Reproductive Hormones: Menotropins and Gonadotropins

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

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.