The binding of the steroidal pheromone 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P) to membranes prepared from the goldfish olfactory epithelium was investigated using an in vitro radioreceptor assay. Maximum specific binding occurred after a 60-min incubation at 4°C. Binding increased linearly with increasing amounts of tissue. 17α,20β-P binding saturated at a ligand concentration of approximately 4.0 nM, matching well with data obtained from electrophysiological recordings of the in situ sensitivity of the olfactory epithelium to 17α,20β-P. Scatchard analysis yielded a single class (r = 0.95) of high-affinity (Kd = 1.02 ± 0.06 nM), low-capacity (Bmax = 1.38 ± 0.24 pmol/mg protein) receptors. Olfactory epithelial membranes were highly enriched in 17α,20β-P receptors; binding was 10 to 20 times higher than in membranes prepared from gut, liver or brain. The specificity of binding was not absolute. Progestins (progesterone, 17α,-hydroxyprogesterone) and androgens (androstenedione, testosterone) competed with 17α,20β-P for binding; however, these steroids were less potent at displacing radiolabeled 17α,20β-P than was 17α,20β-P itself. Estrogens and glucocorticoids did not displace 17α,20β-P in this preparation. These results are consistent with the respective abilities of these compounds to elicit electro-olfactogram activity, and confirm the presence of membrane-bound steroidal receptors in olfactory tissue.
|Original language||English (US)|
|Number of pages||12|
|State||Published - Apr 1991|
Bibliographical noteFunding Information:
These studies were supported by Alberta Heritage Foundation for Medical Research postdoctoral fellowships to P.M.R. and P.W.S., and by grants from the Natural Sciences and Engineering Council of Canada (N.E.S. and R.E.P.), the Minnesota Agricultural
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