Roles of histamine and diamine oxidase in mucosa of rat small intestine after ischemia-reperfusion

Association of plasma diamine oxidase and intestinal fatty acid-binding protein with severity of disease in patient with heat stroke

OBJECTIVES

The aim of this study was to describe the role of intestinal fatty acid-binding protein (iFABP) and allergy-related diamine oxidase (DAO) in patients with heat stroke (HS).

METHODS

A total of 10 patients with HS in intensive care unit and 10 healthy volunteers were enrolled in this study. The plasma intestinal permeability markers iFABP and DAO were measured since the time of admission. The whole blood endotoxin was also assessed. The associations between iFABP, DAO, and endotoxin level were analyzed. Then, white blood cell count, procalcitonin, and C-reactive protein were examined. In addition, we also determined the levels of proinflammatory cytokines such as IL-1α, IL-6, and TNF-α.

RESULTS

Comparing with the healthy control, the plasma iFABP and DAO level in patients with HS increased significantly (P < .05). The kinetic curve showed that plasma iFABP and DAO level reached peak value at day 3 and day 4 after admission, respectively. The endotoxin level was positively correlated with iFABP and DAO level. We also observed a significantly increased level of procalcitonin and C-reactive protein but not white blood count in patients with HS. After treatment, the iFABP and DAO level decreased significantly (P < .05). A significant increase in level of IL-1α and IL-6 was also found in patients with HS.

CONCLUSIONS

The plasma concentrations of DAO and iFABP could reflect a better function of the intestinal mucosa barrier in patients with HS. Plasma iFABP and DAO level decreased significantly after the treatment and, thus, might be a predictor for the severity of HS.

A combination of plasma DAO and citrulline levels as a potential marker for acute mesenteric ischemia

INTRODUCTION

There is no valid and reliable diagnostic test for early diagnosis of acute mesenteric ischemia (AMI). The aim of this study was to measure the plasma levels of diamine oxidase (DAO) and citrulline in AMI to gain insight into its early diagnosis.

MATERIAL AND METHODS

A total of 21 Wistar albino rats were divided into three groups, that is, control group, short-term ischemia group, and prolonged ischemia group. The superior mesenteric artery was occluded for 15 min in the short-term ischemia group and for 12 h in the prolonged ischemia group. Twelve hours later, the experiment was terminated and plasma DAO and citrulline levels were measured. Intestinal tissue was evaluated for the histopathological changes.

RESULTS

Compared to the control group, the short-term and prolonged ischemia groups showed significant increases in the plasma levels of DAO, whereas the plasma citrulline levels decreased significantly. Prolonged ischemia caused a larger increase in the plasma DAO levels and a larger decrease in the plasma citrulline levels compared to the short-term ischemia (p=0.011 and p=0.021, respectively). Intestinal damage was shown to develop more in the prolonged ischemia group (p=0.001).

CONCLUSION

In the early period of AMI, the plasma DAO levels increase while citrulline levels decrease, and the extent of these changes depends on the duration of ischemia.

Beneficial effects of a plant histaminase in a rat model of splanchnic artery occlusion and reperfusion

Splanchnic artery occlusion (SAO) followed by reperfusion causes endothelial injury and inflammation which contribute to the pathophysiology of shock. We investigated the effects of pea seedling (Latyrus cicera) histaminase, known to afford protection against the deleterious effects of cardiac ischemia/reperfusion, given to rats subjected to SAO/reperfusion-induced splanchnic injury. Histaminase (80 IU kg, 15 min before reperfusion) significantly reduced the drop of blood pressure and high mortality rate caused by SAO/reperfusion. Histaminase also reduced histopathological changes, leukocyte infiltration (myeloperoxidase), and expression of endothelial cell adhesion molecules in the ileum. Histaminase counteracted free radical-mediated tissue injury, as judged by a significant decrease in the plasma and tissue levels of peroxidation and nitration products (oxidized rhodamine, malondialdehyde, nitrotyrosine), DNA damage markers (8-hydroxy-2'-deoxyguanosine, poly-adenosine diphosphate-ribosylated DNA) and consumption of tissue antioxidant enzymes (superoxide dismutase). As a result, histaminase led to a reduction of ileal cell apoptosis (caspase 3, terminal deoxynucleotidyltransferase-mediated UTP end labeling-positive cells). These results show that histaminase exerts a clear-cut protective effect in SAO/reperfusion-induced splanchnic injury, likely caused by oxidative catabolism of proinflammatory histamine and antioxidant effects resulting in hindrance of free radical-mediated tissue injury, endothelial dysfunction, and leukocyte recruitment. Thus, histaminase could be used therapeutically in intestinal ischemia.

The selective inhibition of inducible nitric oxide synthase prevents intestinal ischemia-reperfusion injury in mice

Nitric oxide (NO) involvement in intestinal ischemia-reperfusion (I/R) injury has been widely suggested but its protective or detrimental role remains still question of debate. Here, we examine the impact of supplementation or inhibition of NO availability on intestinal dysmotility and inflammation caused by mesenteric I/R in mice. Ischemia 45min and reperfusion 24h were performed by superior mesenteric artery occlusion in female Swiss mice. Saline-treated sham-operated (S) or normal mice without surgery (N) served as controls. Drugs were subcutaneously injected 0, 4, 8, and 18 h after ischemia. Upper gastrointestinal transit (GIT, estimated through black marker gavage), intestinal myeloperoxidase activity (MPO), intestinal malondialdehyde levels (MDA), Evans blue extravasation (EB), intestinal histological damage, and mean arterial pressure (MAP) were considered. In I/R mice, GIT was significantly delayed compared to S and N groups; MPO activity and EB extravasation enhanced, whereas MDA levels did not change. Compared to N and S groups, in I/R mice selective iNOS inhibitor P-BIT significantly prevented motor, MPO and EB changes; putative iNOS inhibitor aminoguanidine significantly counteracted GIT delay but not neutrophil recruitment and the increase in vascular permeability; NOS inhibitor l-NAME and NO precursor l-arginine were scarcely or no effective. Furthermore, in S mice aminoguanidine caused a significant increase of MPO activity reverted by H(1) histamine receptor antagonist pre-treatment. Unlike P-BIT, aminoguanidine and l-NAME injection increased MAP. These findings confirm a detrimental role for iNOS-derived NO overproduction during reperfusion. Aminoguanidine-associated neutrophil recruitment suggests that this drug could act through mechanisms additional to iNOS inhibition involving both eNOS blockade, as indicated by its hemodynamic effects, and indirect activation of H(1) histamine receptors.

The role of nitric oxide in the gastric acid secretion induced by ischemia-reperfusion in the pylorus-ligated rat

In a rat model of the ischemia-reperfusion with pylorus ligation, gastric ulcer was formed, although gastric acid secretion was reduced. When the polymorphonuclear leukocytes were inactivated in advance, gastric ulcer was not formed, but acid secretion was increased, indicating that gastric acid is not a cause of the ulcer formation in this model. The mechanism of gastric acid suppression accompanied by ischemia-reperfusion was examined in relation to the role of oxygen-free radicals in this rat model. Prior administration of superoxide dismutase did not modulate acid secretion, but N-nitro-L-arginine methyl ester (L-NAME) increased acid secretion. The action of L-NAME was antagonized specifically by L-arginine, but not by D-arginine. S-nitroso-N-acetylpenicillamine did not inhibit basal acid secretion but antagonized the action of L-NAME. Aminoguanidine increased significantly the gastric acid output that was suppressed by ischemia-reperfusion. When polymorphonuclear leukocytes were inactivated by treatment with their antibody, the gastric acid output recovered to the level in the pylorus-ligated rat without ischemia-reperfusion. These results suggested that nitric oxide (NO) produced by the infiltrated polymorphonuclear leukocytes plays an important role in the suppression of acid secretion induced by ischemia-reperfusion.

Roles of nitric oxide synthases in platelet-activating factor-induced intestinal necrosis in rats

OBJECTIVE

To examine the role of constitutive and inducible nitric oxide synthases (cNOS and iNOS) in platelet-activating factor (PAF)-induced shock and intestinal injury.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Hospital research laboratory.

SUBJECTS

Young adult male Sprague-Dawley rats were anesthetized and studied.

INTERVENTIONS

Rats were injected with PAF, either alone or after the following pretreatments: a) selective iNOS inhibitors aminoguanidine or S-methylisothiourea; b) 3-morpholinosydnonimine, a NO donor; c) S-methylisothiourea + 3-morpholinosydnonimine; and d) antineutrophil antibody (to deplete neutrophils).

MEASUREMENTS AND MAIN RESULTS

Blood pressure, hematocrit, white blood cell counts, intestinal injury, and intestinal cNOS and iNOS activities were assessed. We found that: a) cNOS is the predominant NOS in the intestine and its activity is inversely correlated to the level of tissue injury; b) there is a time-dependent increase in cNOS activity in sham-operated animals, which was abolished by PAF; c) Western blotting and immunohistochemistry showed iNOS present in the normal intestine, localizing mainly in crypt cells; d) iNOS inhibitors attenuated PAF-induced injury in animals with high cNOS activity, but had no protective effect in animals with low cNOS activity; e) 3-morpholinosydnonimine, alone or together with S-methylisothiourea, alleviated PAF-induced injury; and f) neutrophil depletion blocked the suppressive effect of PAF on cNOS and prevented injury.

CONCLUSIONS

We conclude that cNOS and iNOS play different roles in PAF-induced intestinal injury. Caution should be exerted concerning potential therapeutic uses of iNOS inhibitors.

Histidine and histamine metabolism in rat enterocytes

To study the metabolic fate of L-histidine and histamine in rat isolated enterocytes, enterocytes were incubated in the presence of 0.1 mM L-[U-14C] histidine. At the rate of 11.1 +/- 2.7 pmol/10(6) cells/30 min, the amino acid was incorporated into cellular proteins. 80 microM cycloheximide, i.e. a protein synthesis inhibitor, inhibited this incorporation by 70 +/- 17%. L-histidine was used for cellular protein synthesis which depended on time and concentration. 0.1 mM L-[U-14C] histidine was little oxidized by intestinal cells, i.e. 0.12 +/- 0.06 pmol/10(6) cells/30 min, and was not converted into histamine. When 10 mM histamine was added to the incubation medium, it completely inhibited the incorporation of 0.1 mM [1,4-14C] putrescine into isolated enterocytes. In enterocyte homogenates, this corresponded to inhibition by histamine of putrescine incorporation as catalyzed by transglutaminase activity. Since histamine incorporation into TCA-precipitable material derived from enterocyte homogenates depended on time and concentration, we concluded that exogenous, but not de novo-formed histamine was able to compete with putrescine incorporation into enterocytes as catalyzed by transglutaminase activity.

Effect of an elemental vs a complex diet on polyamine metabolism in rat isolated enterocytes

BACKGROUND

Polyamines play an important role in the proliferation and differentiation of enterocytes. Ornithine decarboxylase (ODC) is the rate-limiting enzyme for polyamine biosynthesis. Elemental diets, providing easily absorbable nutrients such as free amino acids, are used in clinical practice to treat growth failure and malnutrition. They are very different from complex diets normally consumed. Little information is available about the influence of elemental diets on metabolic capacities of enterocytes. This study was undertaken in rats to assess the effects on polyamine metabolism of an elemental diet compared with a complex diet.

METHODS

Rats were fed the elemental diet (group ED) or the control diet (group C) for 14 days. The dietary intakes were isocaloric and isonitrogenous in groups C and ED. Villous enterocytes were then isolated and metabolic capacities or enzyme activities were assessed.

RESULTS

Both the enterocyte capacity to decarboxylate ornithine through ODC (measured in viable enterocytes) and ODC activity (measured in homogenates) were severely decreased in group ED. The polyamine content in enterocytes, however, was maintained at a similar level in both groups. This coincided with a decrease in the main enzymatic activity responsible for putrescine catabolism (ie, diamine oxidase activity) in group ED.

CONCLUSIONS

Although nutrition manipulation was shown to alter polyamine biosynthesis in this study, the polyamine homeostasis was probably maintained, at least in part, through down-regulation of diamine oxidase.

Inhibition of diamine oxidase promotes uptake of putrescine from rat small intestine

In blood from the portal vein of anaesthetized rats the levels of histamine and putrescine were 2-3-fold lower compared to arterial blood. Putrescine concentration was increased severalfold and the difference between portal and arterial blood abolished in animals pretreated with the specific diamine oxidase inhibitor aminoguanidine. Histamine concentration was 40% lower in portal compared to arterial blood in animals treated with the mast cell degranulator compound 48/80. In animals pretreated with aminoguanidine, compound 48/80 enhanced the level of histamine and no difference was observed between arterial and portal blood. The amounts of intravenously injected [14C]-labeled histamine was about 15% lower in portal compared to arterial blood. The uptake of [14C]-putrescine from the small intestine was estimated. In urine from animals pretreated with aminoguanidine the concentration of [14C]-putrescine was more than 40-times higher than in control animals corresponding to a calculated uptake of about 7% in aminoguanidine treated animals. Our results suggest that intestinal diamine oxidase clears the blood from diamines and prevents luminal uptake of putrescine.

Histaminergic control of mucosal repair in the small intestine

The aim of the present paper was to summarize histamine-mediated repair of rat intestinal mucosa. To evaluate intestinal repair, we examined lipid transport (an index of intestinal mucosal function) after 15 minutes occlusion of the superior mesenteric artery. Rats were pretreated with alpha-fluoromethylhistidine (a suicide inhibitor of histidine decarboxylase, a synthesizing enzyme of histamine), H1-receptor antagonist (chlorpheniramine maleate), H2-antagonist (cimetidine), or H3-antagonist (thioperamide) before ischemia-reperfusion (I/R). Lipid transport to rat mesenteric lymph decreased significantly 24 hours after I/R in all groups tested compared to sham-treated rats. Lipid transport was restored 48 hours after I/R in the vehicle-pretreated control group. Lipid transport was not restored to the control level 48 hours after I/R in rats pretreated with H1-antagonist and a suicide inhibitor of histidine decarboxylase. In contrast, intestinal function was restored to the control level 48 hours after I/R in rats pretreated with H2- and H3-antagonists. These results support our previous findings that newly formed histamine after I/R plays an important role in mucosal recovery through H1-receptors.

Role of inducible nitric oxide synthase expression and peroxynitrite formation in guinea pig ileitis

BACKGROUND & AIMS

Inflammatory bowel disease is characterized by increased synthesis of nitric oxide. The aim of this study was to determine if inducible NO synthase (iNOS) was responsible for tissue injury, potentially via peroxynitrite formation, in the guinea pig model of gut inflammation.

METHODS

Inflammation was induced in guinea pig ileum by intraluminal administration of the hapten trinitrobenzene sulfonic acid in 50% ethanol. iNOS gene expression was assessed by reverse-transcriptase polymerase chain reaction and Western blotting, immunohistochemistry was determined by its localization, and activity was inhibited with the specific inhibitor aminoguanidine administered via the drinking water for 7 days. Nitration of tyrosines was assessed by immunohistochemistry.

RESULTS

In control animals, iNOS gene expression was minimal to absent, whereas, in hapten, inflammation-marked iNOS gene expression was evident from day 1 to 7. Nitrotyrosine and iNOS immunohistochemistry were colocalized, and positive staining was most intense in epithelia and neurons. Inhibition of NO formation prevented nitrotyrosine formation. Aminoguanidine inhibited the inflammatory response and restored morphology.

CONCLUSIONS

The colocalization of tyrosine nitration with iNOS immunoreactivity suggests that iNOS may be responsible for tissue injury and the formation of NO-dependent nitrating species, potentially peroxynitrite. Inhibition of iNOS may afford a new therapeutic approach to the treatment of inflammatory bowel disease.

Role of histamine in a rat model of colitis

We examined the possible involvement of mast cells in a rat model of colitis, by monitoring levels of histamine at various times after inducing inflammation with intrarectal trinitrobenzene sulfonic acid in 50% ethanol. The ability of a histamine H1 antagonist, diphenhydramine, to modify colitis was also assessed. As expected, trinitrobenzene sulfonic acid in 50% ethanol induced a sustained colitis. Myeloperoxidase levels in macroscopically damaged tissue peaked at one week, and declined thereafter. In contrast, tissue histamine levels were normal at one week, then increased in damaged tissue to approximately four times normal levels at four weeks. Indices of inflammation were markedly suppressed at one week by diphenhydramine, while tissue histamine levels were unaffected. Chronic colitis in rats is thus apparently accompanied by a local mast cell hyperplasia or influx. Moreover, antagonism of a major mast cell mediator, histamine, significantly reduces the severity of inflammation in this model.

Newly synthesized histamine accelerates ornithine decarboxylase activity in rat intestinal mucosa after ischemia-reperfusion

We previously demonstrated that both histamine synthesis (histidine decarboxylase activity) and polyamine synthesis (ornithine decarboxylase activity) increased in the rat intestinal mucosa after ischemia-reperfusion, whereas the relationship between these two factors remains unclear. To elucidate this relationship, we performed the present study. The superior mesenteric artery was occluded for 15 min followed by reperfusion. After ischemia-reperfusion, histidine decarboxylase activity and ornithine decarboxylase activity in the rat jejunal mucosa were measured in a time-dependent manner. Histidine decarboxylase activity increased 1 hr after ischemia-reperfusion, although ornithine decarboxylase activity did not; however, its activity did increase 6 hr after. The increase of ornithine decarboxylase activity was attenuated when the increase of histamine synthesis was suppressed by the inhibition of histidine decarboxylase activity caused by pretreatment with alpha-fluoromethylhistidine, a suicide inhibitor of histidine decarboxylase. Pretreatment with H1-receptor antagonist attenuated the increase of ornithine decarboxylase activity after ischemia-reperfusion. These results indicate that the newly synthesized histamine, as indicated by an increase of histidine decarboxylase activity, increases ornithine decarboxylase activity after ischemia-reperfusion of the rat intestinal mucosa.

Diamine oxidase in relation to diamine and polyamine metabolism

Diamine oxidase catalyzes the oxidative deamination of short chain aliphatic diamines, like putrescine, and histamine. The enzyme is rate-limiting in the terminal catabolism of polyamines, which are endogenous polycations important for cell growth and differentiation. This review examines the behavior of diamine oxidase in mammalian tissues in relation to diamine and polyamine metabolism under physiological and pathological conditions. The role of diamine oxidase in the control of putrescine levels in growing tissues and the known mechanisms responsible for the enzyme expression are also described.

Role of histamine receptors in intestinal repair after ischemia-reperfusion in rats

BACKGROUND/AIMS

Previously, we showed that an elevated production of histamine promotes the healing of injured intestinal mucosa after ischemia-reperfusion. The aim of the present study was to determine whether histamine-mediated repair of the intestinal mucosa after ischemia-reperfusion involves the engagement of H1 or H2 receptors.

METHODS

The superior mesenteric artery was occluded for 15 minutes followed by reperfusion, and H1- or H2-receptor antagonists were infused intraduodenally. After ischemia-reperfusion, ornithine decarboxylase activity in the jejunal mucosa and lipid transport to mesenteric lymph were examined.

RESULTS

In jejunal mucosa, ornithine decarboxylase activity markedly increased at 6 hours after reperfusion and remained elevated at 48 hours. The ischemia-reperfusion-induced increase in ornithine decarboxylase activity was attenuated (in a dose-dependent manner) by an H1-receptor antagonist (chlorpheniramine maleate) but not by an H2 antagonist (cimetidine). Intraperitoneal injection of an H3 antagonist (thioperamide) increased histamine output in mesenteric lymph and stimulated intestinal ornithine decarboxylase activity. Transport of dietary lipid into mesenteric lymph was depressed 24 hours after an ischemic insult, yet it returned to the normal level 48 hours after ischemia-reperfusion. The recovery of the lipid transport normally observed at 48 hours after ischemia-reperfusion was attenuated by the H1 antagonist.

CONCLUSIONS

The beneficial effects of histamine on the repair of intestinal mucosa after ischemia-reperfusion results from the engagement and activation of the H1 receptor.