Studies on the receptors to 5alpha-androst-16-en-3-one and 5alpha-androst-16-en-3alpha-ol in sow nasal mucosa.

The presence of receptors to the "boar taint" pheromones 5alpha-androst-16-en-3-one and 5alpha-androst-16-en-3alpha-ol has been demonstrated in sow olfactory mucosa. Binding studies indicated that a sufficiently low concentration of olfactory tissue homogenate exhibited saturation of binding of 5alpha-androst-16-en-3-one, and this was of high affinity compared with control tissues of non-olfactory and heated olfactory tissues. Analysis of receptor binding of 5alpha-androst-16-en-3-one gave a value for the affinity constant (Ka) of approx. 8.3-10(8) M-1 and the value for the molar concentration of binding sites (n[M]) was approx. 3.3 pmol/mg protein. Almost identical values of Ka and n [M] were obtained when receptor binding of 5alpha-[5alpha-3H]androst-16-en-3alpha-ol was investigated (Ka 8.4-10(8) M-1; n [M] 3.7 pmol/mg protein). This suggests that the same receptor binds both 5alpha-androst-16-en-3-one and 5alpha-androst-16-en-3alpha-ol with equally high affinity. In a preliminary investigation to establish the specificity of the receptor, the binding of 17beta-hydroxy-5alpha-androstan-3-one was assayed; this steroid is odourless but has a similar structure except in ring D to 5alpha-androst-16-en-3-one. Binding was of the low affinity, non-specific type only, indicating that the sow olfactory receptors are not sensitive to this androgen.