Cholecystokinin (CCK) and its analogues are known to exert trophic effects on the exocrine pancreas, whereas at high doses, they produce pancreatic injury. This study was carried out to study the effect of starvation on the dose-dependent pancreatotrophic effect of CCK-8 in rats. Normal or fasted rats were treated with CCK-8 doses ranging from 0.5 to 32 and 0.5 to 8 micrograms kg-1, respectively, twice daily for 5 days. Pancreatic size, protein, DNA, secretory enzyme and trypsin inhibitor (PSTI) contents as well as histology were examined. In normal rats, CCK-8 increased the pancreatic content of protein, amylase, serine proteases and PSTI with maximum values between doses of 2 and 16 micrograms kg-1. The dose of 32 micrograms kg-1, however, yielded less trophic responses. Given to fasted rats, CCK-8 increased the weight as well as protein and secretory enzyme contents of the pancreas with maximum values between doses of 1 and 4 micrograms kg-1. The first dose supramaximum for the trophic responses was as low as 8 micrograms kg-1. Histology revealed necroinflammatory damage (acinar cell vacuolization, focal cell necrosis) in the exocrine pancreas at supramaximum doses of CCK-8 in both groups. Cell necroses and vacuolization were less but present even at doses optimum for trophism and exhibited dependence on both the dose of CCK-8 and nutrition. In either the normal or fasted animals, the periinsular acini were relatively less affected by the toxic effects of CCK-8 than the teleinsular ones. The results indicate that starvation makes the exocrine pancreas more sensitive to necroinflammatory effects of CCK-8. The relative protection seen in periinsular acini suggests a modulatory influence of islet hormones on development of CCK-induced acinar cell injury.