脑室和静脉注射吗啡对狗移行性综合肌电的影响

用10只狗作慢性实验,沿胃窦、小肠缝植8对银-氯化银双极电极,观察脑室和静脉注射吗啡对移行性综合肌电(migrating myoelectric complex,MMC)的影响。结果:(1)在十二指肠MMC周期时程的43％以后,静脉注射吗啡能诱发MMCⅢ相活动提前发生;在42％以内则无效应。(2)静脉注射3,000μg吗啡后,MMC周期延长,胃窦慢波频率减少;静脉注射300μg吗啡,对MMC周期时程和胃窦慢波频率无影响。(3 )脑室注射吗啡后,胃、小肠慢波首先发生自下而上的逆行性抑制,随之各部位峰电活动增多,十二指肠还发生痉挛性收缩的峰电活动,动物伴有呕吐的前驱症状和呕吐,MMC周期延长,胃窦慢波频率减少。(4)切断双侧膈上迷走神经后,脑室注射吗啡对胃和小肠肌电活动影响消失,但呕吐及其前驱症状仍然发生。     

甘草对大鼠小肠动力功能影响的实验研究

目的:初步探讨甘草对大鼠小肠动力的作用,及其作用与胃肠激素的相关性.方法:观察甘草组与空白组移行性综肌电(MMC)周期持续时间、Ⅲ相持续时间、Ⅲ相每分钟快波数(FM)和每簇的快波数(FC)的变化;采用免疫组织化学法结合显微图像定量分析扫描系统检测十二指肠、空肠嗜铬细胞及其肌间神经丛中5-羟色胺(5-HT)、P-物质(SP)、血管活性肠肽(VIP)的相对含量.结果:①甘草组与空白组比较MMCⅢ相FM和FC明显减少,MMC周期明显延长,Ⅲ相持续时间明显缩短,统计有显著性差异(P＜0.05).②甘草组十二指肠、空肠粘膜及肌间神经丛内5-HT表达明显较空白组减少,比较有显著性差异,小肠粘膜无明显SP、VIP阳性免疫反映物表达,但小肠肌间神经丛内SP含量明显减少、VIP含量明显增加,组间比较有显著性差异(P＜0.05,P＜0.01).结论:甘草对大鼠小肠动力有抑制作用,这种抑制作用与5-HT、SP、VIP分泌失调密切相关.     

红霉素对狗胃肠道电活动的影响

以移行性综合肌电(MMC)作指标,研究红霉素(EM)消化道副作用与平滑肌电活动的关系。结果发现,在狗消化间期,静脉注射EM50～400μg/kg,在3～7min内即诱发剂量依赖性早发MMCⅢ相。此早发Ⅲ相起于胃、十二指肠,向小肠尾端移行,其锋电发生率、Ⅲ相持续时间和移行速度等均与自发Ⅲ相类似。胃、十二指肠内分别注射EM500μg/kg,经24.5±7.5min和23.7±2.2min才诱发移行性Ⅲ相。双侧膈上迷走神经切除后,EM仍诱发早发Ⅲ相,但其移行速度减慢(p<0.01),阿托品能阻断EM诱发Ⅲ相的发生。EM在Ⅲ相诱发后的70～250min甚至更长时间内仍使MMC周期和Ⅲ相起始紊乱,甚至完全破坏MMG,代之以超速扩布锋电簇活动。EM不影响进食后狗的胃肠电活动。因此,EM消化道反应的发生可能与其被吸收进血液后通过内在胆碱能神经启动早发Ⅲ相及其后较长后效应有关。     

日节律紊乱对大鼠妊娠及子代的影响

本研究利用持续光照大鼠模型,观察日节律紊乱对大鼠妊娠及其子代早期的生长发育的影响,并初步探讨其与褪黑素及孕酮变化的关系。妊娠期给予24 h持续光照,观察日节律紊乱对大鼠分娩的影响。大鼠受孕后,在不同妊娠阶段采集血清,检测褪黑素和孕酮水平。在妊娠15日龄,随机选取一半孕鼠,剖腹观察胚胎吸收率。剩余母鼠继续饲养,观察分娩情况及产后仔鼠生长发育情况。结果显示:(1)持续光照条件下的日节律紊乱,可以导致大鼠不良妊娠结局,胚胎吸收率上升,活产仔鼠数量下降;(2)持续光照条件下的日节律紊乱,可以抑制褪黑素分泌,降低孕酮水平;(3)持续光照条件下的日节律紊乱,可以干扰大鼠的分娩节律,导致分娩时程延长,但对妊娠天数没有产生影响;(4)孕期大鼠暴露于持续光照条件下的日节律紊乱状态,可以影响仔鼠的宫内发育及子代早期生长发育。以上结果表明,持续光照导致的日节律紊乱,对于妊娠大鼠及新生大鼠,均会产生不良影响。本研究为临床指导孕期女性生物节律调节以及褪黑素的应用,提供理论依据。     

狗小肠部分切除对移行性综合肌电的影响

将9只狗的小肠总长度的30％,50％及75％的上端分别切除,观察其对移行性综合肌电(MMC)发生规律和红霉素诱发MMCⅢ相的影响。结果发现,所有小肠部分切除的狗,残余小肠的慢波节律均较小肠完整时相应部位明显减慢;75％上端小肠切除的狗,MMC活动消失。小肠完整的狗,静脉注射红霉素均能使MMCⅢ相提前发生;30％上端小肠切除的狗,红霉素仅在一半的实验中可诱发MMCⅢ相,50％及75％上端切除后,红霉素不能诱发MMCⅢ相。但静脉注射吗啡后在所有动物模型上均能诱发MMCⅢ相。提示小肠MMC的周期活动需要空肠以上小肠的存在,红霉素仅在小肠上端能诱发MMCⅢ相。     

15甲基前列腺素 F_(2α)和13去氢ω—乙基前列腺素 F_(2α)对妊娠大鼠血中孕酮的影响

15-甲-PGF_(2α)和13-去氢-ω 乙-PGF_(2α)在相同剂量时均能使妊娠7天的大鼠血浆孕酮浓度下降。15-甲-PGF_(α2)组于用药后4、8和24小时血浆孕酮浓度下降,分别为用药前的56.6%、43.7%和13.3%。在给药后72小时所有动物子宫中胚胎已被吸收。13-去氢ω-乙-PGF_(2α)组于用药后4、8和24小时血浆孕酮浓度分别为用药前的63.5%、34.4%和51.9%,给药后72小时大多数动物子宫中仍有胚胎,但胚胎比对照组显著为小,且多游离于子宫中。在给15-甲-PGF_(2α)前30分钟和第二次给15-甲-PGF_(2α)的同时,肌注 HOG 20国际单位,能完全对抗15-甲-PGF_(2α)的降低妊娠大鼠血浆孕酮浓度和抗早孕作用,给药后24小时内血浆孕酮浓度与对照组相似,全部动物维持妊娠,胚胎大小和数目也与对照组相似。恒速静注15-甲-PGF_(2α)(20微克)于麻醉妊娠大鼠,30分钟后已使子宫卵巢静脉血中孕酮含量由用药前1.271±0.154微克/10分钟下降到0.279±0.083微克/10分钟,给药后60分钟仍维持于低水平。如预先静注 HOG 20国际单位,可使子宫卵巢静脉血中孕酮含量由用药前1.123±0.162微克/10分钟升高到1.496±0.018微克/10分钟,在 HCG作用的基础上再静脉恒速注入15-甲-PGF_(2α),虽可使子宫卵巢静脉血中孕酮含量下降到1.179±0.042微克/10分钟,但不能降低到     

15甲基前列腺素F_(2α)对兔卵巢环磷酸腺苷和孕酮含量的影响

于假孕第7天的家兔,分別静脉注射15-甲-PGF_(2α)、HCG、HCG 15-甲-PGF_(2α),茶碱,茶碱 15-甲 PGF_(2α),观察用药后卵巢内 cAMP 和孕酮含量的变化。结果表明15-甲-PGF_(2α)能使卵巢内孕酮相 cAMP 含量明显下降,HCG 能促进孕酮合成,使卵巢内孕酮和cAMP 含量增加。HCG 和15-甲-PGF_(2α)联合应用则卵巢中孕酮和 cAMP 的含量与对照组比较均无显著差别,这表明15-甲-PGF_(2α)对 HCG 增加细胞内 cAMP 含量和促进孕酮合成均有颉颃作用,以上结果提示15-甲-PGF_(2α)的溶黄体作用与降低卵巢内 cAMP 水平是相关的。注射茶碱后卵巢内 cAMP 和孕酮含量均较对照组显著增加,茶碱是磷酸二酯酶抑制剂,表明茶碱增高孕酮的合成可能与提高卵巢细胞内 cAMP 水平是有关的,也表明磷酸二酯酶促进 cAMP转变为5′AMP 的过程也参与假孕兔卵巢孕酮合成的调节。茶碱与15-甲-PGF_(2α)合并应用后卵巢中 cAMP 和孕酮含量均不增加,与对照组比较无明显差別,表明15-甲-PGF_(2α)有颉颃茶碱使卵巢细胞内 cAMP 含量增加和促进孕酮合成的作用,实验结果进一步支持了15-甲-PG-F_(2a)溶黄体作用机制可能与细胞内 cAMP 水平降低有关。     

天花粉蛋白引产前后血清HCG含量的变化

人类胎盘的合体滋养层细胞能分泌激素,诸如绒毛膜促性腺激素(简称HCG)、孕酮等,这些激素是维持正常妊娠的重要因素。当胎盘发育到一定阶段后,即使切除卵巢,妊娠仍能继续维持下去。另外,根据临床上发现,先兆流产者的HCG分泌量往往下降到一     

大白鼠妊娠早期(1—6天)子宫孕酮受体的变化

本实验中大鼠妊娠第三天(D_3)出现血浆孕酮含量和子宫细胞胞核中孕酮受体含量显著同步升高和胞质中孕酮受体含量明显下降的现象,为D_5胚泡着床准备了必要的条件。D_6时血浆孕酮,胞质和胞核中孕酮受体以及子宫重量均升高,标志胚泡着床后的生理变化。     

顺铂对大鼠小肠电活动的影响

顺铂是近年来临床上广泛应用的一种抗癌药,有明显的消化道副作用。为探讨顺铂消化道副作用的发生机理,我们以移行性综合肌电(MMC)~[1]为指标,观察顺铂对大鼠小肠电活动的影响以及这种影响与植物神经系统的关系。 1 材料和方法 采用体重250～300g雄性Wistar大鼠,异戊巴比妥钠(30mg/kg)麻醉后,沿小肠浆膜面埋植两对铂丝双极电极。十二指肠1对,位于幽门下2cm处。空肠1对,位于Treitz韧带下10cm处。电极导线自腹     

Influence of microbial species on small intestinal myoelectric activity and transit in germ-free rats

The effect of an intestinal microflora consisting of selected microbial species on myoelectric activity of small intestine was studied using germ-free rat models, with recording before and after specific intestinal colonization, in the unanesthetized state. Intestinal transit, neuropeptides in blood (RIA), and neuromessengers in the intestinal wall were determined. Clostridium tabificum vp 04 promoted regular spike burst activity, shown by a reduction of the migrating myoelectric complex (MMC) period from 30.5 +/- 3.9 min in the germ-free state to 21.2 +/- 0.14 min (P < 0.01). Lactobacillus acidophilus A10 and Bifidobacterium bifidum B11 reduced the MMC period from 27.9 +/- 4.5 to 21.5 +/- 2.1 min (P < 0.02) and accelerated small intestinal transit (P < 0.05). Micrococcus luteus showed an inhibitory effect, with an MMC period of 35.9 +/- 9.3 min compared with 27.7 +/- 6.3 min in germ-free rats (P < 0.01). Inhibition was indicated also for Escherichia coli X7 gnotobiotic rats. No consistent changes in slow wave frequency were observed. The concentration of neuropeptide Y in blood decreased after introduction of conventional intestinal microflora, suggesting reduced inhibitory control. Intestinal bacteria promote or suppress the initiation and aboral migration of the MMC depending on the species involved. Bacteria with primitive fermenting metabolism (anaerobes) emerge as important promoters of regular spike burst activity in small intestine.     

Peripheral versus central components of the effects of dermorphin on intestinal motility in the fed rat

The effects of subcutaneous (s.c.), intraperitoneal (i.p.), intrathecal (i.t.) and intracerebroventricular (i.c.v.) injection of dermorphin (DER) on intestinal myoelectrical activity were examined in fed rats with chronically implanted electrodes on the small and large bowel. DER s.c. restored the 'fasting' pattern of duodenal activity, i.e., the migrating myoelectric complex (MMC), corresponding to an inhibition by about 40% of the fed pattern for 120 min at a dose as small as 0.5 nM per rat. DER i.p. strongly inhibited (about 65%) the fed pattern for 120 min. A fasting pattern lasting 80 min, or a marked inhibition lasting 150 min were recorded after 0.5 nM DER i.t. or i.c.v., respectively. On the contrary, the colonic pattern of activity was inhibited by DER whatever the route used, although the duration of inhibition was different from each other. For both the small and large intestine, similar doses of DER were more efficient by i.c.v. than by i.t. routes, and by i.p. than by s.c. routes. A plurality of sites of action is suggested, including local receptors which are activated, particularly at the duodenal level by i.p. DER (0.5 nM). The supraspinal component of the immediate effects of i.c.v. DER (0.1 nM) were demonstrated by a preferential effect on the colon that was even more intense than after i.t. DER.     

Mucosal mast cell responses in the small intestine of rats infected with Echinostoma hortense

Mucosal mast cell (MMC) responses and worm recovery rates in rats infected with Echinostoma hortense were investigated from day 3 to day 56 post-infection (p.i.). Experimental infected group showed apparently higher number of MMC in each part of the small intestine than that of the control group. The number of MMC in the duodenum increased gradually after the infection and reached a peak on day 35 p.i. Thereafter, the number of MMC continued to decrease at a slow pace. The kinetics of MMC responses in the upper and lower jejunum were similar to that of the duodenum, but the number of MMC in the jejunum was lower. The worm recovery rate decreased with respect to time of which it was markedly reduced on day 49 and 56 p.i. The duration in which a high number of MMC appeared was similar to that in which a low rate in worm recovery was recorded. These results indicate that intestinal mastocytosis may play an important role in the expulsion of E. hortense.     

Effect of aldosterone antagonists on aldosterone-induced activation of Mg2+ -HCO3- -ATPase and carbonic anhydrase in rat intestinal mucosa

In previous studies, Mg2+ -dependent, HCO3- -activated ATPase in the brush border and carbonic anhydrase in the cytoplasm of rat duodenal and jejunal mucosa decreased after adrenalectomy. Both enzyme activities increased to near normal levels 4 h after i.p. injection of aldosterone (40 micrograms/kg). These results suggest the possibility that both enzymes in the small intestinal mucosa may be mediators of the action of aldosterone. In the present studies, therefore, the effects of actinomycin D (500 micrograms/kg, i.p.), spironolactone (50 mg/kg, s.c.) and potassium canrenoate (50 mg/kg, s.c.) on aldosterone-induced activation of both enzymes in the upper small intestinal mucosa from adrenalectomized rats were examined to clarify the mechanism of action of aldosterone in enzyme levels. Actinomycin D inhibited carbonic anhydrase activity in small intestinal mucosa from normal rats 4 h after i.p. injection but had no effect on ATPase activity, while two other drugs had no effect on either enzyme activity in normal rats up to 4 h later. Pretreatment with these 3 drugs 1 h before aldosterone administration (40 micrograms/kg, i.p.) to adrenalectomized rats blocked the aldosterone-induced activation of ATPase and carbonic anhydrase in the upper small intestine. On the other hand, adrenalectomy and administration of aldosterone and its antagonists, alone or in combination, had no effect on kidney enzyme activities. These results confirm that Mg2+ -HCO3- -ATPase and carbonic anhydrase are mediators of the action of aldosterone in the upper small intestinal mucosa.     

Effects of hypoxia on the development of intestinal enzymes in neonatal and juvenile rats

Hypoxia in the neonate is known to alter the activity of hepatic and pancreatic enzymes involved in lipid and carbohydrate metabolism. The purpose of this study was to evaluate the effect of neonatal hypoxia on the activity of intestinal enzymes, and to determine whether the administration of glucocorticoids to neonates can mimic the effects of hypoxia. Hypoxia in neonatal rats (0-7 days) increased protein content, and lactase and maltase activity in the duodenal and the jejunal segments of the small intestine compared with normoxic controls. Hypoxia in juvenile rats (28-35 days) did not change these enzymes. Two weeks after returning hypoxic (0-7 days) pups to normoxia, their body weight remained lower than the age-matched controls. In the group recovering from hypoxia, sucrase, maltase, and leucine aminopeptidase activities were lower in the duodenal and the jejunal segment. Compared with controls, LDH activity was lower only in the jejunal intestine in the group recovering from hypoxia. All enzyme activities returned to control levels 3 weeks after recovery. Neonatal rats treated with dexamethasone had a decrease in body weight, but increases in sucrase and maltase activity in both the duodenal and the jejunal segment. Hypoxia in newborn rats caused a delayed maturation of small intestinal enzymes. Increases in serum glucocorticoids after hypoxic exposure probably do not play a major role in the delayed maturation of the disaccharidase activity in the small intestine.     

Bovine pancreatic secretion in the first week of life: potential involvement of intestinal CCK receptors.

The aim of this study was to evaluate pancreatic juice secretion of calves in the first postnatal days, and determine a potential involvement of cholecystokinin (CCK) and intestinal CCK receptor in its regulation. Nine neonatal Friesian calves (five controls and four treated intraduodenally with FK480, a CCK-A receptor antagonist) were surgically fitted with a pancreatic duct catheter and a duodenal cannula before the first colostrum feeding. Collections of pancreatic juice and duodenal luminal pressure recordings were started early after recovery from anaesthesia and continued for 6 days. From day 2 or 3 of life, periodic fluctuations in pancreatic secretions were observed in concert with duodenal myoelectric motor complex (MMC) and variations in plasma pancreatic polypeptide (PP) concentrations. Intraduodenal administration of FK480 reduced pancreatic juice secretion while intravenous infusion of CCK had no effect. Immunocytochemistry indicated an association of mucosal CCK-A and -B receptors with neural components of the small intestine. In conclusion, periodic activity of the exocrine pancreas exists in neonatal calves soon after birth and local neural intestinal CCK-A receptors could be partly responsible for the modulation of neonatal calf pancreatic secretion.     

Somatostatin inhibits bombesin-induced effects on migrating myoelectric complexes in the small intestine of the rat

The effect of i.v. infusions of bombesin and somatostatin, administered either separately or in combination, on migrating myoelectric complexes (MMCs) in the small intestine were studied in conscious, fasted rats. The myoelectrical activity was recorded by means of three bipolar electrodes chronically implanted into the duodenum and jejunum. Infusion of bombesin (0.5, 0.9 and 3 pmol . kg-1 . min-1) interrupted the MMC and induced irregular spiking activity similar to that observed on feeding. Only after the highest dose a consistent inhibition of the MMCs and a significant increase (P less than 0.05) of the spiking activity were achieved at all recording levels. Somatostatin (90 pmol . kg-1 . min-1) did not interrupt the MMC, but reduced significantly the incidence of the activity fronts and spiking activity of the MMCs (P less than 0.05). The effects of bombesin (3 pmol . kg-1 . min-1) on the MMC pattern were inhibited by simultaneous infusion of somatostatin (P less than 0.05). In a second series of experiments, using anesthetized rats, infusion of bombesin (0.5 and 3 pmol . kg-1 . min-1) increased the plasma concentration of neurotensin- gastrin-like immunoreactivities in a dose-dependent manner. The results show that bombesin alters the myoelectrical activity of the small intestine from a fasting to a fed pattern. Since the effect of bombesin was inhibited by the hormone release inhibitor somatostatin, it is suggested that the effect of bombesin on MMC may be secondary to the release of gastrointestinal peptides, such as neurotensin or gastrin.     

Cholecystokinin-dependent selective inhibitory effect on 'minute rhythm' in the ovine small intestine

Cholecystokinin (CCK) can exert multiple actions on intestinal motility but its effect on the small-intestinal 'minute rhythm' (MR) is virtually unknown. Therefore, the electrical activity from the abomasal antrum, duodenal bulb, duodenum, jejunum and ileum was continuously recorded in six sheep before, during and after slow intravenous administration, of three doses each, of cholecystokinin-octapeptide (CCK-OP) and cerulein. In four of these sheep, two additional electrodes and the strain gauge force transducer were also inserted in the duodenum. Chronic experiments were performed in the fasted and non-fasted animals and saline or CCK peptides were injected during phases 1, 2a or 2b of the duodenal migrating myoelectric complex (MMC). The administration of both CCK peptides in various doses evoked an inhibitory effect mostly in the duodenal bulb, except for the lowest dose of cerulein. The effects of 20 times greater doses of CCK-OP than that of cerulein were more pronounced. The introduction of both CCK peptides during phase 1 of the MMC produced no marked or significant response. In non-fasted animals, the effects of both hormonal peptides, given during phase 2b of the MMC, were often stronger than those given during phase 2a, while in fasted animals the effects of CCK peptides, administered in the course of phases 2a and 2b of the MMC, were similar. Both higher doses of CCK peptides increased the number of spike bursts within the given MR pattern in the duodenum and decreased the incidence of MR mostly in the duodenal bulb. The inhibitory effects of both CCK peptides on the bulbar MR exhibited a dose-response character, though the lowest dose often evoked the slight stimulatory response. It is concluded that CCK principally exerts an inhibitory effect upon the MR in the duodenal bulb and modifies the MR in the duodenum by increasing the spike burst number in a given MR pattern. Both these actions of CCK peptides seem to be physiological. There is a positive relationship between the intensity of the refractory period and the demonstrated effect of CCK in the duodenum.     

Enteral and systemic release of leukotrienes during anaphylaxis of Nippostrongylus brasiliensis-primed rats

Rats with acquired immunity to the intestinal nematode Nippostrongylus brasiliensis develop anaphylaxis after i.v. challenge with an extract of worm antigen, with the small intestine being the primary shock organ. In the present study we have shown that these events were associated with significant elevations in intestinal and plasma concentrations of leukotrienes LTB4 and LTC4. The changes were observed in immune rats over 10-, 30-, and 60-min intervals after antigen challenge but were absent in control animals. These lipid mediators were identified both in the perfusate of the gut lumen, which contained large quantities of mucus, and in homogenates of intestinal tissue. In addition, significant elevations in the concentrations of plasma LTB4 and LTC4 were detected in immune challenged rats but not in controls. Leukotrienes were identified by radioimmunoassay and validated by reverse-phase high-performance liquid chromatography (RP-HPLC). RP-HPLC analysis of SRS-A leukotrienes in immune challenged rats indicated that LTC4 was the predominant sulfidopeptide leukotriene at 10 min, with almost complete biodegradation to LTD4 and LTE4 within 30 min. Infected rats also had significant increases in the numbers of intestinal mucosal mast cells (MMC) and eosinophils. Evidence of MMC activation during anaphylaxis was obtained by showing significant elevations of intestinal and systemic concentrations of their exclusive serine enzyme, rat mast cell proteinase II (RMCPII). Thus, the release of substantial amounts of leukotrienes in the gut and plasma of N. brasiliensis-primed rats after interaction with worm antigens suggests that these potent mediators may play an important role in allergic-type hypersensitivity known to occur during immune reactions against parasitic helminths.     

Effects of intracerebroventricular administration of neurotensin,substance P and calcitonin on gastrointestinal motility in normal and vagotomized rats

The effects of intracerebroventricular (ICV) vs. intravenous (IV) injection of neurotensin, substance P and calcitonin on intestinal myoelectrical activity were examined in fed rats. ICV administered neurotensin and calcitonin restored the ‘fasted’ pattern of intestinal activity, i.e. the migrating myoelectric complex (MMC) at a dose as low as 12 and 0.2 pmol, respectively, whereas substance P only reduced significantly ($\text{P < 0.01}$) the duration of the postprandial pattern when injected ICV (48 pmol).Administered systemically at doses 100 times higher than the smallest active doses by the ICV route, calcitonin induced a fasted pattern, while neurotensin and substance P did not modify the fed pattern.The effects of ICV administration of neurotensin and calcitonin were abolished after vagotomy but the shortening effect of substance P on the duration of the postprandial pattern was still present.It is concluded that these three neuropeptides act centrally to control the pattern of intestinal motility in fed rats by shortening the ‘fed’ pattern for substance P and by restoring the MMC pattern for calcitonin and neurotensin, this last effect being mediated by the vagus.