Effect of subcutaneous pancreatic tissue transplants on streptozotocin-induced diabetes in rats. II. Endocrine and metabolic functions

The present study examines the effect of subcutaneous pancreatic tissue grafts (SPTG) on endocrine and metabolic functions in streptozotocin (STZ)-induced diabetic rats using radioimmunoassay and biochemical techniques. SPTG survived even after 15 weeks of transplantation and significantly improved the weight of STZ-diabetic rats over a 15-week period. Although blood glucose-, cholesterol-, and glycosylated-haemoglobin (GHb) levels were not significantly lower in STZ-diabetic rats treated with SPTG, the values of these biochemical parameters were lower than those in untreated diabetic rats. Plasma and pancreatic immunoreactive C-peptide (IRCP) levels did not improve after SPTG (IRCP expressed as mean ± standard deviation were 0.22 ± 0.07, 0.072 ± 0.02 and 0.08 ± 0.03 pg ml^-1 in the plasma non-diabetic, diabetic and treated rats respectively, while IRCP levels in the pancreas of the non-diabetic, diabetic and treated rats were 433.8 ± 0.1, 22.9 ± 0.01 and 10.4 ± 0.01 pg mg tissue^-1 respectively). SPTG, however, improved plasma immunoreactive insulin (IRI) levels in both plasma and pancreas. IRI values in plasma were 54.7 ± 13.6, 18.0 ± 5.0 and 22.1 ± 4.3 μUI ml^-1 in non-diabetic, diabetic and treated rats respectively and were 277.3 ± 37.1, 14.7 ± 1.8 and 30.3 ± 15.9 μIU μg tissue^-1 in the pancreas of non-diabetic, diabetic and treated rats respectively. There was improvement in immunoreactive glucagon (IRG) levels after SPTG. IRG values in the plasma of non-diabetic, diabetic and treated rats were 147.0 ± 10.7, 408.0 ± 76.5 and 247.7 ± 3 pg ml^-1 respectively whereas, IRG measured in the pancreas was 1642.25 ± 424.23, 1899.0 ± 290.4 and 1714.1 ± 301.98 pg μg tissue^-1 in non-diabetic, diabetic and treated rats, respectively. The pancreas:plasma ratio of pancreatic hormones was deranged in untreated diabetes but improved after SPTG, In conclusion, SPTG significantly improved the weight gain, pancreatic insulin content, plasma IRG and pancreas: plasma ratio of IRCP, IRI and IRG. It also reduced blood glucose-, cholesterol-, and glycosylated-hemoglobin levels in STZ-diabetic rats.