Lipopolysaccharide-induced changes in mesenteric afferent sensitivity of rat jejunum in vitro: role of prostaglandins

B. Wang,1 J. Glatzle,1 M. H. Mueller,1 M. Kreis,1 P. Enck,1 and D. Grundy2

1Department of General Surgery, University of Tuebingen, Tuebingen, Germany and 2Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom

Submitted 26 July 2004 ; accepted in final form 13 March 2005


    ABSTRACT
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Bacterial translocation across the intestinal mucosal barrier leads to a macrophage-mediated inflammatory response, visceral hyperalgesia, and ileus. Our aim was to examine how mediators released into mesenteric lymph following LPS treatment influence intestinal afferent sensitivity and the role played by prostanoids in any sensitization. Intestinal lymph was collected from awake rats following treatment with either saline or LPS (5 mg/kg ip). Extracellular multiunit afferent recordings were made from paravascular mesenteric nerve bundles supplying the rat jejunum in vitro following arterial administration of control lymph, LPS lymph, and LPS. Mesenteric afferent discharge increased significantly after LPS lymph compared with control lymph. Peak discharge occurred within 2 min and remained elevated for 5 to 8 min. This response was attenuated by pretreatment with naproxen (10 µM), and restored upon addition of prostaglandin E2 (5 µM) in the presence of naproxen, but AH6809 (5 µM), an EP1/EP2 receptor(s) antagonist, failed to decrease the magnitude of LPS lymph-induced response. LPS itself also stimulated mesenteric afferent discharge but was unaffected by naproxen. TNF-{alpha} was significantly increased in LPS lymph compared with control lymph (1,583 ± 197 vs. 169 ± 38 pg/ml, P < 0.01) but exogenous TNF-{alpha} failed to evoke any afferent nerve discharge. We concluded that inflammatory mediators released from the gut into mesenteric lymph during endotoxemia have a profound effect on afferent discharge. These mediators influence afferent firing via the release of local prostaglandins.

cytokines; lymph; hypersensitivity


A SMALL BUT SIGNIFICANT SUBGROUP of irritable bowel syndrome (IBS) patients can trace the onset of their symptoms to a bout of acute gastroenteritis (27). It has been suggested that in these postinfectious IBS patients an acute inflammatory insult leads to the development of chronic symptoms (27, 28) and while psychosocial factors play a major role, there is evidence that an augmented inflammatory response may be a predisposing factor (12). Certainly there is a wealth of evidence demonstrating that inflammatory mediators alter the sensitivity of intestinal afferents (18). Many IBS patients exhibit a lowered visceral sensory threshold to pain; thus it is conceivable that in postinfectious IBS that visceral hypersensitivity may be secondary to an inflammatory insult (28). Understanding the etiology of chronic changes in visceral hypersensitivity may therefore be of considerable benefit to patients with postinfectious IBS.

LPS from Gram-negative bacteria, also known as endotoxin, can trigger a macrophage-driven cytokine cascade that is referred to as an acute-phase response. This drives a local inflammatory reaction and generates behavioral responses known as sickness behavior that include fever, anorexia, and hyperalgesia (21). In animal models, systemic LPS can cause ileus (8), rectal hypersensitivity (5), and also produces a profound increase in the afferent discharge emanating from the bowel wall (19). The macrophage-driven cytokine cascade following LPS administration gives rise to an increase in circulating IL-1{beta} and TNF-{alpha} (7). These cytokines orchestrate both the local inflammatory response and the central nervous system, consequences that are manifested as illness behavior. These central nervous system consequences appear to involve both direct effects of circulating cytokines and activation of afferent inputs to the central circuits that regulate temperature, feeding behavior and pain modulation (7, 21). The mechanisms underlying these changes in afferent sensitivity have not been determined although recent work from our laboratory suggests that prostanoids may play a pivotal role in the sensitization process (19, 23). However, changes in afferent sensitivity following systemic LPS can involve the generation of mediators locally in the gut wall, but also elsewhere in the body, which reach the gut via the circulation. Thus the contribution of local vs. systemic mediators to LPS-driven hyperalgesia needs to be determined.

Mediators released from the gut wall during sepsis appear in the lymph and can mediate inhibition of gastrointestinal motility (10). Harvesting lymph from LPS-treated animals therefore represents a method of assessing the contribution of such systemic mediators to the LPS-driven hyperalgesia. In the present study, we harvested lymph from LPS-treated animals and control animals and compared the effect of this lymph with the effect of LPS itself on the activation of afferents supplying the rat jejunum. With this model, it has been possible to distinguish for the first time the direct effects of LPS on afferent nerve discharge vs. indirect effects triggered by gut-derived mediators originally released by LPS challenge. Here we demonstrate the contribution of prostaglandins to these direct and indirect effects on afferent firing.


    MATERIALS AND METHODS
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Animals

Forty-four male Sprague-Dawley rats (300–350 g) purchased from Charles River (Sulzfeld, Germany) were fed regular laboratory chow with free access to water and housed under controlled conditions with a 12:12-h light-dark cycle. Institutional guidelines for the care and use of laboratory animals were followed throughout the study and approved by the institutional review board at the University of Tuebingen.

Mesenteric Lymph Collection

Surgical preparation. Rats (n = 8) were fasted overnight but allowed water ad libitum before surgery. Mesenteric lymph was collected as described previously (9, 10). Briefly, rats were anesthetized with methohexital sodium (60 mg/kg ip; Brevital; Johns Pharma, St. Louis, MO) and the mesenteric lymph duct, draining the area of the superior mesenteric artery, was cannulated with a polyvinyl tube (medical grade; 0.50 mm ID, 0.80 mm OD; Dural Plastics and Engineering, Dural, NSW, Australia) fixed in place with a drop of ethyl cyanoacrylate glue (Krazy Glue; Elmer’s Products, Columbus, OH) and exteriorized through a surgical incision in the right flank. A second cannula (silicone elastomer; 1 mm ID, 2.15 mm OD) was passed through the fundus of the stomach into the duodenum and secured with a purse-string suture. After surgery, rats were placed in Bollman cages and a glucose-saline solution (0.2 M glucose, 145 mM NaCl and 4 mM KCl) was infused continuously through the duodenal cannula at a rate of 3 ml/h to equalize fluid loss via the lymph. After a 24-h recovery period, mesenteric lymph was collected for 12 h following intraperitoneal administration of either normal saline as control or LPS (5 mg/kg, from Escherichia coli, Serotype 0111:B4). Lymph was collected in ice-chilled tubes, centrifuged, and an aliquot was taken for the cytokine assays. The lymph collected from each of the two groups of animals was pooled and frozen at –80°C until used. Animals were killed by anesthetic overdose at the end of this procedure.

Determination of TNF-{alpha} and IL-1{beta} in lymph. Concentration of TNF-{alpha} and IL-1{beta} in mesenteric lymph taken from each animal were determined using standard rat TNF-{alpha} and IL-1{beta} Immunoassay Kits (Biosource, Camarillo, CA) with sensitivity < 3 pg/ml.

Mesenteric Afferent Nerve Recordings

Rats (n = 36) were anaesthetized with pentobarbitone sodium (60 mg/kg ip) and a midline laparotomy was performed. The terminal jejunum and its arterial supply were identified. A branching section of artery with a clear projection to a segment of the jejunum was chosen, and any side branches were ligated. The jejunal segment with its attached mesenteric arcade was quickly removed and immersed in ice-cold saline. Rats were then killed by anesthetic overdose. After flushing the gut lumen, the tissue was transferred to an organ bath consisting of two main compartments as described previously (3). The gut "tube" was fixed at both ends in one compartment (organ chamber), which was continuously perfused with Krebs buffer (in mM: 117 NaCl, 4.7 KCl, 25 NaHCO3, 1.2 NaH2PO4, 1.2 MgCl2, 11 glucose, and 2.5 CaCl2, pH maintained at 7.4 with 95% O2-5% CO2) at a rate of 5 ml/min. The aboral end of the segment was connected to a pressure transducer (DTXPlus transducer; Ohmeda, Singapore) to record changes in intraluminal pressure to reflect intestinal motor activity. The mesenteric arcade was pulled through an aperture leading into a separate recording chamber. The mesenteric artery was cannulated and connected with a pump to permit intravascular perfusion with Krebs buffer (0.15 ml/min). To prevent accumulation of fluid in the recording chamber, the venous effluent was allowed to drain into the organ chamber by puncturing the small veins draining the segment. The aperture linking the two compartments was then sealed with Vaseline petroleum jelly, and the recording compartment was filled with heavy liquid paraffin. The preparation was allowed to warm slowly, reaching a working temperature of ~34°C before mesenteric nerve recording was obtained.

Under a stereo microscope, one of the two paravascular nerve bundles was exposed between the artery and vein. The surrounding connective tissue was carefully removed, and the nerve bundle was wrapped around one arm of a bipolar platinum recording electrode. One piece of connective tissue was attached to the second electrode. The electrodes were connected to an Neurolog headstage (Digitimer NL 100), and the signal was amplified (NL 104, 20,000) and filtered (NL 125 band width 100–1,000 Hz) then relayed to a spike processor (Digitimer D130) to allow discrimination of action potentials from noise using manually set amplitude and polarity window. Whole nerve activity was continually monitored as spike discharge [impulses (imp)/s] and stored together with the raw nerve signal and output from the pressure transducer on a computer running Spike-2 software (Cambridge Electronic Design).

Experimental Protocols

Experiments were performed on preparations in which baseline afferent discharge was maintained for at least 10 min and a robust nerve response to a submaximal dose of intra-arterial 5-HT (47 µg/ml, 0.3 ml) could be evoked. Preparations that failed to respond to 5-HT were assumed to be inadequately perfused and were excluded from the study. A 15-min recovery was allowed before beginning the subsequent protocols.

Three groups of experiments were performed in this study. In the first, Krebs solution, control lymph, LPS lymph, and then LPS (3 mg/ml) were infused intra-arterially, each over a 2-min period and separated by an interval of 15 min (n = 8). In pilot experiments (n = 3), LPS at this concentration was shown to evoke a robust mesenteric afferent response and was used as a standard stimulus at the end of each experiment. The time course and magnitude of the LPS response was comparable when given alone or following LPS lymph, indicating that the response to LPS was not conditioned by prior administration of LPS lymph.

The second series of experiments examined the involvement of prostanoid synthesis in LPS-induced responses. In these experiments LPS lymph and then LPS were infused as above, following pretreatment with naproxen in the perfusing fluid (10 µM, n = 6), naproxen (10 µM) plus PGE2 (5 µM, n = 5), or AH6809 (5 µM, n = 6). All treatments began 10 min before beginning the recording of baseline discharge.

In the final series of experiments, TNF-{alpha} was administered either intra-arterially (0.3 ml, 1 and 10 ng/ml, n = 4) or in the perfusing fluid at a final concentration of 10 ng/ml (n = 4) to test the influence of this inflammatory cytokine on afferent firing.

Materials

All salts used for the Krebs buffer were obtained from Sigma (St. Louis, MO) or Merck and were of AnalaR grade. LPS, naproxen ([–]-sodium 6-methoxy-{alpha}-methyl-2-naph-thaleneacetate), PGE2 ([5Z, 11{alpha}, 13E, 15S]-11, 15-dihydroxy-9-oxoprosta-5, 13-dienoic acid), and AH6809 (6-Isopropoxy-9-oxoxanthene-2-carboxylic acid) were obtained from Sigma. Recombinant rat TNF-{alpha} (Biosource) was dissolved in 0.1% BSA in buffered saline to a concentration of 10 ng/ml and stored at –86°C until use. PGE2 (1 mg) was dissolved in 0.1 ml of absolute ethanol and then 0.9 ml of a 2% solution of sodium carbonate was added to make a stock solution of 1 mg/ml. AH6809 was dissolved in dimethyl sulphoxide (6 mM) and frozen at –20°C before use.

Data Analysis and Statistics

All multiunit recordings showed a continuous pattern of on-going discharge in the absence of any intentional stimulation. Baseline discharge was determined during the 5-min period before stimulation. Increases in mesenteric discharge above this baseline following treatment are expressed as impulses per second and presented as means ± SE. These increases in discharge under the various experimental conditions were evaluated using ANOVA followed by post hoc Dunnett’s multiple comparison test using the software package of GraphPad Prism 3.02 (San Diego, CA). Biochemical data derived from samples of control and LPS lymph were compared using an unpaired Students’ t-test. Values of P < 0.05 were considered significant.


    RESULTS
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Effects of LPS Lymph and LPS on Mesenteric Afferent Discharge

Whole-nerve discharge did not change following the infusion of Krebs buffer; however, both LPS lymph and LPS evoked a significant increase in whole-nerve discharge (Fig. 1). In every case following LPS (n = 11) and in three of eight cases following LPS lymph, this increase in discharge was accompanied by a reduction in jejunal contractile activity (Fig. 1). LPS induced a more sustained inhibition in the contractile activity than LPS lymph (see bottom trace in Fig. 1 for example). Mesenteric discharge peaked around 100 s following the onset of infusion and the magnitude of this peak was similar for LPS lymph and LPS (Figs. 2 and 3). The time course of recovery of mesenteric afferent firing was also similar for LPS lymph and LPS (Fig. 2). The administration of control lymph did not result in a significant increase in mesenteric afferent discharge (n = 8) although in two individual cases there was a modest increase in afferent discharge (Fig. 3) and in one of these, there was an associated reduction in spontaneous contractile activity.



View larger version (24K):
[in this window]
[in a new window]
 
Fig. 1. Mesenteric afferent response to LPS lymph and LPS in rat jejunum in vitro. The upper trace shows "snapshots" of the raw nerve recording taken during baseline and during the response peak to LPS lymph and LPS. Note the recruitment of large amplitude spikes following treatment. The middle trace is a sequential rate histogram of whole-nerve afferent impulse (imp) activity before and following (arrows) perfusion with LPS lymph and LPS. The bottom trace shows the corresponding intraluminal pressure demonstrating the inhibition of jejunal motility in response to LPS lymph or LPS.

 


View larger version (26K):
[in this window]
[in a new window]
 
Fig. 2. Profile of the increase in afferent discharge following LPS lymph and LPS compared with the response to Krebs buffer and control lymph. The mean increase in afferent discharge above baseline discharge is plotted during consecutive 50-s epochs. Note that LPS lymph and LPS evoke a similar time course of afferent activation. *P < 0.05 vs. control lymph.

 


View larger version (12K):
[in this window]
[in a new window]
 
Fig. 3. Scatterplot showing the peak increases in afferent discharge in individual preparations for control lymph, LPS lymph, and LPS. For the latter, data are separated into the 8 experiments in which all 3 conditions were applied and the 3 pilot experiments (pilot exp) receiving LPS alone.

 
Effect of TNF-{alpha}

The level of TNF-{alpha} in mesenteric lymph was almost 10 times higher in animals treated with LPS compared with saline-treated controls (1,583 ± 197 vs. 169 ± 38 pg/ml, P < 0.001, see Fig. 4). In contrast, the concentration of IL-1{beta} was similar in control and LPS lymph (64 + 15 vs. 60 + 8 pg/ml).



View larger version (15K):
[in this window]
[in a new window]
 
Fig. 4. TNF-{alpha} concentrations in control and LPS lymph. Note the 10-fold increase in the concentration of TNF-{alpha} in LPS lymph compared with control lymph. **P < 0.001 vs. control lymph (n = 4 patients).

 
TNF-{alpha} at 0.1 or 10 ng/ml administered either intra-arterially (n = 4) or into the organ bath (n = 4) had no effect on whole mesenteric afferent nerve discharge (Fig. 5).



View larger version (39K):
[in this window]
[in a new window]
 
Fig. 5. Vascularly perfused TNF-{alpha} failed to alter mesenteric afferent discharge. The upper trace is the neurogram with an expanded region illustrating action potentials. The middle trace is the sequential rate histogram of whole nerve afferent impulse activity, and the bottom trace is intraluminal pressure. Neither the rate of mesenteric afferent discharge nor luminal pressure was altered after application of TNF-{alpha} (10 ng/ml, 0.3 ml).

 
Effect of Naproxen, PGE2, and AH6809

The involvement of prostanoids in the response to LPS and LPS lymph was investigated by adding the cyclooxygenase (COX) inhibitor naproxen (10 µM) to the bathing medium. Baseline discharge in tissue treated with naproxen was 5.4 ± 1.3 imp/s (P > 0.05, vs. control group 12.4 ± 3.6 imp/s). The response to LPS lymph was significantly attenuated by naproxen (Fig. 6). Addition of PGE2 (5 µM) to the naproxen containing Krebs augmented baseline firing to 19.3 ± 2.8 (imp/s) and also fully restored the response to LPS lymph (Fig. 6). The mesenteric afferent response to LPS was attenuated by naproxen but this failed to reach significance (Fig. 7). In contrast, PGE2 in the presence of naproxen augmented the LPS-induced response (Fig. 7). LPS-mediated inhibition of spontaneous contractile activity persisted after treatment with naproxen but the duration of this inhibition was significantly reduced (169.0 ± 22.9 vs. 484.4 ± 78.4 s, P < 0.05).



View larger version (22K):
[in this window]
[in a new window]
 
Fig. 6. The profile of the mesenteric afferent response to LPS lymph following naproxen (10 µM) and after the addition of PGE2 (5 µM). Note that the response was significantly attenuated in the presence of naproxen but fully restored upon addition of PGE2. *P < 0.05 vs. LPS lymph.

 


View larger version (22K):
[in this window]
[in a new window]
 
Fig. 7. Histogram showing the peak increase in afferent discharge in response to LPS lymph (top) and LPS (bottom). Naproxen significantly attenuated only the response to LPS lymph. In contrast, PGE2 significantly augmented the response to both LPS lymph and LPS. For the former, this was sufficient to restore the LPS lymph response to a comparable level to that obtained in the absence of naproxen while the response to LPS in the presence of naproxen and PGE2 significantly exceeded that to LPS alone.

 
The response to both LPS and LPS lymph was not attenuated by treatment with AH6809 (Fig. 8), and indeed the response to LPS was significantly augmented in animals treated with AH6809.



View larger version (20K):
[in this window]
[in a new window]
 
Fig. 8. Histogram showing the response to LPS lymph (top) and LPS (bottom) in the absence and presence of the EP receptor antagonist AH6809. Note that far from attenuating these responses the peak discharge was higher after treatment, which in the case of LPS was significantly above the control response. P < 0.05.

 

    DISCUSSION
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
The present study provides new insight into the local effects of LPS on mesenteric afferent discharge. Mesenteric lymph containing mediators released from the gut during endotoxemia evoked a significant mesenteric afferent nerve discharge compared with lymph collected from control animals. This observation supports the concept that LPS-induced inflammation leads to increased mesenteric afferent discharge which may contribute to visceral hypersensitivity. Such gut-derived inflammatory products play a major role in shock-induced pathological responses (1, 11). Moreover, systemic LPS induces a wide range of effects including fever, sickness behavior, and hyperalgesia that depend in part on activation of afferents whose terminals lie within the bowel wall (15). Our hypothesis that inflammatory mediators within mesenteric lymph can participate in this process of hyperalgesia is supported by our present results. In some experiments control lymph also increases mesenteric afferent discharge. However, it should be borne in mind that even these control animals had undergone abdominal surgery to place the lymphatic cannula and may have developed a macrophage-mediated postoperative ileus (17). We attempted to minimize such a contribution by allowing 24-h recovery following surgery before collecting the lymph.

Another important observation in our study was that LPS itself also activated afferent discharge with a similar time course to the response seen with LPS lymph. This might suggest that LPS acts directly on the afferent endings or on other elements within the bowel wall to release mediators that act locally to augment afferent firing. The short latency of this response might imply an action on the LPS receptor that is present on macrophage and other structures within the bowel wall (2). This sensitivity to LPS raises the possibility that the afferent response to LPS lymph arises as a consequence of LPS itself entering the lymph following intraperitoneal administration and exerting a direct effect on primary afferents. Although we did not measure the concentration of LPS in the mesenteric lymph, this explanation would seem unlikely because the response to LPS lymph was markedly attenuated by pretreatment with naproxen, whereas LPS itself still could mediate a marked and robust response following treatment with the cyclooxygenase inhibitor naproxen.

The short latency for activation of mesenteric afferent discharge following the LPS lymph and LPS is remarkable, suggesting that mediators released following the LPS accumulate rapidly in the interstitial fluid within the gut wall. The rapid recovery of discharge following treatment would also imply that these mediators are rapidly eliminated following their release either by reuptake or dissipation through the rapid perfusion system. This time course is very different from that seen following LPS administration in vivo in which afferent discharge rises substantially 15 min after administration, coinciding with an augmenting sensitivity to both mechanical stimulation (distension) and chemical mediators (5-HT) (20). However, even in these in vivo experiments, a small transient increase in discharge was observed immediately following administration of LPS, and this may coincide with the actions seen in the present study in vitro (20).

LPS-induced inflammatory responses depend on the release of proinflammatory cytokines such as IL-1, IL-6, and TNF-{alpha}. Indeed, inflammatory cytokines acting locally may directly or indirectly stimulate and/or sensitize nociceptors, thereby contributing to sensory hyperalgesia (5, 16). Previous work implicating TNF-{alpha} in the development of neuropathic pain follows the observation that exogenous TNF-{alpha} elicits a PKA-dependent response in rat sensory neurons (29). However, in the present study, TNF-{alpha} at concentrations considerably higher than that found in mesenteric lymph after LPS treatment did not stimulate mesenteric afferent discharge. It appears, therefore, that the afferent response to LPS lymph was not induced by TNF-{alpha} alone. However, this does not rule out the possibility for TNF-{alpha} acting as part of a cascade of cytokine contributing to more longer-term changes in afferent sensitivity rather than the direct short-term effects that were observed in the present study (4).

Prostaglandins play an important role in communication between the gastrointestinal immune system and the enteric nervous system. During intestinal inflammation, prostaglandins are released from a variety of cell types, including sympathetic nerve terminals and immunocompetent cells (4, 26). It is well known that prostaglandins increase the sensitivity of sensory nerves to inflammatory mediators by acting on prostaglandin EP receptors expressed on both vagal and spinal afferent endings (13). The present study demonstrates that inflammatory mediators released from gut into lymph influence mesenteric afferent firing via a COX-related mechanism, since the response to LPS lymph was inhibited by the COX inhibitor naproxen. This observation is in agreement with the concept that prostanoids play a pivotal role in modulating visceral sensitivity during inflammation.

There are at least two isoforms of the COX enzyme, COX-1 and COX-2. COX-1 is constitutively expressed and may be involved in controlling baseline visceral afferent sensitivity. However, during inflammatory conditions such as colitis, upregulation of the COX-2 occurs, leading to augmented prostanoid synthesis, and this enzyme may therefore be important in hyperalgesia during inflammation (18). Naproxen inhibits both COX-1 and COX-2, but the short latency in duration of the responses observed in the present study would suggest that it is the constitutive isoform that is being influenced by naproxen in the present study. The background of prostanoids may serve to sensitize the afferent endings to other mediators (possibly also prostanoids) that are present in the LPS lymph. This interpretation is supported by the observation that the addition of PGE2 to the bathing medium can restore the afferent response to LPS lymph.

PGE2 evokes a powerful activation of mesenteric afferents and mediates the sensitivity of afferent responses to both IL-1{beta} and bradykinin (16, 23). In the gastrointestinal tract, EP1 receptors appear to play a major role in direct activation of mucosal mesenteric afferents, while EP2 receptors may also play a sensitizing role (13, 23). It is interesting that in the present study, the EP1/EP2 receptor antagonist AH6809 failed to mitigate the mesenteric afferent response to LPS lymph despite the marked influence of PGE2 on the afferent response to LPS lymph. This may suggest that other subtypes of EP receptors, including EP3 and EP4, play a role in the response. On the other hand, PGE2 is not the only prostanoid released by LPS that potentially could contribute to modulation of afferent sensitivity in this model.

Disturbances in intestinal motility following LPS was widely reported using both in vivo and in vitro models (6, 14, 22, 24, 25). Most studies reported inhibition of intestinal motility with intestinal motor dysfunction involving endogenous nitric oxide, prostanoids, and cytokines. Observations in the present study that jejunal contractile activity is inhibited by LPS and that this period of inhibition is decreased after naproxen is consistent with this view. The effect of LPS lymph on jejunal motility was less than that of LPS itself, because application of LPS lymph inhibited spontaneous contractions in only three of eight experiments, and even for these three, the duration of inhibition was much shorter than for LPS. The prolonged effect of LPS might be explained by an inflammatory cascade with multiple intermediate mediators, several of which inhibit motility. In contrast, LPS lymph, because it is likely to be made up of the end products of such a cascade, would be expected to have a shorter duration of action. Alternatively, initially active inflammatory mediators may have been catabolized or otherwise degraded by the time the LPS lymph was collected, thus providing another possible basis for the disparity in duration of action between LPS and LPS lymph.

In summary, the present study indicates that gut-derived mediators released by LPS have a profound effect on mesenteric afferent sensitivity. TNF-{alpha} is unlikely to have a direct influence on afferent excitability but prostaglandins appear to play a modulating influence.


    GRANTS
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
This work was supported by the Deutsche Forschungsgemeinschaft Grant 311/3–1 (to J. Glatzle).

B. Wang is an Alexander von Humboldt Foundation funded research fellow.


    ACKNOWLEDGMENTS
 
This work was presented, in part, at the Digestive Disease Week, Orlando, Florida, May 17–22, 2003.


    FOOTNOTES
 

Address for reprint requests and other correspondence: D. Grundy, Dept. of Biomedical Science, Univ. of Sheffield, Sheffield, S10 2TN, UK (e-mail: d.grundy{at}sheffield.ac.uk)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


    REFERENCES
 TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

  1. Adams CA Jr, Hauser CJ, Adams JM, Fekete Z, Xu DZ, Sambol JT, and Deitch EA. Trauma-hemorrhage-induced neutrophil priming is prevented by mesenteric lymph duct ligation. Shock 18: 513–517, 2002.[ISI][Medline]
  2. Beutler B. TLR4 as the mammalian endotoxin sensor. Curr Top Microbiol Immunol 270: 109–120, 2002.[ISI][Medline]
  3. Brunsden AM, Jacob S, Bardhan KD, and Grundy D. Mesenteric afferent nerves are sensitive to vascular perfusion in a novel preparation of rat ileum in vitro. Am J Physiol Gastrointest Liver Physiol 283: G656–G665, 2002.[Abstract/Free Full Text]
  4. Bueno L and Fioramonti J.Visceral perception: inflammatory and non-inflammatory mediators. Gut 51, Suppl I: i19–i23, 2002.[CrossRef]
  5. Coelho AM, Fioramonti J, and Bueno L. Systemic lipopolysaccharide influences rectal sensitivity in rats: role of mast cells, cytokines, and vagus nerve. Am J Physiol Gastrointest Liver Physiol 279: G781–G790, 2000.[Abstract/Free Full Text]
  6. Cullen JJ, Caropreso DK, Hemann LL, Hinkhouse M, Conklin JL, and Ephgrave KS. Pathophysiology of a dynamic ileus. Dig Dis Sci 42: 731–737, 1997.[CrossRef][ISI][Medline]
  7. Dantzer R. Cytokine-induced sickness behavior: mechanisms and implications. Ann NY Acad Sci 933: 222–234, 2001.[Abstract/Free Full Text]
  8. Eskandari MK, Kalff JC, Billiar TR, Lee KK, and Bauer AJ. Lipopolysaccharide activates the muscularis macrophage network and suppresses circular smooth muscle activity. Am J Physiol Gastrointest Liver Physiol 273: G727–G734, 1997.[Abstract/Free Full Text]
  9. Glatzle J, Kalogeris TJ, Zittel TT, Guerrini S, Tso P, and Raybould HE. Chylomicron components mediate intestinal lipid-induced inhibition of gastric motor function. Am J Physiol Gastrointest Liver Physiol 282: G86–G91, 2002.[Abstract/Free Full Text]
  10. Glatzle J, Leutenegger CM, Mueller MD, Kreis ME, Raybould HE, and Zittel TT. Mesenteric lymph collected during peritonitis or sepsis potently inhibits gastric motility in rats. J Gastrointest Surg 8: 645–652, 2004.[CrossRef][ISI][Medline]
  11. Gonzalez RJ, Moore EE, Ciesla DJ, Neto JR, Briffl WL, and Silliman CC. Hyperosmolarity abrogates neutrophil cytotoxicity provoked by post-shock mesenteric lymph. Shock 18: 29–32, 2002.[CrossRef][ISI][Medline]
  12. Gwee KA, Collins SM, Read NW, Rajnakova A, Deng Y, Graham JC, McKendrick MW, and Moochhala SM. Increased rectal mucosal expression of interleukin 1{beta} in recently acquired post-infectious irritable bowel syndrome. Gut 52: 523–526, 2003.[Abstract/Free Full Text]
  13. Haupt W, Jiang W, Kreis ME, and Grundy D. Prostaglandin EP receptor subtypes have distinctive effects on jejunal afferent sensitivity in the rat. Gastroenterology 119: 1580–1589, 2000.[ISI][Medline]
  14. Hellstrom PM, Al-Saffar A, Ljung T, and Theodorsson E. Endotoxin actions on myoelectric activity, transit, and neuropeptides in the gut. Role of nitric oxide. Dig Dis Sci 42: 1640–1651, 1997.[CrossRef][ISI][Medline]
  15. Holzer P. Sensory neurone responses to mucosal noxae in the upper gut: relevance to mucosal integrity and GI pain. Neurogastroenterol Motil 14: 459–475, 2002.[CrossRef][ISI][Medline]
  16. Hori T, Oka T, Hosoi M, Abe M, and Oka K. Hypothalamic mechanisms of pain modulatory actions of cytokines and prostaglandin E2. Ann NY Acad Sci 917: 106–120, 2000.[Abstract/Free Full Text]
  17. Kalff JC, Carlos TM, Schraut WH, Billiar TR, Simmons RL, and Bauer AJ. Surgically induced leukocytic infiltrates within the rat intestinal muscularis mediate postoperative ileus dysfunction. Gastroenterology 117: 378–387, 1999.[ISI][Medline]
  18. Kirkup AJ, Brunsden AM, and Grundy D. Receptors and Transmission in the Brain-Gut Axis: Potential for Novel Therapies. I. Receptors on visceral afferents. Am J Physiol Gastrointest Liver Physiol 280: G787–G794, 2001.[Abstract/Free Full Text]
  19. Liu CY, Jiang W, Mueller MH, Grundy D, and Kreis M. Mechanisms controlling lipopolysaccharide (LPS) induced changes in mesenteric afferent sensitivity in the rat small intestine (Abstract). Gastroenterology 124, Supp 1: W1422, A-667, 2003.
  20. Liu CY, Jiang W, Mueller MH, Kirkup AJ, Grundy D, and Kreis ME. Systemic lipopolysaccharide sensitizes mesenteric afferent nerve fibers in the rat small intestine (Abstract). Neurogastroenterol Motil 14: 581, P48, 2002.
  21. Maier SF, Goehler LE, Fleshner M, and Watkins LR. The role of the vagus nerve in cytokine-to-brain communication. Ann NY Acad Sci 840: 289–300, 1998.[Abstract/Free Full Text]
  22. Martinez-Cuesta MA, Esplugues JV, and Whittle BJ. Modulation by nitric oxide of spontaneous motility of the rat isolated duodenum: role of tachykinins. Br J Pharmacol 118: 1335–1340, 1996.[ISI][Medline]
  23. Maubach KA and Grundy D. The role of prostaglandins in the bradykinin-induced activation of serosal afferents of the rat jejunum in vitro. J Physiol 515: 277–285, 1999.[Abstract/Free Full Text]
  24. Nissan A, Zhang JM, Lin Z, Haskel Y, Freund HR, and Hanani M. The contribution of inflammatory mediators and nitric oxide to lipopolysaccharide-induced intussusception in mice. J Surg Res 69: 205–207, 1997.[CrossRef][ISI][Medline]
  25. Rebollar E, Arruebo MP, Plaza MA, and Murillo MD. Effect of lipopolysaccharide on rabbit small intestine muscle contractility in vitro: role of prostaglandins. Neurogastroenterol Motil 14: 633–642, 2002.[CrossRef][ISI][Medline]
  26. Sharkey KA and Kroese ABA. Consequences of intestinal inflammation on the enteric nervous system: neuronal activation induced by inflammatory mediators. Anat Rec 262: 79–90, 2001.[CrossRef][ISI][Medline]
  27. Spiller RC. Postinfectious irritable bowel syndrome. Gastroenterology 124: 1662–1671, 2003.[CrossRef][ISI][Medline]
  28. Talley NJ and Spiller R. Irritable bowel syndrome: a little understood organic bowel disease? Lancet 360: 555–564, 2002.[CrossRef][ISI][Medline]
  29. Zhang JM, Li HQ, Liu BG, and Brull SJ. Acute topical application of tumor necrosis factor {alpha} evokes protein kinase A-dependent responses in rat sensory neurons. J Neurophysiol 88: 1387–1392, 2002.[Abstract/Free Full Text]




This Article
Abstract
Full Text (PDF)
All Versions of this Article:
289/2/G254    most recent
00329.2004v1
Alert me when this article is cited
Alert me if a correction is posted
Citation Map
Services
Email this article to a friend
Similar articles in this journal
Similar articles in ISI Web of Science
Similar articles in PubMed
Alert me to new issues of the journal
Download to citation manager
Google Scholar
Articles by Wang, B.
Articles by Grundy, D.
Articles citing this Article
PubMed
PubMed Citation
Articles by Wang, B.
Articles by Grundy, D.


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2005 by the American Physiological Society.