Fate of 2-deoxy-2-[F-18]fluoro-D-glucose in control and diabetic rats

Recent experiments conducted in vitro have documented a marked difference i n the time course for D[U-C-14]glucose net uptake by pieces of pancreatic t issue versus isolated pancreatic islets. The present study aimed, therefore , at assessing whether the endocrine pancreas contributes to a detectable e xtent to the overall net uptake of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) b y the pancreatic gland. For this purpose, the radioactive content of the pa ncreas was compared to that of plasma, erythrocytes, liver, brain, hypophys is and parotid gland 3 min, 15 min and 240 min after the intravenous inject ion of FDG to both control rats and animals injected with streptozotocin an d later treated with insulin or not. In the control rats, the radioactive c ontent (cpm/mg wet wt.) of erythrocytes was always lower than that of liver . In other organs, it displayed the following hierarchy pancreas < parotid < hypophysis < brain, the absolute values being either lower (3 min) or muc h higher (240 min) than in liver. In the diabetic rats, whether treated wit h insulin or not, the radioactive content of erythrocytes, pancreas, brain, hypophysis and parotid gland, relative to the paired value found in liver, was equal or lower than that of control rats when the animals were hypergl ycemic and equal or higher than that of control rats when the animals becam e hypoglycemic as the result of intensive insulin treatment. Even only 3 mi n after the injection of FDG, and despite persistent hyperglycemia in the s treptozotocin-injected and insulin-treated rats, the pancreas/liver paired ratio in radioactive content failed to be significantly lower in the diabet ic animals than in control rats. These findings indicate that 2-deoxy-2[F-1 8] fluoro-D-glucose is not a suitable tool to detect any preferential label ling of insulin-producing cells, relative to acinar cells, at least when co nsidering only the total radioactive content of the pancreatic gland.