Gastrointestinal perception: pathophysiological implications

Abstract

Physiological gut stimuli during the digestive process are not normally perceived. However, gut stimuli activate a variety of afferent pathways and in some circumstances may induce conscious sensations. Experimental evidence gathered during the past decade suggests that patients with functional gut disorders and unexplained abdominal symptoms may have a sensory dysfunction of the gut, so that physiological stimuli would induce symptoms. Assessment of visceral sensitivity is still poorly developed, but in analogy to somatosensory testing, differential stimulation of visceral afferents may be achieved by a combination of stimulation techniques, which may help to characterize sensory dysfunctions. Visceral afferent input is modulated by a series of mechanisms at different levels of the brain gut axis, and conceivably, a dysfunction of these regulatory mechanisms could cause hyperalgesia. The sensory dysfunction in functional patients seems associated to altered reflex activity, and both mechanisms may interact to produce the symptoms. Evidence of a gut sensory-reflex dysfunction as a common pathophysiological mechanism in different functional gastrointestinal disorders, would suggest that they are different forms of the same process, and that the clinical manifestations depend on the specific pathways affected.

Stress and visceral pain: From animal models to clinical therapies

“…Increased sympathetic tone has been shown to raise the level of perception to gastrointestinal stimuli (Azpiroz, 2002). Stress can affect different aspects of visceral pain including referred pain area, as well as accompanying motor and autonomic reflexes (Cervero, 2009).…”

Selective effects of nutrients on gut sensitivity and reflexes

“…[7][8][9][10][11] However, from a technical standpoint, dissecting the purely sensory effects from the mechanical effects of intraluminal nutrients on gastric function is technically challenging, because gastric relaxation has confounding effects on perception. Moreover, the effect of gastric relaxation on sensations induced by distension depends on the testing paradigm.…”

Effect of selective CCK1 receptor antagonism on accommodation and tolerance of intestinal gas in functional gut disorders

“…The product was supplied in two coded boxes, containing vials of 10 mL of DEX or saline, identical in appearance. Boxes were labeled with sequential numbers [1][2][3][4][5][6][7][8][9][10][11][12] referring to the subjects and followed by the appropriate acronym identifying the study population subgroup, and with an ordinal number according to a randomized sequence of treatment.…”

“…Based on a large body of experimental evidence, it has been proposed that FGD are related to mixed sensory-reflex dysfunctions of the gut, and that the individual manifestations depend on the specific pathways affected. 1,2 This model explains both the heterogeneity and the frequent overlap of clinical syndromes. The underlying cause of these sensory-reflex dysfunctions is not clear, and different predisposing and triggering mechanisms have been proposed.…”