Progesterone, synthesis

Another approach to pregnancy termination has been the utilization of progesterone synthesis inhibitors. These compounds block production of progesterone by the corpus luteum and the early placenta. When adrninistered with a prostaglandin, their use can result in medically induced abortions. 

Pathophysiologic changes associated with menopause are caused by loss of ovarian follicular activity. The postmenopausal ovary is no longer the primary site of estradiol or progesterone synthesis. 

Progesterone synthesis inhibition. Fresh root, on the perfused ovaries of rabbits fed a carrot-rich diet, was active . Pro-oxidant activity. The root, at a concentration of 1%, was active at 120° F on peanut oil . 

It stimulates placental progesterone synthesis and increases the secretion of placental hormones. 

The ovary also produces inhibin and activin. These peptides consist of several combinations of and 3 subunits and are described in greater detail later. The oc3 dimer (inhibin) inhibits FSH secretion while the 33 dimer (activin) increases FSH secretion. Studies in primates indicate that inhibin has no direct effect on ovarian steroidogenesis but that activin modulates the response to LH and FSH. For example, simultaneous treatment with activin and human FSH enhances FSH stimulation of progesterone synthesis and aromatase activity in granulosa cells. When combined with LH, activin suppressed the LH-induced progesterone response by 50% but markedly enhanced basal and LH-stimulated aromatase activity. Activin may also act as a growth factor in other tissues. The physiologic roles of these modulators are not fully understood. 

Ascorbic acid depleted from adrenal cortex or ovary on progesterone formation Niacin diphosphopyridine nucleotide (DPN) involved in progesterone synthesis... 

General anabolic effects stimulates release of insulinlike growth factor-I Stimulates milk synthesis Ovary luteinization, progesterone synthesis testis interstitial cell development, androgen synthesis... 

Luteinizing hormone (LH] Female T ovulation T estrogen and progesterone synthesis from corpus luteum Male t testosterone synthesis... 

Gs Luteinizing hormone Adenylyl cyclase Increase estrogen, progesterone synthesis... 

In chicken granulosa cells, TMB-8, a putative antagonist of intracellular calcium mobilization, inhibited progesterone synthesis in calcium free medium and also inhibited LH stimulated 45Ca release from digitonin permeabilized cells [31]. The latter occurred in two phases after 1-2 min followed by a slower phase after 5 min. Forskolin and 8-Br-cyclic AMP stimulated only the slow phase of calcium mobilization. These studies indicate that LH may initially stimulate calcium mobilization in granulosa cells via a cyclic AMP-independent pathway followed by a slower cyclic AMP-dependent pathway. 

Some chemicals can have multiple effects on fertility. Alkaloids in cigarette smoke, nicotine, cotinine, and anabasine, administered alone or as a mixed aqueous extract of cigarette smoke, for example, inhibit progesterone synthesis and have a cytotoxic effect that reduces the fertilization, implantation, and embryonic viability. I7... 

Gocze PM, Porpaczy Z, Freeman DA. Effect of alkaloids in cigarette smoke on human granulose cell progesterone synthesis and cell viability. Gynecol Endocrinol 1996 10(4) 223 8. 

Treatment of perfused ovaries with NOS inhibitors has been reported to increase (Yamauchi et al., 1997) and decrease (Bonello et al., 1996) estradiol concentrations in the rabbit and rat respectively, while progesterone synthesis was unaffected (Yamauchi et al., 1997 Bonello et al., 1996). 

If implantation occurs, human chorionic gonadotropin, produced initially by the trophoblast and later by the placenta, maintains steroid hormone synthesis by the corpus luteum during the early stages of pregnancy. Thereafter, the placenta itself becomes the major site of estrogen and progesterone synthesis. 

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