Lecture 13 - Hormones Flashcards
Describe the classical pathway of hormones
- Hormones are released from the cell sin which they are synthesized, then circulate in blood largely bound to sex hormone binding globulin (SHBG) (tightly bound) and albumin (loosely bound)
- Only unbound hormones enter cytoplasm of target tissue cells where they bind to a hormone receptor (HR) forming a hormone-receptor complex (HR-C) which then dimerizes and translocates into the cell nucleus.
- Specific cofactors (coactivators or corepressors) unique to each tissue interact with both the air-C and hormone response elements (HREs) on the target gene.
- Gene transcription is either activated or repressed depending on the hormone, the receptor, the tissue, and cofactors (>300 identified) involved
- Hormone activity depends on presence and density of specific hormone receptors, binding proteins, coactivators and corepressors
Describe other pathways for hormones
Intracellular signalling pathways and direct effects on cellular membranes via the estrogen receptors (i.e. non-genomic related)
What are the target tissues for ER-alpha?
prevalent in uterus, ovary, breast
also in liver, bone, adipose tissue, brain
What are target tissues for ER-Beta?
colon, vascular endothelium, lung, bladder and brain
What are target tissues for ER-alpha and ER-Beta?
ovary, central nervous system and CV tissues
What are target tissues for PR-alpha?
predominant in uterus and ovary
What are target tissues for PR-Beta?
predominant in breast
What are target tissues for AR?
Vagina, ovary, testes, bones, muscles
Urogenital tract
_____ = dominant female hormone
estrogen
What does estrogen do?
- sexual maturation and growth (females and males)
- development of endometrial lining
- maintain structure & function of skin and blood vessels (vasodilator, antioxidant)
- decrease rate of bone resorption
- liver alterations - increase production of CBG, SHBG, TBG, transferrin, angiotensinogen
- increase HDL, decrease LDL, slight decrease in plasma cholesterol, increase triglycerides
- enhances coagulability of blood: increase clotting factors 2, 7, 9, and 10, increase fibrinogen, decrease antithrombin 3, despite increase in plasminogen levels and decrease platelet adhesiveness
- induces synthesis of both estrogen and progesterone receptors
What does progesterone do?
- Precursor to estrogens, androgens, and adrenocortical steroids
- Downregulates ER & suppresses estrogenic stimulation of endometrium
- Induce maturation & secretory changes in endometrium
- High affinity for P receptors, differing affinities for androgen & glucocorticoid receptors
- Progesterone metabolites have a anxiolytic and hypnotic effect on brain
- Antagonizes the mineralocorticoid receptor - decreases sodium resorption and H20 retentions
What is the Hypothalamic-Pituitary-Gonadal Axis?
- Responsible for regulation of menstrual cycle in females and the regulation of testosterone production and spermatogenesis in males
- Gonadotropin-releasing hormone (GnRH) secreted from hypothalamus in pulses
- GnRH stimulates anterior pituitary gland to secrete follicle stimulating hormone (FSH) and luteinizing hormone (LH)
- FSH and LH stimulate ovarian synthesis of E and P respectively in females and spermatogenesis and testosterone production respectively in males
- Circulating levels of estrogen and progesterone in women and testosterone in men result in both positive and negative feedback of GnRH, FSH, & LH release
Briefly describe the menstrual cycle
GnRH releases FSH, stimulates release of estrogen
Increased estrogen leads to release of LH, LH continues to stimulate the follicle
LH releases corpus luteum
**see clinical notes
What types of patients is estrogen-containing contraceptives CI in?
- age 35 and over who smoke
- hypertension
- diabetes with severe vascular disease
- history of stroke or ischemic heart disease
- migraine headaches with focal neurological symptoms (aura)
- multiple risk factors for CVD (older age, smokers, obesity, DM, HTN)
- breast, endometrial, ovarian or cervical cancer
- active liver disease
- thromboembolic disorder (past or current)
- pregnancy
List the MOA’s of hormonal contraceptives
1) suppression of gonadotropin (FSH/LH) secretion - dose-dependent inhibition of ovulation
(COC work this way, POP do not always inhibit ovulation)
2) inhibits the development of the dominant ovarian follicle/suppression of ovarian steroid production by suppression of FSH (estrogen effect)
3) Endometrial effects (atrophy) making it less suitable for implantation (progestin effect)
4) Thickening of cervical mucus impeding sperm transport (progestin effect)
5) Impairment of normal tubal motility and peristalsis which interferes with ovum and sperm transport (progestin effect)
_____ ______ = synthetic estrogen used in most estrogen-containing COC
ethanol estradiol
What does addition of an ethanol substituent to estradiol inhibit?
first-pass metabolism and increases potency
_____ is a prodrug of ethanol estradiol
mestranol
Review slide 15-17
sounds g
List some well known benefits of oral contraceptive pills
- prevent pregnancy
- cycle regulation & decreased menstrual flow
- decreased peri-menopausal symptoms
- help relieve menstrual pain (decreased dysmenorrhea)
- relieve PMS-related problems and PMDD
- improve hirsutism & acne
- decreased risk of fibroids/possibly fewer ovarian cysts
- maintenance of bone mineral density
List some less known benefits of oral contraceptive pills
- treat PCOS; hypothalamic amenorrhea
- reduce pelvic inflammatory disease
- reduce ectopic pregnancies (exception POP’s can cause an increase risk of this)
- improve symptoms of endometriosis
- reduce risk of ovarian CA by 50% (after 5 years of use; persists for 10-20 yrs after discontinuation of OC)
- reduce risk of endometrial CA by 50-60% (after 8 years of use)
- possible reduction of benign breast disease (reduced biopsies)
- may be protective against colon cancer
Signs of too much estrogen
nausea, breast tenderness, headache, bloating
Signs of too little estrogen
spotting, breakthrough bleeding early/mid-cycle
Signs of too much progestin
breast tenderness, headache, fatigue, mood changes, bloating
Signs of too little progestin
breakthrough bleeding late cycle
Signs of too much androgen
weight gain, acne, hirsutism, increased LDL, decreased HDL
What are some common side effects of COC?
1) irregular/unexpected bleeding
2) breast tenderness and nausea
3) weight gain
4) mood changes
5) chloasma (skin discolouration)
List some less prevalent side effects of COC
- venous thromboembolism
- MI
- stroke
- gallbladder disease
- breast cancer
List some medications that may cause contraceptive failure
- enzyme-inducing anticonvulsants
- antifungals
- antibiotics
- HIV meds
- herbal (st. johns wort)
- bile acid sequestrants
List some medications that may increase OC activity
- strong CYP3A4 inhibitors (gluconazole, ketoconazole, itraconazole, grapefruit juice)
- vitamin C > 1 g doses
List some common myths about COC
1) women on the COC should have periodic pill breaks
2) the COC affects future fertility
3) the COC causes birth defects if pregnancy occurs while taking it
4) the COC must be stopped in all women over 35 years of age
5) COCs cause acne
Weight > _____ may increase risk of pregnancy & clots in patch users
90 kg (198 lbs)
The ____ is effective in obese women
ring
List some points about the POP
- Norethidrone 0.35 mg PO daily continuously (no HFI)
- Good for those CI to estrogen
- Good for those postpartum, breast feeding, and those with endometriosis
List the MOA behind the POP
1) thicken cervical mucus inhibiting sperm penetration
2) lowers the mid cycle LH & FSH peaks
3) alternations in endometrium and impairment of sperm motility
What is considered a missed pill for the POP
> 3 hrs
MOA of depo injection
1) suppress ovulation
2) increase cervical mucus & atrophy of endometrium
common side effects of depo injection ?
- early weight gain
- irregular bleeding
- headache
Others:
- decreased libido
- mood changes
- decreased BMD- improves when discontinued or can add back E
- delay of ovulation approx 9 months after last dose
What are the two IUS’s available in canada?
1) Mirena
- also approved for abnormal (heavy) menstrual bleeding
- 5 years
2) Jaydess
- smaller, better for nulliparous women
- 3 years
MOA of IUDs
- thicken cervical mucus
- high Ing conc in endometrium - decrease E and P receptors and strong anti proliferative effects