AJP - Gastrointestinal and Liver Physiology, Vol 248, Issue 1 15-G19, Copyright © 1985 by American Physiological Society
Neurotensin: a central neuromodulator of gastrointestinal motility in the dog
L. Bueno, J. Fioramonti, M. J. Fargeas and M. P. Primi
The effects of intracerebroventricular and intravenous injection of
neurotensin on gastrointestinal and colonic motility were examined in
fasted and fed conscious, intact, and vagotomized dogs. When administered
intracerebroventricularly at 20 ng X kg-1 or higher doses in the fasted
state, neurotensin reduced the duration of the periods of gastric motility
for 3-4 h. During this time the jejunal migrating motor complex was
replaced by isolated phases of regular activity occurring at a rhythm of
2-3/h, while colonic motility was unaffected. These effects were abolished
after vagotomy and were not observed for 25 times higher doses when
administered intravenously. Injected intracerebroventricularly at a dose of
100 ng X kg-1 30 min after a meal, neurotensin significantly reduced (P
less than 0.01) the duration of the fed pattern (2.7 +/- 0.7 vs. 8.7 +/-
1.2 h for control); this effect was not observed when neurotensin was
administered intracerebroventricularly 20 min before or 120 min after a
meal or when injected intravenously. Systemic administration of neurotensin
at a dose of 500 ng X kg-1 significantly increased (P less than 0.05)
during 2 h the colonic motility indexes in both fasted and fed dogs before
and after vagotomy. It is concluded that neurotensin can act i) centrally
to control the pattern of antral and jejunal motility in the fasted and fed
dogs, these effects being mediated by the vagus; and ii) peripherally to
control the pattern of colonic motility, this response being unaffected by
vagotomy.
