Copper deficiency in rats increases pancreatic enkephalin-containing peptides and insulin.
Free enkephalins (enk) and higher molecular weight enkephalin-containing peptides (enk-c-p) are present in the endocrine pancreas of rats, presumably in B cells. To determine whether these opioid peptides show dynamic alterations as insulin content of pancreas changes, we utilized a copper deficient rat model, in which the exocrine pancreas atrophies and the endocrine pancreas is "intact" and insulin (IRI) content increases. Dietary copper deficiency (-C) was produced in weanling male rats for 4 and 7 weeks. The deficient and copper supplemented (+C) groups were further subdivided to receive all dietary carbohydrate as either 62% fructose (F) or 62% starch (S). -CF rats showed the most severe deficiency. After 7 weeks, total units of pancreatic IRI in -CF were 7.5 +CF 2.1, -CS 7.9 and in +CS 2.8 (p less than 0.001). Pancreatic content of Met5- and Leu5-enk was measured in extracts which were purified on C-18 Seppaks with and without prior treatment with trypsin and carboxypeptidase B. -C animals showed progressive, significant increases in pancreatic content of Leu-enk-c-p, with a decrease in free Leu- and Met-enk (p less than 0.02-0.01). The pancreatic findings are compatible with a co-localization of enkephalins and insulin in the endocrine pancreas and are suggestive of co-regulation.
D000818:Animals; D001835:Body Weight; D003300:Copper / Q000172:deficiency*; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009929:Organ Size; D010179:Pancreas / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D004040:Dietary Carbohydrates; D007328:Insulin; D011506:Proteins; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D003300:Copper