Plasma levels of neurotensin in gastroplasty for morbid obesity.

Fasting and postprandial plasma levels of the tridecapeptide neurotensin were determined in ten women before and three months after gastroplasty for morbid obesity. Measurements were by radioimmunoassay in unextracted plasma with two antisera recognizing intact neurotensin (NT1-13) or intact neurotensin together with small C-terminal fragments, which may circulate as metabolites of neurotensin. Levels of both intact neurotensin and C-terminal immunoreactivity in obese women were in the same order of magnitude as those found previously in lean persons. Fasting levels measured with both antisera were significantly reduced following gastroplasty (P less than 0.01). Meal-stimulated levels and increments were unchanged. The cause of this prolonged reduction is at present unknown, but may be a reduced luminal stimulation of the small intestine or an altered vagal tonus following gastroplasty.