Aggravation of nonsteroidal antiinflammatory drug gastropathy by glucocorticoid deficiency or blockade of glucocorticoid receptors in rats

Our previous investigations suggest that the reduction of stress-induced corticosterone release, or inhibition of corticosterone actions, promotes stress-induced gastric erosions in rats. In this study the effect of glucocorticoid deficiency on susceptibility to gastric mucosal injury by nonsteroidal antiinflammatory drugs (NSAIDs) was evaluated in rats. Gastric erosions induced in male rats by indomethacin (25 mg/kg sc) or acidified aspirin (40 mM po) were studied one week after adrenalectomy with or without corticosterone replacement or after occupation of glucocorticoid receptors by the antagonist RU-38486 during the period of erosion formation. Corticosterone for replacement (4 mg/kg sc) was injected 15 min before the administration of indomethacin or acidified aspirin to adrenalectomized rats. The antagonist RU-38486 (10 mg/kg po) was administered twice, 20 min before and 60 min after NSAID administration. Plasma corticosterone levels were measured by fluorometry. Gastric erosions were quantitated by measuring the area of damage. Indomethacin or acidified aspirin induced both plasma corticosterone rise and gastric erosions. Adrenalectomy decreased both basal and NSAID-induced corticosterone levels and markedly promoted gastric erosion formation caused by the NSAID. An acute corticosterone replacement mimicking indomethacin-and aspirin-induced corticosterone rise prevented the effect of adrenalectomy on the gastric erosions. The administration of the glucocorticoid/progesterone antagonist RU-38486 significantly potentiated the formation of gastric erosions induced by indomethacin as well as aspirin. These observations suggest a gastroprotective action of glucocorticoids released in response to NSAID treatment against NSAID-induced injury.     

Gastroprotective action of glucocorticoids during the formation and the healing of indomethacin-induced gastric erosions in rats.

The aim of the present study consisted of the investigation of glucocorticoid role in the formation and the healing of indomethacin-induced (25 mg/kg, s.c.) gastric erosions in rats. The effect of deficiency of glucocorticoid production followed by corticosterone replacement on the formation and the healing of the gastric erosions was evaluated. Glucocorticoid production was decreased by adrenalectomy or by delayed inhibitory action after a single pharmacological dose of cortisol (300 mg/kg i.p.) injected 1 week before the onset of ulcerogenic stimulus. Indomethacin induced corticosterone rise and caused gastric erosions. The loss of indomethacin-induced plasma corticosterone rise potentiated the formation of indomethacin-induced erosions in both models. The area of gastric erosions in rats with glucocorticoid deficiency was considerably larger than that in control animals 4 h after indomethacin administration as well as during 48 h after the drug administration (period of erosion healing). Injecting corticosterone in rats with glucocorticoid deficiency significantly decreased the formation of indomethacin-induced gastric erosions and promoted their healing. Thus, the present data support the gastroprotective action of glucocorticoids in the formation and in the healing of indomethacin-induced mucosal injury.     

Deficiency of glucocorticoid production delays the healing of acute gastric mucosal erosion and chronic ulcers in rats

Effects of glucocorticoid deficiency followed by corticosterone replacement on the healing of gastric erosions and chronic gastric ulcers have been investigated in rats. Glucocorticoid deficiency was induced by adrenalectomy performed after the formation of gastric erosions or ulcers. Gastric erosions were produced by indomethacin (35 mg/kg, i.p.) or by 6 h immobilization at temperature 8 degrees C, chronic gastric ulcers were induced by 60% acetic acid. All ulcerogenic stimuli caused an increase in corticosterone production. Adrenalectomy created corticosterone deficiency and delayed the healing of gastric erosions and chronic gastric ulcers. The effect of adrenalectomy was more evident in the indomethacin ulcerogenic model. Replacement by corticosterone prompted the healing of gastric erosions and ulcers in adrenalectomized animals. These data suggest a participation of endogenous glucocorticoids in a restoration of gastric mucosal integrity.     

The role of glucocorticoids in healing of indomethacin-induced lesions in the rat gastric mucosa

Pretreatment with a single large dose of cortisol a week before indomethacin administration, or an adrenalectomy induced a glucocorticoid production deficiency in rats. The area of gastric erosions in these rats was considerably larger than in the control animals in 4, 24, and 48 hours after the indomethacin administration. Administration of corticosterone noticeably prompted the healing of the erosions in the rats with glucocorticoid deficiency. The findings suggest a gastroprotective effect of glucocorticoids in healing of indomethacin-induced mucosal injury.     

Various ulcerogenic stimuli are potentiated by glucocorticoid deficiency in rats

The effects of glucocorticoid deficiency with or without corticosterone replacement on susceptibility to gastric mucosal injury by various ulcerogenic stimuli have been evaluated in rats. Gastric erosions were induced in male rats by stimuli of different modalities and intensities: 20% ethanol (po), aspirin (300 mg/kg, ip), acidified aspirin (40 mM, po) and 100% acetic acid (applied to gastric serosa). Glucocorticoid supply was decreased by adrenalectomy or by delayed inhibitory action after a single pharmacological dose of cortisol (300 mg/kg, ip) injected one week before the onset of ulcerogenic stimulus. Corticosterone for replacement (4 mg/kg, sc) was injected in rats with glucocorticoid deficiency 15 min before the onset of ulcerogenic stimulus. Plasma corticosterone levels were measured by fluorometry. Gastric erosions were quantitated by measuring the area of damage. Ulcerogenic stimuli induced both plasma corticosterone rise and gastric mucosal injury. The area of mucosal damages induced various stimuli ranged from small to extensive. Glucocorticoid deficiency significantly potentiated an ulcerogenic action of every ulcerogenic stimulus. Replacing corticosterone prevented or significantly decreased erosion-potentiating effect of glucocorticoid deficiency. These results show that endogenous glucocorticoids released during ulcerogenic influences help gastric mucosa to resist a harmful action of both weak and strong ulcerogenic stimuli.     

Deficit of glucocorticoid production in rats aggravates ulcerogenic effects of stimuli of various modality and intensity

Effects of glucocorticoid deficiency and corticosterone replacement on gastric mucosal injury induced by various ulcerogenic stimuli have been evaluated in rats. Gastric erosions were induced in male rats by stimuli of different modalities and intensities. Glucocorticoid deficiency was induced by adrenalectomy or delayed inhibitory action after a single pharmacological dose of cortisol (300 mg/kg, i.p.) injected one week before the onset of ulcerogenic stimulus. Ulcerogenic stimuli induced both a plasma corticosterone rise and a gastric mucosal injury. The area of mucosal damages induced various stimuli ranging from a small to extensive those. Glucocorticoid deficiency significantly potentiated an ulcerogenic action of each ulcerogenic stimulus. Replacement by corticosterone (4 mg/kg, s.c., 15 min before the onset of ulcerogenic stimulus) prevented or significantly decreased the erosion--potentiating effect of glucocorticoid deficiency. These results show that endogenous glucocorticoids released during ulcerogenic influences help gastric mucous membrane to resist against a harmful action of both weak and strong ulcerogenic stimuli.     

Compensatory gastroprotective action of glucocorticoid hormones in the rats with ablation of capsaicin-sensitive neurons

We tested the hypothesis that contribution of glucocorticoids in gastroprotection become especially important during ablation of capsaicin-sensitive neurons. For this, the effect of desensitization of capsaicin-sensitive neurons on the gastric mucosa was compared in groups of rats with different glucocorticoid supply: sham-operated and adrenalectomized without and with corticosterone replacement (4 mg/kg sc). Functional ablation of capsaicin-sensitive neurons was performed with neurotoxic doses of capsaicin (20 + 30 + 50 mg/kg sc). Indomethacin in the dose 35 mg/kg was given as an ulcerogenic stimulus. It was shown that combination of adrenalectomy with desensitization of capsaicin-sensitive neurons potentiated the effect of sensory desensitization alone on indomethacin-induced gastric erosions. Corticosterone replacement prevented this effect of adrenalectomy. The results suggest a pivotal compensatory role of glucocorticoids in maintenance of gastric mucosal integrity during ablation of caspsaicin-sensitive sensory neurons.     

Role of gastric microcirculation in the gastroprotection by glucocorticoids released during water-restraint stress in rats

Our previous investigations demonstrated that glucocorticoids released in response to stress protect gastric mucosa against stress-induced ulceration. This study was designed to determine whether gastric microcirculation is involved in the mechanism of gastroprotective glucocorticoid action. For this we evaluated the effects of deficiency of glucocorticoid production during 3 hr water-restraint stress and corticosterone replacement on the stress-induced gastric erosions, gastric microcirculation and arterial pressure in rats. The stress was produced in awake rats and gastric microcirculation and arterial pressure were evaluated in animals anesthetized in 3 hr after the onset of water-restraint stress. An in vivo microscopy technique for the direct visualization of gastric microcirculation was employed. The gastric submucosal and the superficial mucosal microvessels were monitored on television screen through a microscope and the pictures were stored by microfilming for the analysis of red blood cell velocity and vessel diameter. Gastric microcirculation was estimated on the base of both the volume blood flow velocity in submucosal microvessels and the diameter of superficial mucosal venous microvessels. Gastric erosions were quantitated by measuring the area of damage. Plasma corticosterone levels were also measured after 3 hr stress by fluorometry. Water-restraint stress induced an increase in corticosterone level, an appearance of gastric erosions, a decrease in volume blood flow velocity of submucosal microvessels, a dilatation of superficial mucosal microvessels, a decrease in arterial pressure. The deficiency of glucocorticoid production during water-restraint stress promoted the stress-induced gastric ulceration, a dilatation of mucosal microvessels, a decrease of blood flow velocity in submucosal microvessels and of arterial pressure. Corticosterone replacement eliminated the effects of deficiency of glucocorticoid production on all of the parameters under study. Thus, the stress-induced corticosterone rise decreased gastric ulceration, restricted both the reduction of blood flow velocity in submucosal microvessels and a dilatation of superficial mucosal venous microvessels during water-restraint stress. These data suggest that the gastroprotective action of glucocorticoids during stress may be provided by the maintenance of gastric blood flow.     

Mechanisms by which endogenous glucocorticoid protects against indomethacin-induced gastric injury in rats

We investigated the mechanisms underlying the protective action of glucocorticoids against indomethacin-induced gastric lesions. One-week adrenalectomized rats with or without corticosterone replacement (4 mg/kg sc) were administered indomethacin (25 mg/kg sc), and gastric secretion (acid, pepsin, and mucus), motility, microvascular permeability, and blood glucose levels were examined. Indomethacin caused gastric lesions in sham-operated rats, with an increase in gastric motility and microvascular permeability as well as a decrease in mucus secretion. Adrenalectomy significantly worsened the lesions and potentiated these functional disorders. Glucose levels were lowered by indomethacin in sham-operated rats, and this response was enhanced by adrenalectomy. The changes observed in adrenalectomized rats were prevented by supplementations of corticosterone at a dose mimicking the indomethacin-induced rise in corticosterone, whereas the protective effect of corticosterone was attenuated by RU-38486, a glucocorticoid receptor antagonist. We conclude that the gastroprotective action of endogenous glucocorticoids may be provided by their support of glucose homeostasis and inhibitory effects on enhanced gastric motility and microvascular permeability as well as maintaining the production of mucus.     

Transformation of physiological gastroprotective effects of glucocorticoids into pathological ulcerogenic consequences

The study was designed to investigate how physiological gastroprotective action of glucocorticoids could be transformed to pathological proulcerogenic effect. Time-dependent effects of single injection of dexamethasone on stress-induced gastric erosions, corticosterone and blood glucose levels, somatic parameters were investigated in fasted rats. Dexamethasone injected at the same dose attenuated or aggravated the stress-induced gastric erosions depending on the time of the injection. In case of dexamethasone injection 1-12 hrs before stress, we observed its gastroprotective action. Further increase in the time interval caused transformation of the gastroprotective action of dexamethasone to proulcerogenic effect. Accordingly to the results obtained, dexamethasone-induced long-lasting maintenance of blood glucose levels accompanied with signs of catabolic effect as well as dexamethasone-induced corticosterone deficiency may be responsible, at least partly, for the transformation of gastroprotective effect of dexamethasone to the proulcerogenic one.     

Histopathology of gastric erosions. Association with etiological factors and chronicity

Background: The histopathologic characteristics of the antral erosions, and a comparison with samples systematically collected from the background antral mucosa, have not been studied previously. Similarly, unknown is the association of these features with suspected etiological factors and chronicity of erosion. Material and Methods: We studied 117 patients with gastric erosions in the absence of peptic ulcer disease. With 28 patients available for a follow‐up 19 years later, sites of erosions and background mucosa were biopsied and histopathology of both independently assessed at both visits. Helicobacter pylori status was examined from the biopsies taken in the initial and follow‐up gastroscopies. Only subjects originally displaying antral erosions were included. The presence of Herpes simplex virus (HSV) antibodies was analyzed and use of nonsteroidal anti‐inflammatory drug (NSAID) was inquired. Results: Initially, the inflammation was more active in the region of erosions than elsewhere in antral mucosa. More active inflammation in the erosion was associated with HSV seropositivity, Helicobacter pylori infection, and the recent use of NSAIDs. In the follow‐up visit, antral erosions were present in 38% (3/8) of Helicobacter pylori negatives and in 35% (7/20) of positives (p = ns). The Helicobacter pylori positive subjects with chronic or recurrent erosions had initially higher scores of neutrophils compared to subjects with nonrecurrent or nonchronic erosions (2.7 ± 0.5 vs 1.2 ± 1.0; p = .002). Conclusions: Focally enhanced inflammation is characteristic for gastric erosions. This focal inflammation was associated with HSV seropositivity or NSAID use suggesting that such inflammation may be important in the pathogenesis of gastric antral erosions. Highly active inflammation in the erosions associates with their chronicity.     

Stimulation of the immune response against SRBC by reduction of corticosterone plasma levels: Mediation by mononuclear phagocytes

The effects of reduction in corticosterone plasma levels on the immune response of the mouse have been studied. Reduction of corticosterone levels was achieved by (1) repeated corticosterone injections (feedback), (2) adrenalectomy, and (3) continuous injections of aminoglutethimide phosphate (AGP). With the three methods a reduction in the corticosterone production paralleled by an augmentation in monocyte numbers and DH reactivity was obtained. The humoral response was only affected after immunization with supraoptimal doses of antigen. These results indicate that fall of corticosterone plasma level results in a rise of the blood monocyte number. These monocytes are available (effective) in both cellular and humoral reactions.     

Co-secretion of aldosterone and cortisol by an adrenocortical carcinoma

We report a rare case of adrenocortical carcinoma. A 26-year-old woman presented with hypokalemia and hypertension due to hyperaldosteronism. She had no signs of Cushing's syndrome. Endocrinological data showed excess of aldosterone production and nonsupressible cortisol production on 2 mg of dexamethasone. Magnetic resonance imaging showed left adrenal tumor. Transabdominal left adrenalectomy was performed and histopathological diagnosis was adrenocortical carcinoma. Her blood pressure and hypokalemia returned to normal after adrenalectomy. There is no recurrence after 36 months. We want to emphasis the importance of adrenal tests before the operation even if there are no signs of excess cortisol production.     

Daily rhythms of pituitary-ovarian function in the immature hamster are independent of adrenal and pineal influence

In female hamsters, the daily rhythm of LH appeared on the 15th or 16th day after birth with a peak occurring at about 16:00 h (14L:10D, lights on 06:00 h). Progesterone concentrations increased and became rhythmic a few days later. In serum samples collected at 14, 16, 18, 20, 25, 30, 40 and 60-62 days of age between 13:00 and 23:00 h, significant rhythms of serum cortisol and corticosterone concentrations were not detected before 25 days of age; furthermore, the phase of the rhythms did not stabilize to the adult pattern until about 40 days of age. As in the adult, significant rhythms were present in both sexes and the levels of cortisol were greater than those of corticosterone. Injection of pig ACTH (50 i.u./kg body wt, i.p.) significantly increased serum cortisol by 10 days of age, but corticosterone did not respond until 25 days of age. Thus, for cortisol at least, the appearance of 24-h rhythms in the serum is probably not dependent on the ability of the adrenal to respond to ACTH. Ovariectomy had no effect on the late afternoon surge of serum cortisol; similarly, adrenalectomy of immature females did not abolish the surge of LH. Ovariectomy did not alter the daily rhythm of pineal melatonin content and pinealectomy had no effect on the daily afternoon surge of LH. These results demonstrate functional independence of circadian rhythms in the pituitary-gonadal axis and the pituitary-adrenal axis of the immature hamster and also independence of daily rhythms of pineal melatonin and pituitary release of LH.     

Sex-dependent effect of melatonin on the secretory activity of rat and hamster adrenal gland in vitro

Adrenal quarters from adult male or female hamsters were incubated in the presence of melatonin (10(-7) or 10(-4)M), and cortisol concentration in the incubation medium was assayed by RIA. Melatonin did not change cortisol output by adrenals obtained from the male hamsters, while a slight stimulatory effect was observed in female glands, the lower concentration of melatonin being more effective than the higher one. At both concentrations tested, melatonin notably stimulated corticosterone output by isolated rat adrenocortical cells derived from the males, and lowered corticosterone secretion by the cells obtained from the female glands only at a concentration of 10(-7) M. The lower concentration of melatonin increased ACTH (0.1 mU.ml-1)-stimulated corticosterone output by the cells of male and female rat adrenals. The pineal hormone was ineffective at a concentration of 10(-4) M, as well as in the presence of a higher dose of ACTH (1.0 mU.ml-1). These findings indicate a distinct sex-dependent effect of melatonin on in vitro cortisol and corticosterone production, and demonstrate that the modulatory effect of melatonin of the secretion of steroid hormones is more effective at lower concentrations.     

ACTH sensitivity of isolated human pathological adrenocortical cells: variability of responses in aldosterone, corticosterone, deoxycorticosterone and cortisol production

In vitro aldosterone, deoxycorticosterone, corticosterone and cortisol production of human adrenocortical cells derived from adenomas (Conn's syndrome, Cushing's syndrome), from hyperplastic adrenals (Cushing's syndrome) and from adrenals surrounding aldosteronoma are described. Cells from adenomas causing either Cushing's syndrome or Conn's syndrome harboured the highest basal and ACTH-stimulated corticosteroid production. Adrenocortical cells derived from micronodular hyperplasia causing Cushing's syndrome and cells from cortisol producing adenoma displayed predominantly cortisol and corticosterone secretion both under basal conditions and following stimulation with ACTH. Aldosteronoma cells showed highly variable aldosterone, deoxycorticosterone, corticosterone and cortisol response to ACTH. However, in aldosteronoma cell suspensions, the basal and ACTH-stimulated ratios of aldosterone to cortisol were increased when compared to ratios of steroids produced by cells from other adrenal tissues. Chronic treatment with spironolactone of patients with Conn's syndrome before surgery was associated with a decreased ratio of aldosterone to corticosterone, revealing that 18-hydroxylase in aldosteronoma cells may be inhibited during long-term therapy. Non-tumorous cells isolated from adrenals surrounding aldosteronoma displayed less aldosterone prior to and after stimulation with ACTH than aldosteronoma cells.     

Eradication of Helicobacter pylori does not reduce the incidence of gastroduodenal ulcers in patients on long-term NSAID treatment: double-blind, randomized, placebo-controlled trial

BACKGROUND: Helicobacter pylori and nonsteroidal antiinflammatory drugs (NSAIDs) are the major causes of gastroduodenal ulcers. Studies on the benefit of eradication of H. pylori in NSAID users yielded conflicting results. OBJECTIVE: To investigate whether H. pylori eradication in patients on long-term NSAIDs reduces the incidence of gastroduodenal ulcers. METHODS: Patients on long-term NSAID treatment and who are H. pylori positive on serologic testing, were randomly assigned to either H. pylori eradication (omeprazole, amoxicillin, and clarithromycin) or placebo. Primary endpoint was the presence of endoscopic gastric or duodenal ulcers 3 months after randomization. RESULTS: One hundred sixty-five (48%) of a total of 347 patients were on gastroprotective medication. At endoscopy, gastroduodenal ulcers were diagnosed in 6 (4%) and 8 (5%) patients in the eradication and placebo group, respectively (p = .65). During follow-up of 12 months, no symptomatic ulcers or ulcer complications developed. No significant differences were found in the development of gastroduodenal erosions, dyspepsia, or in quality of life. CONCLUSION: H. pylori eradication therapy in patients on long-term NSAID treatment had no beneficial effect on the occurrence of ulcers, erosions, or dyspepsia. Ulcer rates in both study arms are remarkably low, in both patients with and without gastroprotective therapy.     

Gastric mucosal blood flow changes in Helicobacter pylori infection and NSAID-induced gastric injury

Background. The impact of H. pylori infection on gastric mucosal blood flow and NSAID‐induced gastric damage is unclear. Aim. To study the effects of H. pylori infection on gastric mucosal blood flow, both at basal conditions and after NSAID exposure, and its relation with mucosal damage and nitric oxide production. Methods. Gastric mucosal blood flow, nitric oxide production and gastric damage were assessed in time after H. pylori SS1 or E. coli inoculation in mice. Experiments were conducted in basal conditions or after oral exposure to indomethacin (20 mg/kg). Results. H. pylori infected mice exhibited a significant increase in gastric blood flow and gastric nitric oxide production 1 week after infection, but those parameters returned to basal levels by 4 weeks. NSAID challenge elicited a similar reduction in gastric blood flow [25–35%] in H. pylori‐infected and control animals. However, only 1 week H. pylori‐infected mice, which exhibited a significant baseline hyperemia, were able to maintain gastric blood flow values within the normal range after NSAID exposure. NSAID‐induced gastric damage was increased in H. pylori‐infected mice by 4 weeks, but not 1 week after infection. Conclusions. Underlying H. pylori infection aggravates acute NSAID‐induced gastric damage. However, at early phases, gastric hyperemia associated with increased nitric oxide production may exert some protective role.     

Mucosal damage induced by preferential COX-1 and COX-2 inhibitors: role of prostaglandins and inflammatory response

Nonsteroidal anti-inflammatory drugs (NSAID) are well known to induce gastric mucosal damage including bleeding, ulceration and perforation in humans and animals too. These effects are related with the inhibition of the enzyme cyclooxygenase, which is the main established mechanism of action for these drugs. Fasted rats were given piroxicam, preferential COX-1 inhibitor (10-20 mg/kg) or meloxicam, preferential COX-2 inhibitor (7.5-15 mg/kg) orally. Six or nine hours (h) later, respectively, the stomach was excised, the severity of the damage assessed and myeloperoxidase (MPO) activity measured, as well as prostaglandin PGE(2) content. Furthermore, in order to assess the effects of these oxicams over previously damaged gastric mucosa, 1 ml of 0.6 N HCl was administered p.o. followed, 1 h after, of the correspondent dose of each NSAID, and the same parameters were determined. Oral administration of both drugs dose-dependently caused acute gastric haemorrhage erosions. Myeloperoxidase activity was significantly increased by piroxicam administration. In addition, PGE(2) content was significantly reduced. The association between the administration of the acid and NSAID caused a worsening of the damage and, while myeloperoxidase activity did not modify by both piroxicam and meloxicam, PGE(2) levels were reduced. These results suggest that the PG derived from both COX-1 and COX-2 pathway plays a beneficial role in the gastroprotection, and thus caution should be exercise in the clinical use of preferential COX-2 inhibitors.     

Glucocorticoid effects on gastric peroxidase activity

The peroxidase activity in rat gastric mucosa is inhibited after administration of glucocorticoids. The synthetic steroid dexamethasone is more potent than the naturally occurring steroids, such as cortisone or corticosterone. Almost complete inhibition of the enzyme occurs after 24 h with a single dose of 100 micrograms dexamethasone/120 g body weight. Other mitochondrial enzyme activities, like monoamine oxidase, succinic dehydrogenase and Mg2+-ATPase, remain unaltered under the same experimental condition. Submaxillary peroxidase and thyroid peroxidase activity are not inhibited by dexamethasone. Gastric peroxidase activity is increased 200-250% on the 6th day after adrenalectomy. This effect is blocked by the administration of dexamethasone. In fact, the enzyme becomes more sensitive to dexamethasone after adrenalectomy, since it is inhibited by more than 90% at the dose of 25 micrograms/120 g body weight. The inhibition by dexamethasone in normal animals is reversible. The enzyme is also inhibited after the administration of a single dose of ACTH. The apparent Km of the enzyme for H2O2 is not altered after dexamethasone treatment or after adrenalectomy. The increase in enzyme activity following adrenalectomy is not blocked by actinomycin D or by alpha-amanitin, but is prevented by puromycin or cycloheximide. After administration of dexamethasone, the iodide concentration process in the gastric mucosa is not affected, but the organification of iodide is significantly diminished.