Modifying Effects of Soybean Trypsin Inhibitor on Development of Eosinophilic Nodules and Basophilic Foci in the Exocrine Pancreas of Male Sprague‐Dawley Rats Treated with 4‐Hydroxyaminoquinoline 1‐Oxide

Administration of 4‐liydroxyaniinoquiiioline 1‐oxide (HAQO) to rats results in development of 2 types of pancreatic acinar lesions, namely eosinophilic nodules and basophilic foci. To cast light on the biological character of these lesions, 5‐week‐old male Sprague‐Dawley rats were given a single intravenous injection of HAQO at a dose of 7 mg/kg and, thereafter, fed soybean trypsin inhibitor (SBTI) at dose levels of 10% and 5%. At week 57, all rats were killed for pathological examination of pancreatic tissue. The incidence of eosinophilic nodules was significantly higher in the HAQO/ SBTI group than in the HAQO‐alone group, whereas the basophilic acinar foci were observed to occur less frequently and to be smaller in the HAQO/SBTI‐treated animals. Administration of SBTI is known to increase the blood level of cholecystokinin, a trophic factor for pancreatic acinar cells. Thus, the present findings suggest that long‐term elevation of this endocrine factor can affect the two types of pancreatic acinar lesions in essentially different ways, namely enhancing development of eosinophilic nodules, while suppressing the occurrence of basophilic foci.