L4: Sex Steroids Flashcards
What are the classes of steroid hormones?
- glucocorticoids
- mineralcorticoids
- androgens
- progestagens
- oestrogens
What is the function of glucocorticoids?
increase protein turnover and gluconeogenesis, anti-inflammatory
What is the function of mineralcorticoids?
control sodium and potassium balance in the body
What is the function of androgens?
maintain functional activity of male reproductive system, anabolic and sexual behaviours
What is the function of progestagens?
maintenance of pregnancy
What is the function of oestrogens?
maintain functional activity of female reproductive system (menstrual cycle and labour); also actions on cardiovascular system and bone
Define the complexity of steroid hormones, six possible forms
- Multiple enzyme pathways
- They are reflected by availability of substrate, complicated because you can make steroids from cholesterol everywhere in every membrane
- There is a possibility of interaction and interconversion between active and inactive forms
- There’s multiple signalling pathways (not only genomic, but there’s also non-genomic)
i) They can act in endocrine or local effect (paracrine, autocrine)
ii) Organ, tissue and cell interactions because of receptor expression and availability
iii) Genomic and non-genomic - Multiple receptor types
i) With multiple molecular pathways
ii) With multiple promotor / repressor transcription actions - Bioavailability of the steroid for its receptor – actions of binding proteins
Which hormones control the human menstrual cycle and how?
- estrogen (follicle steroidogenesis)
- progesterone (corpus lutem steroidogenesis)
What is the length of the human mesntrual cycle?
28 days
On which day of menstrual cycle do humans ovulate?
14
What happens during ovulation? Hormone changes, uterine lining changes
- After ovulation, empty follicle turns into corpus luteum (progesterone factory), which then turns proliferative uterus into secretory uterine lining, it’s secretory so it can support fertilized oocyte
What is the receptive state of the menstrual cycle? how long is it
State of the uterine lining ready for implantation, days 20-24, 7-10 days in secretory phase
What are the principal pathways of steroidogenesis in follicular cells?
Theca cell is producing substrate that is being released to granulosa cell and then that makes the oestrogen.
Check L4, SLIDE 9 for diagramm
What are the potential targets to disrupt the fertility of the human menstrual cycle (contraception)?
Fertility relies upon co-ordinated interactions between Hypothalamic-Pituitary-Ovarian axis, ovary and uterus –> targets
- folliculogenesis
- ovulation
- embryogenesis
- estrogen
- LH, FSH
- Progesterone
- Receptive state
What is the combined contraceptive pill?
combination of an oestrogen and a progesterone analogue, taken 21 of 28 days