What is the primary secretory product of the CL?
Progesterone
CL must have secretory power, which is called?
vigor
What controls ability of CL to produce adequate concentration of P4?
number of luteal cells
CL Vascularity
Where are luteal cells derived from?
Granulosa cells
T of F. GC Divide post ov
False, do not
What depends on luteinization of GC cells?
P4
What is needed to deliver precursors from general circulation for P4 and delivery of P4 to systemic circulation in CL vascularity?
high blood flow
P4 is the reporductive inhibitior, why?
P4 has a negative feedback at hypothalamus level
What happens to GnRG during P4 negative feed?
Decreases GnRH pulse frequency. Pre ov surge and behavioral estrus
P4 decreases what, except in mares?
myometrial tone
in the mare, actually stimulate myometrial contraction
Positive feedback on uterine gland secretions from the endometrium aids in sustaining ____________ development prior to attachement
embryo
Positive feed on development of the _______ gland especially during pregnancy.
Mammary
What are the 7 steps to P4 synthesis?
- Cholesterol transported to luteal cell by low and high density glycoproteins, from CHOL- glycoprotein complex
- LH binds receptors (at the same time) on plasma membrane
- LH binding activate G-protein, therefore activating adenylate cyclase
- AC prootes conbersion of ATP to cAMP
- Activation of protein kinases
- Mitochondial ensymes convert CHOL to prenenalone (PREG)
- PREG leave mitochondria and immediately converted to P4
Describe step 1 of P4 synthesis in depth
bind receptors on plasma membrane of the luteal cell
complex is internalized the CHOL separates
Receptor is recycled to membrane allowing more transport of CHOL
Describe step 7 of P4 synthesis in depth
Enters the luteal vasculature to then enter systemic ciruculation
Then delivered to target cells
True of False. Luteolysis is irreversible loss of P4 secretion
True
What are the functions of protein kinase activation
A. accelerate LDL receptor internalization
B. activate CHOL esterate, cleaves CHOL from its ester
C. Promotes CHOL transport into mitochondria
What causes luteolysis?
Prostaglandin (PGF2a)
True of False. but exogenous and indigenous luteolysis are slow
False, both fast, 1-4 days
Why is the uterus is required for luteolysis (except primates)?
PGF2a
Ewes with intact uterus how long will the CL live?
15-17 days
in Ewes without intact uterus CL lived how long?
148 days, similar to gestation
True of false. Uterine absence extend CL without normal luteolysis
True
A partial uterectomy life span of CL?
Contralateral (opposite side) 15-17 days
Ipsilater (same side) 35 days
What is the endometrium?
Lining of the uterus
Where is PGF2a secreted from?
endometrium
True of false. PGF2a has a short half life. 90% with on pass through lungs of sows, and 40% in cows and ewes
False. 90% cows and ewes, 40% sows
Why does PGF2a skip the systemic circulation?
it is destroyed in pulmonary system, this is why the vasculature of the uterus is so important
What is the UOV?
Uterine ovarian veini (blue), Drains the ut and ovary
What is OA?
ovarian artery (red) supplies arterial blood to the ovary
What allows the PGF2a the ability to transfer between UOV and OA?
Counter current exchange system between them
The Ut. Vein has ______ _________ of PGF2a
high concentration (This creates a concentration gradient and passive transport)
Ov. Artery had very _____ _________ of PGF2a
low concentration (This creates a concentration gradient and passive transport)
Describe the pathway of PGF2a
Endometrium secreted PGF2a
PGF2a enters ut. vein drainage
Passive diffusion allows entrance into ov. artery
High concentration of PGF2a in ovary results in luteolysis
In Women and primates does the uterectomy have an influence on ovarian cyclicity?
no
What stimulates endometrial PGF2a seceretion?
- Large luteal cells secrete OT
- OT stimulates PGF2a synthesis
- 1st half of cycle= very little PGF2a
- Late luteal phase= PGF2a pulsatile release
Describe luteolysis in women.
- OT acts on ovary for PGF2a synthesis
- End of cascade in uteretomy women= no menses
What two hormones play a role in PGF2a secretion?
P4 levels and
Oxytocin (OT)
The first theory of PGF2a secretion states “Uterus msut be exposed to elevated P4 for a period of days before it can synthesize and secrete PGF2a to cause luteolysis” How?
During 1st half of cycle, uterus exposure to high p4 prevents OT receptors.
- after 10 days, P4 loses ability to block OT receptors
- Ot and PGf2a stimulate each other in a positive feedback manner
The second theory of PGF2a secretion is?
high P4 levels results in low P4 receptors in the uterus, PGF2a is then synthesized and secreted
Luteolysis results in?
- decreased P4 secretion and structural regression luteal cells
- final destruction, ‘clean up microphages
- reduced feedback on hypothalamus
- reduced feedback allows increase GnRH pulse frequency “kick starts” hormonal cascade= new follicular phase
What is progesterone known as?
Cyclicity manipulator
what drug is PGF2a?
Luteolyse
in horses the druge for progesterone is?
Regu-Mate