Effect of neurotensin on pancreatic growth and pancreatic polyamine metabolism in rats.

The neuropeptide neurotensin is known to play a role in the regulation of exocrine pancreatic secretion, but actually there are conflicting results as to whether or not neurotensin exerts a trophic response on the pancreas and there are no data concerning its effect on pancreatic polyamine metabolism. In the present study, acute and long-term effects of various intraperitoneal dosages of neurotensin that resulted in mildly supraphysiological and even unphysiological high plasma concentrations of neurotensin were studied. Furthermore, neurotensin was simultaneously administered with cholecystokinin (1 microgram CCK-8/kg body wt ip every 8 h) for five days. The administration of neurotensin resulted in an acute significant decrease of pancreatic amylase and trypsinogen concentrations (p < 0.001), which indirectly confirms the potent effect of neurotensin on pancreatic exocrine secretion. In contrast to that, neither during the short-term study (100 micrograms neurotensin/kg body wt ip every 8 h for 2, 4, 6, 8, 16, and 24 h) nor during the long-term study (1 microgram, 100 micrograms, or 200 micrograms neurotensin/kg body wt ip three or eight times daily for 10 d) did neurotensin administration result in any increase of the various parameters of pancreatic growth and polyamine metabolism. Simultaneous administration of neurotensin and CCK failed to alter or further increase the known stimulatory effect of CCK on pancreatic polyamine metabolism and pancreatic growth after 5 d of treatment. These data indicate that neither alone nor in combination with cholecystokinin did various dosages of neurotensin exert any significant stimulation on pancreatic growth or the parameters of pancreatic polyamine metabolism.