Endocrinology of Pregnancy and Parturition Flashcards
1
Q
Compare and contrast lipid and protein hormones in terms of
- solubility
- site of receptors
- mechanism of action
- examples
A
Lipid-Based Hormones - hydrophobic - receptors in cytoplasm/nucleus - MoA = induces gene transcription and translation - e.g. Steroids: oestrogens, progesterone, crotisol, androgens Protein Hormones - hydrophilic - receptors in cell membrane - MoA = initiates second messenger intracellular signalling mechanisms sich as cAMP - e.g. Gonadotrophins: FSH, LH, hCG Somatomammotrophic: prolactin, hPL, GH Small peptides: GnRH, oxytocin
2
Q
hCG
- What is its the structure?
- Where is it secreted from?
- Where does it act?
- What are its 3 functions?
- Describe renal excretion and its clinical application
- How do levels change during pregnancy?
A
- glycoprotein - alpha and beta subunits
- secreted from syncytiotrophoblast
- acts of LH receptors
- functions: maintain CL, stimulate DHEA production in the foetal adrenals, in males, stimulates testosterone –> virilisation
- beta subunit renal excreted, pregnancy test
- levels double every 48hours in pregnancy
3
Q
Progesterone
- what is it secreted by?
- what are its functions?
- give a clinical application
- what are its effects on the endometrium?
- any other effects?
A
- secreted by CL initially, then placental secretion occurs between 6-8 weeks
- maintains the decidua, relaxes the myometrium
- progesterone essential to continuation of pregnancy, administration of progesterone inhibitor (Miferpristone) also resulted in pregnancy loss
- Endometrium - decidual transformation, immune modulation
- via progesterone receptor B, downregulates synthesis of contractile associated proteins such as fat junctions and oxytocin receptors. negatively regulates human placental lactogen
4
Q
Describe how progesterone is a substrate for sterioidgenesis?
What enzymes are lacking in the feotus and the placenta and what are the implications of this?
A
- Placenta lacks 17alphahydroxylase and so cannot convert progesterone to DHEA
- Foetal adrenal glands lacks 3BHSD and so cannot convert pregnenolone to progesterone.
- These modifications result in an alternative pathway for oestrogen synthesis.
- Alternative pathway: cholesterol converted to DHEA in foetal adrenal, DHEA converted to estriol in foetal liver, reenters maternal circulation
5
Q
List the 3 types of oestrogen
When does each predominate?
A
Oestrone = E1 --> predominates in menopause Oestradiol = E2 --> regulates menstruation Oestriol = E3 --> pregnancy specific (by-product of sterioidogenic pathway)
6
Q
What is the role of oestrogen following implantation?
A
- main source is the and the foetal liver
- oestradiol, E2 is the most patient
Maternal effects: - vascular changes
- increase is prothrombotic mechanisms –> increase protein C, decrease ATIII and Protein S
- increase contractile associated proteins (opposite of progesterone), gap junctions, oxytocin, breast development
7
Q
What is the role of placental growth hormone (PGH)?
A
- secretion starts from 15-20 weeks
- modifies receptors which transport glucose across eh foetal compartment
- non-pulsatile secretion, levels correlate with placental size
- stimulates maternal gluconeogenesis and lipolysis
- no functional GH receptor until near term
8
Q
What is another name for HPL
Where is it secretion from
What is its function
A
- also called human chorionic somatomammotropin
- secreted from syncytiotrophoblast
- functions as a metabolic screwdriver by chi foetus resets maternal CHO homeostasis
- short half life of 15 minutes
9
Q
What are the main effects of HPL?
A
- induces breast maturation
- increased IGF-1, insulin resistance increases, lipoylsus and gluconeogeneis increases
- -> increase glucose and ketones to foetus
10
Q
Overall what is the effect of HPL and PGH?
A
- increased maternal glucose for the foetus
11
Q
Is progesterone pro-contractile or pro-relaxant?
Is oestradiol pro-contractile or pro-relaxant?
A
progesterone = pro-relaxant oestradiol = pro-contractile
12
Q
How do estradiol and progesterone regulate partuition?
A
- progesterone suppreses myometrial contraciton, preventing birth
- does this by regulating oestrogen receptors
13
Q
What is meant by cervical effacement?
A
- thinning of the cervix
- collagen fibres reduce
- glycosaminoglycans increased
- MMPs increase
14
Q
Describe Friedman’s partogram
A
- analysis of 500 women during labour
- changes in cervical dilation from the latent to the active phases takes on a sigmoidal shop e
- multiparae attain active phase faster than nulliparas
15
Q
What are the features of the latest and active phases of labour?
A
- latent phase = cervial changes
- active phase = progressive cervical dilation
