Ghrelin对糖尿病大鼠下丘脑弓状核胃扩张敏感神经元和胃运动的影响

目的:探讨Ghrelin对糖尿病大鼠下丘脑弓状核胃扩张敏感神经元和胃运动的影响。方法:逆行追踪结合免疫组化观察ARC中GHSR-1的表达,细胞外放电记录,观察ghrelin对GD神经元放电活动的影响及电刺激ARC对GD神经元放电活动和胃运动的影响。结果:电生理实验结果表明,在ARC Ghrelin能够能激发GD兴奋性神经元(GD-E)和GD抑制性神经元(GD-I)。然而,ghrelin可以兴奋更少的GD-E神经元,在正常大鼠中ghrelin对于GD-E的兴奋作用比在DM大鼠中的作用弱。在体胃运动研究表明,在ARC中微量注射ghrelin可以明显的增强胃运动,并且呈现剂量依赖关系。Ghrelin在糖尿病大鼠促胃动力作用低于正常大鼠。Ghrelin诱导的效应可被生长激素促分泌素受体(GHSR)拮抗剂阻断[d-lys-3]-GHRP-6或bim28163。放射免疫法和实时荧光定量PCR数据表明胃血浆ghrelin水平,在ARC ghrelin mRNA的表达水平先上升后下降,糖尿病大鼠(DM)中,在ARC中GHSR-1a mRNA表达保持在一个比较低的水平。结论:ghrelin可以调节GD敏感神经元以及胃运动,通过ARC中ghrelin受体。在糖尿病大鼠中,Ghrelin促进胃运动作用减弱可能与ARC中ghrelin受体表达减少有关。     

Orexin在隔核对大鼠胃传入信息的调控

目的:研究orexin在隔核对大鼠胃传入信息的调控作用。方法:选取健康成年雄性Wistar大鼠138只(体质量250-300 g),记录神经元放电活动,鉴定隔核胃牵张(GD)敏感性神经元;隔核微量注射orexin-A或orexin-A受体拮抗剂SB334867,观察隔核GD敏感性神经元放电活动变化;隔核微量注射不同浓度的orexin-A,观察大鼠胃运动的变化。结果:隔核微量注射orexin-A的大鼠胃运动幅度和频率显著增加,并呈剂量依赖关系(P0.05-0.01),微量注射SB-334867可完全阻断orexin-A对胃运动的影响。隔核微量注射orexin-A后,有36个GD-E神经元兴奋(P0.01),16个GD-I神经元抑制。Orexin-A受体拮抗剂SB334867可完全阻断orexin-A对GD敏感神经元的作用。结论:隔核注射orexin能促进大鼠胃运动,并影响胃牵张敏感神经元的放电活动。     

下丘脑弓状核微量注射Orexin-A对大鼠胃传入信息和胃运动的影响

目的:探讨ARC orexin-A对胃传入信息以及胃运动的调控及机制。方法:采用细胞外放电记录方法,鉴定ARC orexin胃牵张敏感神经元(Gastric distention sensitive neurons,GD),并探讨ARC内orexin-A对GD神经元放电活动的影响及机制;采用ARC微量注射orexin-A和及其受体阻断剂SB334867,观察大鼠胃收缩幅度和频率的改变。结果:大鼠ARC共记录到149个GD神经元,其中GD-E神经元91个,GD-I神经元58个。ARC微量注射orexin-A,62个(62/91,68.1%)GD-E神经元兴奋性显著增加,其放电频率由4.27±0.58 Hz增加到8.46±0.95 Hz(P0.01);39个(39/58,67.2%)GD-I神经元兴奋性也显著增强,其放电频率由4.02±0.53 Hz增加到5.43±0.57 Hz(P0.05)。然而,ARC给予大鼠orexin-A受体拮抗剂SB334867,再给予orexin-A,orexin-A兴奋效应完全被阻断(P0.05)。胃运动实验结果显示:在ARC注射不同浓度orexin-A,大约5 min后,大鼠胃收缩幅度和频率呈剂量依赖性增加(P0.05~0.01)。ARC注射SB334867,可完全消除orexin-A对大鼠胃运动的兴奋效应(P0.05)。结论:ARC orexin-A对大鼠GD神经元和胃运动有调控作用,该作用可能通过调控Orexin A受体活动实现的。     

生长素对胃运动和对海马胃肠敏感神经元放电活动的影响

目的:探讨海马ghrelin对GD敏感神经元放电和弓状核ghrelin对胃运动的影响。方法:在细胞外记录海马的放电情况,并且检测清醒大鼠的胃运动。通过PCR免疫印迹和免疫荧光组织化学染色等方法来测定GHSR-1a在海马中的表达。用逆行追踪和免疫荧光组织化学染色检测ghrelin神经元的投射情况。Ghrelin况荧光金双标记的神经元以及GHSR-1a的表达分别可以在ARC和海马中观察到。结果:Ghrelin或者ARC电刺激可以兴奋海马区的胃牵张敏感神经元。Ghrelin受体拮抗剂[d-Lys-3]-GHRP-6预处理可以完全或者部分阻断这种兴奋作用。海马注射ghrelin可以显著促进胃运动,并且呈现剂量依赖关系,而且这种作用可以被[d-Lys-3]-GHRP-6所阻断。电刺激ARC能够促进胃运动。然而,预处理时[d-Lys-3]-GHRP-6可以减弱这些作用。电损毁海马可以减弱胃运动的兴奋作用,这个作用通过电刺激ARC产生的。结论:通过海马促进胃运动中ghrelin起着重要的作用。ARC可能参与调节海马对胃动力的影响。     

Effects of ghrelin on glucose-sensing and gastric distension sensitive neurons in rat dorsal vagal complex

Ghrelin has been identified as the endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Recent studies have shown that site-specific injection of ghrelin directly into the dorsal vagal complex (DVC) of rats is equally as sensitive in its orexigenic response to ghrelin as the arcuate nucleus of the hypothalamus (ARC). It is as yet unclear how circulating ghrelin would gain access to and influence the activity of the neurons in the DVC in which GHS receptors are expressed. In the present study, neuronal activity was recorded extracellularly in the DVC of anesthetized rats in order to examine the effects of ghrelin on the glucosensing neurons and the gastric distension (GD) sensitive neurons. The 82 neurons were tested with glucose, of which 26 were depressed by glucose and identified as glucose-inhibited (glucose-INH) neurons; 11 were activated and identified as glucose-excited (glucose-EXC) neurons. Of 26 glucose-inhibited neurons examined for response to ghrelin, 23 were depressed, 1 was activated, and 2 failed to respond to ghrelin. Nine of 11 glucose-excited neurons were suppressed by ghrelin application, and the responses are abolished by the pretreatment with the GHS-R antagonist, [D-Lys-3]-GHRP-6. In addition, of 47 DVC neurons examined for responses to gastric distension (GD), 25 were excited (GD-EXC), 18 were inhibited (GD-INH). 18 out of the 25 GD-EXC neurons were excited, whereas 15 out of 18 GD-INH neurons were suppressed by ghrelin. In conclusion, the activity of the glucosensing neurons in the DVC can be modulated by ghrelin, the primary effect of ghrelin on the glucose-INH and glucose-EXC neurons was inhibitory. Two distinct population of GD-sensitive neurons exist in the rat DVC: GD-EXC neurons are activated by ghrelin; the GD-INH neurons are suppressed by ghrelin. There is a diversity of effects of ghrelin on neuronal activity within the DVC, it is as yet unclear how this diversity in ghrelin's effects on cellular excitability contributes to ghrelin biological actions to influence food intake and gastric motility.     

胃动素对大鼠下丘脑胃牵张敏感神经元和胃运动的影响(英文)

目的:研究胃动素对下丘脑弓状核胃牵张敏感神经元放电活动和胃运动的影响。方法:采用4管玻璃微电极细胞外记录胃动素对大鼠弓状核胃牵张敏感神经元活动,采用胃内置传感器观察胃动素对对清醒大鼠胃运动的影响。结果:65.5%的弓状核神经元为胃扩张敏感性神经元,其中55.6%为胃扩张兴奋性神经元,44.4%为抑制性神经元。胃扩张刺激后兴奋性神经元的放电频率显著增加(P<0.01),而抑制性神经元的放电频率显著降低(P<0.01)。弓状核内微量注射胃动素,70%的兴奋性神经元在胃扩张刺激后表现为兴奋作用,17.5%的神经元表现为抑制作用,并且放电频率显著增加(P<0.05)。同样,在抑制性神经元中,65.6%在注射胃动素后引起电活动增强,放电频率显著降低(P<0.05)。而胃动素受体拮抗剂GM-109可以完全阻断这种由胃动素诱导的兴奋作用,提示,胃动素在弓状核通过其特异性受体调控神经元活动。在胃运动实验中,弓状核微量注射胃动素后,胃运动的收缩频率和幅度都显著增加(P<0.05);同时,这种兴奋作用也可被GM-109阻断。结论:研究证实了弓状核胃动素神经元接收来自胃感受器的外周躯体感觉传入神经的冲动,并通过某些下级核团通路发挥...     

Synergistic action of gastrin and ghrelin on gastric acid secretion in rats

Gastrin and ghrelin are secreted from G cells and X/A-like cells in the stomach, respectively, and respective hormones stimulate gastric acid secretion by acting through histamine and the vagus nerve. In this study, we examined the relationship between gastrin, ghrelin and gastric acid secretion in rats. Intravenous (iv) administration of 3 and 10 nmol of gastrin induced transient increases of ghrelin levels within 10 min in a dose-dependent manner. Double immunostaining for ghrelin and gastrin receptor revealed that a proportion of ghrelin cells possess gastrin receptors. Although (iv) administration of gastrin or ghrelin induced significant gastric acid secretion, simultaneous treatment with both hormones resulted in a synergistic, rather than additive, increase of gastric acid secretion. This synergistic increase was not observed in vagotomized rats.These results suggest that gastrin may directly stimulate ghrelin release from the stomach, and that both hormones may increase gastric acid secretion synergistically.     

Nesfatin-1及MCH对大鼠胃酸分泌和胃运动的影响

目的:本实验主要探究nesfatin-1对胃运动和胃酸分泌的影响,以及弓状核(ARC)-下丘脑外侧区(LHA)nesfatin-1神经通路在该过程中的作用。方法:采用逆行追踪和免疫组织化学染色实验观察ARC-LHA nesfatin-1神经通路的构成;在体胃运动实验观察nesfatin-1对胃运动的影响以电刺激ARC对胃运动的影响;采用幽门结扎法测量胃液和胃酸分泌量。结果:LHA微量注射nesfatin-1抑制胃运动和胃酸分泌,但是预先注射黑色素浓集激素(MCH)受体拮抗剂PMC-3881-PI减弱nesfatin-1对胃运动和胃酸分泌的抑制作用。电刺激ARC后,胃收缩幅度和频率显著增强,胃酸分泌明显增多。nesfatin-1抗体或PMC-3881-PI对电刺激ARC诱导的胃运动没有显著影响,但是能够改变电刺激ARC诱导的胃酸分泌。结论:ARC-LHA间nesfafin-1通路可调控大鼠胃运动和胃酸分泌,并且黑色素浓集激素也参与调节该过程。     

大鼠下丘脑外侧区内微量注射胃动素对胃窦运动和迷走背核复合体神经元电活动的影响

采用清醒大鼠胃运动记录和玻璃微电极记录神经元活动的实验方法 ,研究下丘脑外侧区 (lateralhy pothalamicarea,LHA)微量注射胃动素 (motilin) ,对清醒大鼠胃窦运动和对麻醉大鼠迷走背核复合体 (dorsalvagalcomplex ,DVC)中胃扩张敏感神经元电活动的调节作用。LHA内微量注射胃动素 (0 37nmol/ 0 5 μl)可使胃窦运动增强 76 2 9± 4 0 9% (P <0 0 1)。DVC中 6 0个胃扩张 (gastricdistention ,GD)敏感神经元中 ,39(6 5 % )个GD刺激引起电活动增强 ,2 1(35 % )个电活动减弱 ,分别称之为GD兴奋型神经元和GD抑制型神经元。双侧LHA微量注射胃动素 0 37nmol/ 0 5 μl,14个GD抑制型神经元中有 12个单位放电频率增加 4 4 35± 7 89% (P <0 0 1) ;2 4个GD兴奋型神经元中有 15个单位放电频率减少 7 17± 7 89% (P <0 0 5 )。结果提示 ,中枢胃动素可能通过LHA-DVC-迷走神经实现对胃窦运动的调控     

Ghrelin stimulates gastric emptying but is without effect on acid secretion and gastric endocrine cells

Ghrelin, a recently discovered peptide hormone, is produced by endocrine cells in the stomach, the so-called A-like cells. Ghrelin binds to the growth hormone (GH) secretagogue receptor and releases GH. It is claimed to be orexigenic and to control gastric acid secretion and gastric motility. In this study, we examined the effects of ghrelin, des-Gln¹⁴-ghrelin, des-octanoyl ghrelin, ghrelin-18, -10 and -5 (and motilin) on gastric emptying in mice and on gastric acid secretion in chronic fistula rats and pylorus-ligated rats. We also examined whether ghrelin affected the activity of the predominant gastric endocrine cell populations, G cells, ECL cells and D cells. Ghrelin and des-Gln¹⁴-ghrelin stimulated gastric emptying in a dose-dependent manner while des-octanoyl ghrelin and motilin were without effect. The C-terminally truncated ghrelin fragments were effective but much less potent than ghrelin itself. Ghrelin, des-Gln¹⁴-ghrelin and des-octanoyl ghrelin neither stimulated nor inhibited gastric acid secretion, and ghrelin, finally, did not affect secretion from either G cells, ECL cells or D cells.     

Effect of ghrelin on gastric myoelectric activity and gastric emptying in rats

Ghrelin is a recently discovered peptide in the endocrine cells of the stomach, which may stimulate gastric motility via the vagal nerve pathway. However, the mechanism of ghrelin-induced changes in gastrointestinal motility has not been clearly defined. The purpose of this study was to investigate the pharmacological effects of ghrelin on gastric myoelectrical activity and gastric emptying in rats, and to investigate whether cholinergic activity is involved in the effects of ghrelin. The study was performed on Sprague-Dawley rats implanted with serosal electrodes for electrogastrographic recording. Gastric slow waves were recorded from fasting rats at baseline and after injection of saline, ghrelin, atropine, or atropine+ghrelin. Gastric emptying of non-caloric liquid was measured by the spectrophotometric method in conscious rats. Intravenous administration of rat ghrelin (20 microg/kg) increased not only dominant frequency, dominant power and regularity of the gastric slow wave but also the gastric emptying rate when compared with the control rats (P<0.01, P<0.05, P<0.05, P<0.001 respectively). These stimulatory actions of ghrelin on both gastric myoelectrical activity and gastric emptying were not fully eliminated by pretreatment with atropine sulphate. These results taken together suggest that ghrelin may play a physiological role in the enteric neurotransmission controlling gastric contractions in rats.     

The effects of nesfatin‐1 in the paraventricular nucleus on gastric motility and its potential regulation by the lateral hypothalamic area in rats

The current study investigated the effects of nesfatin‐1 in the hypothalamic paraventricular nucleus (PVN) on gastric motility and the regulation of the lateral hypothalamic area (LHA). Using single unit recordings in the PVN, we show that nesfatin‐1 inhibited the majority of the gastric distention (GD)‐excitatory neurons and excited more than half of the GD‐inhibitory (GD‐I) neurons in the PVN, which were weakened by oxytocin receptor antagonist H4928. Gastric motility experiments showed that administration of nesfatin‐1 in the PVN decreased gastric motility, which was also partly prevented by H4928. The nesfatin‐1 concentration producing a half‐maximal response (EC50) in the PVN was lower than the value in the dorsomedial hypothalamic nucleus, while nesfatin‐1 in the reuniens thalamic nucleus had no effect on gastric motility. Retrograde tracing and immunofluorescent staining showed that nucleobindin‐2/nesfatin‐1 and fluorogold double‐labeled neurons were observed in the LHA. Electrical LHA stimulation changed the firing rate of GD‐responsive neurons in the PVN. Pre‐administration of an anti‐ nucleobindin‐2/nesfatin‐1 antibody in the PVN strengthened gastric motility and decreased the discharging of the GD‐I neurons induced by electrical stimulation of the LHA. These results demonstrate that nesfatin‐1 in the PVN could serve as an inhibitory factor to inhibit gastric motility, which might be regulated by the LHA.

     

Exogenous and endogenous ghrelin in gastroprotection against stress-induced gastric damage

Ghrelin, identified in the gastric mucosa has been involved in control of food intake and growth hormone (GH) release but little is known about its influence on gastric secretion and mucosal integrity. The effects of ghrelin on gastric secretion, plasma gastrin and gastric lesions induced in rats by 75% ethanol or 3.5 h of water immersion and restraint stress (WRS) were determined. Exogenous ghrelin (5, 10, 20, 40 and 80 microg/kg i.p.) increased gastric acid secretion and attenuated gastric lesions induced by ethanol and WRS and this was accompanied by the significant rise in plasma ghrelin level, gastric mucosal blood flow (GBF) and luminal NO concentrations. Ghrelin-induced protection was abolished by vagotomy and attenuated by suppression of COX, deactivation of afferent nerves with neurotoxic dose of capsaicin or CGRP(8-37) and by inhibition of NOS with L-NNA but not influenced by medullectomy and administration of 6-hydroxydopamine. We conclude that ghrelin exerts a potent protective action on the stomach of rats exposed to ethanol and WRS, and these effects depend upon vagal activity, sensory nerves and hyperemia mediated by NOS-NO and COX-PG systems.     

Differential distribution of ghrelin-O-acyltransferase (GOAT) immunoreactive cells in the mouse and rat gastric oxyntic mucosa

The enzyme that acylates ghrelin was recently identified in mice as the fourth member of the membrane-bound O-acyltransferases superfamily (MBOAT4) and named ghrelin-O-acyltransferase (GOAT). Only one report showed GOAT mRNA expression in ghrelin-expressing cells of the mouse stomach. We investigated the distribution of GOAT protein in peripheral tissues and co-expression with endocrine markers in the gastric mucosa using a custom-made anti-GOAT antibody. Tissues were collected from male Sprague-Dawley rats and C57BL/6 mice. Western blot revealed two immunoreactive bands in rat and mouse gastric corpus mucosal proteins, a 50 kDa band corresponding to the GOAT protein and a 100 kDa band likely corresponding to a dimer. Western blot also detected GOAT in the plasma and levels were strongly increased after 24-h fasting in mice and slightly in rats. GOAT-immunoreactive cells were located in the gastric corpus mucosa and the anterior pituitary gland, whereas other peripheral tissues of rats and mice examined were negative. In mice, GOAT-immunoreactive cells were mainly distributed throughout the middle portion of the oxyntic glands, whereas in rats they were localized mainly in the lower portion of the glands. Double labeling showed that 95 ± 1% of GOAT-immunoreactive cells in mice co-labeled with ghrelin, whereas in rats only 56 ± 4% of GOAT-positive cells showed co-expression of ghrelin. The remainder of the GOAT-immunopositive cells in rats co-expressed histidine decarboxylase (44 ± 3%). No co-localization was observed with somatostatin in rats or mice. These data suggest species differences between rats and mice in gastric GOAT expression perhaps resulting in a different role of the MBOAT4 enzyme in the rat stomach. Detection of GOAT in the plasma raises the possibility that ghrelin octanoylation may occur in the circulation and the fasting-induced increase in GOAT may contribute to the increase of acylated ghrelin after fasting.     

Modulation of gastric motility by brain-gut peptides using a novel non-invasive miniaturized pressure transducer method in anesthetized rodents

Acute in vivo measurements are often the initial, most practicable approach used to investigate the effects of novel compounds or genetic manipulations on the regulation of gastric motility. Such acute methods typically involve either surgical implantation of devices or require intragastric perfusion of solutions, which can substantially alter gastric activity and may require extended periods of time to allow stabilization or recovery of the preparation. We validated a simple, non-invasive novel method to measure acutely gastric contractility, using a solid-state catheter pressure transducer inserted orally into the gastric corpus, in fasted, anesthetized rats or mice. The area under the curve of the phasic component (pAUC) of intragastric pressure (IGP) was obtained from continuous manometric recordings of basal activity and in responses to central or peripheral activation of cholinergic pathways, or to abdominal surgery. In rats, intravenous ghrelin or intracisternal injection of the thyrotropin-releasing hormone agonist, RX-77368, significantly increased pAUC while coeliotomy and cacal palpation induced a rapid onset inhibition of phasic activity lasting for the 1-h recording period. In mice, RX-77368 injected into the lateral brain ventricle induced high-amplitude contractions, and carbachol injected intraperitoneally increased pAUC significantly, while coeliotomy and cecal palpation inhibited baseline contractile activity. In wild-type mice, cold exposure (15 min) increased gastric phasic activity and tone, while there was no gastric response in corticotropin releasing factor (CRF)-overexpressing mice, a model of chronic stress. Thus, the novel solid-state manometric approach provides a simple, reliable means for acute pharmacological studies of gastric motility effects in rodents. Using this method we established in mice that the gastric motility response to central vagal activation is impaired under chronic expression of CRF.     

Impaired ghrelin signaling is associated with gastrointestinal dysmotility in rats with gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is often associated with decreased upper gastrointestinal motility, and ghrelin is an appetite-stimulating hormone known to increase gastrointestinal motility. We investigated whether ghrelin signaling is impaired in rats with GERD and studied its involvement in upper gastrointestinal motility. GERD was induced surgically in Wistar rats. Rats were injected intravenously with ghrelin (3 nmol/rat), after which gastric emptying, food intake, gastroduodenal motility, and growth hormone (GH) release were investigated. Furthermore, plasma ghrelin levels and the expression of ghrelin-related genes in the stomach and hypothalamus were examined. In addition, we administered ghrelin to GERD rats treated with rikkunshito, a Kampo medicine, and examined its effects on gastroduodenal motility. GERD rats showed a considerable decrease in gastric emptying, food intake, and antral motility. Ghrelin administration significantly increased gastric emptying, food intake, and antral and duodenal motility in sham-operated rats, but not in GERD rats. The effect of ghrelin on GH release was also attenuated in GERD rats, which had significantly increased plasma ghrelin levels and expression of orexigenic neuropeptide Y/agouti-related peptide mRNA in the hypothalamus. The number of ghrelin-positive cells in the gastric body decreased in GERD rats, but the expression of gastric preproghrelin and GH secretagogue receptor mRNA was not affected. However, when ghrelin was exogenously administered to GERD rats treated with rikkunshito, a significant increase in antral motility was observed. These results suggest that gastrointestinal dysmotility is associated with impaired ghrelin signaling in GERD rats and that rikkunshito restores gastrointestinal motility by improving the ghrelin response.     

Ghrelin accelerates gastric emptying via early manifestation of antro-pyloric coordination in conscious rats

Ghrelin is known to enhance gastric motility and accelerate gastric emptying of liquid and solid food in rats. As solid gastric emptying is regulated by the coordinated motor pattern between the antrum and pylorus (antro-pyloric coordination), we studied the correlation between solid gastric emptying and antro-pyloric coordination in response to ghrelin. Rats were given 1.5 g of solid food after a 24-h fasting. Immediately after the ingestion, ghrelin (0.4-8.0 microg/kg) or saline was administered by intraperitoneal (i.p.) injection. Ninety minutes after the feeding, rats were euthanized and gastric content was removed to calculate gastric emptying. To evaluate the antro-pyloric coordination, strain gauge transducers were sutured on the antrum and pylorus. The incidence of postprandial antro-pyloric coordination was compared between ghrelin-and saline-injected rats. In saline-injected rats, gastric emptying was 58.3+/-3.7% (n=6). Ghrelin (4.0-8.0 microg/kg), accelerated gastric emptying. Maximum effect was obtained by ghrelin (4.0 microg/kg), which significantly accelerated gastric emptying to 77.4+/-3.7% (n=6, p<0.05). The number of antro-pyloric coordination 20-40 min after feeding was significantly increased in ghrelin-injected rats, compared to that of saline-injected rats (n=4, p<0.05). It is suggested that enhanced antro-pyloric coordination play an important role in accelerated solid gastric emptying induced by ghrelin.     

糖尿病大鼠弓状核-海马肥胖抑素通路构成及对胃运动和胃排空的影响

目的: 探究糖尿病大鼠弓状核(ARC)-海马肥胖抑素(obestatin)神经通路构成,以及该通路对大鼠胃运动、胃排空的影响。方法: 健康雄性Wistar大鼠采用果糖溶液诱导胰岛素抵抗加腹腔注射链脲佐菌素的方法制备糖尿病模型,造模之后,随机分为5组:对照组(NS组)、0.1、1和10 pmol obestatin组、obestatin+NBI27914组,每组7只;各组通过置管分别向海马内注射0.5 μl 生理盐水(NS)、obestatin(0.1 pmol、1 pmol、10 pmol)和混合液(10 pmol obestatin + 60 pmol NBI27914),给药后立即记录大鼠胃运动,15 min后进行胃排空研究;通过荧光金(FG)逆行追踪及免疫组化方法比较正常及糖尿病大鼠ARC-海马obestatin神经通路构及ARC obestatin mRNA表达的异同。结果: 与正常大鼠相比,糖尿病大鼠ARC FG/obestatin双标神经元数目显著减少(P＜0.05),ARC obestatin mRNA表达量显著下降(P＜0.05);obestatin各组可剂量依赖性的抑制大鼠胃运动及胃排空(P＜0.05~0.01),obestatin的这些效应可被促肾上腺皮质激素受体1(CRFR1)阻断剂NBI27914部分阻断(P＜0.05);obestatin对糖尿病大鼠胃运动和胃排空的抑制效应显著减弱(P＜0.05)。结论: ARC-海马之间存在obestatin神经和功能通路,参与糖尿病大鼠胃运动及胃排空调控,且CRFR1信号通路参与该过程。该通路功能的减弱可能参与了糖尿病早期胃动力紊乱的发病。     

Reduced ghrelin production induced anorexia after rat gastric ischemia and reperfusion

The gastrointestinal (GI) tract is one of the most susceptible organs to ischemia. We previously reported altered gastric motility after gastric ischemia and reperfusion (I/R). However, there have also been few reports of alterations in the eating behavior after gastric I/R. Ghrelin is a GI peptide that stimulates food intake and GI motility. Although ghrelin itself has been demonstrated to attenuate the mucosal injuries induced by gastric I/R, the endogenous ghrelin dynamics after I/R has not yet been elucidated. The present study was designed to investigate the relationship between food intake and the ghrelin dynamics after gastric I/R. Wistar rats were exposed to 80-min gastric ischemia, followed by 12-h or 48-h reperfusion. The food intake, plasma ghrelin levels, gastric preproghrelin mRNA expression levels, and the histological localization of ghrelin-immunoreactive cells were evaluated. The effect of exogenous ghrelin on the food intake after I/R was also examined. Food intake, the plasma ghrelin levels, the count of ghrelin-immunoreactive cells corrected by the percentage areas of the remaining mucosa, and the expression levels of preproghrelin mRNA in the stomach were significantly reduced at 12 h and 48 h after I/R compared with the levels in the sham-operated rats. Intraperitoneal administration of ghrelin significantly reversed the decrease of food intake after I/R. These data show that gastric I/R evoked anorexia with decreased plasma ghrelin levels and ghrelin production, which appears to be attributable to the I/R-induced gastric mucosal injuries. The decrease in the plasma ghrelin levels may have been responsible for the decreased food intake after gastric I/R.     

Effect of motilin on the discharge of rat hippocampal neurons responding to gastric distension and its potential mechanism

The study aims to find the effect of motilin on neuronal activity of gastric distension-responsive neurons in rat hippocampus and its possible mechanism. Single unit discharges in the hippocampal CA1 region were recorded extracellularly by means of four-barrel glass micropipettes in anesthetized rats and the expression of nNOS in hippocampus was observed by fluo-immunohistochemistry staining. Of the 171 recorded neurons, 76.0% were GD-excitatory (GD-E) neurons and 24.0% were GD-inhibited (GD-I) neurons. The 57.6% of GD-E neurons showed an excitatory response to motilin and the same effect was observed in 51.7% GD-I neurons. However, when NOS inhibitor nitro-l-arginine methyl ester (l-NAME) was administrated previously, the followed motilin-induced excitatory responsiveness of GD-responsive neurons was reduced. In contrast, discharge activity of GD-responsive neurons with motilin was enhanced by pretreatment of NO precursor l-arginine. The expression of nNOS-IR positive neurons was significantly increased in CA1 after administration of motilin. Our findings suggested that motilin excited the GD-responsive neurons in the hippocampal CA1 region and the excitatory effect of motilin may be mediated by the endogenous NO.