Effects of repeated restraint stress on gastric motility in rats

Abstract

In our daily life, individuals encounter with various types of stress. Accumulation of daily life stress (chronic stress) often causes gastrointestinal symptoms and functional gastrointestinal diseases. Although some can adapt toward chronic stress, the adaptation mechanism against chronic stress remains unknown. Although acute stress delays gastric emptying and alters upper gastrointestinal motility, effects of chronic stress on gastric motility still remain unclear. We investigated the effects of acute (single stress) and chronic (repeated stress for 5 consecutive days) stress on solid gastric emptying and interdigestive gastroduodenal contractions in rats. It is well established that acute restraint stress inhibits solid gastric emptying via central corticotropin-releasing factor (CRF). To investigate whether the sensitivity to CRF is altered following chronic stress, CRF was administered intracisternally. Ghrelin is involved in regulating gastric emptying and upper gastrointestinal motility in rodents. The changes in plasma active ghrelin levels and mRNA expression in the stomach were studied following chronic stress. To evaluate the effects of chronic stress on the hypothalamus-pituitary-adrenal (HPA) axis, plasma corticosterone levels were also measured. Delayed gastric emptying observed in acute stress was completely restored following chronic stress. Acute stress abolished gastric phase III-like contractions, without affecting duodenal phase III-like contractions in the interdigestive state. Impaired gastric phase III-like contractions were also restored following chronic stress. Plasma ghrelin levels and ghrelin mRNA expression were increased significantly after chronic stress. Intracisternal injection of CRF delayed gastric emptying and impaired gastric motility in rats who received chronic stress. Plasma corticosterone concentrations were no more elevated following chronic stress. The restored gastric emptying following chronic stress was antagonized by the administration of ghrelin receptor antagonists. The adaptation mechanism may involve upregulation of ghrelin expression and attenuation of the HPA axis. In contrast, the sensitivity to central CRF remained unaltered following chronic stress in rats.

Alteration of antral and proximal colonic motility induced by chronic psychological stress involves central urocortin 3 and vasopressin in rats

“…The effects of such physical stress on upper GI motility were quite different from those of the psychological stress stimuli of the present study. Acute restraint stress in rats decreased gastric motility; however, repeated restraint stress for five successive days reversed the decrease in gastric motility (45). Water immersion stress for 24 h delayed gastric emptying in rats; however, water immersion stress for five successive days accelerated gastric emptying (32).…”

Central apelin mediates stress-induced gastrointestinal motor dysfunction in rats

“…For AS, rats were loaded with restraint stress for 90 min. Briefly, rats were placed on a wooden plate with their trunks wrapped in a confining harness, as previously reported (10,84,85). Rats were able to move their limbs and head but not their trunks.…”

“…Measurement of solid GE. For the evaluation of GE, rats were fasted for 24 h. Preweighed pellets (1.6 g) were given, as previously reported (10,84,85). In GE measurements, drugs were administered 20 min before giving the pellets and rats were allowed to finish eating within 10 min.…”

Gender Differences in Ghrelin Response to Chronic Immobilization Stress in Rats: Possible Role of Estrogen

“…The mechanisms that drive the fasting-induced increased ghrelin synthesis and inhibition upon re-feeding may be linked to changes in insulin status under these conditions as shown by the inverse correlation between changes in circulating levels of insulin and those of circulating and gastric ghrelin and ghrelin changes in response to insulin (Wang et al 2006). Moreover, exposure to prolonged stressors such as daily 90-min restraint stress for 5 days in rats (Zheng et al 2009) or tail pinch stress (10 min every 4 h for 24 h) in fasted mice (Asakawa et al 2001) also increased gastric ghrelin mRNA expression (Zheng et al 2009). Moreover, Kristensson et al (2006) reported that water immersion elicited a significantly larger increase in plasma ghrelin levels in the high-anxiety Wistar Kyoto strain than in the low anxiety Sprague-Dawley rats.…”