Expression and localization of c-Fos and NOS in the central nerve system following esophageal acid stimulation in rats

Diagnostic value of the pepsin concentration in saliva and induced sputum for gastroesophageal reflux-induced chronic cough: a prospective clinical study

Background

Finding a simple, effective and rapid diagnostic method to improve the diagnosis of gastroesophageal reflux-induced chronic cough (GERC) is indicated. Our objective was to determine the diagnostic value of the pepsin concentration in saliva and induced sputum for GERC.

Methods

171 patients with chronic cough were enrolled. The diagnosis and treatment followed the chronic cough diagnosis and treatment protocol. Saliva and induced sputum were collected, and the pepsin concentration was determined using Peptest. A Gastroesophageal Reflux Diagnostic Questionnaire (GerdQ) was completed. The diagnostic value of the pepsin concentration in saliva and induced sputum for GERC was analysed and compared.

Results

The salivary pepsin concentration predicted GERC with an area under the receiver operating characteristic curve (AUC) of 0.845. The optimal cut-off value was 76.10 ng·mL-1, the sensitivity was 83.58% and the specificity was 82.69%. The pepsin concentration in the induced sputum supernatant for GERC had an AUC of 0.523. When GerdQ was used for GERC diagnosis, the AUC was 0.670 and the diagnostic value of salivary pepsin was better compared to GerdQ (DeLong test, p=0.0008). Salivary pepsin had a comparable diagnostic value to GerdQ (AUC 0.779 versus 0.826; p=0.4199) in acidic GERC. Salivary pepsin had superior diagnostic value compared to GerdQ (AUC 0.830 versus 0.533; p<0.0001) in non-acidic GERC.

Conclusions

A salivary pepsin concentration >76.10 ng·mL-1 is of good diagnostic value for GERC, especially in non-acidic GERC. The pepsin concentration in induced sputum has a low diagnostic value.

Destruction of the Dorsal Motor Nucleus of the Vagus Aggravates Inflammation and Injury from Acid-Induced Acute Esophagitis in a Rat Model

Background/Aims

The aim of this study is to examine the protective effect of the cholinergic anti-inflammatory pathway (CAP) in experimental esophagitis in rats.

Methods

A total of 40 male Sprague-Dawley (SD) rats were randomly divided into five groups as follows: control group, sham + saline group, sham + acid group, operation + saline group, and operation + acid group. Two weeks after the dorsal motor nucleus of the vagus (DMV) destruction, hydrochloric acid with pepsin was perfused into the lower part of the esophagus for 90 min. The rats were sacrificed 60 min after perfusion. The esophagus was prepared for hematoxylin and eosin (HE) staining, and the degree of inflammation and NF-κB activation in the esophagus was measured. Inflammatory cytokines (TNF-α, IL-6, IL-1β, and PGE2) in the esophagus were measured by ELISA. The brain was removed and processed for c-fos immunohistochemistry staining. The c-fos-positive neurons were counted and analyzed.

Results

The TNF-α, IL-1β, IL-6, and PGE2 concentrations in the esophageal tissue increased after acid perfusion. The microscopic esophagitis scores and the activation of NF-κB p65 in the esophagus were significantly higher in the operation + acid group than in the operation + saline group. c-fos-positive neurons significantly increased in rats receiving acid perfusion in the amygdala (AM), the paraventricular nucleus of the hypothalamus (PVN), the parabrachial nucleus (PBN), the nucleus of the solitary tract (NTS)/DMV, the nucleus ambiguous (NA), the reticular nucleus of the medulla (RNM), and the area postrema (AP). After DMV destruction, c-fos expression was reduced in the AM, PVN, PBN, NTS/DMV, NA, RNM, and AP, especially in the AM, PVN, NTS/DMV, RNM, and AP.

Conclusions

The DMV is an important nucleus of the CAP. The DMV lesion can aggravate esophageal inflammation and injury from acid-induced acute esophagitis in a rat model. The CAP has a protective effect on the acute esophagitis rat model and could be a new therapy for reflux esophagitis (RE).

Effect of distal esophageal irritation on the changes of cystometry parameters to esophagus and colon distentions in rats

The coexistence of different visceral pathologies in patients suffering from irritable bowel syndrome, interstitial cystitis, and other pathologies, necessitates the study of these pathologies under complicated conditions. In the present study, cystometry recordings were used to investigate the effect of distal esophageal chemical irritation on the urinary bladder interaction with distal colon distention, distal esophageal distention, and electrical stimulation of abdominal branches of vagus nerve. Distal esophageal chemical irritation significantly decreased the intercontraction time via decreasing the voiding time. Also, distal esophageal chemical irritation significantly decreased the pressure amplitude by decreasing the maximum pressure. Following distal esophageal chemical irritation, distal esophageal distention was able to significantly decrease the intercontraction time by decreasing the storage time. However, 3 mL distal colon distention significantly increased the intercontraction time by increasing the storage time. On the other hand, following distal esophageal chemical irritation, electrical stimulation of abdominal branches of vagus nerve did not have any significant effect on intercontraction time. However, electrical stimulation of abdominal branches of vagus nerve significantly increased the pressure amplitude by increasing the maximum pressure. The results of this study demonstrate that urinary bladder function and interaction of bladder with other viscera can be affected by chemical irritation of distal esophagus.

Extra-esophageal manifestations of gastroesophageal reflux disease: controversies between epidemiology and clicnic

Gastroesophageal reflux disease (GERD) is widely associated with asthma, chronic cough, and laryngitis. Many studies have focused on acidic reflux; however, acid is just one of many factors that can cause pulmonary injury. The discrepancy between the high frequency of GERD in asthmatic patients and the ineffective reflux therapy outcomes in these patients suggests that GERD may cause injury through other mechanisms, such as pepsinogen, pepsin, bile salts, or other components of reflux materials, instead of the acid. Research using appropriate and innovative methodologies to investigate these potential inflammatory agents in patients with GERD is required to determine the underlying factors associated with pulmonary disorders in these patients.

Differential activation of pontomedullary nuclei by acid perfusion of different regions of the esophagus

The objective of this study was to determine the brain stem nuclei and physiological responses activated by esophageal acidification. The effects of perfusion of the cervical (ESOc), or thoracic (ESOt) esophagus with PBS or HCl on c-fos immunoreactivity of the brain stem or on physiological variables, and the effects of vagotomy were examined in anesthetized cats. We found that acidification of the ESOc increased the number of c-fos positive neurons in the area postrema (AP), vestibular nucleus (VN), parabrachial nucleus (PBN), nucleus ambiguus (NA), dorsal motor nucleus (DMN), and all subnuclei of the nucleus tractus solitarius (NTS), but one. Acidification of the ESOt activated neurons in the central (CE), caudal (CD), dorsomedial (DM), dorsolateral (DL), ventromedial (VM) subnuclei of NTS, and the DMN. Vagotomy blocked all c-fos responses to acid perfusion of the whole esophagus (ESOw). Perfusion of the ESOc or ESOt with PBS activated secondary peristalsis (2P), but had no effect on blood pressure, heart rate, or respiratory rate. Perfusion of the ESOc, but not ESOt, with HCl activated pharyngeal swallowing (PS), profuse salivation, or physiological correlates of emesis. Vagotomy blocked all physiological effects of ESOw perfusion. We conclude that acidification of the ESOc and ESOt activate different sets of pontomedullary nuclei and different physiological responses. The NTSce, NTScom, NTSdm, and DMN are associated with activation of 2P, the NTSim and NTSis, are associated with activation of PS, and the AP, VN, and PBN are associated with activation of emesis and perhaps nausea. All responses to esophageal fluid perfusion or acidification are mediated by the vagus nerves.

Modulation of activity in swallowing motor cortex following esophageal acidification: a functional magnetic resonance imaging study

Esophageal acid exposure induces sensory and motility changes in the upper gastrointestinal tract; however, the mechanisms involved and the effects on activity in the brain regions that control swallowing are unknown. The aim of this study was to examine functional changes in the cortical swallowing network as a result of esophageal acidification using functional magnetic resonance imaging (fMRI). Seven healthy volunteers (3 female, age range=20-30 years) were randomized to receive either a 0.1 M hydrochloric acid or (control) saline infusion for 30 min into the distal esophagus. Postinfusion, subjects underwent four 8 min blocks of fMRI over 1 h. These alternated between 1 min swallowing water boluses and 1 min rest. Three-dimensional cluster analysis for group brain activation during swallowing was performed together with repeated-measures ANOVA for differences between acid and saline. After acid infusion, swallowing-induced activation was seen predominantly in postcentral gyrus (p<0.004). ANOVA comparison of acid with saline showed a significant relative reduction in activation during swallowing of the precentral gyrus (M1) BA 4 (p<0.008) in response to acid infusion. No areas of increased cortical activation were identified with acid vs. saline during swallowing. Esophageal acidification inhibits motor and association cortical areas during a swallowing task, probably via changes in vagal afferent or nociceptive input from the esophagus. This mechanism may play a protective role, facilitating acid clearance by reduced descending central motor inhibition of enteric/spinal reflexes, or by preventing further ingestion of injurious agents.

Expression and colocalization of NADPH-diaphorase and Fos in the subnuclei of the parabrachial nucleus in rats following visceral noxious stimulation

To investigate whether neural nitric oxide synthase (nNOS) in the parabrachial nucleus (PB) is involved in processing visceral noxious stimulation, we mapped the distribution of histochemical staining for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), a marker for nNOS, and immunohistochemical staining for Fos, a neuronal activity marker, in the subnuclei of the PB following 2% formalin injection into the stomach of rats. NADPH-d and noxious-stimuli induced Fos staining were also examined in tissue containing PB cells labeled by the retrograde transport of fluogold (FG) injected into the central nucleus of the amygdala (CeA). We found that the number of Fos immunoreactive (Fos-IR) neurons was significantly increased in the dorsal lateral (dl), external lateral (el) and Kölliker-Fuse (KF) subnuclei of the PB. We observed that intensely labeled (type 1) NADPH-d positive neurons were mainly located in the rostral part of the PB; they extended long processes adjacent Fos-IR neurons, but no Fos/type 1 NADPH-d double-labeled neurons were seen. In contrast, lightly labeled (type 2) NADPH-d positive neurons were principally localized in the dl of the PB, in which a few Fos/type 2 NADPH-d double-labeled neurons were detected. Additionally, a large number of FG/Fos double-labeled neurons were observed to be surrounded closely by the intensive NADPH-d staining in the el of the PB. These results suggest that neurons in the el of the PB that project to the CeA are activated by visceral noxious stimulation and could be indirectly influenced by nitric oxide in the PB.