Kenneth J. Ryan

Estrogen formation in the brain

Abstract Diverse observations that androgens could be converted to estrogens in extraglandular sites, that only aromatizable androgens produce effects similar to those of estrogens at the central level, and that estrogens and androgens are localized in the same neuronal areas of the brain with a pattern that favors estradiol with respect to nuclear uptake all led to the search for and ultimate finding that androgens can be aromatized in specific areas of the brain. The reaction seems to be influenced by the hormonal state of the animal, occurs in all species thus far tested, and may represent one mechanism for androgen action in the central nervous system.

Estrogen formation by the isolated perfused rhesus monkey brain.

Perfusion of two isolated brains from immature male rhesus monkeys with [3H]androstenedione resulted in the identification of free and conjugated [3H]estrone and free [3H]estradiol from the perfusates. In the dissected cerebral tissues, estrogens were recovered only from the hypothalamus and limbic system. The production of estrogens from androstenedione during the 40-minute perfusions in these two experiments totaled 1.58 and 2.83 nanograms.

Comparative Endocrinology of Gestation

Publisher Summary This chapter discusses the comparative endocrinology of gestation. The comparative endocrinology of pregnancy is a broad field and it is advantageous to consider it under headings that represent separate functional units. Three endocrine systems can be defined on the basis of their function in relationship to the physiology of pregnancy: preimplantation, postimplantation, and metabolic-homeostatic. These are discrete but interrelated systems and each has an essential role in mammalian reproduction. The preimplantation endocrine system controls gametogenesis, sexual behavior, ovulation, conception, and implantation. For many nonmammalian vertebrates, a “preimplantation” system has sufficed to accomplish fertilization of the ovum and its expulsion into an environment that is suitable for the subsequent development of the embryo. It is from a “preimplantation” system, that postimplantation endocrine activity can be assumed to have evolved. The development of the postimplantation endocrine system is a central aspect of the evolution of viviparity. The gonadotropic hormones, both from the pituitary and the placenta, have an important function in promoting the synthesis of the essential steroid hormones, estrogen and progesterone, in the ovary.

Adenyl cyclase in the human placenta

n This study demonstrated that the human placenta possesses an adenyl cyclase system responsive to catecholamines and sodium flouride (NaF). 2.5 gm human term placentas were homogenized, centrifuged, washed, resuspended, and used as the enzyme system when placed with various agents. Incubations and the determination of adenosine 3, 5 monophosphate (cyclic AMP) formed were performed. Samples stimulated by .0001 M catecholamines (L-epinephrine or L-norepinephrine) or .01 M NaF had higher levels of cyclic AMP than the controls (p. 005 for catecholamine-treated samples and p. 001 for NaF-treated samples). A concentration of .0001 M L-epinephrine or L-norepinephrine appeared to be a maximum effective dose and .0000001 M a minimum. L=epinephrine was 10 times as effective in the stimulation as L-norepinephrine. With .0001 M, 499 and 439 pmoles/10 minutes per 25 mg of tissue was formed, whereas in the control (no added hormones) 256 pmoles/10 minutes were formed. 3.2% ethanol activated the system by a small amount (p.02). Propranolol alone did not appear to have any effect; however, the effect of .0001 M L-epinephrine was reduced by 95% in the presence of .00001 M propranolol. Propranolol had no effect on NaF-stimulated activity.n

Endocrine control of gestational length. A time to be born.

Abstract The implications of the comparative endocrinology of pregnancy in mammals with extended gestational periods, the natural and experimental effects of the fetal adrenal upon pregnancy length, and the binding of steroids to specific serum and tissue proteins have been reviewed. Two models for the control of the evolution of myometrial activity during pregnancy have been proposed as bases for an experimental approach to the problem of the endocrine regulation of gestational length.

The in vitro biosynthesis and metabolism of progesterone and estrogens by chimpanzee placental tissue.

Abstract The biosynthesis and metabolism of progesterone and estrogens have been studied in chimpanzee placental tissue in vitro. The conversion of androstenedione-4-14C to estrone and estradiol-17β and of pregnenolone-7α-3H to progesterone has been demonstrated. In addition, the following metabolites were isolated following incubation of either pregnenolone-7α-3H or progesterone-4- 14 C: 20α-dihydroprogesterone, 20β-dihydroprogesterone, 6β-hydroxyprogesterone, 5α-pregnane-3,20 dione. The compound 5α-pregnan-3β o1-20-one was identified only after incubation with pregnenolone-7α-3H, while 5β-pregnane-3, 20 dione was identified only after incubation with progesterone-4- 14 C. No estrogens could be demonstrated following the incubation of placental preparations with either of the C 21 substrates.

Intravenous prostaglandin F2α for therapeutic abortion

Abstract The use of prostaglandin F 2α in increasing (25 to 250 mcg. per minute) and constant (50 to 100 mcg. per minute) doses via intravenous infusion in a group of 15 women undergoing therapeutic abortion is described. The constant lower dose regimen was superior to the graded dose program from the standpoint of both obtaining abortion and minimizing side effects. Although no serious side effects were encountered, troublesome nausea, vomiting, and diarrhea were frequent. The occurrence of prolonged infusion times (which could not be forecast from the gestational age or parity of the patients), an over-all failure rate of 42 per cent, and the accompanying side effects obviate this form of treatment as an alternative to suction evacuation of the uterus for routine therapeutic abortion.