Motilin- and Neuropeptide Y-like Immunoreactivity in a Psychophysiological Stress Experiment on Patients with Functional Dyspepsia.

Bo H. JONSSON [1]

PER M. HELLSTROM [2]

Abstract--Background: Thc aim of the study was to compare plasma motilin-like immunoreactivity (MOT-LI) and neuropeptide Y (NPY)-like immunoreactivity (NPY-LI) in patients with functional dyspepsia (PD) during a controlled psychophysiological experiment. Method: 25 patients (12 men, 13 women), age 24-50, with recurrent FD, and 25 pair-wise sex- and age-matched community control subjects were studied. In an experiment, after a rest period, subjects were studied during a 15-min stress interview. The aim of the interview was to elicit anxiety. Before and during the intervention blood samples were drawn for peptide analyses. Outcome measures were the Gastrointestinal Symptom Rating Scale, fasting blood glucose, heart rate and blood pressure as well as the subjects' self-ratings on visual analogue scales. The plasma concentrations of MOT-LI and NPY-LI are given as anti-logarithms.

Results: Mean plasma MOT-LI concentration was 7.3 (CI: 5.7-9.4) pmol/L in the patient group, and 7.9 (CI: 6.1-10.2) pmol/L in the control group. Mean plasma NPY-LI concentration was 14.2 (CI: 12.3-16.4) pmol/L in the patient group, and 13.4 (CI: 11.8-15.3) pmol/L in the control group. Using ANCOVA (covariates: group, gender, age, body mass index and smoking) MOT-LI was related to lower indigestion symptomatology (p[less than]0.04) and positive change in joyfulness during the interview (p[less than]0.03). In the patient group delta motilin correlated with increased joyfulness (p[less than]0.03) and decreased sadness (p[less than]0.03). The NPY-LI increase during the interview was related to higher fasting blood glucose before the interview (p[less than]0.01) and a stronger increase in systolic blood pressure during the test (p[less than]0.05). Conclusion: During a stress interview plasma MOT-LI is positively related to less indigestion symptomatology and joyfulness, while changes in plasma NPY-LI were positive ly related to sympathetic nervous system activity, but not to gastrointestinal symptoms.

key words: functional dyspepsia (FD), stress interview, motilin, neuropeptide Y (NPY)

Introduction

FUNCTIONAL DYSPEPSIA (FD) is a disorder characterised by upper abdominal pain and certain other symptoms in patients where an organic disease is not found (Talley, 1991). The prevalence of FD in Western populations averages 20 to 25 percent. If reflux symptoms are included this number increases to 40 percent (Jones, 1990; Talley, 1992). Data from the U.S. and the U.K. show that only one out of four subjects with dyspepsia consults a physician for these symptoms (Talley, 1998).

Many FD patients have antral hypomotility, delayed gastric emptying and disturbed intestinal motility (Labo, 1986; Malagelada, 1991). However, it is often difficult to establish a causal relationship between motor abnormalities and symptoms (Malagelada, 1991; Koskenpato, 1998). Other physiological aspects than motility, such as peptides, have been less investigated.

A low vagal tone has been described in FD patients (Hausken, 1993; Haug, 1994). A stress related stimulation via sympathetic neural pathways has been suggested as an explanation for inhibition of gastric tone (Thompson, 1994).

In a laboratory experiment with FD patients, we sampled blood plasma for biochemical analyses. Previously, we have reported that the plasma cholecystokinin (CCK) concentration increased significantly during a stress interview (Jonsson, 1998). No similar change took place in the pair-wise matched control group. Plasma concentrations of gastrin (Jonsson, 1998) and prolactin (Jonsson, 1999) increased significantly in both groups. We found a positive relationship between the plasma somatostatin level and the self-rated score of dyspeptic symptoms (Jonsson, 1998). Somatostatin release is stimulated by sympathetic nervous activity and inhibited by vagal nerve activity (Uvnas-Moberg, 1987).

In this paper we report the analyses of motilin and neuropeptide Y (NPY), in our controlled study of FD patients, during a …