Metabolism of Androgens in Vitro by the Submaxillary Salivary Gland of the Mature Domestic Boar

Abstract

Homogenates of the submaxillary glands of mature domestic boars were incubated with radioactively labelled C19 steroids. The metabolism of [7\g=a\-3H]dehydroepiandrosterone and [7\g=a\-3H]androstenedione was primarily to the end products 5\g=a\-androstane-3,17-dione and androsterone, but some testosterone, 5\g=a\-dihydrotestosterone and 5\g=a\-androstane-3\g=a\,17\g=b\-diol were also formed. When [7\g=a\-3H]5-androstene-3\g=b\,17\g=b\-diol was used as a substrate, the major metabolite was testosterone. Both [7\g=a\-3H]5-androstene-3\g=b\,17\g=b\-diol and [ 1\ g=a\ , 2\ g=a\ -3H] \ x=req-\ testosterone were converted to 5\g=a\-dihydrotestosterone and high yields of 5\g=a\-androstane\x=req-\ 3\g=a\,17\g=b\-diol, but only small yields of 5\g=a\-androstane-3\g=b\,17\g=b\-diol and androsterone were obtained. High yields of 5\g=a\-androstane-3\g=a\,17\g=b\-diol and to a lesser extent 5\g=a\-androstane\x=req-\ 3\g=b\,17\g=b\-diol were formed from the substrate [1\g=a\,2\g=a\-3H]5\g=a\-dihydrotestosterone.Conversely, when both 3H-labelled androstanediols were used as substrates, 5\g=a\-dihydrotestosterone was formed in equal amounts together with a large yield of 5\g=a\-androstane-3\g=a\,17\g=b\-diol from the 3\g=b\-epimer. There was no evidence for steroid sulphatase or aromatase activity in these incubations. These findings support the prohormone concept that precursor steroids of testosterone, known to be present in boar testis, could act as an additional source of potent androgens in peripheral target organs to androgens in this species.In a number of incubations with [1\g=a\,2\g=a\-3H]testosterone, free oestradiol-17\g=b\ and oestrone, but not oestrone sulphate enhanced the formation of androstenedione, but reduced the formation of 5\g=a\-dihydrotestosterone.However, both free and conjugated oestrogen reduced the formation of 5\g=a\-androstane-3\g=a\,17\g=b\-diol. These findings are discussed in relation to the high levels of oestrogen found in male pigs.

Development of some male characteristics supported by oestrone but not dehydroepiandrosterone in the boar

“…There is evidence indicating that DHA and 5-androstenediol may be important precursors of testosterone in the pig testis (Ruokonen, 1978) as has been suggested for the testes of dogs (Yamaji, Motohashi, Tanioka & Ibayashi, 1968;Oh & Tamaoki, 1973) and men (Vihko & Ruokonen, 1975). However, there is also evidence indicating that, in the boar, 5-ene unsaturated C19 steroids may be important prohormones for testosterone in extragonadal tissues such as the submaxillary gland (Booth, 1977) and the accessory sex organs (Booth, 1980). Administration of 5-androstenediol to prepubertally castrated boars (2 mg/5 kg) maintained the accessory organs in a manner comparable to that produced by the same amount of testosterone (Booth, 1980).…”

A study of some major testicular steroids in the pig in relation to their effect on the development of male characteristics in the prepubertally castrated boar

“…The methanolic extract was subsequently subjected to the Brown's partition (Brown, 1955) to provide separate neutral and phenolic fractions. Androgens were isolated by a combination of thin-layer and paper chromatography (Booth, 1977) and the steroids were quantified by gas-liquid chromatography Booth (1975). Oestrone and oestradiol-17ß were separated from each other by thin-layer chromatography and quantified either by radioimmunoassay (Singh & Booth, 1978), for unconjugated oestrogens, or by gas-liquid chromatography (conjugated oestrogens) as described above.…”

“…Some of these C19 steroids, notably dehydroepiandrosterone (DHA) and 5-androstenediol may be important precursors of testosterone in the pig testis, as they are in the testis of dogs (Yamaji, Motohashi, Tanioka & Ibayashi, 1968;Oh & Tamaoki, 1973) and man (Vihko & Ruokonen, 1975). These 5-unsaturated C19 steroids may also be prohormones for testosterone in androgen end-target organs, and Booth (1977) has shown that DHA and especially 5-androstenediol are readily converted to testosterone and 5a-reduced metabolites in the submaxillary salivary gland of the boar. This finding and other evidence (Booth, 1972(Booth, , 1975Booth, Hay & Dott, 1973) indicates that the submaxillary gland is an important androgen end-target organ in the male pig, modified to accumulate and release the pheromonal 16-unsaturated C19 steroids (16-androstenes).…”

Studies on the metabolism of neutral steroids by preimplantation rabbit blastocysts in vitro and the origin of blastocyst oestrogen

“…Subsequent isolation and identification of radiometabolites were carried out, as described by Booth (1977), with the Bush A paper chromatography system to separate mono-and di-hydroxy metabolites of progesterone, and thin-layer chromatography (two runs with toluene:ethyl acetate (9:1 v/v), one run with benzene:ether (9:1 v/v) (Gower, 1964)) for non-polar steroids to separate 5a-from 5ß-pregnanedione.…”

“…Unlabelled oestradiol and oestrone (20 µg each) were added to each of the diethyl ether extracts, and the 83 % aqueous methanol extract (the petroleum ether phase was discarded), before evaporation to dryness by rotary vacuum evapora¬ tion. The residues corresponding to the blastocysts, uterine flushings and total uterine tissue were subjected to thin-layer chromatography with benzene:acetone (4:1 v/v), and the distribution of radioactivity on the chromatograms was located with a scanner as previously described (Booth, 1977); areas corresponding to oestradiol and oestrone were eluted for liquid scintillation counting.…”