1N - Fundamentals Of Neuroendocrinology

Front 1

What are the 4 ways cells communicate with each other?

Back 1

Gap Jxns: direct cell-cell
Nerve Synapses - Neurotrans.
Paracrine - Local regulation
Endocrine - Secreted hormones into circulation

Front 2

What is the hypothalamus composed of?

Back 2

Collection of nuclei which control pituitary function.

Front 3

What two nuclear regions are involved in POSTERIOR PITUITARY control?

Back 3

Supraoptic and paraventricular nuclei

Front 4

What are the ONLY TWO HORMONES BY POSTERIOR PITUITARY?

Back 4

ADH and oxytocin.

Front 5

Which pituiary region is of neural origin?

Back 5

POSTERIOR!

Anterior originates from ectodermal evagination of orophranyx and migrates to join posterior pituiary.

Front 6

How is the ANTERIOR PITUITARY NEUROREGULATED?

Back 6

Hormones are secreted into the PORTAL CIRCULATION (primarily via ARCUATE NUCLEUS) to Anterior Pituitary

Front 7

The PORTAL CIRCULATION IS PARTICULARLY INVOLVED IN WHAT PITUITARY?

Back 7

ANTERIOR!

Front 8

What hormones are secreted by each cell type?

Somatotrophs?
Lactotrophs?
Thryotrophs?
Corticotrophs?
Gonadotrophs?

Back 8

Somatotrophs - Growth Hormone
Lactotrophs - Prolactin
Thyrotrophs - TSH
Corticotrophs - ACTH
Gonadotrophs - LH & FSH

Front 9

What TWO TRANSCRIPTION FACTORS control PRIMORDIAL ANTERIOR PITUITARY DIFFERENTIATION?

Back 9

PROP1, PIT1

Front 10

Individuals deficient in PROP1, PIT1 exhibit what symptoms?

Back 10

They exhibit panhypothyroidism. Stunted growth, delayed puberty, hypothyroidism, amenorrhea

Front 11

What is the hypothalamus in relation to anterior pituitary?

Back 11

HYPOTHALAMUS IS FINAL COMMON PATHWAY for multiple systems to reach the anterior pituitary.

Hypothalamus also interacts with other areas of the CNS.

Front 12

How do sterior/thyroid hormones elicit actions DIFFERENTLY than hormones in circulation?

Back 12

Steriod/thyroid hormones interact directly with cells. Cross blood-brain barrier and produce specific receptor-mediated actions

Hormones in circulation elicit changes INDIRECTLY.

Front 13

Where are the cell bodies of GnRH-synthesizing neurons located?

Back 13

Since GnRH is involved in ANTERIOR PITUITARY, then cell bodies are in ARCUATE NUCLEUS (of the hypothalamus) and travel VIA PORTAL CIRCULATION

Front 14

Where do GnRH-synthesizing cells originate from?

Back 14

They originate in OLFACTORY PLACODE (from ectorderm).

Front 15

What is Kallman's Syndrome

(hint, involved in GnRH production?)

Back 15

Failed migration of GnRH-producing cells from olfactory placode to Arcuate Nucleus.

The result is an ABSENCE of PUBERTAL DEVELOPMENT AND IMPAIRED SMELL.

These patients have pubic hair because this ADRENAL responsible for this.

Front 16

What is the role of GnRH?

Back 16

Determines the onset of puberty, basal levels of gonadotropin secretion, phasic release of gonadotropins for folliculogenesis and ovulation.

Front 17

GnRH is pulsatile OR continuous secretion?

What are GnRH amplitude/frequency relations between follicular and luteal phase of menstrual cycle?

Back 17

Luteal cycle = Higher amplitude, lower frequency

Follicular cycle = Lower amplitude, higher freuqncy.

These amplitude/frequency changes result from FSH/LH release from pituitary

Front 18

What is the difference between a LONG-ACTING GnRH AGONIST and a GnRH PUMP?

Back 18

LONG-ACTING GnRH AGONIST: Will intially increase levels of FSH and LH, but CAN eventually SHUT DOWN testes/ovary system due to GnRH receptor downregulation on pituitary gonadotrophs.

GnRH AGONIST is good for IVF, precocious (early onset) puberty, estogen-sensitive conditions like fibroids/endometriosis

GnRH PUMP is pulsatile (LIKE IS SUPPOSED TO BE), which can INDUCE folliculogenesis and ovulation in GnRH-deficient patients. In men, can induce puberty/spermatogenesis

Front 19

Are FSH/LH secreted in pulsatile or continuous fashion?

Back 19

PULSATILE!

Front 20

Alpha-subunit for LH and FSH is identical to what other hormones?

Back 20

TSH, hCG. It is the B-subunit involved in unique biologic activity.

LH VERY SIMILAR TO hCG. Can replace LH with hCG to induce ovulation.

Front 21

What cells produce INHIBIN in men/women?

Back 21

INHIBIN in men is produced by SERTOLI cells. (Testes - Laydig cells make testosterone)

INHIBIN produced in granulosa cells in women. Granulosa cells also produce estradiol

Front 22

What are the 3 FUNCTIONS OF FSH in females?

Back 22

1) Increases FSH receptor numbers

2) Stimulates granulosa cell ESTRADIOL production by aromatase induction

3) Stimulates growth and proliferation of granulosa cells

Front 23

What are the 3 FUNCTIONS OF LH in females?

Back 23

1) Stimulate THECA CELLS to produce ANDROGENS which are CONVERTED TO ESTROGENS in GRANULOSA CELLS

2) LH surge induces ovulation

3) LH triggers estrogen and progesterone secretion by granulosa cells AFTER ovulation

Front 24

What are 3 FUNCTIONS OF FSH in males?

Back 24

1) Testicular growth

2) Stimulates SERTOLI cells - essential for spermatogenesis

3) Sertoli cells PRODUCE ANDROGEN BINDING PROTEIN, which concentrates testosterone in the testis.

Front 25

What are 2 FUNCTIONS OF LH in males?

Back 25

1) Stimulates Leydig cell testosterone production

2) Required for maturation of spermatozoa

Front 26

What are the roles of following hormones in REGULATION OF GnRH?

Prolactin?
CRH?
LEPTIN?
OPIATES?
MELATONIN?
NEUROPEPTIDE Y/KISSPEPTIN?

Back 26

Prolactin - SUPRESSES GnRH (lactating amenorrhea)
CRH - SUPRESSES GnRH (stress-related amenorrhea)
LEPTIN - INCREASES GnRH (satiation-related hormone. Anorexica are lepin deficient)
OPIATES - SUPPRESSES GnRH - (naltrexone can fix this)
MELATONIN - SUPPRESSES GnRH (pineal gland)
NEUROPEPTIN Y, KISSPEPTIN - BOTH STIM/INHIB.

Front 27

What are PEAK LEVELS in GONADOTROPIN IN LIFETIME?

Back 27

MIDGESTATION (2nd trimester) - fetus' H-P axis is fully functional

POST-BIRTH: Surge in Gonadotropin due to LACK OF INHIBITION FROM PLACENTAL STEROIDS.

Puberty-reproyears - Increase in pubtery and fluctuations during menstruations

Menopause - LOSS OF INHIBITORY FEEDBACK FROM OVARIES. INCREASE IN FSH AND LH

Front 28

HYPOTHYROIDISM can lead to what repro abnormalities?

HINT: All menstrual cycle related

Back 28

ALL MENSTRUAL CYCLE RELATED

1) Anovulation

2) Menstrual irregularities

3) Amenorrhea

Front 29

A-subunit of TSH is similar to A-subunit of which other hormones?

Back 29

FSH, LH, hCG.

TSH stimulates Iodide uptake, production and release of thyroxine (T4) and triiodothyronin (T4), increased gland vascularity and size.

Front 30

What are levels of TRH during hypothyroidism and hyperthyroidism?

Back 30

TRH is ELEVATED if TSH levels are low (HYPOTHYROIDISM)

Conversely, TRH is DECERASED if TSH levels are high (HYPERTHYROIDISM)

Front 31

What is TRH's relation to PROLACTIN?

Back 31

TRH STIMULATES PROLACTIN. PROLACTIN SUPPRESSES GnRH.

Front 32

TRUE/FALSE?

HYPERPROLACTINEMIA LEADS TO HYPOGONADISM?

Back 32

TRUE. Although NOT DIRECTLY.

Increased prolactin suppresses GnRH (remember lactating amenorrhea).

This results in anovulation, amenorrhea, infertility in women and decreased libido, infertility, impotence in men.

Front 33

What is the MAJOR INHIBITOR OF PROLACTIN?

Back 33

DOPAMINE.

Remember, antipsychotics that block D2 receptor have HYPERPROLACTINEMIA as a side-effect. "Disinhibition of inhibition"

Front 34

What are the MAJOR STIMULATORS OF PROLACTIN?

Back 34

1) Chest-wall nerve stimulation (suckling, nipple stim)

2) TRH (hypOthyroidism)

3) Estrogen

4) STRESS!