Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society
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Neurogastroenterol. Motil. · Oct 2009
Fall in density, but not number of myenteric neurons and circular muscle nerve fibres in guinea-pig colon with ageing.
In guinea-pig ileum, ageing has been associated with a decrease in enteric neurons. This study examined guinea-pig colon and measured changes in gut dimensions, neuron size, density and ganglionic area. Changes in motor nerve fibres in the circular muscle were also measured. ⋯ The percentage area of NOS- and SP-immunoreactive (IR) nerve fibres in the circular muscle decreased (P < 0.001), but the total area of NOS and SP-IR nerve fibres increased (P < 0.01) due to an age-related increase in muscle thickness. The density of myenteric neurons in guinea-pig mid-colon halved from 2 weeks to 2 years, but when the increase in colon dimensions was considered, the number of neurons decreased by only 19%. The percentage area of motor nerve fibres in the circular muscle decreased with no change in total volume of nerve fibres.
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Neurogastroenterol. Motil. · Oct 2009
Essential role for TRPV1 in stress-induced (mast cell-dependent) colonic hypersensitivity in maternally separated rats.
Irritable bowel syndrome is in part characterized by an increased sensitivity to colonic distension. Stress is an important trigger factor for symptom generation. We hypothesized that stress induces visceral hypersensitivity via mast cell degranulation and transient receptor ion channel 1 (TRPV1) modulation. ⋯ In conclusion, the present data on stress-induced visceral hypersensitivity confirm earlier reports on the essential role of mast cells and NGF. Moreover, the results also suggest that TRPV1 modulation (in the absence of overt inflammation) is involved in this response. Thus, mast cells and TRPV1 are potential targets to treat stress-induced visceral hypersensitivity.
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Neurogastroenterol. Motil. · Sep 2009
Clinical TrialEffects of clonidine and sumatriptan on postprandial gastric volume response, antral contraction waves and emptying: an MRI study.
Gastric emptying (GE) may be driven by tonic contraction of the stomach ('pressure pump') or antral contraction waves (ACW) ('peristaltic pump'). The mechanism underlying GE was studied by contrasting the effects of clonidine (alpha(2)-adrenergic agonist) and sumatriptan (5-HT(1) agonist) on gastric function. Magnetic resonance imaging provided non-invasive assessment of gastric volume responses, ACW and GE in nine healthy volunteers. ⋯ Gastric emptying was delayed. There was a negative correlation between gastric relaxation and GE rate (r(2 )=49%, P < 0.001), whereas the association between ACW frequency and GE rate was inconsistent and weak (r2=15%, P = 0.05). These findings support the hypothesis that nutrient liquid emptying is primarily driven by the 'pressure pump' mechanism.
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Neurogastroenterol. Motil. · Jul 2009
Randomized Controlled TrialThe effect of gastric secretion on gastric physiology and emptying in the fasted and fed state assessed by magnetic resonance imaging.
Conventional measurement of gastric secretion is invasive and cannot assess the intra-gastric distribution of gastric contents or the effects of secretion on gastric function. This study assessed the effect of gastric secretion on gastric volume responses and emptying (GE) using a validated fast T(1) mapping magnetic resonance imaging (MRI) technique. Twelve healthy participants were studied in the fasted state and after 200 kcal Gadolinium-DOTA labelled glucose meal during intravenous infusion of pentagastrin or placebo in double-blind, randomized order. ⋯ This study shows volume and distribution of gastric secretion can be quantified in-vivo by non-invasive MRI T(1) mapping. Increased GCV drove TGV accommodation without evidence of a direct effect of pentagastrin or excess acid on gastric function. Secretion increases GCV thus prolongs GE as assessed by T(50); however, GE rate is unchanged.
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Neurogastroenterol. Motil. · Jul 2009
Randomized Controlled TrialCharacterization of gastric volume responses and liquid emptying in functional dyspepsia and health by MRI or barostat and simultaneous C-acetate breath test.
The assessment of gastric accommodation and emptying by different methodologies provides inconsistent results. We aimed to compare magnetic resonance imaging (MRI), barostat and 13C-acetate breath test (BT) for the assessment of gastric volume responses and emptying in healthy controls (HC) and patients with functional dyspepsia (FD). Eight HC and eight FD patients underwent: (i) continuous BT with simultaneous MRI in the upright position after ingestion of isocaloric, 300 kcal, 200 and 800 mL meals, both labelled with 100 mg of (13)C-acetate; and (ii) BT with gastric barostat after ingestion of the 200 mL meal. ⋯ In contrast, T(1/2)(BT) was similar between meals and groups (200 mL: HC 111 +/- 11 min vs FD 116 +/- 19 min; 800 mL: HC 114 +/- 14 min vs FD: 113 +/- 17 min). (ii) Barostat measurements showed similar postprandial volume increases between groups. We conclude that direct measurements by MRI provide a sensitive, non-invasive assessment of gastric accommodation and emptying after a meal. In contrast to MRI, BT did not detect faster emptying of high-volume compared to low-volume liquid nutrient meals in HC or FD.