Endocrinology of partrition Flashcards
In most species which hormone rises and which falls just prior to parturition?
Oestradiol rises and progesterone falls
What is the foetal signal for parturition?
Foetal cortisol
What effect does foetal cortisol have?
-Increases the activity of 3 enzymes: aromatase, desmolase, 17-a-hydroxylase
What is the most important glucocorticoid in birds/ rodents?
-Corticosterone
What impact does skunk cabbage have on the HPA axis?
- Causes cycloptic lambs and prolongs gestation
- Results in an absence of the hypophysial stalk
- Adrenal hypoplasia
- All results in insufficient steroid production
Describe the regulation of contraction
-Oxytocin: increases force, duration and frequency of contractions
-Prostaglandins: PGF2a= contraction
PGI2= relaxation
PGE2= important in cervical softening
-Neural input: autonomic NS via pelvic plexus innervates uterus (endo/ myometrium) through a and b adrenergic receptors
Which uterine receptors cause contraction and which cause relaxation?
A1= contraction B2= relaxation (high progesterone increases the number B receptors)
What is the importance of COX-2?
- Positive feedback system
- COX -2 increased by stretch and oestradiol
- COX-2 converts arachidonic acid into prostaglandins
- Prostaglandins increase effectiveness of oxytocin
When would you treat an animal with oxytocin?
- It is given to strengthen contractions and expel placenta/ membranes
- Helps treat uterine inertia, haemorrhage, retained placentas
What do oxytocin receptor antagonists do?
- Reduce contractions
- Used to treat animals in spontaneous preterm labour
What do PGF2a do?
- Cause luteolysis (for oestrus synchronisation/ abortion)
- Strengthens contractions
What do Beta 2 adrenergic agonists do?
- Inhibits contractions and causes relaxation
- Given to reduce contractions
- Given during labour- e.g. C-section/ Correct dystocia
