胃动素对大鼠海马神经元放电活动的作用机制

目的：研究胃动素对大鼠海马胃扩张神经元放电活动影响的机制。方法：采用微电极细胞外记录方法在体观察胃动素对胃扩张（GD）神经元放电活动作用的机制。结果：①海马CA1区内的39个胃扩张兴奋性（GD—E）神经元中有21个（54％）对胃动索呈现兴奋性效应；在16个胃扩张抑制性GD—I）神经元中有10个神经元（63％）表现为兴奋效应，4个神经元放电频率降低；②海马CA1区注射胃动素后，33个GD—E神经元中有22个（67％）表现为兴奋性效应。注射一氧化氮合酶（NOS）抑制剂左旋精氨酸甲酯（L-NAME）后再注射胃动素，神经元的放电频率由（3．98±0．54）Hz减小到（2．09士0．42）Hz（P〈0．05），22个原对胃动素有反应的神经元减少到15个，对胃动素的兴奋性由67％下降到46％；同样，在GD-I神经元中，细胞放电频率由（2．57±0．48）Hz下降到（1．85±0．30）Hz（P〈O．05）。但NO前体左旋精氨酸（L-AA）可明显加强胃动素对海马神经元的放电活动，放电频率由3．25±0．49Hz增加到4．59±0．61Hz（P〈o．05）。胃动素兴奋性神经元也从26个（57％）增加到32个（70％）。同样，注射L-AA后胃动素使GD-I神经元放电频率由（3．51±0．41）Hz增加到（4．44±0．49）Hz（P〈0．05）；但L-AA的同分异构体6-右旋精氨酸（D—AA）对胃动素诱导海马神经元放电活动元改变（P〉0．05）。结论：L-AA可增强胃动素对海马胃扩张神经元的兴奋作用；而L—NAME减弱此作用。

Mechanism of motilin'effect on electric activity of hippocampal neurons in rats

Objective：To investigate the influence of motilin to electric activity of hippocampal neurons in rats with gastric distension（GD）. Methods： （1）In the electrophysiological experiment： in 46 rats, extraeellular recordings in vivo were made from hippocampus with 3-barrel microelectrode. Neurons were categorized as GD,exeitatory （GD-E） or inhibitory （GD-I） neurons tested with GD were observed the mechanism of motilin on electric activity. Results： Data obtained from eleetrophysiological experiments： （1）Motilin could excite the discharge activity of GD neurons. There were 39 neurons in hippocampal responded to the GD stimulation 21 of them （21/39,54 % ）, which showed excitatory response to GD classlied as GD-E neuron. And 10 of neurons （10/16,63 %）were excited by GD stimulation as GD-I neurons; （2） With L-NAME, the excited effect of motilin on hippocampus GD neurons. Twenty-two neurons （67%） were excited. The eclipse period was （67±5.9）s and the persistence time was （156±9.5） s. After L-NAME injection, the discharge was reduced from （3.98 ± 0.54）Hz to （2.09 ± 0.42） Hz （P〈 0. 05） and the neurons were reduced to 15 （46%）. 30% of the GD-E neurons had no respond to motilin. At the same time the excited effect was decreased from 67% to 46%. While the same effect on GD-I neurons occured： the discharge was reduced from （2.57 ±0.48） Hz to （1. 85±0. 30） Hz （P〈0.05） ; In the influence of L-AA, the excited effect on hippocampus GD neurons of motilin was enhanced. The discharge increased from （3.25±0.49） Hz to （4.59 ±0.61） Hz （P〈0.05）. The motilin exciting neurons increased from 26 （57 % ） to 32 （70 % ）. And the discharge of GD-I neurons increased from （3.51 ± 0. 41）Hz to （4.44 ± 0.49） Hz （P〈0.05） ; On the contrary,D-AA had no obvious influence on motilin. The discharge changed from （4.88 ± 0.58）Hz to （4.54 ± 0.51）Hz （P〉0.05）. Conclusion： L-AA can increase the exciting function of GD neurons in hippocampus, on the contrary, L-NAME can decrease such function.