Abstract
To study the release of β-endorphin-like immunoreactivity (β-EpLI) in diabetes mellitus, two groups of diabetic rats were prepared by administration of 30 or 60mg/kg body weight of streptozotocin (STZ). Concentrations of insulin and β-EpLI in portal plasma and various tissues were measured in these rats, and the following results were obtained.
1. Concentrations of β-EpLI in portal plasma and pancreatic tissues of both groups of STZ-induced diabetic rats were significantly increased as compared with those of the control group.
2. Concentrations of β-EpLI in the pituitary tissues of both groups of STZ-induced diabetic rats did not change significantly as compared with those of the control group.
3. Portal plasma levels of β-EpLI and the concentration of β-EpLI in the pancreatic tissue of diabetic rats (60mg/kg body weight) given lente insulin every day differed little from those of the control group.
These results suggested that the pancreas might participate, at least partly, in the increase of β-EpLI release in STZ-induced diabetic rats. Furthermore, from the observations that portal plasma levels of β-EpLI in STZ-induced diabetic rats given lente insulin for seven days were similar with those of the control group, it was considered that increases of portal plasma β-EpLI in rats with STZ-induced diabetes were due to insulin deficiency.
