Androgen receptor in the harderian glands of the golden hamster: Characterization and the effects of androgen deprivation, the pituitary, and gender

The Harderian glands of the golden hamster were found, by a competitive binding assay using [³H]mibolerone as the ligand, to have a high affinity androgen receptor. In intact male hamsters, this receptor was present in both cytosolic and nuclear KCl-extractable fractions. Castration or hypophysectomy led to 3- to 5-fold increases in the concentrations of cytosolic receptor with decreased dissociation constants. Hypophysectomy with maintenance of prolactin levels (by removal of pituitaries and their implantation either in the sella turcica or under the kidney capsule) had no effect on androgen receptor binding, compared to hypophysectomy alone. Female hamsters had androgen receptor levels which were 2 to 4 times higher than those of intact males. Hypophysectomy led to elevated receptor binding in ovariectomized female hamsters and this rise was prevented by maintaining prolactin levels. Binding of [³H]mibolerone in male glands was effectively inhibited by 5α-dihydrotestosterone, whereas the parent molecule, testosterone, required approximately a 10-fold greater molar excess to achieve the same amount of inhibition. Estradiol and progesterone were relatively poor inhibitors of the observed binding of [³H]mibolerone, while dexamethasone was ineffective. Sucrose gradient studies indicated that the Harderian androgen receptor migrated to the 8S region, as expected for this receptor in molybdate-containing gradients. These results indicate that the androgen receptor in the hamster Harderian gland is a 5α-dihydrotestosterone receptor. © 1994 Wiley-Liss, Inc.