Circadian coupling between pancreatic secretion and intestinal motility in humans

Abstract

Human interdigestive intestinal motility follows a circadian rhythm with reduced nocturnal activity, but circadian pancreatic exocrine secretion is unknown. To determine whether circadian changes in interdigestive pancreatic secretion occur and are associated with motor events, pancreatic enzyme outputs, proximal jejunal motility, and plasma pancreatic polypeptide concentrations were measured during consecutive daytime and nighttime periods (12 h each) in seven healthy volunteers using orojejunal multilumen intubation. Studies were randomly started in the morning or evening. Nocturnally, motility decreased (motor quiescence: 67 +/- 22 vs. 146 +/- 37 min; motility index: 3.59 +/- 0.33 vs. 2.78 +/- 0.40 mmHg/min; both P < 0.05) but amylase output increased (273 +/- 78 vs. 384 +/- 100 U/min; P < 0.05) and protease output remained unchanged (P > 0.05); consequently, enzyme/motility ratio increased. Amylase outputs were always lowest during phase I. Motor but not pancreatic circadian activities were associated with sleep. Pancreatic polypeptide plasma concentrations were unchanged. Consequently, intestinal motor and pancreatic exocrine functions may have different circadian rhythms, i.e., decreased motor and stable secretory activity during the night. However, the association between individual phases of interdigestive motor and secretory activity is preserved. The nocturnal increase in enzyme/motility ratio is probably not caused by increased cholinergic tone.

Daily Rhythm of Serum Lipase and α-Amylase Activity in Fed and Fasted Dogs

“…The persistence of circadian rhythms of lipase and a-amylase in food-deprived dogs indicates that they are not driven by the digestive process. This is in agreement with the results of a previous study 2 showing that the daily rhythm of secretion in the pancreas in a rat is independent of gastrointestinal stimulation; these results are in contrast to those of a previous study 16 that showed a direct correlation between amylase output and jejunal motor activity in humans. Thus, circadian effects may modulate interdigestive pancreatic enzyme patterns in dogs.…”

Physiological parameters governing the action of pancreatic lipase

“…Additional peak levels of secretion also appear to occur at non-specific time points within the interdigestive (fasting) stages of motility (34,35) . During the fed state, intestinal motor responses to the presence of nutrients in the duodenum appear to occur over the same period of time as pancreatic secretory responses (36) .…”

Effect of the electrical currents generated by the intestinal smooth muscle layers on pancreatic enzyme activity: An in vitro study

“…A number of studies have documented that MMC and exocrine pancreatic secretion are closely interrelated. Specifically, it has been shown that the secretion of pancreatic enzymes is strictly parallel with the MMC phases, with the highest enzyme secretion observed during phase III of MMC and the minimal enzyme secretion during phase I of MMC [Laerke et al, 2000;Keller et al, 2001]. These findings could indirectly illustrate one of the possible mechanisms to regulate the availability of peptides or amino acids for gut absorption.…”