不同能量需求的棕色田鼠胃肠道一氧化氮合酶和血管活性肠肽的分布

Distribution of nitric oxide synthase and vasoactive intestinal peptide in the gastrointestine of mandarin vole Microtus mandarinus under different energy demands

为研究在能量需求变化的情况下生理功能调节在消化道适应性变化中的地位,并探讨生理调节与消化道形态结构适应性变化的关系,采用NADPH-黄递酶(NDP)组织化学法、VIP免疫组织化学法和整装铺片技术对哺乳和非哺乳雌性棕色田鼠及雄性棕色田鼠胃肠道管壁肌间神经丛和黏膜下神经丛一氧化氮合酶(Nitricoxide synthase,NOS)和血管活性肠肽(Vasoactive intestinal peptide,VIP)阳性神经元的分布进行观察。结果显示:哺乳和非哺乳雌性棕色田鼠及雄性棕色田鼠NOS阳性神经元分布于肌间神经丛,VIP分布于黏膜下神经丛,未观察到共染现象。NOS和VIP阳性神经元在哺乳雌性棕色田鼠胃及小肠前段的肌间神经丛和黏膜下神经丛的分布显著高于非哺乳雌鼠和雄鼠,而在回肠、盲肠和结肠差异不显著。由此说明,不同繁殖状态下,能量需求的不同促使消化道发生适应性变化,首先是生理功能及其调节机制的变化。同时提示消化道适应策略与消化道各段生理功能及能量胁迫程度有关[动物学报51(5):830-839,2005]。

Theoretical models of digestion derived from chemical reactor theory revealed that under higher energy demand, animals have to increase food intake. At the same time, morphologic regulation of the digestive tract occurs to retain digestion efficacy, a regulatory process that is divided into several phases. To investigate the role physiological adaptation plays in adaption of the digestive tract under different energy demands, and the relationship between physiological neuro-modulation and morphological adaptation, we used the mandarin vole Microtus rnandarinus as the animal model. We compared resting metabolism, digestibility, and morphological adaptive changes （length, mass, perimeter and mucosal thickness of different parts of digestive tract） among males, non-lactating females and lactating females. By measuring oxygen consumption, we concluded that the resting metabolic rate （RMR） of lactating females was significantly higher than non-lactating individuals. Using histochemical and immunocytochemical methods, we examined the distribution of vitric oxide synthase （NOS） and vasoactive intestinal peptide （VIP）, two important inhibitory transmitters in non-adrenergic and non-cholinergic （NANC） nerves, which were closely related to relaxation of intestinal smooth muscle, local blood flow and mucus secretion in the intestines. The density of NOS positive neurons in myenteric plexus （MP） was colon 〉 ileum 〉 duodenum 〉 stomach 〉 jejunum 〉 cecum, and VIP positive neurons in submucosal plexus （SP） was stomach〉intestines. We did not observe NOS positive neurons in SP, nor VIP in MP. Compared with nonlactating females, lactating females had wider distribution of NOS positive neurons in myenteric plexus and VIP positive neurons in submucosal plexus in stomach, duodenum and jejunum, but in the later part of intestine tract, there were no significant differences. The stomach and forepart of the small intestine were more closely related with increased energy demands evoked by pregnant and low temperature, while the later part of digestive tract is more closely linked to food quality. We concluded that the ENS＇s adaptation is a prior strategy to retain average digestibility, to settle higher energy demands more effectively and economically, and these adaptive changes preceded morphological changes of digestive tract, related with the extent of energy threatening. We also conclude that different adaption strategies in different sections of gastrointestinal tract derive from their different function [Acta Zoologica Sinica 51 （5） ： 830 - 839, 2005].