ASSAY OF ANDROGENS ADMINISTERED BY INUNCTION TO THE CHICK'S COMB

ABSTRACT Androgens dissolved in oil or absolute ethanol may be assayed by inunction to the chick's comb. In an oil solution, the sensitivity is of the order of 10 to 20 μg of testosterone per chick total dose, while absolute ethanol as a solvent permits the detection of about 1 to 2 μg of testosterone. The corn oil vehicle has the higher order of precision with a mean λ of 0.257 as compared to a λ of 0.305 for the absolute ethanol experiment. When a corn oil vehicle was used, inunction of a 17C = O-Δ4-3C = O compound was more active than the corresponding 17β-OH steroids, but this was not so in the androstane (5α) series. 17α-Methyl compounds tended to be more active than the corresponding 17-desmethyl steroid. The introduction of an 11-oxygen function with or without a 9α-fluoro group severely decreased androgenic activity. Δ16-Dehydroprogesterone was reasonably androgenic in this test using the corn oil vehicle. When absolute ethanol was used as the solvent, the 17C = O-Δ4-3-C = O compound was slightly more activie than the corresponding 17β-hydroxy steroid, 17α-methyl steroids were more active than the 17α-desmethyl steroids and an 11-oxygen function decreased the activity. Introduction of the 17α-ethyl group in 19-nortestosterone resulted in a compound 270% as active as testosterone, – an unexpected finding since this type of activity enhancement was not found when the 17α-ethyl group was added in the 19-nor-(5α)-dihydrotestosterone series or in Δ5-androstene-3β,17β-diol. Oxygen substitution at carbon 3 in the steroid molecule was not necessary for androgenic activity when the compound was inuncted on the comb in absolute alcohol. The relationship between the androgenic activity of various compounds when administered by different routes, inunction, subcutaneous injection and by admixture with the food is discussed. No simple interrelationship could be described. However, in some instances it is quite possible that unusually low activities observed when the compounds were administered orally may have been due to poor absorption from the gastrointestinal tract. Compounds in this category include dehydroepiandrosterone, Δ5-androstene-3β,17β-diol and epiandrosterone. All these compounds have a 3β-5α or Δ5-3β-OH grouping.