PLACENTAL HORMONES Flashcards
(127 cards)
1
Q
primary site of hormone production
A
corpus luteum
2
Q
Part of the reproductive system that is considered as steroid hormone producing
A
Placenta
3
Q
Steroid hormones
A
- Estrogen
- Progesterone
4
Q
Hypothalamic-releasing hormones
A
- GnRH
- CRH
- TRH
- GHRH
5
Q
Protein hormones
A
human placental lactogen chorionic gonadotropin АСТH chorionic thyrotropin parathyroid hormone- related neuropeptide Y inhibin activin
6
Q
also called “Pregnancy hormone”
A
HUMAN CHORIONIC GONADOTROPIN (HCG)
7
Q
HCG like LH acts via
A
LH/hCG receptor
8
Q
HCG is almost exclusively produced by
A
syncitiotrophoblast
9
Q
_______ is also produced by fetal kidneys
A
B-hCG
10
Q
HCG is also produced by
A
Neoplastic trophoblast
11
Q
Detection of _____ in the urine is almost always indicative of pregnancy
A
hCG
12
Q
HCG plasma half life
A
24 hours
13
Q
LH plasma half life
A
2 hours
14
Q
HCG is composed of 2 subunits
A
alpha (92 amino acids) and beta (145 amino acids)
15
Q
subunit that is structurally related to LH, FSH, and TSH
A
A subunit
16
Q
subunit of HCG is similar to LH
A
B subunit
17
Q
subunit of FSH is similar to TSH
A
B subunit
18
Q
codes for alpha subunits of all four glycoproteins
A
chromosome 6
19
Q
codes for B-HCG and B- LH
A
chromosome 19
20
Q
rate-limiting step in the formation of the complete
molecule
A
synthesis of the B- subunit
21
Q
secrete both free a and B- subunits and the
complete molecule
A
trophoblast
22
Q
HCG alpha and beta subunits are detectable in the plasma of pregnant women during
A
7-9 days after LH surge
23
Q
hCG enters maternal blood at the time of
A
blastocyst implantation
24
Q
maximum level of hCG is detected during
A
8-10 weeks
25
HCG begins to decline in maternal plasma during
10-12 weeks
26
HCG is considered nadir or in the lowest during
20 weeks
27
hCG plasma level parallels
urine level
28
amount of HCG by 6 weeks after LMP
1IU/ml
29
amount of HCG by 60th – 80th days after LMP
100 IU/ml
30
hCG in fetal plasma is ___ of the mother
3%
31
similar to maternal plasma but declines later in pregnancy
hCG in amniotic fluid
32
Levels of HCG is high during
```
o multiple fetuses
o single erythroblastotic fetus
o H. mole
o chorioCA
o a fetus with Down syndrome
```
33
Levels of HCG is low during
o ectopic pregnancy
| o spontaneous abortion
34
____ produced in cytotrophoblast, acts on syncitiotrophoblast to stimulate HCG secretion
GNRH
35
Other agents that regulate HCG synthesis
- Inhibin
- Interleukin 6
- Epidermal growth factor
- CAMP
36
Abnormal hCG levels is due to
- D antigen isoimmunization
| - Severe DM
37
Metabolic clearance of HCG per day
3ml/min or 4 liters of plasma/day
38
% Renal excretion of HCG
30%
39
% Metabolism of HCG in liver and kidneys
70%
40
Basis for pregnancy tests
Assay of HCG
41
Biologic functions of hCG
1. Rescue and maintenance of corpus luteum in early pregnancy→ continued progesterone production
2. Down-regulation of hCG /LH receptors in corpus luteum when trophoblasts produce sufficient progesterone for pregnancy maintenance
3. Stimulates fetal testicular testosterone secretion and promote male sexual differentiation
4. Stimulates the maternal thyroid via LH/hCG receptors and TSH receptors
5. Promotes relaxin secretion by the corpus luteum
6. Promote uterine vascular vasodilatation and
myometrial smooth muscle relaxation
7. Induces ovulation in the FSH primed ovaries of
non- pregnant women
42
also known as:
| chorionic growth hormone, chorionic somatomammotropin
Human Placental Lactogen (hPL)
43
Human Placental Lactogen (hPL) is structurally related to ______
Prolactin
44
Human Placental Lactogen (hPL) is produced by ________
Syncitiotrophoblast
45
Human Placental Lactogen (hPL) is produced also in conditions such as:
- bronchogenic CA
- hepatoma
- lymphoma
- pheochromocytoma
46
Human Placental Lactogen (hPL) ____ after fertilization will go to the placenta
5-10 days
47
At ________ hPL is already in the serum of pregnant woman
5th week of pregnancy
48
hPL rises until ______ proportional to placental mass
34th-36th week of pregnancy
49
______ is the amount of hPL late in pregnanacy
5-15 ug/L
50
- secreted primarily into maternal circulation action is
mainly on maternal
- fail-safe mechanism to ensure nutrient
supply to fetus in times of maternal starvation
hPL
51
Metabolic actions of hPL
1. Lipolysis
- increase circulatory FFA
- provides source for maternal metabolism and fetal secretion
2. Anti insulin action
- increase maternal insulin favoring protein synthesis
- ensures the metabolizable source of animo acid for transport to the fetus
52
NOT required for a successful pregnancy outcome
hPL
53
continually increasing in magnitude as pregnancy progresses, terminating abruptly after delivery of the fetus and placenta
Estrogen
that is why pregnancy is said to be a hyperestrogenic state
54
Estrogen is produced exclusively by the _______
syncitiotrophoblast
55
At ______ maternal ovaries produce small amounts of estrogen
2-4 weeks of pregnancy
56
At ______ >50% of estrogen in the maternal circulation is produced in placenta
7th week of gestation
57
In the _____
Acetate and Cholesterol
--------> Androstenedione
Theca cells
58
In the _________
| Androstenedione (Acted upon by Aromatase) ----------> Estrone (acted upon by 17B HSD) -----------> estradiol 17B
Granulosa cells
59
Estrogen in the ______
Androstenedione ---------> Estrone
Testosterone -------------> Estradiol 17B
Adipose tissue
60
Precursors for estrogen synthesis :
o Maternal plasma dehydroepiandrosterone
sulfate (DHEAS)
o Liver: 16-hydroxydehydroepiandrosterone
o Fetal DHEAS
61
Placenta is rich in
Sulfatase activity
62
Sulfatase hydrolyzes _____
C19 steroid sulfate
63
Immediate precursor for estrogen synthesis
C19 steroid sulfate
64
Non-pregnant women, ratio of estradiol and estrone to estriol = ____
1
65
During pregnancy (near term) ratio of estradiol and estrone to estriol increases to ____
10
66
There is direct placental synthesis of estriol from ______
16 aOH C, steroids
67
_____ source of 90% of precursor of placental estriol in near term normal human pregnancy
Fetus
68
Largest organ of the fetus
Fetal adrenal gland
69
daily production of steroid in fetal adrenal gland
100-200 mg/day
70
daily production of steroid in adult adrenal gland
30-40 mg/day
71
Early development of the fetal adrenal gland is under
Trophic influences
72
Trophic influences such as:
- fetal ACTH
- Pit. PRL
- growth factor from placenta
73
fetal adrenal cortex grows rapidly, ____ larger than those of adults
25x
74
_____ & _____ are produced by the placenta in minor fraction
- Progesterone
| - Pregnenolone
75
_______ from de novo synthesis of acetate by the fetal adrenals - minor fraction
Cholesterol
76
Hydrolysis of circulating ____ from the fetal circulation (major fraction)
LDL
77
principal precursor for fetal steroidogenesis
Fetal plasma cholesterol
78
Sources of fetal cholesterol:
o 20% - maternal transfer
| o 80% - de novo synthesis by fetal liver
79
_____ is low because of rapid use by fetal adrenals for steroidogenesis
Fetal plasma LDL
80
Fetal-induced Modificationsof Estrogen Production
1. Fetal death or ligation of the umbilical cord
2. Fetal anencephaly
3. fetal adrenal hypoplasia 4. Placental sulfatase deficiency
5. Placental aromatase deficiency
6. Down syndrome
7. Depressed fetal adrenal use of LDL
81
marked decrease in placental estrogens - precursor of placental estrogen is lost
Fetal death or ligation of the umbilical cord
82
diminished availability of C-19 steroid precursors absence of adrenal cortex
Fetal anencephaly
83
precludes the
hydrolysis of C19-steroid sulfates - step in estrogen
biosynthesis
Placental sulfatase deficiency
84
cannot convert
| dehydroepiandrosterone to estradiol
Placental aromatase deficiency
85
low estriol- inadequate formation
| of C19 steroids in adrenal glands
Down syndrome
86
Causes hypertension
| and severe DM
Depressed fetal adrenal use of LDL
87
Maternal Conditions that Affect Placental Estrogen Formation:
1. Glucocorticosteroid treatment
2. Adrenal dysfunctions
3. Ovarian androgen-producing tumor
4. Renal disease
5. Hypertensive disorder and diabetes
6. Neoplastic trophoblastic disease
88
inhibit ACTH secretion - decreased maternal and fetal secretion of fetal estrogen production
Glucocorticosteroid treatment
89
decreased estrone and estradiol
Adrenal dysfunctions
90
fetus is not virilized because androgens passing through placenta is efficiently converted to estradiol
Ovarian androgen-producing tumor
91
lower estriol levels in urine of pregnant women because of decreased renal clearance
Renal disease
92
decreased estrogen formation due to decrease in uteroplacental blood flow
Hypertensive disorder and diabetes
93
low estrogen because no fetal adrenal source of C19-steroids
Neoplastic trophoblastic disease
94
Estriol - Assess Fetal Status
1. Measurement of urinary or plasma estriol has no clinical use in high-risk pregnancy management
2. Part of triple screening - Down syndrome together with AFP and HCG
95
After _____ very little progesterone produced by ovaries
6-8th weeks
96
At ____ will not reduce levels of urinary pregnanediol or estrogens even if bilateral oophorectomy or surgical removal of corpus luteum is done
7-10th week
97
Biosynthesis of Progesterone is is the responsibility of
Syncitiotrophoblast
98
production rate in late, single, normal pregnancies
250
| mg/day
99
production rate in multiple fetuses
> 600 mg/day
100
Principal precursor of Progesterone by 90%
Maternal plasma LDL cholesterol
101
In the _______
| Cholesterol (acted by Cytochrome P450) ----------> Pregnenolone
Mitochondria
102
In the _______
| Pregnenolone (acted by HMG CoA Reductase) --------> Progesterone
Microsome
103
_____ preferably uses LDL cholesterol for progesterone biosynthesis
Trophoblast
104
rate of progesterone biosynthesis is dependent on
number of LDL
105
__ placental progesterone enters maternal plasma
80%
106
Is there a relationship between fetal well-being and progesterone
None
107
Receptor for progesterone synthesis is first seen in _____
4 weeks post- conception
108
Derived from propiomelanocortin (POMC)
Chorionic Adreno Corticotropin Hormone (ACTH)
109
POMC – precursor for:
o АСТH
o Melanocyte-stimulating hormone
o Enkephalins
o a, ß and gamma endorphins
110
secreted into the mother or fetus
| but ACTH does not cross the placenta (fr mom to fetus)
placental ACTH
111
produced by placenta
| no significant biological role
Chorionic Thyrotropin
112
demonstrated in adult tissues - uterus, corpus luteum, mammary tissue
fetal tissues - parathyroid, kidney and placenta
serves as parathormone of the fetus - active transport
of calcium across trophoblast from mother to fetus
Parathyroid Hormone related Protein (PTHTP)
113
widely distributed in brain
found in the periphery → sympathetic neurons
innervating the CVS, respiratory, GIT and GUT
systems
isolated in placenta, localized in cytotrophoblast
Neuropeptide-Y (NPY)
114
high concenration of potassium
increase release of
| NPY from trophoblast
115
treatment of placental cell with NPY
release of CRH
116
acts to inhibit FSH release by the pituitary precludes ovulation during pregnancy
Inhibin
117
hormone that is greater during labor
Activin
118
acts as hCG-releasing hormone
Gonadotrophin releasing hormone (GNRH)
119
indicative of a hierarchy of control of the synthesis of chorionic trophic agents
Presence of Hypothalamic-like releasing hormones
120
act in a paracrine
| manner to regulate GNRH synthesis
1. Inhibin
| 2. Activin
121
synthesized by trophoblasts, amnion, chorion and decidua
Corticotropin Releasing Hormone (CRH)
122
Amount of CRH in non-pregnant woman
15 pg/ml
123
Amount of CRH in early 3rd trimester
250 pg/ml
124
Amount of CRH in Term
1-2 ng/ml
125
CRH is also found in _______
Umbilical venous blood
126
CRH is increased in:
o preterm labor
o fetal asphyxia
o twin pregnancy - 4x
127
Biologic roles of CRH
o smooth muscle relaxation
o induction of myometrial contractions -
induces prostaglandin formation
