Studies on the Mode of Action of Oral Contraceptives: Effect of Chlormadinone on Pituitary FSH and Lh Contents of the Female Rat

Labhsetwar, A. P.

doi:10.1530/jrf.0.0170101

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…Clinical work has suggested direct effects on the ovaries (Brown, Fotherby & Loraine, 1962;Loraine, Bell, Harkness, Mears & Jackson, 1963) and pituitary (Vorys, Ullery & Stevens, 1965). However, results obtained from experimental animals largely support the view that the hypothalamo-pituitary system is the major site of action for these compounds (Pincus, 1965;Kawakami & Sawyer, 1967;Labhsetwar, 1968). It is also possible that certain of these agents act at more than one site in the body (Hilliard, Croxatto, Hayward & Sawyer, 1966 a).…”

Section: Introductionmentioning

confidence: 90%

Effects of Ovarian Steroids on the Norethisterone-Blockade of Ovulation in the Rat

McDonald¹,

Gilmore²

1969

Journal of Endocrinology

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In the majority of normal cycling female rats, a single injection of norethisterone (0\m=.\5mg.) delayed ovulation by 24 hr. The number of animals showing delayed ovulation was dependent upon the stage of the cycle and the time of day at which the steroid was given. Injection on day 1 (oestrus) and day 3 (dioestrus 2) was most effective (80% delay) followed by day 2 (dioestrus 1, 50% delay) and day 4 (pro-oestrus, 0% delay). Oestradiol benzoate (5 \g=m\g.)given to norethisterone-treated rats on day 3 largely overcame the delaying action of the steroid. Similarly the injection of progesterone (1 mg.) on day 4 advanced ovulation by 24 hr. in most of the norethisterone-treated rats. It is suggested that norethisterone exerts its effects at both pituitary and hypothalamic levels.

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Section: Introductionmentioning

confidence: 90%

Effects of Ovarian Steroids on the Norethisterone-Blockade of Ovulation in the Rat

McDonald¹,

Gilmore²

1969

Journal of Endocrinology

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“…Animal experiments suggest that the contraceptive steroids exert their effect on suppression of ovulation by blocking the oestrogen receptor sites in the hypothalamus, and possibly also in the pituitary, with reduction of gonadotrophin release (Labhsetwar, 1968). Animal experiments suggest that the contraceptive steroids exert their effect on suppression of ovulation by blocking the oestrogen receptor sites in the hypothalamus, and possibly also in the pituitary, with reduction of gonadotrophin release (Labhsetwar, 1968).…”

Section: The Effect On Hypothalamic Pituitary Functionmentioning

confidence: 99%

Hormonal Steroid Contraceptives1 I

Seddon

1971

Drugs

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The complex mechanism concerned with the initiation and establishment of a pregnancy involves ovulation, the adequate access to the egg by 'active' spermatozoa followed by the transport of the zygote to the uterine cavity where it can imbed and grow in the suitably prepared endometrium. The sites within a woman vulnerable to the action of contraceptive agents are therefore the hypothalamic-pituitary axis, the ovary, the fallopian tubes, the endometrium and the cervix.Hormonal steroid contraceptives in common use consist of synthetic oestrogens (ethinyloestradiol or mestranol) and progestagens derived from 19-nortestosterone or 17a-hydroxyprogesterone.The mechanism of action of contraceptive drugs is complex because closely related compounds may have different pharmacological effects which will also vary with dose levels and combination with other steroids.Suppression of ovulation may be achieved by oestrogens reducing the release of FSH and the progestagens suppressing the peak of LH release. Some contraceptive steroids may also exert a direct effect upon the ovary, influencing steroidgenesis. Contraception may be achieved without ovulation-suppression, due to the disturbance of the normal luteal phase of the endometrium, and possibly by interfering with tubal transport, although this later inference is based almost solely on animal studies. Progestagens produce changes in the physico-chemical structure of the cervical mucus making it 'hostile' to sperm penetration, but an appreciation of the full effects of progestagens on sperm activity must await the resolution of the role of sperm capacitation in the human.Although there have been reports of masculinisation of the female fetus following the use of large doses of certain progestational steroids for non-contraceptive purpose, there is 1 First of four parts. 2 See subject index in each issue for further indexi ng terms.Hormonal Steroid Contraceptives 400 no evidence that the inadvertent use of hormonal steroids at oral contraceptive dosage during early pregnancy, causes abnormal development of the external genitalia in the newborn.It is possible that some contraceptive steroids may interfere with lactation once it has become firmly established and oestrogen-containing preparations are best avoided early in the puerperium because of the associated increased risk of thromboembolism.Return of fertility after oral steroidal contraception is usually prompt and although the statistical evidence is not certain there is a strong clinical impression that a 'rebound' of increased fertility may occur. However, there is an undetermined small minority of women who remain infertile due to a continued failure of ovulation. Some of these women have had menstrual disturbance before contraception and most respond favourably to ovulationstimulation therapy.Steroid contraceptive compounds not only affect the physiology and structure of most of the reproductive organs but may affect systems remote from those immediately concerned with reproduction. A reduction of BSP excretion by th...

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Biological profile op the steroid 5α-stigmastane-3β,5, 6β-triol-3-monobenzoate

Pakrashi¹,

Chakrabarty²

1981

Contraception

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Studies on the Mode of Action of Oral Contraceptives: Effect of Chlormadinone on Pituitary FSH and Lh Contents of the Female Rat

Cited by 6 publications

References 15 publications

Effects of Ovarian Steroids on the Norethisterone-Blockade of Ovulation in the Rat

Effects of Ovarian Steroids on the Norethisterone-Blockade of Ovulation in the Rat

Hormonal Steroid Contraceptives1 I

Biological profile op the steroid 5α-stigmastane-3β,5, 6β-triol-3-monobenzoate

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