Anterior Pituitary - Endocrine

Question 1

Name the main hormones secreted from the anterior pituitary.

Question 2

Describe the function of each hormone from the anterior pituitary.

Question 3

Describe diseases related to anterior pituitary hormones.

Question 4

5 Distinct Cell Types of the Anterior Pituitary:

Answer 4

• Lactotrophs (PRL)
• Gonadotrophs (FSH, LH)
• Thyrotrophs (TSH)
• Corticotrophs (ACTH)
• Somatotrophs (GH)

Question 5

Pituitary Gland Hormones:

Question 6

Gondadotropin releasing hormone (GnRH)

Released from ?

Regulates?

Answer 6

Hypothalamus releasing hormone

• Stimulates LH + FSH to be released from the anterior pituitary
  
  • Gonadotrophs
• Regulates Gonads (Ovary and testis)
  
  • Target Tissues

Question 7

Prolactin releasing factors (TRH and PRH)

Released from?

Regulates?

Answer 7

• Hypothalamus releasing hormone
• Stimulates PRL to be released from the anterior pituitary
  
  • Lactotrophs
• Regulates Mammary Glands
  
  • Target Tissues

Question 8

Prolactin Inhibiting Factor (Dopamine)

Released from?

Regulates?

Answer 8

• Hypothalamus releasing hormone
• Inhibits PRL to be released from the anterior pituitary
  
  • Lactotrophs
• Regulates Mammary Glands
  
  • Target Tissues

Question 9

Thyrotropin Releasing Hormone

(TRH)

Released from?

Regulates?

Answer 9

• Hypothalamus releases hormone
• Stimulates TSH in the anterior pituitary
  
  • Thyrotrophs
• Regulates thyroid gland
  
  • Target tissue

Question 10

Growth Hormone Releasing Hormone

(GHRH)

Released from?

Regulates?

Answer 10

• Hypothalamus releases hormone GHRH
• Stimulates GH in anterior pituitary
  
  • Somatotrophs
• Regulates bone, liver and muscle
  
  • Target Tissues

Question 11

Growth Hormone Inhibiting Hormone (Somatostatin)

Released from?

Regulates?

Answer 11

• Released from the hypothalamus
• Inhibits GH release from anterior pituitary
  
  • Somatotrophs
• Regulates bone, liver and muscle tissues
  
  • Target tissues

Question 12

Corticotropin Releasing Hormone (CRH)

Released from?

Regulates?

Answer 12

• Hormone released by hypothalamus
• Stimulates ACTH release from the anterior pituitary
  
  • Corticotrophs
• Regulates the adrenal cortex
  
  • Target tissue

Question 13

Prolactin is inhibited by________ from the ________.

Answer 13

Inhibited by dopamine

From the hypothalamus

Question 14

Prolactin:

Answer 14

• Single chain protein
• Produced by lactotrophs in the anterior pituitary
• Peptide hormone
  
  • Structure is close to GH and only differs by 8 AA
• Synthesis is increased during pregnancy and augmented by estrogen
• Secretion is stimulated by suckling

Question 15

When is prolactin synthesis increased?

Answer 15

During pregnancy and augmented by estrogen

Question 16

Functions of Prolactin:

Answer 16

Mammary gland development (during pregnancy):

• High estradiol allows ductal network to grow
• Promotes alveolar epithelial cells differentiation into secretory cells
• High progesterone levels suppresses milk production

Milk Production:

• Prolactin induces lactogenesis (milk production)
• Triggered by stimulus of suckling
• Triggered by decreased progesterone levels at the end of a pregnancy

Question 17

Target of Oxytocin is ______

Answer 17

Muscle cells

Question 18

Target of Prolactin is ________

Answer 18

Milk producing cells

Question 19

T of F: Prolactin is involved in the milk-ejection reflex.

Answer 19

False.

Oxytocin is involved in the milk-ejection reflex

Question 20

Prolactin and Oxytocin:

Answer 20

Prolactin:

• Produced by lactotrophs in the anterior pituitary gland
• Number of lactotrophs will increase during pregnancy to the physiological response and need to produce breast tissue
• Involved in mammary gland development during pregnancy
• Acts on alveolar epithelia cells
  
  • Role in milk formation (lactation)

Oxytocin:

• Produced in the posterior pituitary
• Acts on myoepithelial cells
• Function in milk release
  
  • Stimulates the milk ejection reflex, lactation
  • Lack of oxytocin in a nursing mother would prevent the milk-ejection reflex

Question 21

Control of Prolactin Secretion:

Answer 21

Dopamine is the main regulator for the production and secretion of prolactin

• Inhibitory control by dopamine (restrictive)
• More dopamine = less prolactin released
• Prolactin has (+) short feedback loop on hypothalamus to increase production of dopamine
  
  • Inhibits prolactin secretion
• During pregnancy = increased estrogen–>> increases prolactin production and secretion
  
  • Mammary gland development
• Progesterone inhibits milk formation

After birth:

• Progesterone levels drop
• Milk production begins
• Lactation
  
  • Suckling is the major stimulator of prolactin secretion

Question 22

Suckling Stimulates Prolactin Production

Question 23

Role of Prolactin in Males

Answer 23

• Low, but measurable levels in males
• PRL receptors present in male reproductive and non-reproductive organs and tissues
  
  • Enhanced luetenizing hormone receptors
    
    • Leydig cells in testes
  • Result in testosterone secretion
  • Leads to spermatogenesis