The Effects of Physical and Psychological Stress on the Gastrointestinal Tract: Lessons from Animal Models

Abstract

Physical and psychological stresses are widely accepted as triggers and / or modifiers of the clinical course of diverse gastrointestinal disorders such as peptic ulcer, irritable bowel syndrome or inflammatory bowel disease. Growing experimental evidence from a variety of models such as immobilization, thermal injury or early maternal deprivation in laboratory animals uniformly supports the ability of stress to induce the development of gastric ulcers, altered gastrointestinal motility and ion secretion, and increased intestinal permeability leading to the passage of antigens to the lamina propria and bacterial translocation. Stress can also synergize with other pathogenic factors such as Helicobacter pylori, non-steroidal anti-inflammatory drugs or colitis-inducing chemicals to produce gastrointestinal disease. The brain-gut axis provides the anatomical basis through emotions and environmental influences modulate the gastrointestinal function through the regulation of gastrointestinal immune system and mucosal inflammation; in this sense, mucosal mast cells - at cellular level - and corticotropin releasing factor (CRF) - at molecular level - seem to play a crucial role. On the other hand, an array of adaptive responses have been evolved in order to maintain the homeostasis and to ensure the survival of the individual. In the gut mucosa anti-inflammatory pathways counteract the deleterious effect of the stressful stimuli on the gastrointestinal homeostasis. In the present review we discuss the several experimental approaches used to mimic human stressful events or chronic stress in laboratory animals, the evidence of stress-induced gastrointestinal inflammation and dysfunction derived from them, and the involved cellular and molecular mechanisms that are being discovered during the last years.

Urinary Metabolite Markers of Precocious Puberty

“…Additionally, we observed that the PP subjects were more likely to be overweight (Table I) than their age-matched counterparts in the control group, although their body weights were not up to the standard of obesity. There is strong evidence that chronic life stress directly impacts gastrointestinal function in animals and humans (62)(63)(64) and increases the activity of both the hypothalamic-pituitary-adrenal axis and the sympathoadrenal system (65). As emerging evidence demonstrates the influence of gut microbiota on the development, behavior, and function of CNS (66), it is increasingly important to understand the intricate relationship between CNS, gut microbiota, and metabolic phenotypes in the development of precocious puberty.…”

Colonic bacterial translocation as a possible factor in stress-worsening experimental stroke outcome

“…A common finding observed in several models of stress-induced intestinal inflammation is an increased MPO activity in tissue homogenates (4). The tissue activity of this enzyme correlates linearly with neutrophil infiltration and has been widely used as a marker of acute inflammation (37).…”

“…In fact, iNOS-derived nitric oxide (NO) has been shown to increase intestinal epithelial permeability both in vitro and in vivo (32,36). This effect seems to be related to NO-induced cytoskeleton rearrangement and subsequent TJ dysfunction (4,32). Furthermore, acute stress induces mast cell degranulation in the lamina propria as well as release of prostaglandins (4), and this process is downstream of COX-2 signaling.…”

“…Apart from that, there is growing evidence from experimental studies supporting the ability of psychosocial stress, such as immobilization, to induce physiological abnormalities in the gut, such as increased permeability (4,16,35). Recent findings show that exposure to acute immobilization stress induces a strong colonic inflammatory response and also alters colonic epithelial barrier, leading to colonic epithelial barrier dysfunction and allowing the passage of intestinal bacteria to internal organs (32).…”

Prickly Pear Cactus (Opuntia ficus indicavar.saboten) Protects Against Stress-Induced Acute Gastric Lesions in Rats

“…Among all experimental-stress-inducing methods, those characterized by rodents exposed to an unavoidable, physical stress are the most extensively used. 18 In the present study, WIRS was employed to test the protective effect of the fruits of O. ficus indica var. saboten against stress-induced gastric lesions, since it is a widely used experimental model to induce acute stress ulcers in rats and is known for its reliable reproducibility.…”