Steroid hormone生合成に関する研究
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Corticosteroid biosynthesis in the different cellular zones of beef adrenal cortex was studied in vitro.<BR>Various substrates including acetate, cholesterol, pregnenolone, progesterone, desoxycorticosterone, and desoxycortisol were incubated separately with homogenates of fasciculata-reticularis tissue and with slices of glomerulosa tissue.<BR>Although the following sequences were demonstrated in the adrenal cortex, the results of this experiment indicate the absence of 17α-hydroxylase in the zona glomerulosa and the absence of 18-hydroxylase in the zona fasciculata and zona reticulalis.<BR>Aldosterone<BR>Pregnenolone Progesterone Desoxycorticosterone Corticosterone<BR>17-α-hydroxy-Desoxycortisol progesterone<BR>Incubation of acetate or cholesterol with homogenates or slices of adrenal cortex, however, did not lead to the increase of corticosteroid.<BR>In addition, the incubation of adrenal cortex without substrate resulted in the formation of considerable cortisol and corticosterone, while no cholesterol-route intermediates were detectable in the adrenal homogenates. When the dializate of the adrenal cortex against buffer was lyophilized and incubated with adrenal homogenates, it caused a remarkable increase in the production of corticosteroids. This may be due to the conversion of the dialized precursors to corticosteroids, though these precursors have not yet been isolated.<BR>17α-hydroxylase activities were also demonstrated in the homogenates of HCG-treated-rat testis and in the slices of normal adult human ovaries. These tissues were incubated with 3H-Progesterone and the formation of 17α-hydroxyprogesterone-3H was clearly demonstrated.<BR>The incubation of full term human placenta with 3H-Progesterone, however, did not result in the formation of neither 17α-hydroxyprogesterone nor phenolic steroids.<BR>From these results, it was suggested that, in human placenta, there is a dominant pathway by which dehydroepiandrosterone is formed from cholesterol, not through progesterone, but possibly by the direct cleavage of the side chain C-17 and C-20 ; and dehydroepiandrosterone thus produced in turn converts into Δ<SUP>4</SUP>-androstene-3, 17-dione and testosterone, and then to estrogens.
- 一般社団法人 日本内分泌学会の論文