Gonadal Hormones Overview

Progesterone inhibits further ovulation by preventing the release of LH (luteinizing hormone) from the hypothalamus and pituitary gland.

If implantation of the ovum occurs, the corpus luteum continues to secrete progesterone, maintaining the uterine lining for pregnancy and preventing further ovulation.

Estrogen has a negative impact on bone health and can increase the risk of osteoporosis, particularly after menopause.

Estrogen can impair glucose tolerance, promote sodium/water retention, and lower LDL cholesterol while increasing HDL.

Estrogen increases the synthesis of blood clotting factors, potentially increasing stroke risk.

Estrogen exerts negative feedback on FSH (follicle-stimulating hormone) secretion.

Postmenopausal HT uses lower doses compared to contraceptives, minimizing potential adverse estrogen-related effects.

Osteoporosis treatment involves calcium supplements, vitamin D, calcitriol, bisphosphonates, and calcitonin.

Hormone Replacement Therapy using estrogen, used to treat symptoms of menopause and other conditions.

Synthetic estrogen analogs used in birth control pills (not elaborated on here).

Treatment for women with underdeveloped sex characteristics due to low estrogen production.

Treatment for women experiencing menopause before the typical age, replacing lost estrogen.

Estrogen therapy can increase the risk of breast and endometrial cancer; a progestogen can offset this risk.

Estrogen-like drugs with selective effects on estrogen receptors (acting differently in different tissues).

A SERM that blocks central estrogen receptors, used to treat infertility.

A SERM that blocks peripheral estrogen receptors mainly in breasts, for breast cancer treatment.

Progesterone helps prepare the uterus for pregnancy by thickening the lining, preventing contractions, and inhibiting ovulation.

Progesterone inhibits the release of LH (luteinizing hormone) from the pituitary gland, preventing ovulation.

Progesterone is produced by the corpus luteum, placenta, and in smaller amounts by the adrenal cortex and testes.

Progesterone increases the viscosity of cervical mucus, making it harder for sperm to reach the uterus.

Low progesterone levels can lead to menstrual irregularities, infertility, and miscarriage.

Progesterone causes a slight rise in body temperature after ovulation.

Synthetic progestins are more stable to metabolism, allowing for oral contraceptives.

Progestins are used to treat heavy bleeding, painful periods, and endometriosis.

Mifepristone is a synthetic steroid that blocks progesterone receptors, preventing the hormone from binding to its target cells. This disruption of progesterone's action leads to a decrease in its relaxing effect on the uterus, making it more sensitive to the action of prostaglandins.

When taken early in pregnancy, mifepristone interferes with the progesterone necessary to maintain the pregnancy, ultimately leading to abortion of the fetus. This effect occurs because progesterone is crucial for sustaining the uterine lining and preventing contractions.

Mifepristone is often combined with the prostaglandin analog misoprostol to induce uterine contractions and successfully terminate a pregnancy. Misoprostol enhances the effects of mifepristone by directly stimulating contractions.

Estrogen exerts a negative feedback mechanism on the release of LH and FSH from the pituitary gland, ultimately reducing the likelihood of ovulation.

Progestin works through several pathways: it inhibits the release of LH, thickens cervical mucus making it difficult for sperm to pass through, decreases fallopian tube contractility hindering egg transport, and causes endometrial atrophy making implantation less likely.

Synthetic estrogen analogs have a longer action and higher potency than natural estrogens. This stems from their slower metabolism in the liver and their storage in adipose tissue, from which they are slowly released.

Natural estrogen has reduced oral bioavailability as a result of first-pass metabolism in the liver. This means a significant portion is broken down before it can reach the bloodstream.

To bypass the first-pass metabolism, estrogen can be administered via various routes: transdermal (patches, gels, emulsions, sprays), intravaginally (tablets, creams, rings), or by injection.

The copper IUD creates inflammation in the uterus, making it difficult for an egg to implant. The progesterone IUD changes the lining of the uterus, making it less hospitable for a fertilized egg.

IUDs are generally good for women who've had a child and don't have certain infections or conditions. They are a long-term, effective contraception option.

Emergency contraception, also known as the "morning-after pill", uses high doses of hormones to prevent pregnancy after unprotected sex. It can be used within 72 hours of intercourse.

There are two main types: one containing progesterone (levonorgestrel) alone, and another containing both estrogen and progesterone (ethinyl estradiol and levonorgestrel).

Ulipristal is a progesterone agonist/antagonist that can be used for emergency contraception up to 5 days after unprotected intercourse.

Testosterone is a male hormone responsible for developing male traits, producing sperm, increasing muscle growth, and controlling growth spurts during puberty.

Testosterone aids in bone growth and development, helping prevent bone loss.

Dihydrotestosterone (DHT) is a potent androgen hormone produced in the body through the conversion of testosterone by the enzyme 5α-reductase. It plays a crucial role in male sexual development and function, as well as other bodily processes.

5α-reductase is an enzyme responsible for converting testosterone into DHT (dihydrotestosterone). This conversion is crucial for the development of male secondary sex characteristics and plays a significant role in many bodily functions.

Androgen replacement therapy aims to supplement low levels of testosterone in men due to conditions like hypogonadism, delayed puberty, infertility, or testicular failure. It helps to restore normal hormonal balance and improve associated symptoms.

Anabolic steroids, like nandrolone, can be used to treat conditions like severe anemia caused by bone marrow failure, as well as to help combat protein loss in patients with debilitating conditions.

Common side effects of androgens include liver damage, masculinization in women (like acne and excess hair growth), prostate enlargement in older men, fluid retention causing edema, and infertility due to suppressed hormone production.

5α-reductase inhibitors like finasteride and dutasteride block the conversion of testosterone into DHT (dihydrotestosterone), which can be used to shrink the prostate in men with benign prostatic hyperplasia (BPH).

Androgen receptor blockers like flutamide and bicalutamide block the binding of androgens (like testosterone and DHT) to their receptors, ultimately inhibiting their effects. This is used to treat prostate cancer.

Cyproterone Acetate (CPA) works as an androgen antagonist by competing with DHT for its receptors on target tissues. It also reduces the production of gonadotropins, thereby suppressing androgen production.