Neuroendocrine Control

Question 1

Which hormone is secreted by the parvocellular neurons in the preoptic region?

Answer 1

GnRH

Question 2

Which hormones are secreted by the parvocellular neurons in the paraventricular nucleus?

Answer 2

TRH, CRH

Question 3

Which hormones are secreted by the magnocellular neurons of the paraventricular and supraoptic nuclei?

Answer 3

oxytocin, vasopressin

Question 4

What nucleus produces dopamine, GHRH, somatostatin?

Answer 4

arcuate nucleus of hypothalamus

Question 5

Which neurons extend axons into the pituitary and release hormones directly into circulation?

Answer 5

magnocellular

Question 6

which hormones are produced by the neurohypophysis?

Answer 6

vasopressin and oxytocin

Question 7

in which pituitary gland are hormones stored in axon terminals until needed?

Answer 7

posterior pituitary

Question 8

What is the stimulus for oxytocin release in childbirth? How is it regulated?

Answer 8

• stimulus: contractions of the myometrium and vaginal stretch
• regulation: positive feedback

Question 9

What is the stimulus for oxytocin release in milk ejection? How is it regulated? What is the name for this reflex?

Answer 9

• stimulus: suckling or mechanical manipulation of the breast
• regulation: positive feedback
• name: letdown reflex

Question 10

What is the stimulus for oxytocin release in the brain? How is it regulated?

Answer 10

• stimulus: skin to skin contact, orgasm
• regulation: trust and bonding, stress, anxiety, conflict, etc.

Question 11

brain OXT is involved in regulating what? What disorders can targeting brain OXT potentially treat?

Answer 11

• regulate: anxiety, stress, social behaviours
• disorders: SAD, PTSD, social phobia, addiction, autism

Question 12

What are some therapeutic uses of oxytocin?

Answer 12

• induction of labour
• augmentation of dysfunctional labor
• prevention and treatment of postpartum hemorrhage
• nasal spray for social disorders

Question 13

What is normal release of vasopressin triggered by?

Answer 13

• increase in blood osmolality
• decrease in blood volume
• drop in BP

Question 14

What happens to the level of vasopressin during acute stress?

Answer 14

rapid increase

Question 15

effects of vasopressin on the kidneys?

Answer 15

increase water reabsorption –> increase BP

Question 16

How does vasopression regulate blood pressure?

Answer 16

vasoconstriction due to smooth muscle contraction

Question 17

effect of vasopressin on the anterior pituitary?

Answer 17

contributes to the full ACTH response

Question 18

What are therapeutic uses of vasopressin on the kidney?

Answer 18

• treatment of diabetes insipidus (polyuria and polydipsia - lots of urine and always thirsty)
• nocturnal enuresis

Question 19

what are the therapeutic uses of vasopressin as a vasoconstrictor?

Answer 19

prophylaxis against bleeding in haemophilia

Question 20

What are the therapeutic uses of vasopressin in social behaviour?

Answer 20

autism

Question 21

How is control of the adenohypophysis different from the neurohypophysis?

Answer 21

• adenohypophysis: hormones secreted into CAPILLARIES of hypothalamus (NOT DIRECTLY into hypothalamus)
• portal system that allows for shortcut because hormones do not have to pass through general circulation

Question 22

List the somatotropic hormones.

Answer 22

GH, PRL, placental lactogen

Question 23

List the POMC-derived hormones.

Answer 23

ACTH, alpha-MSH

Question 24

List the glycoprotein hormones.

Answer 24

LH, FSH, hCG, TSH

Question 25

What is the main inhibitor of GH release?

Answer 25

somatostatin

Question 26

What is the main stimulant of GH release?

Answer 26

GHRH

Question 27

How does ghrelin affect GH release? What does it act on? What is its mechanism? Elaborate.

Answer 27

- in short: stimulate GH release via disinhibition - act on: somatotrophs - mechanism: somatostatin antagonist - IGF-1 causes negative feedback inhibition of GH release - decrease GH --> decrease IGF-1 - ghrelin inhibits somatostatin --> decrease GH --> decrease IGF-1 --> NO negative feedback inhibition of GH (i.e. stimulate GH release)

Question 28

what are the direct actions of GH?

Answer 28

- promote postnatal growth --> induce bone growth - increase lipolysis in adipocytes --> decrease body fat - increase AA uptake and nitrogen retention in muscle --> maintain muscle mass and strength

Question 29

What is the indirect action of GH?

Answer 29

key regulator of IGF-1, which causes negative-feedback inhibition of GH release

Question 30

diseases associated with GH deficiency?

Answer 30

- pituitary dwarfism in children - hypopituitarism in adults

Question 31

diseases associated with excessive GH?

Answer 31

- gigantism in children - acromegaly in adults

Question 32

therapeutic uses of GH?

Answer 32

- GH replacement in: pituitary dwarfism, Turner's syndrome short stature, hypopituitarism - Recombinant GH antagonist in: acromegaly, gigantism