HIGH-AFFINITY ANDROGEN BINDING-PROTEINS IN SYRINGEAL TISSUES OF SONGBIRDS

The vocal organ of birds is the syrinx. In zebra finches, Poephila guttata, and canaries, Serinus canarius, song is normally restricted to males and amount of singing is influenced by testosterone (T). We here report that the syringeal muscles of these two oscine songibrds have specific high-affinity androgen binding proteins. The levels of binding present in syrinxes from female and castrate male zebra finches (40-50 fmol/mg protein) are far in excess of those demonstrated to exist in any other striated muscle and are within the range of values observed for classical androgen-sensitive tissues such as the mouse kidney. Canaries do most of their singing via the left syringeal half, but both right and left syringeal halves show a comparable concentration of high-affinity androgen binding proteins. Clearly the L-R asymmetry in syringeal function is not related to an asymmetric concentration of T receptors. © 1979.