The effects of beta-endorphin (beta-Ep) on plasma glucose levels in rats and on glucose metabolism in isolated rat liver cells were examined. Intravenous injection of beta-Ep (5 micrograms/100 g BW) into ether-anaesthetized rats resulted in prompt and sustained hyperglycaemia with increases in the plasma glucagon and somatostatin levels and decrease in the plasma insulin level. When liver cells isolated from fed rats were incubated in the presence of beta-Ep at concentrations of 6 X 10(-8) M to 6 X 10(-7) M, glucose release into the medium increased within 15 min in a dose-related manner. Time course experiments showed that beta-Ep increased the level of cyclic AMP within 3 min. Significant increase in gluconeogenesis in liver cells isolated from fasted rats was also observed on addition of 10(-7) M beta-Ep in the presence of 10 mM L-lactate. These results suggest that the hyperglycaemia induced by beta-Ep may be caused, at least in part, by the effects of beta-Ep on releases of pancreatic hormones and glucose production in liver cells.
An adrenal pheochromocytoma producing somatostatin (SRIF) and vasoactive intestinal polypeptide (VIP) in a 17‐year‐old boy is presented. High concentrations of immunoreactive (IR)‐SRIF were found in plasma taken from the antecubital vein (31.0–33.0 pg/ml) and the inferior caval vein near the tumor (54.6 pg/ml), but after removal of the tumor the values became normal (11.0–15.2 pg/ml). In two portions of the resected tumor, considerable but different amounts of IR‐SRIF (151.7 and 12.1 ng/g wet wt) and IR‐VIP (13.0 and 5.5 ng/g wet wt) were demonstrated with size heterogeneities. Immunohistochemically, many IR‐SRIF cells and a few IR‐VIP cells were observed, but no cell reacting with both anti‐SRIF and anti‐VIP sera was found. Electronmicroscopically, many tumor cells had catecholamine‐like granules (250–350 nm in diameter) while some others had VIP‐like granules (100–140 nm in diameter). However, no granules resembling the SRIF granules seen in the pancreatic D cells were found. This seems to be the first report of an adrenal pheochromocytoma that produces SRIF and VIP simultaneously. It provides information on the histogenesis of hormone‐producing neurogenic tumors. Cancer 52:282‐289, 1983.
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