Neurodistribution of androgen receptor immunoreactivity in the male frog, Rana esculenta.

Sexual behavior in vertebrates depends on the cyclic release of steroids and their binding to the brain receptors. Previously, we demonstrated the presence of specific binding of (3)H-testosterone and staining with PG-21 in the brain of the adult male frog, Rana esculenta. Here, we report our further receptor characterization using an anti-androgen receptor antiserum, PG-21, and the androgen site of action in frog brain. Nuclei, which contained cells labeled for the androgen receptor (AR), were mainly identified in the olfactory bulbs, preoptic-septal region, infundibulum, amygdala, thalamus, tectum, torus semicircularis, and medulla. The neuroanatomical AR staining appears similar to that in other lower vertebrates.