Morphological and histochemical changes in intestinal mucosa in the reserpine-treated rat model of cystic fibrosis

Reserpine improves Enterobacteriaceae resistance in chicken intestine via neuro-immunometabolic signaling and MEK1/2 activation

Salmonella enterica persist in the chicken gut by suppressing inflammatory responses via expansion of intestinal regulatory T cells (Tregs). In humans, T cell activation is controlled by neurochemical signaling in Tregs; however, whether similar neuroimmunological signaling occurs in chickens is currently unknown. In this study, we explore the role of the neuroimmunological axis in intestinal Salmonella resistance using the drug reserpine, which disrupts intracellular storage of catecholamines like norepinephrine. Following reserpine treatment, norepinephrine release was increased in both ceca explant media and Tregs. Similarly, Salmonella killing was greater in reserpine-treated explants, and oral reserpine treatment reduced the level of intestinal Salmonella Typhimurium and other Enterobacteriaceae in vivo. These antimicrobial responses were linked to an increase in antimicrobial peptide and IL-2 gene expression as well as a decrease in CTLA-4 gene expression. Globally, reserpine treatment led to phosphorylative changes in epidermal growth factor receptor (EGFR), mammalian target of rapamycin (mTOR), and the mitogen-associated protein kinase 2(MEK2). Exogenous norepinephrine treatment alone increased Salmonella resistance, and reserpine-induced antimicrobial responses were blocked using beta-adrenergic receptor inhibitors, suggesting norepinephrine signaling is crucial in this mechanism. Furthermore, EGF treatment reversed reserpine-induced antimicrobial responses, whereas mTOR inhibition increased antimicrobial activities, confirming the roles of metabolic signaling in these responses. Finally, MEK1/2 inhibition suppressed reserpine, norepinephrine, and mTOR-induced antimicrobial responses. Overall, this study demonstrates a central role for MEK1/2 activity in reserpine induced neuro-immunometabolic signaling and subsequent antimicrobial responses in the chicken intestine, providing a means of reducing bacterial colonization in chickens to improve food safety.

Digestive System 1

This chapter deals with the digestive system. The major and minor salivary glands and their secretions also represent and integral part of the protective mechanism of the oral cavity, and derangement of saliva production may lead to loss of integrity of the oral mucosa. Drug-induced abnormalities of taste sensation are also well-described phenomena occurring in man although human studies are necessary for the detection of these effects. Inflammation of the oral cavity may involve the buccal mucosa, the gingiva (gingivitis), the tongue (glossitis), and the peridontal tissues (peridontitis). Therapeutic agents can induce inflammatory lesions in the tongue. Moreover, a protective layer of mucus, a visco-elastic material containing high molecular weight glycoproteins produced by the major and minor salivary glands, covers the stratified squamous mucosa of the oral cavity. Salivary secretions also possess digestive enzyme activity although in herbivores and carnivores, it is usually low in contrast to high digestive enzyme activity in omnivorous species.

The effects of high-dose ibuprofen and pancreatic enzymes on the intestine of the rat

BACKGROUND

High-dose ibuprofen therapy limits the progression of lung disease in patients with cystic fibrosis. However, ibuprofen increases intestinal permeability, which potentiates intestinal damage caused by high-dose pancreatic enzyme treatment, as was shown in a previous study by this group. In the present study, the combined effects of ibuprofen and pancreatic enzyme treatment on the intestine and liver were examined.

METHODS

Using a chronically catheterized rat model, high-dose ibuprofen (60 mg/kg x day in two doses), with or without pancreatic enzyme treatment was infused into gastric and duodenal catheters, respectively, for 20 days. Six groups were studied: control group; ibuprofen treatment alone; pancreatic enzyme treatment alone (two groups: normal dose, 10,000 U lipase/kg x day and high dose, 40,000 U lipase/kg x day); and ibuprofen combined with pancreatic enzyme (two groups: ibuprofen with high-dose pancreatic enzyme and ibuprofen and low-dose pancreatic enzyme). After treatment, rats were autopsied, and complete histologic analyses of the entire intestine and liver were performed.

RESULTS

Ibuprofen caused mild ulceration of the small intestine in 50% of rats. Pancreatic enzyme treatment alone did not induce ulceration of the intestine. The combination of pancreatic enzyme and ibuprofen treatment increased the severity of the ulcers in the small intestine but not the number of ulcers or the percentage of rats affected. Ibuprofen treatment alone did not cause ulcers in the large intestine, but with the addition of pancreatic enzymes, ulceration and fibrosis were present.

CONCLUSIONS

Ibuprofen at doses used to limit progression of cystic fibrosis lung disease caused enteropathy in 50% of rats. There was synergism between ibuprofen and pancreatic enzyme treatment in the production of severe ulcers. Ulcers in the cecum and colon were increased with combined ibuprofen and pancreatic enzyme treatment compared with incidence in control animals.

The effect of intestinal permeability on pancreatic enzyme-induced enteropathy in the rat

BACKGROUND

Fibrosing colonopathy in cystic fibrosis occurs in children 2 to 7 years old and is associated with excess doses of high and regular strength lipase pancreatic enzymes, given for more than 6 months. A rat model was developed to study the effects of excessive doses of pancreatic enzymes equivalent to those producing fibrosing colonopathy in cystic fibrosis patients.

METHODS

Five groups of animals were studied after administration of different combinations of pancreatic enzymes, oleic acid, and reserpine.

RESULTS

Pancreatic enzymes alone produced minimal damage to the intestine and none to the liver. Excessive doses of pancreatic enzymes in combination with agents that increased intestinal permeability (oleic acid, reserpine) were associated with intestinal eosinophilia and necrosis of the jejunoileal muscle layer and inflammatory nodules in the liver, which increased with duration of insult.

CONCLUSIONS

Increased intestinal permeability potentiates damage to the intestine caused by excessive pancreatic enzyme dosage. It is a characteristic of cystic fibrosis that may increase vulnerability to fibrosing colonopathy.

Reserpine-induced sulphomucin production by goblet cells in the jejunum of rats and its significance in the establishment of intestinal helminths

The present investigation was undertaken to determine whether reserpine-induced increase in the sulphation of the small intestinal goblet cell mucins of rats affects the establishment of intestinal helminths. When Wistar rats were given daily intraperitoneal injections of reserpine for seven days and were then implanted intraduodenally with 500 Strongyloides venezuelensis adult worms, the number of adult worms established in the intestine of reserpine-treated rats was about half of that established in controls. Furthermore, when mast cell-deficient Ws/Ws rats were treated with reserpine and implanted concurrently with S. venezuelensis and Nippostrongylus brasiliensis adult worms, the establishment of the former, but not the latter, was significantly suppressed. These results imply that the physicochemical properties of the mucins produced and secreted by the small intestinal goblet cells may be critical for the establishment of particular species of intestinal helminths.

Effect of reserpine on the histochemical and biochemical properties of rat intestinal mucin

Biochemical and histochemical parameters of intestinal mucins were examined in control and reserpine-treated rats. An assay for intestinal mucin sulfotransferase was developed and the activity shown to increase 3.4 times over control levels in rats given intraperitonal reserpine (0.5 mg/kg body wt) daily for 7 days. Histochemical staining of intestinal sections revealed an increase in sulfomucins in goblet cells of reserpine-treated rats. The effects were prominent as early as 1 day following injection, particularly in the distal third of the small intestine, and during the next 6 days these changes spread progressively to the middle and proximal thirds. After 3 days of treatment mucins were purified from each intestinal segment and compared to control mucins with respect to composition and [35S]NaSO4 incorporation. Although individual amino acid and carbohydrate molar ratios were unchanged, the total carbohydrate and sulfate content of mucins in treated animals was elevated (two to three times above control) in the middle and distal thirds of the intestine. In vivo [35S]SO4 incorporation into these mucins was also proportionaltely elevated, and was targetted to O-linked oligosaccharide side chains. These findings are consistent with an action of reserpine causing an increased production of mucin which is enriched in glycoprotein components bearing sulfated oligosaccharide chains. The relevance of these findings to the production of hypersulfated and hyperglycosylated mucins in cystic fibrosis is discussed.

The histochemical specificity of high iron diamine-alcian blue

The specificity of the High Iron Diamine-Alcian Blue pH 2.5 (HID-AB 2.5) procedure was examined in tissue sites containing sialogycoproteins alone or differing proportions of sialo- and sulphosialoglycoproteins. Studies with HID in differing final concentrations of hydrochloric acid or sodium chloride confirmed that staining is dependent upon both the pH and the ionic strength of the dye bath and demonstrated a marked heterogeneity in the pKa of the anionic groups of sialosulphoglycoproteins. Use of the sequence High Iron Diamine-Alcian Blue pH 1.0 demonstrated that complete or almost complete staining of O-sulphate esters occurred when HID was prepared in water (final pH 1.3). However, under these conditions HID-AB 2.5 was shown to be non-specific because only black HID staining was observed in sites containing large quantities of sialic acids. This non-specificity was due either to the masking of Alcian Blue staining by HID and/or the black HID staining of anionic groups other than sulphate. These results may account for some of the conflicting data obtained by different groups of investigators who have studied 'transitional mucosa' in human colonic diseases. Caution should be used in drawing conclusions from the use of HID-AB 2.5 without confirmatory evidence from other more specific procedures.

Simple procedure for assessing relative quantities of neutral and acidic sugars in mucin glycoproteins: its use in assessing cyclical changes in cervical mucins

A simple histochemical procedure for assessing relative amounts of neutral and acidic sugars in mucin glycoproteins, and its application in the study of cyclical changes of human cervical mucins, is described. This procedure, the saponification/selective periodate oxidation/borohydride reduction/alcian blue pH 2.5/periodic acid Schiff (KOH/PA*/Bh/Ab 2.5/PAS) method, uses a selective oxidation step to remove the PAS positivity of sialic acid; thus only neutral sugars stain positively with PAS, and acidic sugars (O-sulphate esters and carboxyl groups) stain with alcian blue. This differs from the KOH/Ab/PAS technique which stains sialic acid residues with both alcian blue and PAS. Applying the KOH/PA*/Bh/Ab 2.5/PAS technique to the study of cyclical changes of human cervical mucins, a decreased neutral:acidic sugar ratio in the secretory phase mucins compared with those of the proliferative phase was found. This difference was not seen with KOH/Ab/PAS staining in the same cases. The techniques and reagents used in this procedure can be easily applied in a clinical histopathology laboratory.