[Treatment of endometriosis]

In a randomized study, the effect of gestrinone (2 x 2.5 mg/week) was compared with the effect of danazol (3 x 200 mg/day) in treating 30 patients with laparoscopically proven endometriotic implants for 6 months. Therapy was effective in 80%-90% of cases and pregnancy rates were similar, but the incidence of side effects was different in the groups. In addition, buserelin (900 micrograms/day intranasally) was investigated in a multinational, multicenter trial in 275 patients. In 80%, GnRH agonist treatment induced the disappearance or reduction of endometriotic implants. The main side effects were due to estrogenic suppression. Presently, various methods of hormonal treatment are under investigation, especially to determine recurrency rates of endometriosis and long-term side effects.

Serum concentration and urinary excretion of the luteinizing hormone-releasing hormone agonist buserelin in patients with endometriosis

We studied the pharmacokinetics of iv and intranasally administered buserelin, a LHRH agonist peptide, in 14 women with endometriosis. Serum and urinary buserelin concentrations were determined by specific RIA (buserelin antiserum AS-639). Intact buserelin and the metabolites in urine were separated by reverse phase high performance liquid chromatography and measured by RIA. The mean serum buserelin concentrations were 101 +/- 33 (+/- SD) ng/mL 20 min and 1.12 +/- 0.12 ng/mL 360 min after its iv injection in 6 women, and the mean elimination half-life between 20 and 360 min was 51 min. In serum, intact buserelin was the main constituent (10 min, 90%; 120 min, 74%; 360 min, 52%), and the major metabolite was the buserelin-(5-9) pentapeptide (10 min, 0.6%; 120 min, 19%; 360 min, 12%). In the urine collected 0-1 h after buserelin administration, intact buserelin was 66% and the 5-9 pentapeptide was 28% of the total excretion. In the urine collected between 6-24 h after buserelin administration, intact buserelin accounted for 67% and the 5-9 pentapeptide for 32% of the total excretion. The urinary buserelin concentration was 1345 +/- 156 micrograms/g creatinine 1 h and 25 +/- 5 micrograms/g creatinine 6-24 h after buserelin administration. Serum LH, FSH, and estradiol concentrations increased acutely up to 10-fold above basal values; the mean peak LH, FSH, and estradiol values occurred at 180-240 min, 240 min, and 24 h, respectively. In therapeutic studies with buserelin nasal spray in 5 women, serum concentrations of 0.9-1.4 ng/mL were found 15 min after a single dose of 300 micrograms, intranasally, and the urinary excretion was 2.52-3.68 micrograms/24 h during daily administration of 3 doses of 300 micrograms at intervals of 8 h. These results confirm that buserelin is slowly inactivated and remains available to pituitary receptors for a prolonged period after its iv or intranasal administration.

Contraceptive progestins and gonadotropin secretion in vitro

In an in vitro bioassay using rat pituitary cell cultures the effect of contraceptive progestins was tested on basal and gonadotropin-releasing hormone (GnRH)-induced luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion in vitro. Progestins diminished gonadotropin release in pituitary cells stimulated with GnRH, but did not alter basal values. This inhibitory effect was dose dependent in a range of 10(-10)-10(-5) M tested and the inhibitory action of most of the progestins examined was more potent than that of progesterone. The maximal reduction of LH and FSH values was by 60% of GnRH-induced control levels. Progestins also caused a shift in sensitivity of cells to GnRh (10(-12)-10(-6) M). When time dependence was investigated, some progestins potentiated GnRH effect on gonadotropins in pituitary cell cultures pre-incubated for a short time (4 h) with steroids. More prolonged pre-incubations from 23 to 71 h resulted in a progressive suppression of LH and FSH response to GnRH (10(-7) M). In order to examine intracellular effects, cells were pretreated with progestins and inositol phosphate metabolism was investigated. The data obtained in pituitary cells give evidence that polyphosphoinositide breakdown is potentially an early step in the action of GnRH on gonadotropin secretion by providing diacylglycerol and inositol phosphates. Addition of gonadotropin-releasing hormone to myo-2[3H]inositol-prelabeled rat pituitary cells in primary culture evoked a dose-dependent increase of the accumulation of [3H]inositol phosphates with a rise of inositol triphosphate, inositol diphosphate and inositol monophosphate within 1 min. Using one contraceptive progestin, gestoden, inositol phosphate production was inhibited by 80% compared to controls of GnRH-treated cells without the addition of steroids. The data obtained in this study suggest that this in vitro bioassay using rat pituitary cells is a useful tool in testing progestational compounds regarding their potency on gonadotropin release. In addition, these results show that one possible site of interference of progestins with GnRH-induced gonadotropin secretion may involve polyphosphoinositide breakdown.

Gonadotropin releasing hormone enhances polyphosphoinositide hydrolysis in rat pituitary cells

Addition of gonadotropin releasing hormone to myo-[2-3H]inositol-prelabeled rat pituitary cells in primary culture evoked a dose-dependent increase of the accumulation of [3H]inositol phosphates with a rise of inositol triphosphate within 30 sec of stimulation, followed by a rise in inositol diphosphate and inositol monophosphate. Inositol phosphate accumulation was enhanced up to 5-to-8-fold and was time-dependent between up to 15 min incubation without further increase beyond this time period. Without preincubation with LiCl2, there was no measurable increase of GnRH-induced inositol phosphate accumulation compared to controls. The presence of calcium in the incubation medium did not affect the increase of inositol phosphates. These data give evidence, that polyphosphoinositide breakdown may be an early step in the action of gonadotropin releasing hormone on gonadotropin secretion.