Reproductive Hormones: Menotropins and Gonadotropins

Study Notes

Menotropins (Human Menopausal Gonadotropins, hMG)

Contain a mixture of LH and FSH
Isolated from the urine of postmenopausal women
Urofollitropin (Bravelle) is immunologically purified FSH from the urine of pregnant women
Follitropin α/β are recombinant FSH products
Must be administered parenterally (SC or IM)

Therapeutic Uses of hCG

Stimulates gonadal steroidogenesis in cases of LH insufficiency
Induces external sexual maturation and spermatogenesis in men with secondary hypogonadism
Promotes the descent of the testes in cryptorchidism

Therapeutic Uses of hMG

Stimulates ovulation in women with functioning ovaries
Used in concert with hCG to stimulate follicular growth and maturation

Adverse Effects of Menotropins and hCG

Ovarian enlargement in about 20% of treated women
Ovarian hyperstimulation syndrome in up to 1% of patients
Ascites
Hypovolemia and shock
Acute respiratory distress

Anti-Diuretic Hormone (ADH, Vasopressin)

Synthesized in the hypothalamus and stored in the posterior pituitary
Released in response to increasing plasma osmolarity or hypotension
Acts on three types of specific receptors: V1a, V1b, and V2
Increases permeability of water in renal tubules and transports urea in the inner medullary collecting duct
Causes vasoconstriction at higher doses

Therapeutic Uses of ADH

Desmopressin is the most effective treatment for severe central diabetes insipidus
Reduces nighttime urine production in nocturnal enuresis
Included in the advanced cardiac life support protocol as a substitute for epinephrine in cardiac arrest with asystole

Gonadotropin-Releasing Hormone (GnRH) and Analogs

Adverse effects in women: hot flushes, sweating, diminished libido, depression, ovarian cysts
Adverse effects in men: hot flushes, edema, bone pain, diminished libido, gynecomastia

GnRH Receptor Antagonists

Competitively and reversibly bind to GnRH receptors in the pituitary gland
Block the release of LH and FSH from the pituitary
Examples: Ganirelix, Abarelix, Cetrorelix
Rapidly reduce sex hormone levels without an initial surge
Used in prostate cancer, hormone-sensitive breast cancer, benign disorders such as endometriosis and uterine fibroids, and some cases of infertility

Prolactin-Inhibiting Factor (PIF, Dopamine Agonists)

Therapeutic uses: inhibition of prolactin secretion in amenorrhea, galactorrhea, and prolactin-secreting tumors
Correction of female infertility secondary to hyperprolactinemia
Treatment of Parkinson disease

Growth Hormone

Released in a pulsatile manner, with highest levels during sleep
Decreases with increasing age
Administered SC or IM
Half-life: 25 min
Induces IGF-1 release by the liver, responsible for GH-like actions

Therapeutic Uses of GH

Replacement therapy in children with GH deficiency before epiphyseal closure
Growth failure due to Prader-Willi syndrome
Stimulation of growth in patients with Turner syndrome
Long-term replacement of GH deficiency in adults
Treatment of cachexia and AIDS wasting

Growth Hormone Antagonists

Pegvisomant: blocks the action of endogenous GH
Used specifically for the treatment of acromegaly
Administered SC

Description

Test your knowledge on menotropins, human menopausal gonadotropins, and gonadotropins, including their composition, sources, and purification methods. Learn about the differences between LH and FSH, and how they are produced and used in medical treatments.