Gastrin is present in normal mammalian pancreatic islets, as well as in the antrum and duodenum. Serum
gastrin levels are responsive to many physiologic and pharmacologic factors including
hyperglycemia,
somatostatin, and
glucagon. To evaluate the effects of
streptozotocin diabetes and
islet transplantation on
gastrin homeostasis, young, adult, male Lewis rats underwent
streptozotocin diabetes alone (N = 14), diabetes plus intraperitoneal islet isografts (N = 22), or
sham operation alone (N = 18).
Streptozotocin reduced fasting
gastrin immunoreactivity (107 pg/ml +/- 26 mean +/- SEM) compared to controls (256 pg/ml +/- 31) (P less than 0.001). Islet isotransplantation resulted in restoration of fasting
gastrin immunoreactivity (230 pg/ml +/- 19) to levels significantly greater than diabetics (P less than 0.001) and comparable to control animals (P = NS). Normalization of serum
gastrin levels occurred within one month of
transplantation and persisted for up to 14 months. In addition, media from cultures of 4/7 dispersed neonatal rat pancreas cultures contained
gastrin immunoreactivity.
Streptozotocin diabetes produces hypogastrinemia; intraperitoneal islet isotransplantation normalizes fasting
gastrin immunoreactivity. Rat islet culture medium contains
gastrin-like immunoreactivity. Pancreatic islets would appear to produce or control a portion of circulating
gastrin immunoreactivity.