Exocrine pancreatic digestive enzymes are essential for the digestion of dietary components and are regulated by them. Chronic excess dietary high fat (HF) consumption is a contributing factor of diet-induced obesity (DIO) and associated chronic diseases and requires adaptation by the pancreas. The aim of the present study was to investigate the effects of chronic HF diet feeding on exocrine pancreatic digestive enzyme transcript levels in DIO C57BL/6J mice. C57BL/6J mice were fed diets containing either 10 or 45 % energy (E%) derived from fat for 12 weeks (n 10 mice per diet group). Pancreatic tissue and blood samples were collected at 0, 4 and 12 weeks. The expression of a panel of exocrine pancreatic digestive enzymes was analysed using quantitative RT-PCR and Western blot analysis. The HF (45 E%) diet-fed C57BL/6J mice developed obesity, hyperleptinaemia, hyperglycaemia and hyperinsulinaemia. The transcript levels of pancreatic lipase (PL), pancreatic lipase-related protein 2 (PLRP2) and pancreatic phospholipase A2 (PLA2) were initially elevated; however, they were down-regulated to basal control levels at week 12. The transcript levels of colipase were significantly affected by diet and time. The protein levels of PL and PLRP2 responded to HF diet feeding. The transcript levels of amylase and proteases were not significantly affected by diet and time. The transcript levels of specific lipases in hyperinsulinaemic, hyperleptinaemic and hyperglycaemic DIO C57BL/6J mice are down-regulated. However, these mice compensate for this by the post-transcriptional regulation of the levels of proteins that respond to dietary fat. This suggests a complex regulatory mechanism involved in the modulation of fat digestion.

Nuclear microscopy is a suite of techniques based on a focused beam of MeV protons. These techniques have the unique ability to image density and structural variations in relatively thick tissue sections, map trace elements at the cellular level to the microgram per gram (dry weight) level, and extract quantitative information on these elements. The trace elemental studies can be carried out on unstained freeze-dried tissue sections, thereby minimizing any problems of contamination or redistribution of elements during conventional staining and fixing procedures. The pancreas is a gland with different specialized cells and a complex hormonal activity where trace elements play an important role. For example, zinc has an active role in insulin production, and calcium ions participate in the stimulation and secretion process of insulin. Using nuclear microscopy with a spatial resolution of 1 μm, we have located, using zinc mapping, the islets of Langerhans in freeze-dried normal rabbit tissue sections. The islets of Langerhans contain β-cells responsible for insulin production. Subsequent quantitative analyses have indicated elevations in most elements within the islets of Langerhans, and significantly so for the concentrations of Zn [3,300 compared to 90 μg/g (dry weight)] and Ca [1,100 compared to 390 μg/g (dry weight)].