Classification of anabolic steroids using the method of competitive metabolism.
The effect of increasing concentrations of testosterone (T) and 19-nortestosterone (N) on the in vitro metabolism of [3H]N in minced tissue of the rat seminal vesicle indicates that T and N are equally appropriate substrates for the 5 alpha-reductase. Experiments in which increasing concentrations of 17-methyl-T (MT) or 1-ene-MT were incubated with [3H]T and vesicular mince have revealed that the formation of [3H]5 alpha-dihydro-T is suppressed markedly by MT while 1-ene-MT has no measurable effect. Since 5 alpha-dihydro-MT binds to the androgen receptor with a higher affinity than MT does and (relative to T) MT does not exhibit myotropic-androgenic (= M-A) dissociation, it can be concluded that MT is, whereas 1-ene-MT is not a substrate for the 5 alpha-reductase. Our present and previous data suggest that N exemplifies one class of anabolic steroids that become less androgenic due to 5 alpha-reduction, it shows high myotropic activity, M-A dissociation (= 7-30) and affinity to the androgen receptor. On the other hand, 1-ene-MT belongs to another class of anabolic steroids that are not substrates for the 5 alpha-reductase, exhibit a relatively small myotropic activity, M-A dissociation (= 2-3) and receptor affinity.
D045930:Anabolic Agents / Q000145:classification* / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D042944:Cholestenone 5 alpha-Reductase; D066298:In Vitro Techniques; D008297:Male; D008710:Methenolone / Q000378:metabolism; D008777:Methyltestosterone / Q000378:metabolism; D009277:Nandrolone / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011944:Receptors, Androgen / Q000378:metabolism; D012669:Seminal Vesicles / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism
D045930:Anabolic Agents; D011944:Receptors, Androgen; D013739:Testosterone; D009277:Nandrolone; D008710:Methenolone; D010088:Oxidoreductases; D042944:Cholestenone 5 alpha-Reductase; D008777:Methyltestosterone