The Trophic Effect on the Pancreas of Long-Term Continuous Intravenous Infusion of Secretin and a Cholecystokinin-Like Peptide in Rats

Abstract

Rats were treated for 5 days with continuous intravenous infusion of different doses of secretin and Thr28Nle31CCK25-33 (CCK-LP) alone and combined. The trophic effect on the pancreas was evaluated by means of pancreatic weight and contents of DNA, RNA, and protein. The acute effects on pancreatic protein secretion were studied in anesthetized rats. The findings generally confirmed the trophic effects of secretin and CCK-like peptides on the pancreas. No convincing evidence of potentiation was found between small doses of secretin and CCK-LP for either pancreatic growth or protein secretion. The maximal dose of CCK-LP was the same for pancreatic growth and for protein secretion (2.5 micrograms/kg-h). Potentiation was demonstrated between secretin and the maximal dose of CCK-LP for protein secretion. The maximal effect of CCK-LP on pancreatic growth, however, was not enhanced by secretin.

Short- and Long-Term Effects of Secretin and a Cholecystokinin-Like Peptide on Pancreatic Growth and Synthesis of RNA and Polyamines

“…DNA and RNA were extracted and analyzed as described earlier (10,19). Results were expressed as total content per pancreas.…”

“…A potentiating interaction is here defined as a response to a combination of stimulants which are significantly greater than the sum of the responses to the individual agents given separately. Calculations were performed as described earlier (9,10).…”

Neuropeptide growth factors and cancer

“…VIP also stimulates adenylate cyclase activity and cell proliferation in keratinocytes (Haegerstrand et al, 1989).…”

“…Cholecystokinin has trophic effects on normal pancreas, as shown by measurements of pancreatic weight and DNA synthesis (Haarstad et al, 1986;Douglas et al, 1989). It can also directly stimulate the growth of rat gastric cancer cells in vitro (Kobori et al, 1982) and has been implicated in the growth of gut tumours (Lamers & Jansen, 1988;Hoosein et al, 1990).…”

Cholecystokinin

“…Several studies have demonstrated that CCK can increase pancreatic size (96). Exogenous administration of CCK increased pancreatic mass in hamsters and rats (27,28,68). In the rat, CCK1 receptor but not CCK2 receptor agonists increased pancreatic mass by increasing the number of cells comprising the exocrine pancreas (72).…”