DISTRIBUTION OF ANDROGEN RECEPTOR IMMUNOREACTIVITY IN THE SPINAL-CORDOF WILD-TYPE, ANDROGEN-INSENSITIVE AND GONADECTOMIZED MALE-RATS

The polyclonal antiserum PG21 was used to detect androgen receptor (AR ) protein in three motoneuronal pools of the male rat lumbar spinal co rd, In gonadally intact, wild-type males, the spinal nucleus of the bu lbocavernosus (SNB), dorsolateral nucleus (DLN), and retrodorsolateral nucleus (RDLN) all displayed immunolabeling of cell nuclei. The perce ntage of motoneurons displaying such labeling was highest in the SNB a nd lowest in the RDLN, This pattern of AR immunocytochemical labeling agrees well with previous steroid autoradiographic studies of androgen accumulation in the rat spinal cord, In contrast, virtually no motone urons in any of the three pools displayed nuclear AR immunostaining in longterm gonadectomized males or in gonadally intact males carrying t he Tfm mutation, which renders the AR incompetent, In gonadectomized m ales, labeling was restored in the SNB and DLN, but not the RDLN, 30 m in after an injection of replacement testosterone. Eight hours of test osterone exposure restored immunolabeling in all three motor nuclei, A pparent cytoplasmic staining was seen in SNR motoneurons of untreated castrates and Tfm rats, but not intact rats, suggesting that AR residi ng in the cytoplasm translocates to the nucleus on binding to androgen in these motoneurons. (C) 1995 John Wiley and Sons, Inc.