Cytosol androgen receptors in guinea pig brain and pituitary

Cytosol androgen receptors were assayed in guinea pig brain and pituitary tissues, using [3H]R1881 as ligand. These receptors had an apparent Kd of 0.04 nM and were androgen-specific (R1881 greater than dihydrotestosterone greater than testosterone = estradiol greater than progesterone). Concentrations of cytosol androgen receptors in castrated adult male guinea pigs were 12.2, 11.6, 6.9, 2.6 and 1.3 fmol per mg protein in anterior pituitary, hypothalamus, medial preoptic area, amygdala and cortex, respectively. No significant differences in receptor levels were observed between castrated adult males and females. The concentration of androgen receptors was significantly lower in the hypothalamus, medial preoptic area and anterior pituitary of castrated neonatal males than in castrated adult male guinea pigs. The systemic injection of the alpha 1-adrenergic antagonist, prazosin, had no significant influence on androgen receptor levels in castrated males in any brain area.