208
RACHMIEL LEVESTE
V. ESTROGENS AND PROGESTERONE
In the field of steroid hormones a vast amount of data on detailed examination of the effects of one or another of the hormonally active
materials on rates of reaction and on enzyme content already exists
(Umbreit, 1951; Kochakian, 1951; Dirscherl, 1955). However, none of
the observed phenomena has been of such a nature as to provide a
possible basis for explaining the effects obtained in vivo. Attention
should therefore be drawn to the work of Csapo's laboratory (Csapo
and Corner, 1952; Corner and Csapo, 1953; Csapo and Goodall, 1954),
which is studying the relation between the chemical architecture and
the functional behavior of uterine muscle under the influence of estrogens and of progesterone.
In the castrate animal the uterine muscle atrophies. The concentration of actomyosin falls, out of proportion to the decrease in the other
protein fractions. Qualitatively the isolated actomyosin from an ovariectomized animal behaves perfectly normally. Under the influence of
estrogen therapy the defect is repaired. Thus the estrogens are, so to
speak, growth factors for the myometrial cell, having however a quantitatively more pronounced effect upon the synthesis of the contractile
proteins than upon the other cell proteins. Progesterone, on the other
hand, acts only on a previously estrinized uterus, but does not affect
the amount or the performance of the contractile machinery, when that
is isolated from the rest of the cell. In the intact cell progesterone is
seen to exert profound effects upon performance by changing the threshold of response to electrical stimuli as well as drugs. The progesterone
effect seems to have as its site of action the region embracing the cell
membrane, the area which transmits the stimulus from the membrane
to the contractile apparatus, or both. In accord with the findings of
Hajdu and Szent-Györgyi (1952) and of Szent-Györgyi (1953) concerned
with digitalis and cardiac muscle, Csapo finds that progesterone alters
the relationship between extracellular and intracellular Na and K, which
may account for the change in threshold of excitation observed. Present
indications therefore point to the site of action of progesterone at or
near the cell membrane or boundary region. This work is noteworthy
because it attempts an analysis of hormonal action by a judicious physiological dismemberment of a susceptible tissue, and refers the observed
effects back to well-established phenomena seen in the whole animal.
Villee and his co-workers are analyzing the action of estradiol and
related steroids on the pathway of respiration in placental tissue (Villee
and Gordon, 1955). They have shown that in particulate-free enzyme
preparations of human placenta, estradiol and estrone stimulate the
RACHMIEL LEVESTE
V. ESTROGENS AND PROGESTERONE
In the field of steroid hormones a vast amount of data on detailed examination of the effects of one or another of the hormonally active
materials on rates of reaction and on enzyme content already exists
(Umbreit, 1951; Kochakian, 1951; Dirscherl, 1955). However, none of
the observed phenomena has been of such a nature as to provide a
possible basis for explaining the effects obtained in vivo. Attention
should therefore be drawn to the work of Csapo's laboratory (Csapo
and Corner, 1952; Corner and Csapo, 1953; Csapo and Goodall, 1954),
which is studying the relation between the chemical architecture and
the functional behavior of uterine muscle under the influence of estrogens and of progesterone.
In the castrate animal the uterine muscle atrophies. The concentration of actomyosin falls, out of proportion to the decrease in the other
protein fractions. Qualitatively the isolated actomyosin from an ovariectomized animal behaves perfectly normally. Under the influence of
estrogen therapy the defect is repaired. Thus the estrogens are, so to
speak, growth factors for the myometrial cell, having however a quantitatively more pronounced effect upon the synthesis of the contractile
proteins than upon the other cell proteins. Progesterone, on the other
hand, acts only on a previously estrinized uterus, but does not affect
the amount or the performance of the contractile machinery, when that
is isolated from the rest of the cell. In the intact cell progesterone is
seen to exert profound effects upon performance by changing the threshold of response to electrical stimuli as well as drugs. The progesterone
effect seems to have as its site of action the region embracing the cell
membrane, the area which transmits the stimulus from the membrane
to the contractile apparatus, or both. In accord with the findings of
Hajdu and Szent-Györgyi (1952) and of Szent-Györgyi (1953) concerned
with digitalis and cardiac muscle, Csapo finds that progesterone alters
the relationship between extracellular and intracellular Na and K, which
may account for the change in threshold of excitation observed. Present
indications therefore point to the site of action of progesterone at or
near the cell membrane or boundary region. This work is noteworthy
because it attempts an analysis of hormonal action by a judicious physiological dismemberment of a susceptible tissue, and refers the observed
effects back to well-established phenomena seen in the whole animal.
Villee and his co-workers are analyzing the action of estradiol and
related steroids on the pathway of respiration in placental tissue (Villee
and Gordon, 1955). They have shown that in particulate-free enzyme
preparations of human placenta, estradiol and estrone stimulate the