Endocrinology of pregnancy Flashcards
When does maternal recognition of pregnancy occur?
Before luteolysis.
What are the endocrine/paracrine recognition of pregnancy embryonic signals of different species?
— Ruminants: interferon tau — Sow: oestradiol — Mare: 3 proteins?/oestradiol?/ migration? unknown!! — Dog and cat: none — Women: hCG
What kind of placenta do primates have?
Invasive heamochorial discoid.
What kind of placenta do cows and sheep have?
Synepitheliochorial cotyledonary
What kind of placentas to sows and mares have?
Diffuse epitheliochorial
What kind of placentas to dogs and cats have?
Zonary endotheliochorial
The placenta is an endocrine organ. List 6 placental hormones?
Progesterone eCG hCG Oestrogen Prolactin Placental lactogens Relaxin
What is the production and regulation of progestagens?
Produced by corpus luteum and placenta
Regulated by PGF2a (decreases action) LH (increases action) and oestrogens
What is the function of progestagens?
Stimulate production of histotroph
Uterine milk proteins
Suppress myometrial contractility
Mammary gland development
Which species have no LP shift?
Camelids, bitch (65days), goat (5 months), rabbit (1 month), queen (65 days) and sow (3.8 months)
The gestation length of a cow is 9 months. When does the LP shift occur?
6-8 months in
The gestation length of a ewe is 5 months. When does the LP shift occur?
50 days
The gestation length of a mare is 11 months. When does the LP shift occur?
140-210 days
The gestation length of a woman is 9 months. When does the LP shift occur?
60-70 days
In species without placental take over those species require CL throughout pregnancy, what effect does this have on gestation length?
Species without a LP shift tend to have a shorter gestation.
Where are oestrogens produced in pregnancy?
Produced by fetal cotyledons/trophoblast cells
What are the functions of oestrogen produced during pregnancy?
Stimulate mammary development
Stimulate placental growth
Increase uterine blood flow
Stimulate myometrial growth and preparation for parturition
Where is relaxin produced in different species?
Produced by CL (sow) and placenta (rabbit, mare and dog)
What are the actions of relaxin?
— Softening of connective tissue enabling growth of
fetus
— Relaxation of pelvic ligaments
— Parturition (stimulated by PGF)
What hormone can be used to diagnose pregnancy in the bitch?
Relaxin. It is only produced by the placenta in the dog so is a reliable pregnancy diagnosis.
What do endometrial cups produce?
eCG (aka pregnant mare serum gonadotrophin)
Why does the blood plasma concentration of progesterone seem to drop in late gestation?
Progesterone is needed throughout pregnancy but has peaks and troughs in plasma concentration in mare. It is low because the progesterone is produced locally in the placenta and these stay and have local action and never get into the plasma circulation.
When do endometrial cups appear?
Approx. 40 days.
What does eCG do?
It has FSH and LH-like activity and this is why it is used in other species to stimulate follicle growth. It stimulates
initial follicle/primary CL. Progesterone production therefore increases and other follicles present at that time will ovulate meaning more CL will form but no pregnancy will occur.
What is the main progestagen in the mare and what does it do?
Main is 5-alpha-pregnane.
Produces sequence of Unique oestrogens
Where is prolactin produced and how is it regulated?
Lactotroph of anterior pit. gland and placenta
Inhibited by dopamine
Stimulated by oestradiol
What is the function of prolactin?
Manimary gland
— Induces lobuloalveolar growth
(secrete milk)
-Lactogenesis
CL (rodents, dogs and cats)
— Stimulates progesterone
production
Stimulating Maternal behaviour
Placental lactogen is similar to prolactin. Where is it produced though?
Production . Produced by binucleate cells in ruminants . Released into maternal and fetal circulation
What is placental lactogens function?
Binds to prolactin receptors
Modulates fetal metabolism
Mammary gland development
What are two other placental hormones specific to ruminants that are produced by binucleate cells and can be used for pregnancy diagnosis around 6-8 weeks?
Pregnancy specific protein B (PSPB)
Pregnancy associated glycoprotein (PAG)
When may termination of pregnancy be necessary?
— Unintended mating — Risk to dam’s health — Owners do not want pregnancy to continue — Twinning in mare May need to Induce premature parturition
What are key agents used to terminate pregnancy?
— PGF2a or analogue — Corticosteriods — Oestradiol — Dopamine agonists — Progesterone receptor antagonists Premature induction of parturition — Oxytocin --> direct stimulation of myometrial contractions causing fetal stress that kick starts labor
How does PGF2a work to cause termination of pregnancy?
Key luteolytic agent that acts on CL and is not active on
the placenta
Caution though cannot be used in species who have a LP shift after the LP shift has occured because PGF2a acts on the CL not the placenta. After the LP shift the placenta produces progesterone.
What can be uses in dogs and cats to treat pseudopregnancy and cause termination?
Dopamine agonists as they inhibit prolactin secretion which is a luteotrophic hormone.
How do corticosteroids cause abortion?
. Mimics fetal stress signal
. Induces myometrial contractions
.Results in expulsion of the fetus
Which antibody can cross the placenta in species that have placental transfer?
Only IGg is small enough to cross the placental barrier.
