Topic 94 - Endocrinology of pregnancy; fetoplacental endocrine unit

Question 1

Words to include in endocrinology of pregnancy

Answer 1

• Maintainance of pregnancy
  
  • Ovarian factor
  • Hypo factor
  • Pituitary factor
  • Placental factor

Placental hormones

• Progesterone
  
  • Luteal phase longer
    
    • Corpus luteum graviditatis
  • Species dependent on corpus luteum
    
    • Dog, cat goat, swine
    • Corpus luteum main source of P4
  • Species independent of corpus luteum
    
    • Primates, horse, sheep, cow
    • Placenta transformed into temporal endocrine unit
      
      • Fetomaternal
• Choriogonadotropin
  
  • Human chroionic gonadotropins (hCG)
    
    • Human placenta (location of production)
    • Recognition of maintainance of pregnancy
    • Corpus luteum stimulation
      
      • P4 production
    • LH-like effect (in animals)
  • Equine chorionic gonadotropin (eCG)
    
    • Choroin (location of production)
    • Pregnant mare’s serum gonadotropin (PMSG)
    • Production of accessory corpus luteum during pregnancy
      
      • Extra P4 production
    • FSH-like effects (other animals)
• Placental lactogens (PL)
  
  • PRL-like effect
  • Somatotropic effect
• Estrogen
  
  • ​Fetus-mother-interaction
  • Myometrium (location of production)
  • Ø new fertilization
• Chorionic somatomammotropin (CS)
  
  • Growth stimulation
  • Lactation stimulation
  • Maternal growth hormone
    
    • Ø pass into fetus
    • Ca, K, N retention ↑
    • Glucose utilization ↓

Question 2

Words to include in fetoplacental endocrine unit

Answer 2

• Endocrinological definition
  
  • Steroid synthesis
  • Fetus-mother interaction crucial
  • Enzymes for estrogen synthesis (ø on both sides)
• Fetomaternal endocrine unit
  
  • Independent hormone production of placenta and steroid genitals in fetal adrenal corte x
  • Progesterone
    
    • Placenta → fetal circulation → adrenal cortex
    • Precursor for synthesis of:
      
      • Cortisol dehydroepiandrosterone (DHEA)
      • 16-hydroxy-hydropiandrosterone
  • Fetal arenal gland
    
    • Pregnenolone (synthesized in fetal liver)
      
      • Cortisol dehydroepiandrosterone (DHEA)
      • 16-hydroxy-hydropiandrosterone
    • Conjugated forms reaches placenta
  • Placenta
    
    • Conjugated forms → androstenedione → estrogen → maternal criculation

Hormonal changes during pregnancy

• ​1^st trimester
  
  • LH high
• Permanent high P4
  
  • Morpho-functional preparation of lactating mammary gland
  • Hyperpolarized myometrium
• Ovary + placenta
  
  • Permanent relaxin secretion
• Placenta
  
  • P4
  • E2
  • Androgens
  • Maintainance of pregnancy
  • Fetal sex-differentiation
  • Development of genitalia

Pregnancy tests

• Biological tests
  
  • Gall-Mainini reaction
  • Ascheim-Zondek
  • Friedmann-Lapham
• Immunological test
  
  • Menotest
• Species specific test
  
  • Cow:
    
    • Rectal investigation
    • Plasam or milk progesterone by:
      
      • RIA
      • ELISA
      • EIA
  • Mare:
    
    • Cubony test
      
      • Urine estrogen
    • MIP test
      
      • Detects PMSG
    • Early pregnancy proteins

Question 3

Endocrinology of pregnancy

Which factors maintains pregnancy?

Answer 3

1. Ovarian factor
2. Hypo factor
3. Pituitary factor
4. Placental factor

Question 4

Endocrinology of pregnancy

Name the hormones that should be mentioned

Answer 4

1. Progesterone
2. Choriogonadotropins
   
   1. ​Human chorionic gonadotropin (hCG)
   2. Equinechorionic gonadotropin (eCG)
3. Placental lactogens (PL)
4. Estrogen
5. Chorionic somatomammotropin (CS)

Question 5

Endocrinology of pregnancy

Progesterone

Answer 5

• Key hormone
• Luteal phase becomes longer (Corpus luteum graviditatis)
• At the beginning, ovary is the only source of progesterone, later on species can be divided into two groups:
  
  1. Species dependent on corpus luteum
     
     • Dog, cat, goat, swine
     • Corpus luteum remains the main source of P4
  2. Species independent of corpus luteum
     
     • Primates, horse, sheep, cow
     • Placenta is transformed to temporal endocrine (fetomaternal) unit

Question 6

Endocrinology of pregnancy

Choriogonadotropins

Answer 6

• Human chorionic gonadotropin (hCG)
  
  • Produced in the human placenta
  • Role in human:
    
    • Recognition and maintainance of pregnancy
    • Corpus luteum stimulation
      
      • ​P4 production
  • Role in animals:
    
    • LH-like effect
• Equine chorionic gonadotropin (eCG)
  
  • Pregnant mare’s serum gonadotropin (PMSG)
  • Gonadotropic hormone
  • Produced in the chorion of pregnant mares
  • Role in mares:
    
    • Production of accessory corpus luteum during pregnancy
      
      • Extra P4 production
  • Role in other animals (pharmalogical use):
    
    • FSH-like effect

Question 7

Endocrinology of pregnancy

Placental lactogens (PL)

Answer 7

• PRL-like effect
• Somatotropic effect
• Produced from mid-gestation until the end of it

Question 8

Endocrinology of pregnancy

Estrogen

Answer 8

• Fetus-mother-interaction
• Produced by myometrium
• Inhibits new fertilization

Question 9

Endocrinology of pregnancy

Chorionic somatomammotropin (CS)

Answer 9

• Stimulates:
  
  • Growth
  • Lactation
• Unable to pass into fetus, so it is a maternal growth hormone
  
  • ​Ca, K, N retention ↑
  • Glucose utilization ↓

Question 10

Fetoplacental endocrine unit

Answer 10

• Endocrinological definition:
  
  • For steroid synthesis, fetus-mother interaction is crucial since specific enzymes essential to estrogen syntheis are absent on both sides
  • Hormone production of the placenta and steroid genesis in the fetal adrenal cortex are independent

Steps:

1. P4, secreted by the placenta, reaches the adrenal cortex through the fetal circulation and acts as a precursor there for the synthesis of cortisol
   
   1. ​Placenta → fetal circulation → adrenal cortex
2. Dehydroepiandrosterole (DHEA) and 16-hydroxide-hydroepiandrosterone are formed in the fetal adrenal gland from pregnenolone, synthesized in the fetal liver
3. These compounds (created in the fetus) reach the placenta in conjugated forms, and then, after being converted there to androstenedione, than to estrogen which then enter the maternal circulation
   
   • ​​Compounds created in fetus → conjugated forms (placenta)→ androstenedione (placenta) → estrogen (placenta) → maternal circulation

Question 11

Fetoplacenta endocrine unit

Hormone changes during pregnancy

Answer 11

• Ovary & placenta
  
  • ​Permanently secrete relaxin
• Placenta
  
  • ​Produces:
    
    • P4
    • E2
    • Androgens
  • Role:
    
    • Maintainance of pregnancy
    • Fetal sex-differentiation
    • Development of genitalia