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Follicle stimulating hormone [FSH] in female stimulates ovarian follicle development. The follicle secretes estrogen when it becomes mature it Lutenizing hormone[LH] in female acts on the mature grafian follicle to induce ovulation (LH peak). It also stimulates the Corpus lutum (derived from the Hypothalamus GnRF [+] Anterior Pituitary Anterior Pituitary Gland Gland

Ovarian hormones

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bioassay and pharmacology of ovarian hormones

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Page 1: Ovarian hormones

Follicle stimulating hormone [FSH] in female stimulates ovarian follicle development. The follicle secretes estrogen when it becomes mature it is called grafian follicle.

Lutenizing hormone[LH]in female acts on the mature grafian follicle to induce ovulation (LH peak). It also stimulates the Corpus lutum (derived from the ruptured grafian follicle after ovulation) to secrete progesterone.

HypothalamusGnRF [+]

 

Anterior Pituitary Anterior Pituitary

GlandGland

Page 2: Ovarian hormones

Hormonal inter-relationship in the control of the female reproductive system

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1) Follicular phase • During the first half of this stage FSH secretion Slightly &

acts on one of the ovaries promoting growth of several follicles each contains one ovum. After about a week, one of the follicles out grows the others & secretes increasing amount of estrogen & matures to form grafian follicle while the other small follicles degenerate.

• By -ve feed back mechanism of estrogen secretion FSH secretion regression of the other small follicles, while the dominant follicle can continue its growth due to its local concentration of estrogen which its sensitivity to FSH through number & sensitivity of FSH receptors on it. The secreted estrogen stimulates proliferation of endometrium.

A brief Account on Hormonal A brief Account on Hormonal Changes in the Menstrual CycleChanges in the Menstrual Cycle

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2) Ovarian Phase

The LH secretion peaks due to +ve feed back effect of estrogen secreted from the dominant follicle resulting in rupture of the developed follicle & expulsion of ovum.

3) Luteal Phase

The remaining part of the ruptured follicle develops into corpus luteum, which secretes progesterone.

Page 5: Ovarian hormones

If fertilization occurs:

Fertilized ovum Secrete (hCG)

Human chronic Gonadotrophins

With LH activity Support corpus Lutum secrete Progesterone

Relax uterus & thickness and

vascularity of endometrium.

i.e. prepare it for implantation of

fertilized ovum & Protect it.

If no fertilization occurs:

Degeneration of corpus

luteum sudden drop of

progesteron loss of

endometrium support

necrosis of endometrium

menstrual cycle

N.B.Progesterone is secreted during 9 months of pregnancy, firstly by corpus lupus then by placenta.

This effect is stimulated by LH. The secreted progesterone promotes

secretory function of the endometritm. Then

Page 6: Ovarian hormones

Plasma concentrations of

ovarian hormones and

gonadotrophis in women during

normal menstrual cycle.

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Ovarian HormonesBioassayof Estrogens

# Injection of estrogen the thickness of the vaginal wall, leucocytes cannot pass& only squamus cornified cells are identified in the vaginal smear in

estrous stage. # The number of animals with +ve response is directly

proportional to the estrogen dose.

# The wall of vagina in diestrous stage is very thin& allows the passage of leucocytes into the vaginal lumen. So leucocytes appear in the vaginal smear.

1) Vaginal smear Vaginal smear methodmethodPrinciple:

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Vaginal Smear MethodVaginal Smear Method

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We use ovarictomized rats to avoid endogenous estrogen interference.

4 groups of animals in the diestrous stage are used (2T & 2S)

Choose 2 SM doses of T estrogen (T1 &T2) & 2 SM doses of S (S1& S2) provided that: S2/S1=T2/T1

Each dose is injected in a group of animals & the vaginal smear is made on the third day & examined for the presence of squamus cornified cells.

Plot a relation between log dose& % of animals with +ve response in each group of S&T.

Determine relative potency (R.P)

Procedures:

Page 10: Ovarian hormones

S2T2

T1S1

% +

ve 5

0% r

esp

onse

X Y Log dose

R.P =X/Y

N.B.# It is an in vivo method# 4-point assay# Objective method (accurate)# No cross-over test can be done# this test can be used for screening

& bioassay of estrogen.

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2) Uterus weight 2) Uterus weight methodmethodPrinciple:

* Estrogen uterus weight of ovarectomized female rats.* The in weight is directly proportional to the dose of estrogen.

Ovarictomized or immature female rats to avoid endogenous estrogen interference. 4 groups of the animals are used.

Choose 2 SM doses of S estrogen (S1& S2) & 2 SM doses of T estrogen (T1&T2) provided that: S2/S1=T2/T1

Each dose is injected in a group of animals in the 3rd, 4th,5th & 6th days after ovarectomy. Rats are killed on the 8th day & the uterus is isolated, dried& weighed.

Procedures:

Plot a relation between log dose & % in uterus weight & determine R.P

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S2T2

T1S1

% in

Ute

rus

Wei

ght

X Y Log dose

R.P =X/Y

N.B.* It is an in vivo test* 4-point assay* Objective method (accurate)* No cross-over test can be carried out

because the animals are killed

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## Endometrial proliferation method

# Progesterone causes proliferation of the endometrium of immature of ovarictomizes rabbits.

# The degree of proliferation is directly proportional to the dose of progesterone.

# Proliferation occurs through 4 phases

Principle:

Bioassayof Progesterone

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Endometrial proliferation method for Progesterone

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Procedures:

Choose 2 SM doses of S progesterone( S1&S2) & 2 SM doses of T progesterone (T1&T2) provided that S2/S1=T2/T1

Each dose of progesterone is injected S.C in a group of animals daily for 5 days

Compare the degree of proliferation in T&S

We use immature or ovarictomized female rabbits to avoid interference by endogenous progesterone.

Bring 4 groups of animals

Inject all animals with estrogen for 6 days (for development of uterus to prepare it for progesterone action)

Kill the animal, isolate the uterus & make section through it

Plot a relation between log dose& degree of proliferation the determine R.P.

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S2T2

T1S1

Deg

ree

of P

roli

fera

tion

X Y Log dose

R.P =X/Y

N.B.# It is an in vivo test.# 4-point assay.# No cross-over test can be

carried out because the animals are killed.

Page 17: Ovarian hormones

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