[The contraceptive efficacy and mechanism of action of combinations of ethinyl estradiol and norethisterone acetate]. / Kontratsevtivnaia éffektivnost' i mekhanizm deistviia kombinatsii étniléstradiola i norésterona atsetata.

The purpose of the study was to establish the optimal combinations of ethynilestradiol and norethysterone acetate exhibiting a high contraceptive activity. It was shown that the ratio of 1:20 (ethynilestradiol 0.04 mg/kg and norethysterone acetate 0.8 mg/kg) is characterized by a high contraceptive efficacy. The inhibitory effect on the incretion of lutropin and follitropin leading to the change of the process of oogenesis and gravidary reorganization of the endometrium underlies probably the mechanism of action.

[A comparison of the hormonal and etholotropic activity of luliberin and its analogs]. / Sravnenie gormonal'noi i étoltropnoi aktivnosti liuliberina i ego analogov.

The paper is devoted to comparative analysis of the activity of peptides (LH-RH analogs) with relation to their action on ovulation as well as on the learning capabilities and their effect on immobilization stress in rats. The acceleration of learning processes and elimination of immobilization stress were shown to be caused by LH-RH and its analogs, regulating actively ovulation under experimental conditions. The comparative evaluation of their action has shown that LH-RH analogs-antagonists produce a more marked effect on the process of learning and elimination of stress consequences than its analogs-agonists.

[The effect of oxytocin, prostenon and obzidan on uterine contractile activity in pregnant rats]. / Vliianie oksitotsina, prostenona i obzidana na sokratitel'nuiu aktivnost' matki beremennykh krys.

The results of experimental pharmacological studies may help obstetricians to make a choice of a schedule of using the uterotropic drugs and their doses. In vivo and in vitro experiments on pregnant rats showed that administration of the Soviet-made prostaglandin E2--prostenon--in combination with oxytocin and obsidan in half doses increased its stimulating effect on the myometrium. The use of prostenon and oxytocin against the background of partusisten treatment was not followed by a significant change of their stimulating uterotropic action.

[Changes in the cytologic and electrophysiologic parameters of rat oocytes in response to prostaglandins F2 alpha and E2]. / Izmenenie tsitologicheskikh i élektrofiziologicheskikh parametrov ootsitov krys pod vliianiem prostaglandinov F-2al'fa i E-2.

Influence of prostaglandins F-2 alpha and E-2 on ovulation character and on the state of the ovulated gametes has been studied in rats at the preovulatory period (the preparations have been injected for 3 days, beginning from the 1st day of early proestrus). Under the effect of prostaglandins the amount of postovulated ova decreases, especially in the animals given prostaglandin E-2. Inhibition of ovulation in these animals is accompanied with an increased part of hyperpolarized ova, appearance of some signs of degeneration in the group of depolarized oocytes and absence of oocytes with polarized membrane at the metaphase I stage. These facts can be interpreted as desynchronization of maturation processes and ova ovulation. Mechanisms of the changes revealed in the ovulatory process and the state of gametes under the prostaglandins effect are discussed.

[Effect of an estrogen-progestin preparation alone and in combination with amizil on the structure and electrophoretic parameters of oocytes and early rat embryos]. / Vliianie estrogen-progestinovogo preparata i ego kombinatsii s amizilom na strukturu i élektrofiziologicheskie parametry ootsitov i rannikh émbrionov krys.

An increasing contraceptive effect at a combined administration of steroid drugs with neurotropic substances--M-cholinolytic benactyzine, makes the problem on the character and mechanism of their action. In the experiments performed in rats, under effect of ethinyl estradiol and norethisteron acetate, and especially at their combination with benactyzine, the first signs of overmaturation are revealed in oocytes situating in the follicular cavity. Therefore, oocytes revealed in the rat fallopian tubes leave behind the development of the control oocytes. The drugs investigated, influencing maturation and ovulation mechanisms of oocytes, produce certain physiological and morphological changes in ovaries of the test rats. This, evidently, defines the mechanism of their elevated contraceptive action. Overmaturation of oocytes in follicles, ovulation at later developmental stages results in increasing amount of degenerative forms of embryos and in disturbance of their development.

[Effect of a cyclic luliberin analog on ovulation]. / Issledovanie vliianiia na ovuliatsiiu tsiklicheskogo analoga liuliberina.

A study was made of the cyclic LH-RH analog and its linear precursor on infantile and mature female rats. The compounds showed various biological properties which manifested themselves in their effects on ovulation. The linear analog proved to be an antagonist and the cyclic analog the LH-RH agonist. A hypothesis to the effect that the LH-RH biologically active conformation has a quasicyclic structure, has been confirmed.

[Steroid and nonsteroid postcoital contraceptives]. / Steroidnye i nesteroidnye kontratseptivy postkoital'nogo deistviia.

It has been shown experimentally that a combined use of estrogen-norsteroids prostaglandins and neurotropic substances during preimplantation period produces the most potent contraceptive effect. Analysis of the action mode of combined small doses of steroids, prostaglandins and neurotropic drugs suggests that the contraceptive action is underlain by the inhibitory effect on incretion produced by the luteinizing hormone, this effect being in its turn a reason for variation in the amount and condition of the developing fetuses.

[Mechanism of contraceptive effect of low progestin doses]. / K voprosu o mekhanizme kontratseptivnogo deistviia malykh doz progestinov.

PIP: The effect of megestrol-acetate and ethynodiol-triacetate on the ovulation and on the division of impregnated ovules was examined. Experiments were performed on human oocysts. The progestins were also administered to animals with normal cycle. Males were placed with the females after 3 days of treatment. The time of fecundation was determined from the presence of spermatozoa in vaginal smears. The experiments with incubation of human ovules with megestrol-acetate or ethynodiol-diacetate indicated that maturation, fecundation and development of the ovules up to 4-8 blastomeres are not hindered. This was confirmed by the data obtained from a control group. Thus no cytotoxic effect of progestin was recorded in the preovulation period of the maturation nor during fecundation. The experiments with animals revealed no change in the character of the ovulation provoked by a 14-day treatment with progestins. These results allow to conclude that the contraceptive effect of megestrol-acetate and ethynodiol-diacetate is not linked with a damaging effect on the division of the ovule during its presence in the tubes.^ieng

[Study of the mechanism of postcoital contraception in the combination of streoids and the central m-cholinolytic, amizil]. / Izuchenie mekhanizma postkoital'noi kontratseptsii pri sochetanii steroidov i tsentral'nogo m-kholinolitika amizila

Experiments on female rats showed the blocking of the M-cholinoreactive system with amizyl to significantly contribute to the estrogen/norsteroid contraceptive effect during the postcoital periods. This effect was accompanied by decrease in the gonadotropin level and by the change in the LH/FSH ratio, this creating an unfavourable background for implantation of the fertilized ovicell in the endometrium. There was a change in the transport rate in the tube and a delay in the decidual reaction. Changes in the rate of the ovicell transport were not accompanied by distrubances in the process of fertilization or with the cytotoxic action. Mestranol and ethynylestradiol in combination with norethynodrel (1:20) and with the central cholinolytic amizyl were agents with future prospects for short-term postcoital contraception.