Male WBN/Kob rats derived from the Wistar strain spontaneously develop
chronic pancreatitis as late as 3 months old. To assess the degree of disease severity, we compared the lipolytic
enzyme levels in pancreas of 2-, 4-, and 6-month-old WBN/Kob rats fed isocaloric no fat (NF) and high fat (HF, 57% of total calories) diets and its pathology. Diet treatment did not significantly affect
lipase and group Ib
phospholipase A(2) (PLA(2)) levels in the pancreas at all ages. Development of
chronic pancreatitis at the age of 4 and 6 months was consistent with the tendency of decreasing group Ib PLA(2) specific content determined by
enzyme immunoassay and
lipase activity, and the decreased number of group Ib PLA(2)-positive acinar cells. Pancreatic
lipase and group Ib PLA(2) levels of 4-month-old WBN/Kob rats were significantly lower than those of control Wistar rats at age 4 months irrespective of diet. This allowed us to adopt 4-month-old WBN/Kob rats as a model of
pancreatic insufficiency, which could be a useful tool to examine the role of gastrointestinal
enzymes in
lipid digestion. Ca(2+)-independent PLA(2) activity of brush border membrane-associated
phospholipase B/lipase (PLB/LIP) in ileal mucosa increased significantly in 4-month-old WBN/Kob rats while its content and transcript levels remained constant, suggesting its activation at the
enzyme level. In WBN/Kob rats fed the HF diet at age 4 months, PLA(2) activity catalyzed by PLB/LIP in the proximal ileal mucosa was four times the total PLA(2) activity in the intestinal lumen. These results indicate that PLB/LIP compensates for the depletion of pancreatic lipolytic
enzymes in WBN/Kob rats with pancreas insufficiency.