Effects of intestinal inflammation on specific subgroups of guinea-pig celiac ganglion neurons

A ganglionic intestinointestinal reflex activated by acute noxious challenge

To investigate noxious stimulation-responsive neural circuits that could influence the gut, we recorded from intestinally directed (efferent) nerve filaments dissected from mesenteric nerves close to the small intestine in anesthetized rats. These exhibited baseline multiunit activity that was almost unaffected by vagotomy (VagX) and reduced only slightly by cutting the splanchnic nerves. The activity was halved by hexamethonium (Hex) treatment. When an adjacent gut segment received an intraluminal stimulus 2,4,6-trinitrobenzenesulfonate (TNBS) in 30% ethanol, mesenteric efferent nerve activity increased for more than 1 h. The increased activity was almost unaffected by bilateral vagotomy or splanchnic nerve section, indicating a lack of central nervous involvement, but it was 60% reduced by hexamethonium. Spike sorting discriminated efferent single and predominantly single-unit spike trains that responded to TNBS, were unaffected by splachnectomy but were silenced by hexamethonium. After noxious stimulation of one segment, the adjacent segment showed no evidence of suppression of gut motility or vasoconstriction. We conclude that luminal application of a noxious stimulus to the small intestine activates an entirely peripheral, intestinointestinal reflex pathway. This pathway involves enteric intestinofugal neurons that excite postganglionic sympathetic neurons via a nicotinic synapse. We suggest that the final sympathetic efferent neurons that respond to a tissue damaging stimulus are distinct from vasoconstrictor, secretomotor, and motility inhibiting neurons.NEW & NOTEWORTHY An intraluminal noxious chemical stimulus applied to one segment of small intestine increased mesenteric efferent nerve activity to an adjacent segment. This was identified as a peripheral ganglionic reflex that did not require vagal or spinal connections. Hexamethonium blocked most, but not all, ongoing and reflex mesenteric efferent activity. The prevertebral sympathetic efferent neurons that are activated likely affect inflammatory and immune functions of other gut segments.

Age-related reductions in the excitability of phasic dorsal root ganglion neurons innervating the urinary bladder in female rats

Previous studies have revealed an impairment in bladder sensory transduction in aged animals. To examine the contributions of electrical property changes of bladder primary afferents to this impairment, we compared the electrical properties of dorsal root ganglion (DRG) neurons innervating the bladder among young (3 months), middle-aged (12 months), and old (24 months) female rats. The DRG neurons were labeled using axonal tracing techniques. Whole-cell current-clamp recordings of small and medium-sized neurons were performed to assess their passive and active properties. Two patterns of firing were identified based on responses to super-threshold stimuli (1.5, 2.0, 2.5, and 3.0 × rheobase): tonic neurons fired more action potentials (APs), whereas phasic neurons fired only one AP at the onset of stimulus. Tonic neurons were smaller and had a slower rate of AP rise, longer AP duration, more depolarized voltage threshold, and greater rheobase than phasic neurons. In phasic neurons, there was an age-associated increase in voltage threshold and an increase of rheobase (P < 0.05), suggesting an age-related decrease in excitability. In addition, both middle-aged and old rats had longer AP durations and slower rates of AP rise than young rats (P < 0.05). In tonic neurons, old rats had a greater AP overshoot and greater rate of AP rise, but no age-associated changes were identified in any other electrical properties. Our results suggest that the electrical properties of tonic and phasic bladder afferents are differentially altered with aging. A decrease in excitability may contribute to age-related reductions in bladder sensory function.

A role for interleukin 17A in IBD-related neuroplasticity

BACKGROUND

Changes to the structure and function of the innervation of the gut contribute to symptom generation in inflammatory bowel diseases (IBD). However, delineation of the mechanisms of these effects has proven difficult. Previous work on sympathetic neurons identified interleukin (IL)-17A as a novel neurotrophic cytokine. Since IL-17A is involved in IBD pathogenesis, we tested the hypothesis that IL-17A contributes to neuroanatomical remodeling during IBD.

METHODS

Immunohistochemistry for tyrosine hydroxylase was used to identify sympathetic axons in mice with dextran sulphate sodium (DSS)-induced colitis and controls. Axon outgrowth from sympathetic neurons in response to incubation in cytokines or endoscopic patient biopsy supernatants was quantified.

KEY RESULTS

DSS-induced colitis led to an increase in tyrosine hydroxylase immunoreactivity in the inflamed colon but not the spleen. Colonic supernatants from mice with colitis and biopsy supernatants from Crohn's disease patients increased axon outgrowth from mouse sympathetic neurons compared to supernatants from uninflamed controls. An antibody that neutralized IL-17A blocked the ability of DSS-induced colitis and Crohn's disease supernatants to induce axon extension.

CONCLUSIONS AND INFERENCES

These findings identify IL-17A as a potential mediator of neuroanatomical remodeling of the gut innervation during IBD.

Plasticity of neuroeffector transmission during bowel inflammation1

Altered gastrointestinal (GI) function contributes to the debilitating symptoms of inflammatory bowel diseases (IBD). Nerve circuits contained within the gut wall and outside of the gut play important roles in modulating motility, mucosal fluid transport, and blood flow. The structure and function of these neuronal populations change during IBD. Superimposed on this plasticity is a diminished responsiveness of effector cells - smooth muscle cells, enterocytes, and vascular endothelial cells - to neurotransmitters. The net result is a breakdown in the precisely orchestrated coordination of motility, fluid secretion, and GI blood flow required for health. In this review, we consider how inflammation-induced changes to the effector innervation of these tissues, and changes to the tissues themselves, contribute to defective GI function in models of IBD. We also explore the evidence that reversing neuronal plasticity is sufficient to normalize function during IBD.

Alterations in the distal colon innervation in Winnie mouse model of spontaneous chronic colitis

The gastrointestinal tract is innervated by extrinsic sympathetic, parasympathetic and sensory nerve fibers as well as by intrinsic fibers from the neurons in myenteric and submucosal ganglia embedded into the gastrointestinal wall. Morphological and functional studies of intestinal innervation in animal models are important for understanding the pathophysiology of inflammatory bowel disease (IBD). The recently established Winnie mouse model of spontaneous chronic colitis caused by a point mutation in the Muc2 mucin gene develops inflammation due to a primary epithelial defect. Winnie mice display symptoms of diarrhea, ulcerations and rectal bleeding similar to those in IBD. In this study, we investigated myenteric neurons, noradrenergic, cholinergic and sensory nerve fibers in the distal colon of Winnie (Win/Win) mice compared to C57/BL6 and heterozygote littermates (Win/Wt) using histological and immunohistochemical methods. All Win/Win mice used in this study had inflammation with signs of mucosal damage, goblet cell loss, thickening of muscle and mucosal layers, and increased CD45-immunoreactivity in the distal colon. The density of sensory, cholinergic and noradrenergic fibers innervating the myenteric plexus, muscle and mucosa significantly decreased in the distal colon of Win/Win mice compared to C57/BL6 and Win/Wt mice, while the total number of myenteric neurons as well as subpopulations of cholinergic and nitrergic neurons remained unchanged. In conclusion, changes in the colon morphology and innervation found in Winnie mice have multiple similarities with changes observed in patients with ulcerative colitis.

Morphology and Topography of the Celiac Plexus in Degu (Octodon Degus)

Here, we investigate the morphology and topography of the celiac plexus components in degu (Octodon degus). The study was performed using six adult individuals of both sexes. Macromorphological observations were performed using a derivative of the thiocholine method specially adapted for this study type (Gienc, 1977). The classical H&E technique was used for analysis of the cytoarchitectonic of the ganglion, and the AChE (Karnovsky and Roots, 1964) and SPG (De la Torre, 1980) techniques to observe cholinergic and adrenergic activity. The celiac plexus of degu is located on the ventral and lateral surface of the abdominal aorta, at the level where the celiac artery separates from the aorta. This structure consists of two large and two smaller aggregations of neurocytes connected with postganglionic fibers. Histochemical investigations have demonstrated the mainly cholinergic characteristic of the intraganglionic and postganglionic fibers of the celiac plexus, while the adrenergic fibers accompanied only the blood vessels and neurocytes revealed differentiation of adrenergic activity. Histological analysis revealed that neurocytes occupied about half of the cross-section area, with the nerve fibers, connective tissue, and blood vessels forming the remaining part. Ganglionic cells were oval, and usually contained a single nucleus, although two nuclei were sometimes observed.

Mouse models of sepsis elicit spontaneous action potential discharge and enhance intracellular Ca2+ signaling in postganglionic sympathetic neurons

Sepsis is a severe systemic inflammatory disorder that rapidly activates the sympathetic nervous system to enhance catecholamine secretion from postganglionic sympathetic neurons and adrenal chromaffin cells. Although an increase in preganglionic drive to postganglionic sympathetic tissues has been known to contribute to this response for quite some time, only recently was it determined that sepsis also has direct effects on adrenal chromaffin cell Ca2+ signaling and epinephrine release. In the present study, we characterized the direct effects of sepsis on postganglionic sympathetic neuron function. Using the endotoxemia model of sepsis in mice, we found that almost a quarter of postganglionic neurons acquired the ability to fire spontaneous action potentials, which was absent in cells from control mice. Spontaneously firing neurons possessed significantly lower rheobases and fired a greater number of action potentials at twice the rheobase compared to neurons from control mice. Sepsis did not significantly affect voltage-gated Ca2+ currents. However, global Ca2+ signaling was enhanced in postganglionic neurons isolated from 1 to 24 h endotoxemic mice. A similar increase in the amplitude of high-K+-stimulated Ca2+ transients was observed during the cecal ligation and puncture model of sepsis. The enhanced excitability and Ca2+ signaling produced during sepsis likely amplify the effect of increased preganglionic drive on norepinephrine release from postganglionic neurons. This is important, as sympathetic neurons are integral to the anti-inflammatory autonomic reflex that is activated during sepsis.

Neuroplasticity and dysfunction after gastrointestinal inflammation

The gastrointestinal tract is innervated by several distinct populations of neurons, whose cell bodies either reside within (intrinsic) or outside (extrinsic) the gastrointestinal wall. Normally, most individuals are unaware of the continuous, complicated functions of these neurons. However, for patients with gastrointestinal disorders, such as IBD and IBS, altered gastrointestinal motility, discomfort and pain are common, debilitating symptoms. Although bouts of intestinal inflammation underlie the symptoms associated with IBD, increasing preclinical and clinical evidence indicates that infection and inflammation are also key risk factors for the development of other gastrointestinal disorders. Notably, a strong correlation exists between prior exposure to gut infection and symptom occurrence in IBS. This Review discusses the evidence for neuroplasticity (structural, synaptic or intrinsic changes that alter neuronal function) affecting gastrointestinal function. Such changes are evident during inflammation and, in many cases, long after healing of the damaged tissues, when the nervous system fails to reset back to normal. Neuroplasticity within distinct populations of neurons has a fundamental role in the aberrant motility, secretion and sensation associated with common clinical gastrointestinal disorders. To find appropriate therapeutic treatments for these disorders, the extent and time course of neuroplasticity must be fully appreciated.

Electrophysiological identification of tonic and phasic neurons in sensory dorsal root ganglion and their distinct implications in inflammatory pain

In the mammalian autonomic nervous system, tonic and phasic neurons can be differentiated on firing patterns in response to long depolarizing current pulse. However, the similar firing patterns in the somatic primary sensory neurons and their functional significance are not well investigated. Here, we identified two types of neurons innervating somatic sensory in rat dorsal root ganglia (DRG). Tonic neurons fire action potentials (APs) in an intensity-dependent manner, whereas phasic neurons typically generate only one AP firing at the onset of stimulation regardless of intensity. Combining retrograde labeling of somatic DRG neurons with fluorescent tracer DiI, we further find that these neurons demonstrate distinct changes under inflammatory pain states induced by complete Freund's adjuvant (CFA) or bee venom toxin melittin. In tonic neurons, CFA and melittin treatments significantly decrease rheobase and AP durations (depolarization and repolarization), enhance amplitudes of overshoot and afterhyperpolarization (AHP), and increase the number of evoked action potentials. In phasic neurons, however, the same inflammation treatments cause fewer changes in these electrophysiological parameters except for the increased overshoot and decreased AP durations. In the present study, we find that tonic neurons are more hyperexcitable than phasic neurons after peripheral noxious inflammatory stimulation. The results indicate the distinct contributions of two types of DRG neurons in inflammatory pain.

Divergent neuroendocrine responses to localized and systemic inflammation

The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS can provide negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. However, inflammation and infection can also directly regulate SNS function by peripheral actions on postganglionic cells. The present review discusses how inflammation activates autonomic reflex pathways and compares the effect of localized and systemic inflammation on ACCs and postganglionic sympathetic neurons. Systemic inflammation significantly enhanced catecholamine secretion through an increase in Ca(2+) release from the endoplasmic reticulum. In contrast, acute and chronic GI inflammation reduced voltage-gated Ca(2+) current. Thus it appears that the mechanisms underlying the effects of peripheral and systemic inflammation neuroendocrine function converge on the modulation of intracellular Ca(2+) signaling.

Neural regulation of gastrointestinal inflammation: role of the sympathetic nervous system

The sympathetic innervation of the gastrointestinal (GI) tract regulates motility, secretion and blood flow by inhibiting the activity of the enteric nervous system (ENS) and direct vasoconstrictor innervation of the gut microvasculature. In addition to these well-established roles, there is evidence that the sympathetic nervous system (SNS) can modulate GI inflammation. Postganglionic sympathetic neurons innervate lymphoid tissues and immune cells within the GI tract. Furthermore, innate and adaptive immune cells express receptors for sympathetic neurotransmitters. Activation of these receptors can affect a variety of important immune cell functions, including cytokine release and differentiation of helper T lymphocyte subsets. This review will consider the neuroanatomical evidence of GI immune cell innervation by sympathetic axons, the effects of blocking or enhancing SNS activity on GI inflammation, and the converse modulation of sympathetic neuroanatomy and function by GI inflammation.

Effects of inflammation on the innervation of the colon

Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease lead to altered gastrointestinal (GI) function as a consequence of the effects of inflammation on the tissues that comprise the GI tract. Among these tissues are several types of neurons that detect the state of the GI tract, transmit pain, and regulate functions such as motility, secretion, and blood flow. This review article describes the structure and function of the enteric nervous system, which is embedded within the gut wall, the sympathetic motor innervation of the colon and the extrinsic afferent innervation of the colon, and considers the evidence that colitis alters these important sensory and motor systems. These alterations may contribute to the pain and altered bowel habits that accompany IBD.

Colitis is associated with a loss of intestinofugal neurons

Intestinofugal neurons sense and receive information regarding mechanical distension of the bowel and transmit this information to postganglionic sympathetic neurons in the prevertebral ganglia. Previous studies have demonstrated that trinitrobenzene sulfonic acid (TNBS)-induced colitis is associated with a loss of myenteric neurons that occurs within the first 12 h following the inflammatory insult. The purpose of this study was to test the hypothesis that intestinofugal neurons are among the myenteric neurons lost during TNBS-induced colitis. The retrograde tracing dye Fast Blue was used to label intestinofugal neurons, and immunohistochemical staining for the RNA-binding proteins HuC/D was used to count all myenteric neurons. Ongoing synaptic input to neurons in the guinea pig inferior mesenteric ganglion (IMG) was recorded via conventional intracellular electrophysiology. In control preparations, intestinofugal neurons account for 0.25% of myenteric neurons. In the distal colon of TNBS-treated animals, the proportion of intestinofugal neurons was reduced to 0.05% (an 80% reduction) within the region of inflammation where 20-25% of myenteric neurons were lost. Neither intestinofugal neurons specifically nor myenteric neurons were reduced in more proximal uninflamed regions. There is a reduction in the frequency of ongoing synaptic potentials in visceromotor neurons of the IMG at 12 and 24 h and 6 and 56 days after TNBS. Collectively, the results of this study suggest that intestinofugal neurons are among the myenteric neurons lost during inflammation and may be selectively targeted. Because intestinofugal neurons are a major driver of sympathetic output to the gut, the loss of intestinofugal neurons may have a profound pathophysiological significance.

Enhanced excitability of guinea pig inferior mesenteric ganglion neurons during and following recovery from chemical colitis

Postganglionic sympathetic neurons in the prevertebral ganglia (PVG) provide ongoing inhibitory tone to the gastrointestinal tract and receive innervation from mechanosensory intestinofugal afferent neurons primarily located in the colon and rectum. This study tests the hypothesis that colitis alters the excitability of PVG neurons. Intracellular recording techniques were used to evaluate changes in the electrical properties of inferior mesenteric ganglion (IMG) neurons in the trinitrobenzene sulfonic acid (TNBS) and acetic acid models of guinea pig colitis. Visceromotor IMG neurons were hyperexcitable 12 and 24 h, but not 6 h, post-TNBS during "acute" inflammation. Hyperexcitability persisted at 6 days post-TNBS during "chronic" inflammation, as well as at 56 days post-TNBS when colitis had resolved. In contrast, there was only a modest decrease in the current required to elicit an action potential at 24 h after acetic acid administration. Vasomotor neurons from inflamed preparations exhibited normal excitability. The excitatory effects of XE-991, a blocker of the channel that contributes to the M-type potassium current, and heteropodatoxin-2, a blocker of the channel that contributes to the A-type potassium current, were unchanged in TNBS-inflamed preparations, suggesting that these currents did not contribute to hyperexcitability. Riluzole, an inhibitor of persistent sodium currents, caused tonic visceromotor neurons to accommodate to sustained current pulses, regardless of the inflammatory state of the preparation, and restored a normal rheobase in neurons from TNBS-inflamed preparations but did not alter the rheobase of control preparations, suggesting that enhanced activity of voltage-gated sodium channels may contribute to colitis-induced hyperexcitability. Collectively, these data indicate that enhanced sympathetic drive as a result of hyperexcitable visceromotor neurons may contribute to small bowel dysfunction during colitis.

Altered adrenal chromaffin cell function during experimental colitis

The sympathetic nervous system regulates visceral function through the release of catecholamines and cotransmitters from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Previous studies have shown that norepinephrine secretion is decreased during experimental colitis due to the inhibition of voltage-gated Ca(2+) current (I(Ca)) in postganglionic sympathetic neurons. The present study examined whether colonic inflammation causes a similar impairment in depolarization-induced Ca(2+) influx in ACCs using the dextran sulfate sodium (DSS) model of acute colitis in mice. Alterations in ACC function during colitis were assessed using fura 2-acetoxymethyl ester Ca(2+) imaging techniques and perforated patch-clamp electrophysiology. In ACCs isolated from mice with DSS-induced acute colitis, the high-K(+)-stimulated increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) was significantly reduced to 74% of the response of ACCs from control mice. Acute colitis caused a 10-mV hyperpolarization of ACC resting membrane potential, without a significant effect on cellular excitability. Delayed-rectifier K(+) and voltage-gated Na(+) current densities were significantly enhanced in ACCs from mice with DSS-induced acute colitis, with peak current densities of 154 and 144% that of controls, respectively. Importantly, acute colitis significantly inhibited I(Ca) in ACCs between -25 and +20 mV. Peak I(Ca) density in ACCs from mice with DSS-induced acute colitis was 61% that of controls. High-K(+)-induced increases in [Ca(2+)](i) were also reduced in ACCs from mice with 2,4,6-trinitrobenzene sulfonic acid-induced acute colitis and DSS-induced chronic colitis to 68 and 78% of the control responses, respectively. Our results suggest that, during colitis, voltage-dependent Ca(2+) influx is impaired in ACCs. Given the importance of Ca(2+) signaling in exocytosis, these alterations may decrease systemic catecholamine levels, which could play an important role in inflammatory bowel disease. This is the first demonstration of aberrant ACC function during experimental colitis.

The participation of the sympathetic innervation of the gastrointestinal tract in disease states

Knowledge of neural circuits, neurotransmitters and receptors involved in the sympathetic regulation of gastrointestinal (GI) function is well established. However, it is only recently that the interaction of sympathetic neurons, and of sympathetic transmitters, with the GI immune system and with gut flora has begun to be explored. Changes in the behaviour of sympathetic nerves when gut function is compromised, for example in ileus and in inflammation, have been observed, but the roles of the sympathetic innervation in these and other pathologies are not adequately understood. In this article, we first review the principal roles of the sympathetic innervation of the GI tract in controlling motility, fluid exchange and gut blood flow in healthy individuals. We then discuss the evidence that there are important interactions of sympathetic transmitters with the gut immune system and enteric glia, and evidence that inflammation has substantial effects on sympathetic neurons. These reciprocal interactions contribute to pathological changes in ways that are not yet clarified. Finally, we focus on inflammation, diabetes and postoperative ileus as conditions in which there is sympathetic involvement in compromised gut function.

Clinical and experimental evidence of sympathetic neural dysfunction during inflammatory bowel disease

1. Inflammatory bowel diseases (IBD) alter the function of the enteric nervous system and the sensory innervation of the gastrointestinal (GI) tract. Less is known about whether IBD also affects the sympathetic nervous system (SNS). Given the importance of the SNS in regulating GI function and possibly immune system activation, the present review examines the evidence of sympathetic dysfunction during IBD and its possible consequences. 2. Sympathetic axons within the GI tract innervate several cell types, including vascular myocytes, enteric neurons and immune cells. The major neurotransmitters released from sympathetic varicosities are noradrenaline, neuropeptide Y and ATP or a related purine. 3. Clinical studies of IBD patients have provided evidence of an association between IBD and axonal or demyelinating neuropathy. Assays of autonomic function suggest that ulcerative colitis and Crohn's disease, the two major forms of IBD, have contrasting effects on sympathetic neural activity. 4. Animal models of IBD have been used to examine the effects of these diseases on sympathetic neurophysiology. A decrease in the release of noradrenaline from sympathetic varicosities in inflamed and uninflamed regions of the GI tract has consistently been reported. Recent findings suggest that the decrease in neurotransmitter release may be due to inhibition of N-type voltage-gated Ca(2+) current in post-ganglionic sympathetic neurons. 5. Interest in the role of the SNS in IBD is rapidly increasing. However, much work needs to be done to enhance understanding of how SNS function is altered during IBD and what contribution, if any, these changes make to pathogenesis.

Structural changes in the epithelium of the small intestine and immune cell infiltration of enteric ganglia following acute mucosal damage and local inflammation

An acute enteritis is commonly followed by intestinal neuromuscular dysfunction, including prolonged hyperexcitability of enteric neurons. Such motility disorders are associated with maintained increases in immune cells adjacent to enteric ganglia and in the mucosa. However, whether the commonly used animal model, trinitrobenzene sulphonate (TNBS)-induced enteritis, causes histological and immune cell changes similar to human enteric neuropathies is not clear. We have made a detailed study of the mucosal damage and repair and immune cell invasion following intralumenal administration of TNBS. Intestines from untreated, sham-operated and TNBS-treated animals were examined at 3 h to 56 days. At 3 h, the mucosal surface was completely ablated, by 6 h an epithelial covering was substantially restored and by 1 day there was full re-epithelialisation. The lumenal epithelium developed from a squamous cell covering to a fully differentiated columnar epithelium with mature villi at about 7 days. Prominent phagocytic activity of enterocytes occurred at 1-7 days. A surge of eosinophils and T lymphocytes associated with the enteric nerve ganglia occurred at 3 h to 3 days. However, elevated immune cell numbers occurred in the lamina propria of the mucosa until 56 days, when eosinophils were still three times normal. We conclude that the disruption of the mucosal surface that causes TNBS-induced ileitis is brief, a little more than 6 h, and causes a transient immune cell surge adjacent to enteric ganglia. This is much briefer than the enteric neuropathy that ensues. Ongoing mucosal inflammatory reaction may contribute to the persistence of enteric neuropathy.

Inhibition of sympathetic N-type voltage-gated Ca2+ current underlies the reduction in norepinephrine release during colitis

Inflammatory bowel diseases (IBD) are associated with altered neuronal regulation of the gastrointestinal (GI) tract and impairment of norepinephrine release from sympathetic varicosities. The sympathetic innervation of the GI tract modulates motility, blood flow, and secretion, and therefore defective norepinephrine release may contribute to symptom generation in IBD. Accordingly, our aim here was to utilize the mouse model of dextran sulfate sodium (DSS; 5% wt/vol) of IBD to determine how norepinephrine release is reduced during GI inflammation. We hypothesized that the inflammation-induced reduction in norepinephrine release was due to inhibition of voltage-gated Ca(2+) current (I(Ca)) in prevertebral sympathetic neurons. We compared [(3)H]norepinephrine release in the colon and jejunum and I(Ca) amplitude in superior mesenteric ganglion (SMG) neurons from control mice and mice with DSS-induced colitis. Changes to voltage-gated Ca(2+) channels were investigated by fura 2-AM Ca(2+) imaging, perforated patch-clamp electrophysiology, and real-time PCR. Depolarization-induced norepinephrine release from the inflamed colon and uninflamed jejunum was significantly impaired in mice treated with DSS, as was depolarization-induced Ca(2+) influx in SMG neurons. Colitis reduced I(Ca) in SMG neurons by inhibiting omega-conotoxin GVIA (300 nM)-sensitive N-type Ca(2+) channels. The omega-conotoxin GVIA-sensitive component of norepinephrine release was significantly smaller in the colon during colitis. The inhibition of I(Ca) was accompanied by a decrease in mRNA encoding the Ca(2+) channel alpha subunit (CaV 2.2) and a rightward shift in the voltage dependence of activation of I(Ca). These findings suggest that DSS-induced colitis attenuates norepinephrine release in the colon and jejunum due to inhibition of N-type voltage-gated Ca(2+) channels. This may contribute to functional alterations in both inflamed and uninflamed regions of the GI tract during inflammation.