Introduction to Endocrine Pharmacology: The Hypothalamic-Pituitary Axis

Vocabulary-style flashcards covering key hypothalamic-pituitary topics, hormones, targets, tumor effects, and synthetic drugs mentioned in the notes.

Hypothalamus

Brain region that regulates emotional and autonomic functions and controls anterior and posterior pituitary hormone release.

Median Eminence

Hypothalamic region where hormones are released into the portal circulation to act on the anterior pituitary.

Mammillary Bodies

Hypothalamic structures involved in memory processing; part of the limbic system connections.

Third Ventricle

Midline brain ventricle near the hypothalamus; part of the ventricular system.

Optic Chiasm

X-shaped crossing of the optic nerves located near the hypothalamus.

Anterior Pituitary

Glandular portion of the pituitary that secretes GH, FSH, LH, PRL, ACTH, MSH, and TSH from its hormone-producing cells.

Posterior Pituitary (Neurohypophysis)

Neural portion that stores and releases hormones produced in the hypothalamus: oxytocin and vasopressin (ADH).

Somatotrophs

Anterior pituitary cells that secrete growth hormone (GH/Somatotropin).

Gonadotrophs

Anterior pituitary cells producing FSH and LH, which act on the gonads.

Lactotrophs

Anterior pituitary cells that secrete prolactin (PRL), promoting milk production.

Corticotrophs

Anterior pituitary cells that secrete ACTH (and MSH in small amounts).

Thyrotrophs

Anterior pituitary cells that secrete thyroid-stimulating hormone (TSH).

Growth Hormone (GH / hGH / Somatotropin)

Hormone from somatotrophs that stimulates growth and metabolism in tissues; increases protein synthesis and glucose levels.

Follicle-Stimulating Hormone (FSH)

Gonadotropin stimulating ovarian follicle development and estrogen production in females and spermatogenesis in males.

Luteinizing Hormone (LH)

Gonadotropin that triggers ovulation and stimulates estrogen/progesterone in females and testosterone in males.

Prolactin (PRL)

Hormone promoting milk production in the mammary glands.

Adrenocorticotropic Hormone (ACTH)

Stimulates the adrenal cortex to produce glucocorticoids (e.g., cortisol).

Melanocyte-Stimulating Hormone (MSH)

Hormone associated with skin pigmentation; may influence brain function; its role in humans is limited.

Thyroid-Stimulating Hormone (TSH)

Stimulates the thyroid gland to produce thyroid hormones (T3/T4).

Oxytocin (OT)

Posterior pituitary hormone causing uterine contractions and milk ejection; released in response to nipple stimulation and labor.

Vasopressin / Antidiuretic Hormone (ADH)

Posterior pituitary hormone that conserves body water by reducing urine output; increases blood pressure via vasoconstriction.

Hyposecretion

Too little hormone production, leading to deficient physiological effects.

Hypersecretion

Too much hormone production, leading to excessive physiological effects.

Mass Effects (Pituitary Tumors)

Symptoms caused by tumor growth, such as pain or visual disturbances from pressure on nearby structures.

Sermorelin (GH-RH)

Synthetic growth hormone-releasing hormone that raises GH quickly; used to assess GH responsiveness and treat GH deficiency.

Corticorelin (CRH)

Synthetic corticotropin-releasing hormone that stimulates ACTH and beta-endorphin release; used diagnostically.

Gonadorelin (GnRH)

Synthetic GnRH that stimulates FSH and LH when given pulsatile; used to test or induce ovulation and spermatogenesis.

Goserelin

Long-acting GnRH agonist used to suppress FSH/LH in PCOS, endometriosis, precocious puberty, and certain cancers.

Histrelin

GnRH agonist used similarly to suppress gonadotropins in several conditions.

Leuprolide

GnRH agonist used for suppression of gonadotropins in various disorders, including fibroid-related anemia and cancer.

Nafarelin

GnRH agonist used for suppression or modulation of FSH/LH in selected conditions.

Triptorelin

GnRH agonist used to stimulate or suppress gonadotropins depending on administration pattern.

Ganirelix

GnRH antagonist used to prevent premature LH surge during controlled ovarian hyperstimulation.

Cetrorelix

GnRH antagonist with similar use to Ganirelix in ovarian stimulation protocols.

Octreotide

Synthetic somatostatin analogue; inhibits GH and GI hormone release; used for hormone-secreting tumors and variceal bleeding; adverse effects include abdominal pain, diarrhea, and nausea.

Protirelin

Synthetic TRH that stimulates TSH and prolactin release; used to assess thyroid function and prolactin regulation.

Thyrotropin-Releasing Hormone (TRH)

Hypothalamic hormone that stimulates TSH and prolactin release from the anterior pituitary.

Corticotropin-Releasing Hormone (CRH / Corticorelin)

Hypothalamic hormone that stimulates ACTH and beta-endorphin release; used to distinguish causes of Cushing’s syndrome and hypocortisolism.

Gonadotropin-Releasing Hormone (GnRH) Preparations

GnRH and analogues (e.g., pulsatile or continuous) used to stimulate or suppress FSH/LH for fertility treatment or disease management.

GnRH Antagonists

Drugs (e.g., Ganirelix, Cetrorelix) that block GnRH effects to prevent premature LH surge during fertility protocols.