The effect of octreotide on human gastric compliance and sensory perception.
Somatostatin or its analogue octreotide (OCT) has previously been shown to modulate gastric emptying, intestinal motor activity and visceral sensation. In the current study we sought to determine the effect of a single dose of OCT (1.25 micrograms kg-1 s.c.), which has previously been shown to have both motor and sensory effects, on proximal gastric compliance and on conscious perception of gastric distention. Gastric distention was performed in 13 healthy male volunteers, by either slow ramp distention (60 ml min-1) or by intermittent pressure steps (phasic distention; 4-20 mmHg) using an electronic distention device. Compliance curves (pressure-volume relationship), and thresholds for innocuous (fullness) and noxious sensations (discomfort, pain) were determined following vehicle or OCT injection. OCT consistently and significantly reduced the rate of the gastric accommodation reflex by 50%, resulting in a reduced compliance at distention pressures greater than 10 mmHg during phasic distention. In contrast, no effect was observed on the compliance curve obtained during ramp distention. OCT selectively increased the threshold for fullness during both ramp and phasic distention. During phasic distention, OCT decreased the volume thresholds for noxious (pain) sensations experienced at volumes greater than 300 ml, without affecting the corresponding pressure threshold. These findings suggest that at low distension volumes, OCT in the dosage used has a direct inhibitory effect on afferents mediating innocuous gastric sensations. The hyperalgesic effect observed during phasic distention may be secondary to OCT's inhibitory effect on the gastric accommodation reflex.