Van Ginneken C, Van Meir F, Sommereyns G, Sys S, Weyns A
Laboratory of Veterinary Anatomy and Embryology, Faculty of Medicine, University of Antwerp, Belgium.
Anat Embryol (Berl). 1998 Nov;198(5):399-408. doi: 10.1007/s004290050192.
The expression of the constitutive neural isoform of nitric oxide synthase (bNOS) is dynamic and thus forms an ideal parameter to evaluate whether development and region affect the enteric nervous system. By applying NADPH-diaphorase histochemistry on whole-mount preparations of the myenteric and submucosal plexuses and by using the 'unbiased counting frame', a qualitative and quantitative description of bNOS-expression in enteric neurons in the pig duodenum in various developmental stage and region was obtained. Examinations were carried out on the oral and aboral duodenum of fetal pigs from the second half of gestation, of 1-2-day-old pigs and of 6-8-week-old pigs. In the pig duodenum, three enteric plexuses were readily distinguished: the inner submucous, the outer submucous and the myenteric plexuses. All three plexuses already harboured, to different degrees, bNOS-expressing neurons at midgestation. Although the enteric nervous system was present at midgestation, the enteric neurons had not yet reached their adult phenotype and morphology. During gestation, the number of inner submucous bNOS-expressing neurons increased approximately 50-fold, whereas after birth that number fell to about 10% of the prenatal value. During further postnatal development it returned to prenatal values. In addition, the number of bNOS-expressing myenteric neurons doubled postnatally. These changes favour a role for NO in mediating the development of enteric neurons and point to a greater necessity for inhibitory innervation in the adult pig as compared with the fetal pig. Furthermore, the number of bNOS-expressing outer submucosal and myenteric neurons was significantly higher in the oral duodenal segment compared with the aboral duodenal segment. This regional difference suggests that the oral duodenal segment is more prominently involved in the regulation of NO-mediated gastrointestinal processes than the aboral one. The developmentally and regionally dependent bNOS-expression can be explained by shifts and differences in the balanced system of hormones, presynaptic input and target-derived signals that affects neurotransmitter expression.
一氧化氮合酶组成型神经亚型（bNOS）的表达具有动态性，因此成为评估发育和区域是否影响肠神经系统的理想参数。通过对肌间神经丛和黏膜下神经丛的整装标本进行NADPH-黄递酶组织化学，并使用“无偏计数框”，对猪十二指肠不同发育阶段和区域的肠神经元中bNOS的表达进行了定性和定量描述。对妊娠后半期的胎儿猪、1 - 2日龄猪和6 - 8周龄猪的十二指肠口腔段和肛门段进行了检查。在猪十二指肠中，很容易区分出三个肠神经丛：内侧黏膜下神经丛、外侧黏膜下神经丛和肌间神经丛。在妊娠中期，所有这三个神经丛中都已不同程度地存在表达bNOS的神经元。尽管在妊娠中期肠神经系统已经存在，但肠神经元尚未达到其成年表型和形态。在妊娠期间，内侧黏膜下表达bNOS的神经元数量增加了约50倍，而出生后该数量降至产前值的约10%。在出生后的进一步发育过程中，其又恢复到产前值。此外，出生后表达bNOS的肌间神经元数量增加了一倍。这些变化表明一氧化氮在介导肠神经元发育中发挥作用，并且表明与胎儿猪相比，成年猪对抑制性神经支配的需求更大。此外，与十二指肠肛门段相比，十二指肠口腔段中表达bNOS的外侧黏膜下和肌间神经元数量显著更高。这种区域差异表明，十二指肠口腔段比肛门段更显著地参与一氧化氮介导的胃肠过程的调节。发育和区域依赖性的bNOS表达可以通过影响神经递质表达的激素、突触前输入和靶源信号平衡系统的变化和差异来解释。
