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oestrogens

oestrogens

introduction

  • mainly beta-oestradiol, but also oestrone & oestriol, the latter being the almost totally impotent liver metabolite of the former two.
  • oestrogenic potencies:
    • oestradiol 12 x oestrone & 80 x oestriol;
  • oestradiol mainly secreted from ovary & placenta;
  • oestrone secreted in small amounts from ovary but also formed by peripheral tissue conversion of androgens secreted from adrenal cortices;
  • cellular effect:
    • enter cells, bind to i/cell. receptor, migrate to nucleus, interact with DNA
    • ⇒ alter transcription & increased DNA ⇒ mitosis;
    • a specific anabolic action targeted to certain organs rather than non-specific testosterone anabolic activity;

actions:

pubertal enlargement & changes of female sexual organs:

  • vaginal epithelium from cuboidal ⇒ stratified;
  • pubic hair growth (but mainly via androgens);
  • breast development:
    • stromal tissues increased;
    • extensive ductile system;
    • deposition fat increased;
  • endometrial proliferation;

Fallopian tube

  • glandular proliferation, enhanced cilia;

bones

  • increased osteoblastic activity ⇒ pubertal growth surge
  • ⇒ earlier epiphyseal closure than testostestone
  • ⇒ decreased osteoporosis as:
    • increased bone matrix;
    • increased deposition of bone Ca & P;

other actions

  • Slight increased protein deposition « as for testosterone;
  • Slight increased BMR about 1/3rd as much as testosterone increase;
  • increased fat deposition esp. breasts, s/c tissues, buttocks, thighs;
  • Soft, smooth, thicker, more vascular skin;
  • Slight Na & water retention as adrenocortical effect & only significant in pregnancy?

exogenous oestrogens

phytoestrogens

  • plant derived substances with oestrogenic properties as well as other pharmacologic properties
  • most phytoestrogens bind ERβ more readily than ERα
  • 4 main groups:
    • isoflavonoids: genistein, daidzein, coumestrol and equol
    • flavonoids: 8-prenylnaringenin, 6“-acetylapiin
    • stilbenes: resveratrol (grape skin, red wine)
    • lignans
  • sources:
    • soy beans (genistein, daidzein)
    • parsley (6”-acetylapiin, petroside)
    • nuts, oilseeds, cereals, breads
    • legumes
oestrogens.txt · Last modified: 2016/07/15 23:38 (external edit)