Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Plasma progesterone levels following subdermal implantation of progesterone pellets in lactating women

The magnitude and duration of elevated plasma progesterone levels resulting from subdermal implantation of progesterone pellets were investigated in full nursing women. This condition was chosen because it is associated with a low rate of ovulation and minimal endogenous progesterone production. In addition, treatment with progesterone pellets was intended to be a substitute for oral or parenteral administration of synthetic progestogens to nursing mothers. A control group of full nursing women receiving no hormones provided blood samples so that basal plasma progesterone levels from the second to the sixth post-partum month could be assessed. Progesterone pellets were implanted subdermally on day 30-35 after delivery. Insertion of 2, 4 or 6 pellets each containing 100 mg of progesterone caused an initial elevation of plasma progesterone to 5.9, 9.9 and 13.5 nmol/l, respectively. This initial elevation was followed by a gradual decline, so that basal levels were attained at 70, 100 and 150 days after insertion of 2, 4 or 6 pellets. Implantation of 6 progesterone pellets led to a significant decrease in the ovulation rate of nursing women. These results indicate that subdermal implantation of 6 progesterone pellets can provide biologically effective levels of the hormone for up to 5 months.

Pharmacokinetics of norethindrone acetate in women after the insertion of a single subdermal implant releasing norethindrone acetate

The metabolic clearance rate (MCR) of norethindrone acetate (NETA) and norethindrone (NET) levels in plasma were studied after an iv injection of [3H]NETA in three women before and at 1 week, 1, 2 and 6 months following the insertion of a single silastic subdermal implant releasing microquantities of NETA. No significant change in the MCR of NETA was observed at 1 week (459 +/- 72 1/day), 1 month (489 +/- 113 1/day) and 2 months (522 +/- 144 1/day) compared with that of control (525 +/- 108 1/day). However, MCR of NETA showed significant increase in women exposed to continuous presence of NETA for a period of 6 months (608 +/- 121 1/day; P less than 0.025). NETA was rapidly and extensively metabolized into NET. At 1 week, 1, 2 and 6 months of study, NET was observed to be present in higher amounts compared with NETA. The production rate (PR) of progesterone decreased significantly at 2 and 6 months of NETA implant insertion compared with the PR before the insertion of implant.

[Administration route of natural sex steroids (estradiol, progesterone, testosterone) (author's transl)]

The natural sex steroids (E2, T, P) may be used in therapeutics. Estradiol and testosterone esters (decanoate and undecanoate) may be administered orally. A local effect always follows the percutaneous application of sex steroids, and this is usually accompanied by a systemic effect. But because of the very important metabolism of progesterone by the skin, it is necessary to administer it by other routes (intravaginal, intrarectal) in order to obtain a systemic effect.

A new long-acting injectable microcapsule system for the administration of progesterone

A long-acting injectable microcapsule system for the controlled-release systemic administration of progesterone (P4) is described. The system consists of microcapsules made of the biodegradable polymer, d,l-polylactic acid, which contain crystalline P4. Following injection, P4 is released from the microcapsules by diffusion and biodegradation of the polymer matrix. The rate of P4 release from the prototype microcapsule system in vivo is 1.3 microgram of P4/day/mg of microcapsules, and the duration of release is 30 days. Vaginal estrous cycles in rats and cyclic ovarian function in baboons were inhibited for 1 month following a single injection of P4 microcapsules. The effects of continuous progesterone therapy on reproductive function in both rats and baboons are dose-dependent. The utility of the system as a once-a-month injectable contraceptive is established in the baboon model.

Low-level, progestogen-releasing vaginal contraceptive devices

Silicone rubber vaginal contraceptive devices of four different formulations, which release predetermined, controlled doses of three progestogens at four distinct levels, were designed and fabricated, and tested in 90-day clinical trials. Data obtained with 70 of the devices indicated that in vivo release rates (microgram/day +/- S.D.) for the formulations were: progesterone, 1400 +/- 30; norethindrone (two levels), 49.4 +/- 2.4, 196 +/- 21; d-norgestrel, 21.6 +/- 1.4. Clinical studies with these devices indicate that the women usually ovulate (with the exception of the high-dose norethindrone-releasing devices) while sperm penetration of the cervix was inhibited by all four fromulations, most consistently by the norgestrel-releasing devices.

The interaction of clomiphene, estradiol, and progesterone in the control of rat uterine glycogen metabolism

Uterine glycogen accumulation was studied in ovariectomized rats treated with all combinations of clomiphene citrate (0.25 mg/kg) estradiol (1.0 micron g) and progesterone (5.0 mg). The rats were given three consecutive daily dosages and killed 24 hours after the final dosage. Based on biochemical data, either estradiol or clomiphene increased uterine glycogen concentration and total glycogen, but progesterone did not. Progesterone significantly suppressed both the estradiol and clomiphene-induced glycogen increases. Based on the histochemical results, progesterone also suppressed the estradiol and clomiphene-induced glycogen responses, but the tissue affected differed. Clomiphene markedly increased luminal epithelial glycogen whereas estradiol induced primarily myometrial glycogenesis. Progesterone completely suppressed the clomiphene-induced epithelial effect and partially suppressed the estradiol-induced myometrial effect. Clomiphene also suppressed the estradiol-induced myometrial response. The results indicate that progesterone does have a significant interaction with clomiphene in the control of uterine morphology and biochemistry. The results also stress the importance of correlated histochemical and biochemical studies in the study of clomiphene-induced uterine glycognesis.

Mechanism of oestrogen and progesterone effects on lipid and carbohydrate metabolism: alteration in the insulin: glucagon molar ratio and hepatic enzyme activity

As in women receiving oestrogens the administration of 17beta-oestradiol to ovariectomized female rats caused a rise in fasting plasma triglycerides and a fall in plasma glucose. Progesterone, on the other hand, had no significant effects. In the oestradiol treated rats, the portal vein basal insulin levels were slightly reduced. Oestradiol, however, had a marked suppressive effect on the alpha cells of the pancreas resulting in a greater reduction in basal glucagon and impaired glucagon response to alanine infusions. The relative insulin to glucagon (I/G) molar concentration ratio in portal vein blood was increased. Oestradiol also produced a dose dependent increase in the activity of the liver lipogenic enzymes, acetyl CoA carboxylase and fatty acid synthetase. On the other hand, the activity of the gluconeogenic rate limiting enzyme phosphoenol-pyruvate carboxykinase (PEPCK) was inhibited. The cross-over pattern of gluconeogenic intermediates confirmed inhibition of gluconeogenesis at this step, an effect which is similar to that induced by relative insulin 'excess'. Progesterone produced an increase in the portal vein insulin concentrations. Both the basal and the alanine-stimulated glucagon levels were also increased. The I/G molar ratio in portal vein blood of progesterone treated rats remained unaltered and the hepatic lipogenic and gluconeogenic enzyme activities were similar to control animals. These data suggest that insulin activity is increased relative to glucagon in the liver of oestradiol-treated rats due to the rise in portal vein I/G ratio. The changes in liver lipogenic and gluconeogenic enzymes and the alterations in fasting plasma triglycerides and glucose in response to oestrogens could be secondary to this effect.

Effects of exogenous progesterone and oestradiol on prostaglandin F and 13,14-dihydro-15-oxo prostaglandin F2alpha concentrations in uteri and plasma of ovariectomized ewes

The control of prostaglandin (PG) production by steroid hormones has been investigated in non-pregnant bilaterally ovariectomized sheep, prepared with indwelling utero-ovarian venous catheters and treated with physiological amounts of oestradiol and progesterone. Oestradiol treatment alone (2 × 15 μg/day for 9 days) had no effect on the prostaglandin F (PGF) concentration in uterine caruncles or intercaruncular tissue, on the release of PGF or of 13,14-dihydro-15-oxo PGF (PGFM) from these tissues during incubation in vitro, or on the concentrations of PGF in the utero-ovarian vein or PGFM in the jugular vein. However, oestradiol did accumulate in the uterine tissues. Progesterone treatment alone (2 × 10 mg/day for 9 days) provoked a significant increase in the concentration of PGF in the caruncles, a significant increase in the release of PGF from the caruncles during incubation with arachidonic acid and increased mean concentrations of PGFM in the jugular vein. When oestradiol was superimposed on a progesterone-primed system, there was a further marked increase in the PGF content of the caruncles, release of PGF into the utero-ovarian vein, and increased concentrations of PGFM in the jugular vein. The caruncles always contained more PGF than the intercaruncular area, and released more PGF and PGFM during incubation in vitro. In the progesterone+oestradiol group, there was good correlation between the PGF concentrations in simultaneous samples from the right and left utero-ovarian veins, and for all groups there was a high correlation between utero-ovarian PGF and peripheral PGFM concentrations. The caruncular epithelium of the progesterone-treated animals contained more lipid droplets than those of the other groups.

These data are consistent with a requirement for progesterone in activating 'prostaglandin synthetase' activity, and promoting PGF production, largely from the caruncles. After progesterone priming, the synthesis of PGF by the caruncles and PG release into the vascular system was increased further by oestradiol treatment, whereas oestradiol alone was without effect.

Progestagen effects on elicitation of aggressive behaviour in male mice

Effects of progesterone on production of androgen-dependent aggression-eliciting pheromones were investigated. Two groups of anosmic (non-fighting) castrated mice treated with testosterone or with testosterone and progesterone, respectively, were attacked to the same degree by intact, isolated (fighting) mice while control mice (castrated only) were attacked less. The findings support the ideas that progesterone may inhibit androgen-induced aggression via a neural and not via a somatic mechanism.

Estrogen-induced sexual receptivity and localization of 3H-estradiol in brains of female mice: effects of 5 alpha-reduced androgens, progestins and cyproterone acetate

Sexual receptivity induced in ovariectomized CD-1 mice with chronic daily administration of estradiol benzoate (E2 B) was blocked by concurrent administration of the 5 alpha-reduced androgen, dihydrotestosterone (DHT). Receptivity was restored in these females with progesterone-, but not with dihydroprogesterone-priming 6 hr prior to testing. Delaying the DHT injections until 12 hr after the E2 B injections greatly reduced its inhibitory properties. Receptivity in E2 B-primed females was also blocked by concurrent treatment with cyproterone acetate and 3 alpha-, but not 3 beta-adrostanediol. Pretreatment with DHT, or 3 alpha- or 3 beta-androstanediol failed to consistently affects 3H-estradiol accumulation in crude nuclear and supernatant fractions from brain and pituitary.

The effect of intrauterine progesterone treatment on the endometrial prostaglandin F content in the rabbit

The effect on rabbit endometrial prostaglandin F caused by progesterone delivered directly to the uterus was investigated. Four groups of animals were used in the experiment: (1) no treatment (control); (2) an empty Silastic capsule (as an intrauterine device [IUD]) was inserted in one horn and the other horn was sham-operated; (3) a Silastic capsule releasing 150 microng of progesterone/day was placed in one horn and the other horn was sham-operated; (4) a Silastic capsule releasing progesterone was placed in one horn and the opposite horn received an empty Silastic capsule. In group 1, which received no treatment, no difference was noted. In group 2, the prostaglandin content of the horn containing an empty IUD was significantly higher than that of the sham-operated horn. In group 3, the same significant difference was noted between the prostaglandin content of the IUD-containing, progesterone-treated horn and the sham-operated horn. In group 4, no significant difference was observed between the horn containing an inert IUD and that containing a progesterone-releasing device. The addition of progesterone to an IUD does not significantly affect the elevated prostaglandin content of the endometrium caused by an inert IUD.

Sustained-release hormonal preparations XV: release of progesterone from cholesterol pellets in vivo

Progesterone-sterol pellets were made that porvided a zero-order release of progesterone for 80 days. 4-(14)C-Progesterone was used to measure the release in vitro and in vivo. The dissolution rate in vitro (distilled water as the desorbing medium) for progesterone-cholesterol (59:41 w/w) and the progesterone-beta-sitosterol (47:53 w/w) pellets was 72 microng/100 mm2/24 hr. The average in vivo absorption from subcutaneously implanted pellets in rabbits was 2 +/- 0.1 microng/ml of plasma/cm2 of surface area. Of this amount, 20-25% was progesterone; the remainder was progesterone metabolites and conjugates. Zero-order release (plasma levels) was obtained for approximately 80 days or until about 70% of the available progesterone was exhausted. During this time, the level of excreted radioactivity in urine continuously decreased, indicating that monitoring only this parameter would lead to erroneous conclusions. A long-term effect and increased effectiveness were obtained with a 5-20-mg progesterone equivalent dose, using gel prepared from 2% methylcellulose as the suspending medium.