Endocrine pharmacology: sex hormones mechanism and actions MCQs With Answer

Introduction: This quiz collection focuses on endocrine pharmacology of sex hormones—covering the mechanisms of action, receptor biology, clinical applications, and adverse effects relevant to estrogens, progestins, and androgens. Designed for M.Pharm students in Advanced Pharmacology-II, the questions explore genomic versus non‑genomic signaling, selective receptor modulators, enzyme inhibitors (aromatase, 5α‑reductase), GnRH analogs, contraception strategies, assisted reproductive agents, and pharmacodynamic principles such as feedback regulation and binding protein effects. Each item emphasizes mechanistic understanding and therapeutic rationale to reinforce advanced concepts needed for clinical pharmacology, drug development, and evidence‑based therapeutic decisions in reproductive endocrinology.

Q1. Which description best defines the primary mechanism of action of classical steroid sex hormone receptors?

• Membrane ion channel activation leading to immediate changes in cellular ion flux
• G-protein coupled receptor activation producing rapid second messenger signaling
• Intracellular nuclear ligand‑activated transcription factors that modulate gene expression
• Extracellular enzyme inhibition altering peptide hormone degradation

Correct Answer: Intracellular nuclear ligand‑activated transcription factors that modulate gene expression

Q2. Rapid non‑genomic estrogen actions are primarily mediated through which receptor or pathway?

• Estrogen receptor α binding to DNA elements in the nucleus
• G-protein coupled estrogen receptor (GPER/GPR30) activation at the plasma membrane
• Inhibition of aromatase in adipose tissue
• Upregulation of sex hormone binding globulin (SHBG) synthesis in the liver

Correct Answer: G-protein coupled estrogen receptor (GPER/GPR30) activation at the plasma membrane

Q3. Which hepatic effect is classically associated with oral estrogen therapy and affects sex steroid pharmacokinetics?

• Decrease in albumin synthesis leading to increased free steroid levels
• Increase in sex hormone binding globulin (SHBG) synthesis reducing free androgen availability
• Induction of 5α‑reductase in the liver increasing DHT production
• Inhibition of hepatic CYP3A4 causing prolonged steroid half‑life

Correct Answer: Increase in sex hormone binding globulin (SHBG) synthesis reducing free androgen availability

Q4. The main contraceptive effect of combined estrogen–progestin oral contraceptives is achieved by which mechanism?

• Blocking progesterone receptors in the endometrium to prevent implantation
• Suppressing pituitary gonadotropins to prevent the midcycle LH surge and ovulation
• Directly inhibiting aromatase in ovarian follicles
• Increasing cervical mucus acidity to kill spermatozoa

Correct Answer: Suppressing pituitary gonadotropins to prevent the midcycle LH surge and ovulation

Q5. Tamoxifen is classified as a selective estrogen receptor modulator (SERM). Which profile correctly describes its tissue‑selective actions?

• Antagonist in bone, agonist in breast, antagonist in uterus
• Agonist in breast, antagonist in liver, neutral in bone
• Antagonist in breast, agonist in bone and partial agonist in uterus
• Pure antagonist across all estrogen target tissues

Correct Answer: Antagonist in breast, agonist in bone and partial agonist in uterus

Q6. Why are aromatase inhibitors primarily effective in postmenopausal estrogen receptor‑positive breast cancer?

• They block ovarian estrogen synthesis, which is the major source in postmenopausal women
• They inhibit peripheral conversion of androgens to estrogens, the predominant source after menopause
• They directly antagonize estrogen receptors in breast tissue
• They increase hepatic metabolism of estrogens via CYP induction

Correct Answer: They inhibit peripheral conversion of androgens to estrogens, the predominant source after menopause

Q7. Mifepristone’s primary mechanism in medical termination of pregnancy is:

• Estrogen receptor agonism leading to uterine contraction
• Progesterone receptor antagonism causing decidual breakdown and detachment
• Aromatase inhibition reducing estrogen support of the endometrium
• Oxytocin receptor agonism producing immediate myometrial contraction

Correct Answer: Progesterone receptor antagonism causing decidual breakdown and detachment

Q8. Finasteride reduces prostate volume primarily by which biochemical mechanism?

• Blocking androgen receptor binding of testosterone
• Inhibiting 5α‑reductase type II thereby reducing dihydrotestosterone (DHT) formation
• Stimulating hepatic clearance of testosterone
• Enhancing aromatization of androgens to estrogens

Correct Answer: Inhibiting 5α‑reductase type II thereby reducing dihydrotestosterone (DHT) formation

Q9. Chronic supraphysiologic androgen (anabolic steroid) use commonly impairs male fertility through which mechanism?

• Direct cytotoxicity to spermatogonia in the testes
• Peripheral conversion to estrogen causing uterine‑like tissue growth in testes
• Negative feedback at the hypothalamic–pituitary axis reducing GnRH, LH and FSH and suppressing spermatogenesis
• Competitive inhibition of androgen receptor in Sertoli cells

Correct Answer: Negative feedback at the hypothalamic–pituitary axis reducing GnRH, LH and FSH and suppressing spermatogenesis

Q10. GnRH agonists (e.g., leuprolide) exert a biphasic effect. What accounts for the sustained suppression of gonadotropins after initial stimulation?

• Permanent destruction of pituitary gonadotrophs
• Receptor down‑regulation and desensitization of pituitary GnRH receptors after continuous exposure
• Conversion of GnRH to an antagonist by pituitary enzymes
• Enhanced peripheral metabolism of LH and FSH

Correct Answer: Receptor down‑regulation and desensitization of pituitary GnRH receptors after continuous exposure

Q11. Ulipristal acetate used for emergency contraception is best described as:

• A pure progesterone receptor agonist that stabilizes the endometrium
• A selective progesterone receptor modulator (SPRM) that delays or inhibits ovulation and alters endometrial receptivity
• An estrogen receptor antagonist used to prevent implantation
• An aromatase inhibitor that prevents follicular estrogen synthesis

Correct Answer: A selective progesterone receptor modulator (SPRM) that delays or inhibits ovulation and alters endometrial receptivity

Q12. Clomiphene citrate induces ovulation by which key central mechanism?

• Direct stimulation of ovarian follicle maturation via FSH receptor agonism
• Estrogen receptor antagonism at the hypothalamus producing increased GnRH and subsequent FSH/LH release
• Inhibition of aromatase in granulosa cells increasing intraovarian androgens
• Suppression of prolactin secretion to normalize gonadotropin release

Correct Answer: Estrogen receptor antagonism at the hypothalamus producing increased GnRH and subsequent FSH/LH release

Q13. Which adverse event is most strongly linked to systemic estrogen therapy and requires clinical vigilance?

• Osteoporosis due to bone resorption
• Increased risk of venous thromboembolism (VTE) due to hepatic clotting factor induction
• Profound hypoglycemia from insulin sensitization
• Hyperkalemia from renal potassium retention

Correct Answer: Increased risk of venous thromboembolism (VTE) due to hepatic clotting factor induction

Q14. Danazol, used in endometriosis, exerts its effect primarily by which pharmacological action?

• Pure estrogen agonism to outcompete local progesterone
• Synthetic androgen action that suppresses pituitary gonadotropin secretion and lowers ovarian estrogen production
• Aromatase activation increasing local estrogen in the endometrium
• Selective progesterone receptor modulation enhancing implantation

Correct Answer: Synthetic androgen action that suppresses pituitary gonadotropin secretion and lowers ovarian estrogen production

Q15. Fulvestrant differs from tamoxifen mechanistically because it:

• Acts as a partial estrogen agonist in bone
• Is a pure estrogen receptor antagonist that promotes receptor degradation
• Stimulates hepatic SHBG more than tamoxifen
• Preferentially activates GPER for rapid signaling

Correct Answer: Is a pure estrogen receptor antagonist that promotes receptor degradation

Q16. Progesterone supports early pregnancy primarily through which uterine action?

• Inducing endometrial proliferation to increase implantation surface area
• Transforming the endometrium to a secretory state and reducing myometrial contractility
• Stimulating luteinizing hormone release to maintain the corpus luteum
• Converting androgens to estrogens in the decidua

Correct Answer: Transforming the endometrium to a secretory state and reducing myometrial contractility

Q17. Why are aromatase inhibitors less effective as monotherapy in premenopausal women compared with postmenopausal women?

• Premenopausal women have higher SHBG which sequesters aromatase inhibitors
• Ovarian estrogen production driven by the gonadotropin axis remains a dominant source in premenopausal women
• Premenopausal ovaries lack aromatase enzyme altogether
• Aromatase inhibitors are rapidly inactivated by higher estrogen levels in premenopausal women

Correct Answer: Ovarian estrogen production driven by the gonadotropin axis remains a dominant source in premenopausal women

Q18. Spironolactone is used off‑label for androgen excess in women. Its antiandrogenic actions include:

• Pure aromatase inhibition converting androgens to estrogens
• Androgen receptor antagonism and partial inhibition of androgen synthesis enzymes
• Selective stimulation of SHBG release without receptor effects
• Direct destruction of Leydig cells in the testes

Correct Answer: Androgen receptor antagonism and partial inhibition of androgen synthesis enzymes

Q19. The primary mechanism by which levonorgestrel emergency contraception prevents pregnancy is:

• Destroying a newly implanted zygote in the endometrium
• Blocking fertilization by creating a hostile uterine pH
• Delaying or inhibiting ovulation primarily by suppressing the LH surge
• Acting as a potent estrogen receptor antagonist to prevent implantation

Correct Answer: Delaying or inhibiting ovulation primarily by suppressing the LH surge

Q20. What is the principal pharmacological role of sex hormone‑binding globulin (SHBG) in steroid hormone physiology?

• Acting as a receptor that mediates intracellular steroid signaling
• Binding circulating sex steroids and lowering the free, bioavailable fraction; its levels are increased by estrogens and decreased by androgens
• Enzymatically converting testosterone to dihydrotestosterone in plasma
• Transporting steroids into mitochondria for metabolism

Correct Answer: Binding circulating sex steroids and lowering the free, bioavailable fraction; its levels are increased by estrogens and decreased by androgens

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