Demonstration of an androgen receptor in rat pancreas.

[1,2,6,7-3H]Testosterone (250 muCi) was administered to castrated male rats; after 30 min a labelled testosterone-receptor protein complex with a pI of 5.1 was recovered from the pancreatic cytosol. A labelled testosterone-receptor complex with an identical pI was also extracted from the nuclear fraction of rat pancreas after incubation of minced pancreatic tissue with 0.1 muM-]1,2,6,7-3H]testosterone for 30 min at 37 degrees C. Studies in vitro showed that [1,2,6,7-3H]testosterone was bound to a receptor protein focusing at a pI of 5.1 and with a Kd of 2 nM and a number of binding sites of 4.7 fmol/mg of protein in castrated male rats. The testosterone-receptor complex sedimented at 3.5 S in high-salt sucrose-density gradients, was excluded from Sephadex G-200 and Ultragel ACA-34, was stable towards treatment with dextran-coated charcoal, was relatively sensitive to heat, and was stable to treatment with deoxyribonuclease and ribonuclease, but was sensitive to treatment which proteinase. It is suggested that the pancreatic androgen receptor, which was also present in castrated female rats, may play a role in sex-steroid regulation of pancreatic function.