In vivo production of steroids with central depressant actions by the ovary of the rat

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Abstract
1 In addition to progesterone and 20-dihydroprogesterone, the following unconjugated steroids were isolated from ovarian tissue and ovarian venous blood of mature, non-pregnant rats: pregnenolone, 3βOH-5α-pregnan-20-one, 3αOH-5α-pregnan-20-one, 20αOH-5α-pregnan-3-one and 5α-pregnane-3α, 20α-diol. 2 Their concentration in the ovarian tissue and their secretion rates into the ovarian venous blood was of the same order of magnitude as that of progesterone. 3 In the evening of the day of pro-oestrus significant increases in the ovarian contents of the following steroids were observed: progesterone,+ 140%; 3αOH-5α-pregnan-20-one, +320%; 20αOH-5α-pregnan-3-one, +195%; sum of pregnenolone and 3βOH-5α-pregnan-20-one, +275%. 4 At the same time the ovarian progesterone secretion rate was increased by 365%, that of 3αOH-5α-pregnan-20-one by 190%. 5 A possible physiological role of the ovarian allopregnane derivatives as central depressant agents is discussed.