Pituitary, hypothalamic and pancreatic 7B2 concentrations in rats with streptozotocin-induced diabetes and spontaneously diabetic mice.

Abstract

The pituitary protein, 7B2 has been demonstrated in the pancreas and is known to be present in very high concentrations in pancreatic endocrine tumors. To investigate whether any changes in 7B2 concentrations might be present in the pancreases affected by different types of diabetes and whether the diabetic state itself might affect pituitary and hypothalamic 7B2 concentrations, streptozotocin (STZ)-treated rats and mice with natural-onset diabetes (obese hyperglycemic, or ob/ob, mice and non-obese diabetic, or NOD, mice) were employed. A significant reduction in pancreatic 7B2 concentrations was found in STZ-treated rats. The pancreatic 7B2 concentration was significantly high in ob/ob mice (p less than 0.05, versus the concentration in their lean littermates, and the decrease observed in older NOD mice, appeared to parallel their insulin reserve. Pituitary and hypothalamic 7B2 concentrations were similar in STZ-treated and control rats. A reduction in pituitary and hypothalamic 7B2 concentrations was observed in older NOD mice (both p less than 0.01 versus respective values in younger mice). In ob/ob mice, a significant reduction was also found in hypothalamic 7B2 concentration (p less than 0.01 versus that in control mice). Gel permeation chromatography showed that 7B2 immunoreactivity comprised two molecular components, and the relative proportion in the pancreas differed from that in other tissues. In the pancreas, a smaller molecular component was predominant (elution coefficient, 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)