A team from the University of Newcastle upon Tyne determined whether production of TFF2, a glycosylated trefoil protein, follows a circadian rhythm. In addition, they measured changes in secretion of TFF2 in response to food intake and during sleep.
TFF2 is secreted by gastric antral and pyloric glands and by Brunner's glands of the duodenum, and is found in high concentrations around sites of ulceration.
Twelve asymptomatic adults, on no medication, were enrolled in the study.
|Gastric TFF2 secretion dramatically increases during sleep. |
The 24-hour regimen was designed to allow normal stimulation of gastric secretion in response to food intake and sleep. Gastric juice was collected every 2 hours via a nasogastric tube
Glycosylated and non-glycosylated TFF2 proteins were measured by quantitative western transfer analysis.
The researchers found that there was a dramatic diurnal variation in the concentration of TFF2.
The mean concentration was lowest in the early evening (0.29 µg/ml), increased gradually during the evening, and then sharply during the night to reach 7.9 µg/ml.
The ratio of glycosylated to non-glycosylated TFF2 varied and was higher during the night than in the afternoon.
The pH, total protein, and pepsin concentrations in gastric juice did not vary significantly over 24 hours.
Dr J I Semple, of the Department of Pathology, and colleagues found that diurnal variations in TFF2 secretion occur independently of pepsin and gastric-acid secretion.
"The concentration of glycosylated TFF2 in the gastric lumen falls in response to food intake. TFF2 secretion increases during inactivity and sleep," they comment.
"Secretion of TFF2 in the stomach is highest during the night and that the cytoprotective effects of TFF2 on the gastric mucosa occur mainly during sleep," they conclude.