The Metabolism of Steroids in the Canine Prostate and Testis

The uptake and metabolism of androgens by canine prostate in vitro were studied by means of an experimental design which consisted of superfusion of prostate slices with a medium containing [4-14C]androstenedione and [6,7-3H]testosterone, or [4-14C]testosterone and 5\g=a\-dihydro[1,2-3H]testosterone. The entry or transfer of steroids into the slices, the irreversible metabolism, the conversion between the steroids and their uptake or tissue retention were measured at the steady state. A similar proportion of the three androgens entered the tissue and was irreversibly metabolized. Conversion of testosterone into 5\g=a\-dihydrotestosterone was much greater than the interconversion of testosterone and androstenedione. The prostate slices retained 5\g=a\-dihydrotestosterone in a concentration up to four times that in the medium, whereas testosterone and androstenedione were retained to a smaller extent.By increasing the steroid concentration in the perfusing medium from 0\m=.\03 to 1\m=.\30 \g=m\mol/l, it was shown that the systems regulating entry, uptake and metabolism of the androgens were not saturated within this range of concentration. No substantial differences were observed in the regulation of tissue\p=m-\androgen interaction in vitro between five normal and four hyperplastic canine prostates. This was in contrast with previously reported findings that, in man, normal and hyperplastic prostatic tissue respond in a different way to an increase in steroid concentration in the medium.

Section: Resultssupporting

confidence: 92%

Androgen Dynamics in Vitro in the Canine Prostate Gland

Giorgi¹,

Grant²,

Stewart³

et al. 1972

“…or meso-DHBS administration, despite the unchanged, apparently normal, level of ICSH. This may not be unreasonable since a direct inhibitory action of oestrogens on the testes has been suggested (Slaunwhite et al 1962;Oshima et al 1967;Harper et al 1971). Apart from their effect on the pituitary and testis, oestradiol-17/?…”

Section: Plasma Testosterone and Androstenedionementioning

confidence: 99%

The Effect of Certain Stilboestrol Analogues on Plasma Prolactin and Testosterone in the Rat

Danutra¹,

Harper²,

Boyns³

et al. 1973

Self Cite

Oestradiol-17\g=b\,diethylstilboestrol (DES), dl-dihydrodibutylstilboestrol (dl-DHBS) and meso-dihydrodibutylstilboestrol (meso-DHBS) were injected intramuscularly into male Sprague-Dawley rats in a daily dose of 100 \ g=m\ g for a period of 10 days. Oestradiol-17\g=b\ and DES decreased the weight of the prostate and seminal vesicles to the same extent, whereas meso\x=req-\ DHBS was less effective. dl-DHBS was almost inactive. Only oestradiol\x=req-\ 17\g=b\ and DES caused a decrease in the weight of the testes. The adrenal glands increased in weight after administration of either oestradiol-17\g=b\, DES or meso-DHBS.Four hormones in the plasma were measured: testosterone, androstenedi\x=req-\ one, prolactin and interstitial cell-stimulating hormone (ICSH). DES decreased the plasma concentration of both ICSH and testosterone. Oestradiol-17\g=b\ and meso-DHBS administration resulted in a lowering of the plasma testosterone concentration with no effect on ICSH. Oestradiol-17\g=b\, DES and meso-DHBS markedly increased plasma prolactin concentrations. dl-DHBS appeared to have little biological effect causing only very small changes in all the parameters investigated.

“…Furthermore when tritiated testosterone was incubated with this tissue the nuclei exhibited a selective retention of the radioactivity associated with 5a-androstane-3a,17a-diol (Harper, Pierrepoint, Fahmy & Griffiths, 1971). Such a phenomenon was not found for 5a-dihydrotestosterone nor would this latter androgen stimulate DNA polymerase isolated from the canine prostate.…”

Section: Introductionmentioning

confidence: 84%

DEMONSTRATION OF a SPECIFIC CYTOSOL RECEPTOR IN THE NORMAL AND HYPERPLASTIC CANINE PROSTATE FOR 5α-Androstane-3α, 17α-Diol

Evans¹,

Pierrepoint²

1975

Self Cite

A specific receptor protein has been demonstrated for 5alpha-androstane-3alpha, 17alpha-diol in cytoplasmic extracts of normal and hyperplastic canine prostates. The receptor molecule, with a sedimentation coefficient of 4-5S, has been identified by the use of sucrose gradient centrifugation of tissue fractions which had been labelled in vitro with tritiated 5alpha-androstane-3alpha, 17alpha-diol. The receptor showed a relatively high affinity for this compound whereas binding could not be demonstrated with other labelled C19 steroids. In addition binding of tritiated 5alpha-androstane-3alpha, 17alpha-diol was not affected by the presence of 50-fold excesses of other C19 steroids.