Environmental enrichment reverses proulcerogenic action of social isolation on the gastric mucosa and positively influences pain sensitivity and work capacity.

The aim of the study was to investigate the effects of rat housing conditions-standard conditions, social isolation, environmental enrichment-and the subsequent reversal of these conditions on the vulnerability of the gastric mucosa to ulcerogenic stimuli, somatic pain sensitivity, and treadmill work capacity. Rats, aged 30 days, were placed in standard conditions (SC), social isolation (Is), and environmental enrichment (EE) for 4 weeks. Then half of each group underwent a reversal of housing conditions: SC rats were moved to Is, Is rats were placed in EE, EE rats were moved to Is, for 2 weeks. The other half served as a control with no change in their initial housing. Two weeks after the reversal, vulnerability of the gastric mucosa to ulcerogenic action of indomethacin (IM, 35 mg/kg, sc), somatic pain sensitivity (hot plate test), and work capacity (measured by the running distance on a treadmill) were assessed in control and reversed groups. Social isolation induced a proulcerogenic effect, increasing IM-induced gastric erosions, which was effectively reversed when rats were transferred to an environmental enrichment. Conversely, transferring rats from an environmental enrichment to social isolation exacerbated ulcerogenic action of IM. Somatic pain sensitivity and treadmill work capacity were also influenced by housing conditions, with environmental enrichment showing positive effects. The present findings show that social isolation of rats induces a proulcerogenic effect. Environmental enrichment reverses proulcerogenic action of social isolation on the gastric mucosa and increases resilience to pain stimuli and treadmill work capacity.

Non-Invasive Remote Ischemic Preconditioning May Protect the Gastric Mucosa Against Ischemia-Reperfusion-Induced Injury Through Involvement of Glucocorticoids.

Remote ischemic preconditioning (RIPC) is one of the most effective approaches to attenuate tissue injury caused by severe ischemia-reperfusion (I/R). Experimental studies have demonstrated that RIPC is capable of producing a protective effect not only on heart, but also on brain, lungs, kidneys, liver, intestine, and stomach. We previously demonstrated that glucocorticoids participate in protective effect of local gastric ischemic preconditioning against I/R-induced gastric injury. In the present study we investigated whether RIPC may protect the gastric mucosa against I/R-induced injury through involvement of glucocorticoids. Anesthetized fasted Sprague Dawley male rats were exposed to prolonged gastric I/R (30 min occlusion of celiac artery followed by 3 h of reperfusion) alone or with preliminary brief RIPC (10 min non-invasive occlusion of right hind limb blood flow followed by reperfusion for 30 min). First, we investigated the effect of RIPC on I/R-induced injury by itself. Then to study the role of glucocorticoids similar experiments were carried out: 1) in rats pretreated with the inhibitor of glucocorticoid synthesis, metyrapone (30 mg/kg, i.p), and in control animals; 2) in adrenalectomized rats without or with corticosterone replacement (4 mg/kg, s.c.) and in sham-operated animals; 3) in rats pretreated with glucocorticoid receptor antagonist RU-38486 (20 mg/kg, s.c.) and in control animals. I/R induced corticosterone rise and resulted in the gastric erosion formation. RIPC significantly reduced the erosion area in control animals. Metyrapone injected shortly before RIPC caused a decrease in plasma corticosterone levels and prevented the gastroprotective effect of RIPC and, moreover, further aggravated the deleterious effect of I/R. Adrenalectomy performed 1 week before experiment created long-lasting corticosterone deficiency and had no effect on the gastroprotective effect of RIPC. Nevertheless, corticosterone replacement which mimics the corticosterone rise, similar to RIPS, significantly reduced erosion areas of gastric mucosa in adrenalectomized rats supporting the role of glucocorticoids in gastroprotection. RU-38486, which occupied glucocorticoid receptors, similar to metyrapone prevented the gastroprotective effect of RIPC and, moreover, further aggravated the deleterious effect of I/R. The results of the present study demonstrate for the first time that RIPC may protect the gastric mucosa against I/R-induced injury through involvement of glucocorticoids.

Physiological and Pharmacological Effects of Glucocorticoids on the Gastrointestinal Tract.

The review considers the data on the physiological and pharmacological effects of glucocorticoids on the gastric mucosa and focuses on the gastroprotective role of stress-produced glucocorticoids as well as on the transformation of physiological gastroprotective effects of glucocorticoids to pathological proulcerogenic consequences. The results of experimental studies on the re-evaluation of the traditional notion that stress-produced glucocorticoids are ulcerogenic led us to the opposite conclusion suggested that these hormones play an important role in the maintenance of the gastric mucosal integrity. Exogenous glucocorticoids may exert both gastroprotective and proulcerogenic effects. Initially, gastroprotective effect of dexamethasone but not corticosterone, cortisol or prednisolone can be transformed into proulcerogenic one. The most significant factor for the transformation is the prolongation of its action rather the dose. Gastrointestinal injury can be accompanied by changes in somatic pain sensitivity and glucocorticoids contribute to these changes playing a physiological and pathological role.

The peripheral corticotropin-releasing factor (CRF)-induced analgesic effect on somatic pain sensitivity in conscious rats: involving CRF, opioid and glucocorticoid receptors.

The corticotropin-releasing factor (CRF) is involved in somatic pain regulation and may produce an analgesic effect in humans and animals, although the mechanisms of the CRF-induced analgesia remain unclear. CRF action is mediated by the CRF receptors of subtypes 1 and 2 (CRF-R1 and CRF-R2, respectively). Activation of the hypothalamic -pituitary -adrenocortical axis (HPA) is provided by CRF-R1; but CRF-R2 are also involved in the regulation of the HPA axis, and, respectively, glucocorticoids, the end hormones of the HPA axis, also participate in somatic pain regulation. Additionally, opioids may contribute to the CRF-induced analgesia. This article serves as an overview of the role of CRF-R1 and CRF-R2, as well as glucocorticoid and opioid receptors in peripheral CRF-induced analgesia in conscious rats, while we focused on the data obtained under normal (non-pathological) conditions including results of our studies in rats. The involvement of CRF-R1 and CRF-R2, glucocorticoids and opioid receptors was studied under the same experimental conditions following pretreatment with appropriate antagonists: NBI 27914, astressin2-B, naltrexone and RU 38486, respectively. Somatic pain sensitivity was measured by the tail flick latencies induced by thermal stimulus (tail flick test). Peripheral administration of the CRF caused both an increase in the tail flick latencies (analgesic effect) and plasma corticosterone levels. Pretreatment with NBI 27914, astressin2-B, naltrexone or RU 38486 attenuated the peripheral CRF-induced analgesia. The results obtained suggest that the peripheral CRF-induced analgesic effect may be mediated through the involvement of CRF-R1 and CRF-R2 as well as opioid and glucocorticoid receptors, including CRF-R2 and opioid receptors within periaqueductal gray matter of the midbrain.

Gastroprotective Effect of Stress Preconditioning: Involvement of Glucocorticoids.

Stress plays a leading role in maintaining the physical health of the body. Various health effects of preconditioning mild stress strongly confirm this statement. Preconditioning mild stress, which is everyday event of animal and human life, may attenuate the development and aggravation of diseases including such widespread pathology as gastric ulceration. Preconditioning mild stress may diminish gastric injury formation caused by severe stress. Gastroprotective influence of preconditioning mild stress is known to be mediated by prostaglandins. In the present article, we focus on the data suggesting that glucocorticoids released in response to preconditioning mild stressor are important players of gastroprotective influence of preconditioning stress.

The timing of weaning alters the vulnerability to stress-induced gastric erosion in adult rats.

BACKGROUND AND PURPOSE: Weaning is an important period of life and its timing may influence the resilence for later stress. One of the most important stress-related disorder is gastric ulceration. METHODS: Therefore we aimed to investigate the sensitivity of gastric mucosa to cold (at 16°C) water immersion stress (WIS for 3h) in adult (75-day-old) female and male rats after weaning them at different timepoints (at 17, 21, 30, 36 or 42 postnatal days). The connection with stress was studied by comparing control groups to those underwent WIS at the time of weaning and measuring corticosterone levels at the time of collecting the stomach samples. RESULTS: The timing of weaning has strong impact on all studied parameters. Stress-induced erosion development was the smallest in rats weaned at 36-day independently from preconditioning with WIS at weaning, or sex, despite a clear sex-effect on blood corticosterone levels and body weight. WIS at weaning influenced only the body weight in adult rats weaned at 30-day, being higher in stressed than in control groups. There was no clear overall correlation between erosion area and blood corticosterone measures. CONCLUSION: Taken together our results confirm that the timing of weaning has long-lasting impact on the resiliance of gastric mucosa to ulcerogenic stressful events. In rats the postnatal day 30-36 seems to be optimal for weaning in both sexes as both earlier and later weaning increased vulnerability. Females seems to be more vulnerable to the effect of weaning than males.

The Realization of the Brain-Gut Interactions with Corticotropin-Releasing Factor and Glucocorticoids.

BACKGROUND: The brain and the gut interact bi-directionally through the brain-gut axis. The interaction is mediated by the autonomic nervous system and the hypothalamic-pituitary-adrenocortical (HPA) system. The first brilliant demonstration of the brain-gut interactions was the cephalic phase of gastric and pancreatic secretion discovered by Ivan Pavlov, the first physiologist who was awarded the Nobel Prize for Physiology or Medicine in 1904. This review aims to identify the HPA system as a key hormonal branch of the brain-gut axis in stress. METHODS: We first outlined main components of the brain-gut axis and then focused on the HPA system as a key hormonal branch of the brain-gut axis in stress. We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question. RESULTS: Seventy-one articles were included in the review, the eleventh of them were articles of Filaretova L. and co-authors. We will discuss in our articles how an endocrinological approach to gastroenterological field can advance our understanding of the HPA axis role in regulation of gastric mucosal integrity and uncover new findings. According to these findings activation of the HPA system is gastroprotective component of the brain-gut axis in stress but not ulcerogenic one as it was generally accepted. Corticotropin-releasing factor (CRF) and glucocorticoids are important natural players provided gastroprotection. The results suggest that an initial action of endogenous glucocorticoids, including stress- and CRF-produced ones, as well as exogenous glucocorticoids, even used at pharmacological doses, is physiological gastroprotective. Prolongation of the hormonal action may lead to the transformation of gastroprotective hormonal effect to proulcerogenic one. CONCLUSION: The findings of this review demonstrate that corticotropin-releasing factor and glucocorticoids contribute to the realization of the brain-gut interactions and that activation of the HPA system is gastroprotective component of this interaction in stress.

Stress-induced corticosterone rise maintain gastric mucosal integrity in rats.

BACKGROUND AND PURPOSE: To investigate contribution of glucocorticoids to the maintenance of gastric mucosal integrity during stress we predominantly used ulcerogenic stress models. Using these models we demonstrated that glucocorticoids released in response to the ulcerogenic stimuli attenuated their harmful action on the gastric mucosa. In the present study we hypothesized that mild stressors does not damage the gastric mucosa due to gastroprotective action of glucocorticoids released in response to these stressors. METHODS: To verify the hypothesis the effects of normally non-ulcerogenic mild stimuli (15-30 min cold-restraint) on the gastric mucosal integrity have been studied under the circumstances of inhibition of the hypothalamic-pituitaryadrenocortical axis in rats. The hypothalamic-pituitary-adrenocortical axis was inhibited by: 1) fast inhibitory action of metyrapone, inhibitor glucocorticoid synthesis; 2) fast inhibitory action of NBI 27914, the selective antagonist of cortricotropin- releasing factor receptor type 1; 3) delayed inhibitory action of a single pharmacological dose of cortisol injected one week before the onset of stress stimulus. RESULTS: Each of these pretreatments significantly decreased 15-30 min cold-restraint-produced corticosterone levels: 37.2±1 vs 22.5±1.2 (p<0.05) after metyrapone; 52.1±0.9 vs 41.4±1 (p<0.05) after NBI, and 64.2±4.2 vs 16.7±1.5 (p<0.05) after cortisol pretreatment. The inhibition of stress-induced corticosterone rise resulted in an ap - pearance of gastric lesions after the onset of these mild stressors in rats. CONCLUSION: The results suggest that in rats with inhibited stress-induced corticosterone rise normally non-ulcerogenic stimuli are transformed into ulcerogenic ones and confirm the hypothesis. The findings further support for the point of view that glucocorticoids released during acute stress are gastroprotective factors.

From gastroprotective to ulcerogenic effects of glucocorticoids: role of long-term glucocorticoid action.

Glucocorticoids may have dual action on the gastric mucosa: gastroprotective and ulcerogenic. In this article, we review the data which suggested that an initial action of endogenous glucocorticoids, including stress-produced ones as well as exogenous glucocorticoids is gastroprotective and consider possible mechanisms of the conversion of physiological gastroprotective action of glucocorticoid hormones to their pathological ulcerogenic effect.

THE SURPRISING DUAL ACTION OF GLUCOCORTICOIDS.

Glucocorticoid hormones may have dual action on the stomach: physiological gastroprotective and pathological proulcerogenic one. In physiological conditions, even in acute stress situations, glucocorticoids have an adaptive effect on the stomach and, therefore, are gastroprotective. The findings that we review in this article suggest that glucocorticoids released during acute stress are naturally occurring protective factors that play an important role in maintenance of the gastric mucosal integrity.

Gastroprotective role of glucocorticoids during NSAID-induced gastropathy.

Nonsteroidal anti-inflammatory drugs (NSAIDs) make significant contributions to gastric ulcer disease which remains widespread. Although several factors have been postulated as pathogenic elements of the gastric injury induced by NSAIDs, it is, however believed that prostaglandin deficiency plays a critical role in the pathogenesis of this injury. During prostaglandin deficiency, other defensive mechanisms might operate to attenuate NSAID-induced gastropathy. According to our results, NSAIDs, similar to stress, induce an increase in glucocorticoid production that in turn helps the gastric mucosa to resist the harmful actions of these drugs. In this article, we review our experimental data suggesting that glucocorticoids may play a role as natural defensive factors in maintaining the integrity of the gastric mucosa during NSAID therapy and might operate to attenuate NSAID-induced gastropathy.

Stress and the Stomach: Corticotropin-Releasing Factor May Protect the Gastric Mucosa in Stress Through Involvement of Glucocorticoids.

Stress may contribute to the development of gastric ulcer disease. The results of our previous investigations suggest that glucocorticoids released during acute stress act as gastroprotective hormones, and not as ulcerogenic agents as has been generally accepted for a long time. In this study, we investigated whether corticotropin-releasing factor (CRF) may protect the gastric mucosa against stress-induced gastric injury through involvement of glucocorticoids. Intraperitoneal administration of CRF (1.25 µg/kg, 30 min before stress) markedly increased plasma corticosterone level (at 15 and 30 min after the administration) and significantly suppressed the occurrence of gastric erosion induced by 3-h cold-restraint stress (at 10°C) in conscious rats. To test the participation of corticosterone in the gastroprotective effect of exogenous CRF, two approaches were used: pretreatment by the inhibitor of glucocorticoid synthesis, metyrapone (30 mg/kg, i.p.) and the antagonist of glucocorticoid receptors RU-38486 (20 mg/kg, i.p.). Metyrapone injected shortly before CRF administration caused a fast inhibition of CRF-induced corticosterone response and reversed the protective effect of CRF on the gastric mucosa against the stress-induced erosion. The gastroprotective effect of CRF was also attenuated by the pretreatment rats with glucocorticoid receptor antagonist RU-38486. The results suggest that exogenous CRF may protect the gastric mucosa against stress-induced gastric injury through involvement of glucocorticoids.

The healing of NSAID-induced gastric lesion may be followed by small intestinal and cardiovascular side effects.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among some of the most commonly used medications. Serious adverse effects induced by NSAIDs may occur not only in the upper gastrointestinal tract, but in the small intestine and cardiovascular system. However, these side effects are studied and investigated separately. Here we tested the hypothesis that the healing of indomethacin-induced gastric erosion may be followed by small intestinal and cardiovascular adverse effects. First we examined the development of gastrointestinal lesions 4-24-48-72 h after a single indomethacin (35 mg/kg s.c.) injection given to fasted male rats (refeeding after 4 h). Then with a telemetric device heart rate, core body temperature and locomotion changes were recorded in the freely moving animals for 72 h after indomethacin or its vehicle injection (control). Indomethacin produced hemorrhagic erosion in the glandular stomach 4 h after its administration which was almost completely healed 48 h later. Parallel to the healing a gradual increase of injury to the small intestine became apparent. The control rats' heart rate, core body temperature and locomotion all agreed with a normal circadian rhythm. However, the circadian cycle of rats treated with indomethacin in 24 h after its administration was disrupted: their heart rate rose to it's maximal level and their locomotion and core temperature values fell to their minimal. These results suggest that the healing of gastric erosion induced by a single indomethacin injection may be followed by other pathological events outside of the stomach, among which there may be intestinal injury and a loss of a normal circadian cycle of heart rate as well as body temperature and locomotion.

Glucocorticoids are Gastroprotective under Physiologic Conditions.

Stress may contribute to the development and progression of gastrointestinal disorders. Activation of the hypothalamic-pituitary-adrenocortical (HPA) axis is one of the main characteristics of stress. For several decades it was generally accepted that glucocorticoids released during stress are ulcerogenic hormones. We designed some experimental studies in rats to clarify the validity of this widely held view. To achieve this goal, we examined the effect of glucocorticoid deficiency followed by corticosterone replacement or the glucocorticoid receptor antagonist, RU-38486, on stress-induced gastric erosion and the parameters of gastric function in rats. The data obtained shows that the reduction in the stress-induced corticosterone release, or its actions, aggravates stress-caused gastric erosion. It is suggested that an acute increase in corticosterone during stress protects the stomach against stress-induced injury. According to our results, various ulcerogenic stimuli, similar to stress, induce an increase in corticosterone that helps the gastric mucosa to resist against a harmful action of ulcerogenic stimuli. Glucocorticoids exhibit their gastroprotective effect by both maintaining local defensive factors and inhibiting pathogenic elements. Furthermore, the contribution of glucocorticoids to gastroprotection is tightly related to their contribution to general body homeostasis. Glucocorticoids provide gastroprotective actions in co-operation with prosta-glandins, nitric oxide and capsaicin-sensitive sensory neurons. The results obtained do not support the traditional paradigm and suggest that glucocorticoids released during acute activation of the HPA axis are naturally occurring gastroprotective factors. In this article, we review our recent publications on the role of glucocorticoids in gastroprotection.

Age-dependent role of vasopressin in susceptibility of gastric mucosa to indomethacin-induced injury.

The high prevalence of gastric ulceration underlines the importance of understanding the mechanisms. Based upon its multifactorial role vasopressin (VP) is supposed to be one of the contributory factors, however the data are contradictory. We intended to reevaluate the role of VP in development of gastric ulceration. Naturally VP-deficient Brattleboro rats were used and the indomethacine-induced gastric erosion model (35 mg/kg sc, 4 h) has been chosen because of its clinical importance. Since gastric mucosal vulnerability shows age-dependent alterations, we compared young (4 week old) rats to old ones (1 year old). The lack of VP resulted in attenuation of erosion formation in young rats, while aggravation in old ones. Four hours after indomethacin treatment adrenocorticotropin and corticosterone levels as well as blood glucose levels were higher in VP-deficient rats, independent of the age. Old VP-deficient Brattleboro rats had smaller thymuses. Our results demonstrate the age-dependent role of VP in susceptibility of gastric mucosa to indomethacin-induced injury. Probably the absence of VP per se is not the reason of the data obtained but also the hormonal and metabolic consequences of VP deficiency (e.g. short versus long-term corticosterone and blood glucose elevation as well as related immunodisturbances).

The stimuli-specific role of vasopressin in the hypothalamus-pituitary-adrenal axis response to stress.

Adaptation to a constantly changing environment is fundamental to every living organism. The hypothalamic-pituitary-adrenocortical (HPA) axis is a key component of the adaptation process. The present study tests the hypothesis that vasopressin (AVP) is required for the HPA response to acute stimuli. To accomplish this, naturally AVP-deficient Brattleboro rats were exposed to a wide range of stimuli and their HPA response was compared with heterozygous littermates. The circadian rhythmicity of plasma ACTH and corticosterone was not different between the two genotypes. The ACTH and corticosterone response to volume load, restraint or aggressive attack were decreased in AVP-deficient rats. The stress-induced increase in ACTH, but not corticosterone, was significantly impaired in AVP-deficient animals after novelty, elevated plus-maze, forced swim, hypoglycaemia, ulcerogenic cold immobilisation, lipopolysaccharide, hypertonic saline and egg white injection. The HPA response to social avoidance, ether inhalation and footshock was not different between the genotypes. In vitro, the hypophysis of AVP-deficient animals showed a reduction in stimulated ACTH production and their adrenal glands were hyporeactive to ACTH. A dissociation between the ACTH and corticosterone response was observed in several experiments and could not be explained by an earlier ACTH peak or enhanced adrenal sensitivity, suggesting the existence of paraadenohypophyseal neuroendocrine regulators. Loss of AVP affected the HPA response to a wide variety of stressors. Interestingly, the contribution of AVP to the HPA response was not specific for, nor limited to, a known stressor category. Thus, there is a context-specific requirement for AVP in stress-induced activation of the HPA axis.

Gastroprotective role of glucocorticoid hormones.

Gastric ulcer disease remains widespread; a stressful lifestyle and nonsteroidal antiinflammatory drugs (NSAIDs) make significant contributions to this pathological situation. The findings overviewed here support the idea that glucocorticoid hormones released in response to acute stress or NSAIDs act as gastroprotective substances and exert many of the same actions in the stomach as prostaglandins (PGs) and nitric oxide (NO) as well as capsaicin-sensitive afferent neurons. Glucocorticoids exert a gastroprotective effect by both maintaining local defensive factors (mucosal blood flow and mucus production) and inhibiting pathogenic elements (gastric motility and microvascular permeability). Furthermore, they exert gastroprotective actions in co-operation with PGs, NO, and the afferent neurons; and their compensatory action is observed when the protective mechanism provided by either of these factors is impaired. The gastroprotective action of glucocorticoids is also associated with maintenance of general body homeostasis, including blood glucose levels and systemic blood pressure. In conclusion, glucocorticoids released in response to acute stress or NSAIDs are naturally occurring protective factors that play an important role in maintenance of the gastric mucosal integrity. This led us to re-evaluate the traditional paradigm that glucocorticoid hormones produced during activation of the hypothalamic-pituitary-adrenocortical axis are ulcerogenic in the stomach.

Preconditioning stress prevents cold restraint stress-induced gastric lesions in rats: roles of COX-1, COX-2, and PLA2.

We investigated the protective effect of mild stress on gastric lesions induced by cold-restraint stress, especially concerning prostaglandins (PGs)/cyclo-oxygenase (COX) isozymes. Rats were exposed to severe stress (cold-restraint stress at 10 degrees C for 6 hr) or mild stress (cold-restraint stress at 10 degrees C for 30 min and kept at room temperature for 60 min) followed by severe stress. Severe stress induced gastric lesions, with a concomitant decrease in body temperature (BT). The ulcerogenic response was inhibited by atropine but worsened by indomethacin and SC-560 but not rofecoxib, although none of these agents had any effect on the change in BT. Mild stress suppressed the gastric ulceration and the decrease in BT induced by severe stress, and these effects were reversed by both COX-1 and COX-2 inhibitors. The expression of COX-2 in the stomach was up-regulated from 4 hr after severe stress and this response was slightly expedited by mild stress. COX-2 was also expressed in the hypothalamus under normal and stressed conditions. Quinacrine (phospholipase A(2) inhibitor) attenuated the protective effect of mild stress on the ulceration and decrease in BT caused by severe stress. TA-0910 (TRH analogue) at a low dose also prevented the gastric ulceration and the decrease in BT induced by severe stress. These results suggest that mild stress protects against cold-restraint stress-induced gastric ulceration, and the effect is peripherally and centrally mediated by PGs derived from both COX-1 and COX-2 through the activation of phospholipase A(2). TRH may also be involved in the protective effect of mild stress, probably through regulation of the thermogenic system.

Somatic pain sensitivity during formation and healing of acetic acid-induced gastric ulcers in conscious rats.

A classical feature of visceral pain is its referring to somatic locations. Gastric ulcer is a source of visceral pain. In the present study we investigated whether gastric ulcers may trigger the changes in somatic nociception. For this aim somatic pain sensitivity was estimated under conditions of gastric ulcer development and healing. Gastric ulcers were induced by luminal application of 60% acetic acid under surgical conditions. Control rats were subjected to the same surgical procedure, but with the application of saline instead of the acid. Somatic pain sensitivity (tail flick latency), plasma corticosterone level, adrenal and thymus weight were investigated under conditions of the formation and the healing of gastric ulcers. The application of the acid resulted in the formation of kissing gastric ulcers, the increase of somatic pain sensitivity (the decrease of tail flick latency) as well as the appearance of typical signs of chronic stress: long-lasting increase of plasma corticosterone level, adrenal gland hypertrophy and thymus gland involution. Natural healing of gastric ulcers was accompanied by restoration of pain sensitivity as well as attenuation of the signs of chronic stress. Delay of ulcer healing by the daily indomethacin administration (2 mg/kg, s.c.) prevented the restoration of somatic pain sensitivity. The results suggest that chronic gastric ulcers may trigger somatic hypersensitivity.