Endocrine 08 Part 3

Front 1

What is the major secretory product of the corpus luteum?

Back 1

Progesterone

Front 2

Describe the secretion of progesterone

Back 2

1. The major secretory product of the corpus luteum

2. The placenta also secretes large amounts of progesterone

Front 3

Describe the importance of progesterone in the menstrual cycle

Back 3

The presence of significant amounts of circulating progesterone during the second phase of the menstrual cycle indicates that ovulation has occured

Front 4

Describe the effect of progesterone on body temperature

Back 4

1. Progesterone affects the hypothalamic thermoregulatory center
2. Thus the occurence of ovulation can be monitored by an increase in the basal body temperature
-A biphasic BBT curve (with elevated temperature throughout the second phase of the cycle) thus indicates an ovulatory cycle

Front 5

Describe the effect of progesterone on different areas of the female reproductive system

Back 5

Under the influences of progesterone during the luteal phase, characteristic changes occur in most organs which had previously been stimulated by estrogens during the follicular phase:
a. Vaginal epithelium
b. Endocervical glands
3. Endometrium

Front 6

Describe the effects of progesterone on the vaginal epithelium

Back 6

Regressive changes in both acidophilic and pycnotic cells

Front 7

Describe the effects of progesterone on the endocervical glands

Back 7

Decreased cervical mucus secretion and increased viscosity

Front 8

Describe the effects of progesterone on the endometrium

Back 8

Increased glandular secretory activity

Front 9

Describe hormone preparations of progesterone

Back 9

Readily absorbed as a micronized formulation for oral use or as a vaginal suppository

Front 10

Describe C-21 progestins

Back 10

1. Derivatives of progesterone which have been modified to pass through the GI tract and be active when given orally

2. These include:
a. Medroxyprogesterone acetate
b. Megestrol acetate

Front 11

Describe 19-nortestosterone derivatives

Back 11

1. Derivatives of testosterone in which carbon at position 19 is removed and an ethynyl groups placed at position 17
2. These substances have both progestin and androgen effects, with the former predominating
3. The include:
a. Norethindrone
b. Levonorgestrel

Front 12

Describe the major therapeutic use of progesterone

Back 12

-Contraception
-Also used as a cyclic supplement to estrogen replacement therapy

Front 13

Describe the purpose of the progesterone withdrawal test

Back 13

Used frequently in anovulatory patients to determine the adequacy of endogenous estradiol production and thus indirectly the activity of the hypothalamic-pituitary-ovarian axis

Front 14

Describe the progesterone withdrawal test

Back 14

1. Must be performed with a progesterone preparation devoid of intrinsic estrogenic properties, such as progesterone itself or medroxyprogesterone acetate

2. Menstrual bleeding a few days after treatment withdrawal indicates an active hypothalamic-pitutitary axis and the biological effects of endogenous estrogens

Front 15

Describe RU-486

Back 15

1. Progesterone antagonist which acts by blocking the progesterone receptor (and to a lesser degree the cortisol receptor)
2. Used in combinations with prostaglandins to induce early therapeutic abortions
3. May be able to serve as a contraceptive by blocking progesterone's effects on the endometrium or in cancer therapy such as it treatment of progesterone receptor-bearing tumors

Front 16

What is the main androgen secreted by the Leydig cells?

Back 16

Testosterone

Front 17

Describe dihydrotestosterone

Back 17

Formed when testosterone is reduced at the 5α position, which is the intracellular mediator of biological action

Front 18

Describe the source of estrogen in males and postmenopausal females

Back 18

Testosterone (but not dihydrotestosterone) is aromatized to estradiol in various extraglandular tissues

Front 19

What is the direct precursor to estradiol in the ovary?

Back 19

Testosterone

Front 20

What are the major types of effects from testosterone?

Back 20

1. "Androgenic" effects
2. "Anatbolic" effects
3. "Regulatory" effects

These are organ-specific responses

Front 21

Describe the "Androgenic" effects of testosterone

Back 21

1. Relate to growth of the male reproductive tract and the development of male secondary characteristics
2. These widespread effects are seen at puberty (Growth of external genitalia, hair growth, linear growth, increased prostatic secretion, muscle mass, bone mass, etc)

Front 22

Describe the "Anabolic" effects of testosterone

Back 22

1. Nitrogen retaining
2. These are effects related to their role on somatic tissues, such as liver, kidney, bone, and muscle

Front 23

Describe the "Regulatory" effects of testosterone

Back 23

These effects relate to homeostatic effects on the control of GnRH and gonadotropin secretion

Front 24

Describe the administration of testosterone preparations

Back 24

1. Testosterone is promptly degraded by the liver and is thus not very effective when administered orally
2. Current formulations are restricted to injectable or skin delivery (subcutaneous implants or transdermal) formulations of testosterone or testosterone esters (such as for example testosterone proprionate)

Front 25

Describe testosterone esters

Back 25

Hydrolyzed to yield testosterone

Front 26

Describe skin patches vs injection of testosterone

Back 26

1. Skin patches do better than injection to maintain a more continuous physiological profile of the hormone
2. Skin irritation may be a problem

Front 27

Describe oral preparations of testosterone derivatives

Back 27

1. Oral preparations use derivatives that are alkylated at the 17α position (methytestosterone, fluoxymesterone)
2. There is concern about liver toxicity linked to the 17 alkyl group which limits their use

Front 28

What is the major therapeutic indication for testosterone therapy?

Back 28

To replace a deficient testicular endocrine function (hypogonadism)