Hypothalamic and Pituitary Hormones 2.1

Question 1

ACTH analogs

Answer 1

Corticotropin

Cosyntropin

Question 2

MOA of ACTH analogs

Answer 2

Stimulate adrenal cortex via MC2 receptor -> increased cAMP -> steroid hormone secretion.

Question 3

Clinical application of ACTH analogs (2)

Answer 3

1) Differentiate between primary and secondary adrenal insufficiency
2) Infantile spasm (West Syndrome) treatment

Question 4

Oxytocin MOA

Answer 4

Acts on GPCRs -> stimulates release of prostaglandins & leukotrienes that augment uterine contraction.

Question 5

Small doses of Oxytocin does what?

Answer 5

Increases force and frequency of contractions

Question 6

Higher doses of Oxytocin does what?

Answer 6

evokes sustained contractions. Weak antidiuretic & pressor activity (vasopressin R activation).

Question 7

How does Oxytocin cause milk ejection?

Answer 7

Contraction of myoepithelial cells surrounding mammary alveoli.

Question 8

Oxytocin IV is used when

Answer 8

Initiation and augmentation of labor

Question 9

Oxytocin IM is used when

Answer 9

control of postpartum bleeding

Question 10

Adverse effects of Oxytocin (3)

Answer 10

1) Excessive stimulation of uterine contraction: fetal distress, placental abruption, uterine rupture
2) Inadvertent activation of vasopressin receptors: excessive fluid retention, water intoxication -> hyponatremia, heart failure, seizures, death.
3) Bolus injections can lead to hypotension

Question 11

Oxytocin contraindications (5)

Answer 11

• Fetal distress
• Prematurity
• Abnormal fetal presentation
• Cephalopelvic disproportion
• Uterine rupture predisposition

Question 12

Oxytocin antagonist

Answer 12

Atosiban

Question 13

Released in response to rising plasma tonicity or falling BP

Answer 13

Vasopressin

Question 14

Long acting synthetic analog of vasopressin with minimal V1 activity

Answer 14

Desmopressin

Question 15

V1R activation (via vasopressin agonists) leads to?

Answer 15

Vascular smooth muscle -> vasocontriction

Question 16

V2R activation (via vasopressin agonists) leads to?

Answer 16

Principal cells in collecting duct stimulate aquaporin 2 upregulation -> increased water permeability & reabsorption.