Charactrristics of motilin-induced contraction and its developmental change in the chicken gastrointestinal tract

鸡胃动素（ch-MT）通过肌源性和神经源性（主要是胆碱能）机制引起鸡胃（前胃，Prov）纵向肌条的收缩。另一方面，ch-MT收缩小肠仅通过肌原性机制。消化道对ch-MT的敏感性具有区域依赖性（空肠>回肠>十二指肠>腺胃>结肠）。Ch-MT在体内也能促进胃运动。本实验旨在研究发育变化的反应ch-MT和电场刺激（EFS）诱导的反应的特点，和NO和ch-MT之间的相互作用。还进行了免疫组织化学研究以检查含有ch-MT的细胞的存在。ch-MT收缩的发生：ch-MT收缩的非对数EC值随孵化天数（1 - 50天）的增加而逐渐降低，这是由于通过孵育降低了间接收缩的幅度。<50> 关于我们 GH胆碱能神经。但Prov对Ach和5-HT的反应以及ch-MT诱导的回肠收缩在每个孵化日没有变化。上述结果提示MT在ch-MT和NO相互作用中的生理作用：L-硝基精氨酸甲酯（L-NAME）可增强Ch-MT和EFS引起的Prov收缩，而L-精氨酸可抑制Ch-MT和EFS引起的Prov收缩，对Ach和5-HT的反应无影响。然而，在回肠和阿托品处理的Prov，无论是L-NAME还是L-精氨酸修改的反应，ch-MT。NO合成酶抑制通过减少内源性NO介导的突触前抑制神经ACh释放而增强Prov中ch-MT和EFS的收缩反应。然而，NOS抑制也没有修改ch-MT在胃和肠平滑肌中的肌源性（直接）作用。鸡的神经支配Prov：Prov支配5种植物神经，即胆碱能兴奋神经（0.1 - 20 Hz）、非肾上腺素能非胆碱能兴奋神经（NANC）（0.5 - 1 Hz和10 Hz以上）、NO抑制神经（2 - 7 Hz）、NANC、非NO抑制神经（7 Hz以上）。出壳后1天，胆碱能神经和NO能神经支配已基本完成，而NANC、非NO抑制性神经则缓慢完成。免疫组化：用兔制备特异性ch-MT抗体。MT免疫反应阳性细胞存在于幽门，十二指肠，空肠，回肠，而不是在胃，Prov，直肠和盲肠。含MT的细胞呈递区对ch-MT的敏感性高于其它区域。MT是鸡肠道中的运动刺激激素。少

Chicken motilin (ch-MT) caused contractions of longitudinal muscle strips of the chicken stomach (proventriculus, Prov) though both myogenic and neurogenic (mostly cholinergic) mechanisms. On the other hand, ch-MT contracted the small intestine through only a myogenic mechanism. The sensitivity of gastrointestinal tracts to ch-MT was region-dependent (jejunum > ileum > duodenum > proventricculus > colon). Ch-MT also stimulated the gastric motility in vivo. The present experiments were designed to investigate developmental changes in responsiveness to ch-MT and in characteristics of electrical field stimulation (EFS)-induced responses, and interaction between NO and ch-MT. Immunohistochemical study was also carried out to examine the presence of ch-MT containing cells. Development of ch-MT-induced contraction : Amplitude of the ch-MT-induced contraction not-log EC_<50> value decreased gradually depending on hatching days(1-50 days), because of the reduction of indirect contraction throu … More gh cholinergic nerves. But response to a Ach and 5-HT in Prov, and ch-MT-induced contraction in the ileum were not changed at every hatching day. These result suggest the physiological roles of MT in the chicken small intestinal motility ch-MT and NO interaction : L-Nitroarginine methyleaster (L-NAME) potentiated and L-arginine inhibited ch-MT and EFS-induced contractions in Prov without affecting the response to Ach and 5-HT. However, in the ileum and atropine-treated Prov, neither L-NAME nor L-arginine modified the responses to ch-MT. NO synthase inhibition potentiated the contractile response of ch-MT and EFS in Prov through reduction of endogenous NO-mediated presynaptic inhibition on neural ACh release. However, NOS inhibition did nor modify the myogenic (direct) action of ch-MT in gastric and intestinal smooth muscles. Innervation of chicken Prov : Prov was innervated 5 types of autonomic nerves, such as cholinergic excitatory nerve (0.1 - 20 Hz), nonadrenergicnoncholinergic (NANC) excitatory nerves (0.5 - 1 Hz and over 10Hz), NO inhibitory nerve (2 - 7 Hz), NANC, nonNO inhibitory nerve (over 7 Hz). Cholinergic and NO innervation was already completed on 1 day after hatching but NANC, nonNO inhibitory nerve was slowly. Immunohisyochemistry : Specific ch-MT antibody was produced using rabbits. MT-immunoreactive cells were present in the pylorus, duodenum, jejunum, ileum but not in the gizzard, Prov, rectum and caecum. MT containing cell present regions had a high sensitivity to ch-MT compared with other regions. MT is a motor stimulating hormone in the chicken intestinal tracts. Less