3H]corticosterone binding in rat superior cervical ganglion

Abstract

Binding of [ 3H]corticosterone was examined in the soluble fraction (100,000 g) from superior cervical ganglia dissected from adrenalectomized and perfused rats. A large binding capacity (2100 fmol/mg protein) was found. However, no binding for [ 3H]-dexamethasone and [ 3H]triamcinolone was detected. The binding protein present in the ganglion preparation was characterized by DEAE-cellulose and DNA-cellulose chromatography and by isoelectric focusing. The corticosterone binding protein from the ganglia was found to be different from the cytoplasmic glucocorticoid receptor, but similar to plasma transcortin. A large portion (approximately 75%) of the transcortin-like [ 3H]corticosterone binding protein was located in the interstitial space between the sheath and the ganglionic cells. However, 25% of the binding protein was retained in the desheathed ganglion even after extensive washing with saline. Our findings indicate that cytoplasmic glucocorticoid receptors are not present in the superior cervical ganglion. It is possible that the transcortin-like protein associated with the desheathed ganglion may be intracellular, as other investigators have suggested similar intracellular presence of a transcortin-like protein in the liver, uterus, and pituitary.