Demonstration of an androgen receptor in rat pancreas

Abstract

[1,2,6,7-3H]Testosterone (250 .mu.Ci) was administered to castrated male rats; after 30 min a labeled testosterone-receptor protein complex with a pI [isolectric point] of 5.1 was recovered from the pancreatic cytosol. A labeled 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 .mu.M-[1,2,6,7-3H]testosterone for 30 min at 37.degree. 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 femtomol/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 DNase and RNase, but was sensitive to treatment with proteinase. The pancreatic androgen receptor, which was also present in castrated female rats, may play a role in sex-steroid regulation of pancreatic function.