Progesterone and pregn-4-ene-20α-ol-3-one in rat ovarian venous blood at different stages inreproductive cycle
The authors, in order to perform the analysis of luteal functions, measured progesterone (called P. hereafter) and pregn-4-ene-20α-ol-3-one(called 20-OH-P. hereafter) in the ovarian venous blood of rats, in the various stages of reproductive cycle. The ovarian venous blood 3-7 ml was collected for 2-4 hours by a cannula fitted to a branch of the ovarian veins and was extracted by a modified method of SHORT'S, and was developed on paper-chromatography (Heptane-Formamide), then the absorptions of UV (240 mμ) of each portion of the paper were sought and plotted for densitogram, and by pranimetry of the areas occupied by each of the peaks, P. and 20-OH-P. were calculated and quantitatively analyzed.(1) P. during normal estrus temporarily increases in the afternoon of proestrus when the ovulating hormone is released from hypophysis, its concentration reaches approx. 110 μg/100 ml blood which is equivalent to about 1/3 of that of the second half period of gestation, then somewhat increases in early, diestrus when the corpus luteum develops most. 20-OH-P. is found throughout the estrous cycle, and its maximum value is approx. 240 μg/100 ml blood. That is to say, the ovary of rats secretes P. even during the normal estrous cycle, but the secretion does not last long.(2) P. during gestation is already high on its 4th day and raises to the maximum value of the 15th day, but it is markedly low immediately before and after the parturition. On the other hand, 20-OH-P. showes rather lower value in the first half period of gestation than in normal estrous cycle, but it reaches appox. 260 μg/100 ml blood on the 15th day. This high concentration is found once more immediately after the parturition. The picture of 20-OH-P. showes a characteristic difference from that of P., although it has been reported there was a parallel relationship between P. and 20-OH-P.(3) P. on the 8th day of lactation is secreted in quite a high concentration, and by the fact that P. of the rat having 6 sucklings is higher than that of the rat haviug 2 sucklings in concentration, it is demonstrated that the secretion is evidently affected by the strength of suckling stimulation. With regard to 20-OH-P., the concentration is low and no difference is observed as in the case of P.(4) The ovary of rats hypophysectomized and bearing pituitary graft undeneath renal cupsule, secretes a large amount of P., but a little of 20-OH-P.