丘脑LHA orexin-A免疫阳性神经元表达明显减少(6．97±1．51/0．1 mm2 vs 26．62 ±8．30/0．1 mm2,P<0．01):且下丘脑、中脑、延脑和孤束核中orexin免疫反应物(IR)的含量与对照组相比明显减少(112．54±11．58 fmol/ mg vs 185．23±15．22 fmol/mg,P<0．01:71．95 ±8．45 fmol/mg vs 98．48±12．02 fmol/mg． P<0．05;72．36±6．58 fmol/mg vs 101．29± 15．22 fmol/mg．P<0．05;69．12±4．99 fmol/mg vs 89．21±9．23 fmol/mg,P<0．05),但脑桥内 orexin-IR的含量与对照组相比无显著差异．结论:GES可兴奋下丘脑“饱中枢”-VMH内胃扩张反应性神经元,电刺激作用的强弱与 GES刺激的频率和刺激的持续时间有关:脑内 orexin的降低可能也参与了GES的中枢作用机制．
AIM： To investigate the effects of gastric electrical stimulation （GES） on responsive neurons to gastric distension （GD） in ventromedia hypothalamus （VMH） and the expression of orexin in rat brain. METHODS： Fifty-two adult Wistar rats were used in this experiment. The effects of GES on GD responsive neurons in VMH were observed by recording extracellular potentials of single neuron. GD responsive neurons were classified as GD-excitatory （GD-E） and GD-inhibitory （GD-I） ones according to their responses to GD. GES with three sets of parameters were applied for one minute respectively： GES1 （6 mA, 0.3 ms, 40 Hz, 2 s-on, 3 s-off） with standard pulse trains; GES2 with reduced on-time to 0.1 s and GES3 with decreased frequency to 20 Hz. After GES1 was using for 2 h, we observed the expression of orexin-A imrnunoreactive （orexin-A-IR） positive neurons in lateral hypothalamus area （LHA） by fluorescent irnmunohistochemistry and the content of orexin in rat brain by radioirnmunoassay. RESULTS： Ninety neurons in VMH were recorded, of which 82 （85.41%） responded to GD （3-5 mL, 10-30 s）. Of the 82 GD responsive neurons, 31 （37.8%） were GD-E neurons and 51 （62.2%） were GD-I neurons. 55.0%, 17.6%, and 14.3% of GD-E neurons were excited by GES1, GES2, and GES3 respectively. More GD-E neurons were excited by GES1 than by GES2 and GES3 （P = 0.002 and 0.016, respectively）. Of the GD-I neurons, 63.6%, 37.9%, and 51.9% neurons were excited by GES1, GES2, and GES3, respectively. GES2 was noted to be less effective in comparison with GES1 （P = 0.043）. After GES1 was in application for 2 h, the levels of orexin-A-IR positive neurons were significantly decreased in LHA as comopared with those in control group （6.97 ± 1.51/0.1 mm^2 vs 26.62 ± 8.30/0.1 mm^2, P 〈 0.01）, and the content of orexin peptide was decreased obviously in the hypothalamus （112.54 ± 11.58 fmol/mg vs 185.23 ± 15.22 fmol/mg, P 〈 0.01）, mesencephalon （71.95 ± 8.45 fmol/mg vs 98.48 ± 12.02 fmol/mg, P 〈 0.05）, medulla oblongata （72.36 ± 6.58 fmol/mg vs 101.29 ± 15.22 fmol/mg, P 〈 0.05）, solitary tract nucleus （69.12 ± 4.99 fmol/mg vs 89.21 ± 9.23 fmol/mg, P 〈 0.05） by radioimmunoassay. However, the content of orexin peptide had no significant change in pons. CONCLUSION： GES may activate the GD responsive neurons in VMH and the excitatory effect of GES is related to the frequency and time of stimulation. Decreased expression of orexin in the brain may also take part in the central mechanism of GES.
出处
《世界华人消化杂志》
CAS
北大核心
2006年第4期370-375,共6页
World Chinese Journal of Digestology
基金
国家自然科学基金资助项目
No.30470642
青岛市科技局资助项目
No.05-1-JC-93
关键词
胃电刺激
下丘脑腹内侧核
增食欲素
免疫
Gastric electrical stimulation
Ventromedia hypothalamus, Orexin
Fluorescent immunohistochemistry
Radioimmunoassay
Rats
