oestrogens, progesteron and oral contraceptives Flashcards
17β-Estradiol is synthesised by…?
maturing follicle in 1st half of cycle
How can Estradiol activate ER-responsive gene expression?
ligation and dimerisation of oestrogen receptors in the nucleus
Progesterone is secreted by…?
the corpus luteum in 2nd half of cycle
What occurs when there is an activation of progesterone?
receptors, dimerisation and nuclear translocation drives progesterone-responsive gene expression
What are the actions of estradiol during the menstrual cycle?
modulates FSH and LH release
stimulates endometrial proliferation and growth; breast growth
increases expression of progesterone receptors
stimulates copious watery secretions from cervix
What are the actions of progesterone in the menstrual cycle?
modulates FSH and LH release
stimulates cyclical growth of uterus and breasts
reduces uterine excitability
produces secretion of less abundant, thicker mucus from cervix
reduces effect of E2 in endometrium
Oestrogen and progesterone stimulate…?
growth of the endometrium in preparation for implantation
Progesterone after non-conception induces…
changes in cervical mucous that prevents sperm motility; levels decline as corpus luteum regresses
During conception and implantation progesterone levels…
elevate and are maintained by the developing placenta and pituitary; FSH/LH suppression continues
What is required for embryo survival and immune rejection?
Progesterone
Why does progesterone need to be maintained?
to maintain embryo viability and uterine quiescence
What is the use of oral contraceptives?
mimics the endocrine environment of pregnancy, shutting down the ovulatory cycle and preventing ovulation and fertilisation and implantation
What are the two major groups of Oral Contraceptives?
- Combined oral contraceptives
2. Progestogen-only contraceptives
What is a combined oral contraceptive?
the combination of a synthetic oestrogen and a synthetic progestogen
What are two synthetic oestrogens used in combined OCs?
ethinyloestradiol
mestranol
What are some synthetic progestogen used in OCs?
1st gen - ethisterone
2nd gen - lveonorgestrel
3rd gen - desogestrel
What are the mechanisms of combined OCs?
- inhibit ovulation
- thicken cervical mucus
- reduce receptivity of endometrium
What is the timeline for combined OCs?
21 days OC + 7 day pill break
21 days OCs + 7 days placebo
= induces withdrawal bleeding
What are the benefits of using combined OCs?
highly effective, reversible + safe contraception
decrease risk of ovarian and endometrial cancer
reduced risk of benign breast disease
improvement in acne
What are some common adverse effects of using combined OCs?
breakthrough bleeding (increase oestrogen or progestogen)
nausea, vomiting (decrease oestrogen)
fluid retention, breast tenderness (decrease oestrogen)
melasma (avoid sun + stop oestrogen)
acne/weight gain
depression, fatigue
decreased libido
What are some potential serious adverse effects of combined OCs?
- oestrogen can cause enhanced coagulation and COCs may be associated with increased risk of myocardial infarcation + venous thromboembolism
- increase 20% risk in breast cancer
What are some contraindications for combined OCs?
pregnancy thromboembolic disorders oestrogen-dependent tumours focal migraine major elective surgery breastfeeding
Who are suitable for progestogen-only oral contraceptives?
breastfeeding women
focal migraine
are over 35 and smoke, or other cardiovascular risk factors
before major surgery
What are the mechanisms of progestogen-only OCs?
for cervical mucus thickening and decrease in amount
How do COCs reduce the likelihood of pregnancy by inhibiting…?
- ovulation
- fertilisation
- implantation
