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Biochem > Cell signaling Pathways Steroid Hormoes > Flashcards

Cell signaling Pathways Steroid Hormoes Flashcards

1
Q

what are steroid hormones synthesized from

A

cholesterol

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2
Q

describe the composition of steroid hormones

A

they are lipids that are fat soluble and hydrophobic

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3
Q

what are the two routes that steroid hormones use to exert their biological effects

A

a slower genomic response and a faster nongenomic mechanism

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4
Q

what receptors mediate genomic actions

A

nuclear receptors

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5
Q

what receptors exert nongenomic effects of steroid hormones

A

membrane receptors activate intracellular signaling pathways

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6
Q

describe the de novo synthesis of cholesterol

A

2 acetyl coA + acetoacetyl coA -> HMG CoA -> mevalonate ->isopentyl pyrophophsate-> geranyl pyrophosphate + farnesyl pyrophosphate ->squaliene -?lanosterol -> cholesterol

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7
Q

where do steroid hormones undergo structural changes

A

on side chains or inside of rings

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8
Q

what is estrogen derived from

A

testosterone and androgens

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9
Q

what catalyzes the synthesis of estrogen

A

aromatase

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10
Q

describe female progesterone levels

A

they change through puberty and adolescence (increase until menopause)

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11
Q

describe male levels of progesterone

A

relatively constant, low levels

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12
Q

what do plasma proteins do

A

bind and facilitate the circulation of lipid like hormones

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13
Q

what are some lipid soluble hormones that bind to members of the nuclear steroid/thyroxine receptor family

A

cortisol, retinoic acid, thyroxine

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14
Q

what is cortisol derived from

A

cholesterol

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15
Q

what is retinoic acid dervied from

A

metabolite of vitamin A1, doesnt have steroid ring structure

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16
Q

what is thyroxine derived from

A

tyrosine residues in thyroglobulin, does not have steroid ring structure

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17
Q

what are the domain structures of nuclear steroid receptors

A

variable region, DNA binding, hormone-binding

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18
Q

where are glucocorticoids synthesized

A

adrenal cortex

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19
Q

what do glucocorticoids do

A

regulate metabolism of glucose, stimulate transcription of anti-inflammatory proteins and factors

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20
Q

where is cortisol produced

A

zona fasciculata of the adrenal cortex

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21
Q

what type of steroid hormone is cortisol

A

glucocorticoid

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22
Q

when is cortisol released

A

in response to stress and a low level of blood glucose

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23
Q

what are the effects of cortisol

A
  • increase blood sugar through gluconeogenesis
  • suppress the immune system
  • aid in metabolism of fat, proteins and carbs.
  • decreases bone formation by causing osteocyte apoptosis
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24
Q

how are glucocorticoids used in low doses

A

in adrenal insufficiency

25
Q

how are glucocorticoids used in high doses

A

-oral or inhaled glucocorticoids are used to suppress allergic, inflammatory and autoimmune disorders
-asthma
-post transplant immunosuppressants to prevent rejection and graft-versus-host disease

26
Q

do glucocorticoids prevent infection

A

no

27
Q

what is a side effect of glucocorticoid use

A

inhibit later reparative processes when given post transplant

28
Q

how are glucocorticoids regulated

A

by corticotrophin releasing hormone by nerves in the hypothalamus stimulating ACTH which acts on the adrenal cortex to produce and release cortisol

29
Q

how do glucocorticoids affect inflammatory responses (mechanism)

A

-Gc induces lipocortin which inhibits phosphatidyl choline from forming arachidonic acid.
- this then inhibits the formation of prostaglandins and thromboxanes by COX and subsequently inhibits vasodilation, capillary permeability and leukocyte attraction
- arachidonic acid not forming also inhibits the formation of leukotrienes which are subsequently inhibit phagocytosis, bacterial killing

30
Q

how do glucocorticoids affect immune responses (mechanism)

A
  • GC inhibits the formation of IL-1beta from macrophages which blocks fever and T-cell activation ->B-cell activation and thus antibody production
31
Q

how do NSAIDs inhibit the synthesis of prostaglandins

A

NSAIDs inhibit cox 1 and cox 2 which alter the synthesis of thromboxanes and prostaglandins

32
Q

what is osteoporosis

A

a skeletal disorder characterized by compromised bone strength, increasing the risk of bone fracture

33
Q

how do decreasing estrogen levels affect BMD and fractures

A

-bone loss in women begins 2 years prior to last menses
-estrogen mediated bone loss is completed over 6 years
-bone loss from estrogen is from 6-12%

34
Q

describe the rate of bone loss as a cause of estrogen decrease

A

steep decline at first then gradual decline

35
Q

what is the connection between periodontitis and osteoporosis

A

shared risk factors such as age, genetics, hormone change, calcium, smoking, vitamin D

36
Q

what is the function of selective estrogen receptor modulators (SERMS)

A

they compete with estrogen for the estrogen receptor so estrogen doesn’t bind

37
Q

what are the androgens

A

DHEA, androstenedione, androstenediol, testosterone, DHT

38
Q

what are the groups of steroid hormones

A

glucocorticoids, mineralocorticoids, androgens, estrogens, progesterone and vitamin D

39
Q

what is an estrogen responsive element

A

specific short DNA sequence representing nuclear binding site for estrogen receptor protein and hormone complex

40
Q

when are androgens clinically used

A

-male androgen insufficiency
-treatment of children with growth failure
-bone marrow stimulation in diseases resulting in hypoplastic or aplastic anemia
- masculinizing hormone therapy

41
Q

what is the receptor for androgen

A

testosterone receptors

42
Q

what is androgen insensitivity syndrome

A

mutations in the hormone binding region causing absence of hormone binding or changes leading to testicular feminization

43
Q

what is the estrogen receptor associated with (think diseases)

A

breast cancer and other tumors, control of bone growth, osteoporosis, and uncontrolled growth of the male skeleton

44
Q

what is generalized glucocorticoid resistance and symptoms

A

mutation in ligand binding domain of GR-alpha. presented with history of fatigue, anxiety, hyperandrogenism, and hypertension

45
Q

how do steroid hormones circulate the blood

A

bound to specific binding or carrier proteins

46
Q

how long do genomic actions take

A

hours to day

47
Q

how long do non genomic effects take

A

minutes

48
Q

describe the nuclear mechanism of glucocorticoids

A

-the GC enters the cytoplasm and binds a heat shock protein (hsp)
-the release of hsp causes the GC receptor to dimerize
-the dimer of the receptor and hormone enters the nucleus to bind to the response element

49
Q

what are anabolic steroids

A

synthetic variants of testosterone

50
Q

what are anabolic steroids used for therapeutically

A

to induce male puberty and treat cancer and AIDS

51
Q

what are the health risks of using anabolic steroids

A

bad cholesterol levels, acne, high BP, liver damage, and changes in the left ventricle of the heart

52
Q

what are the adverse effects of anabolic steroids

A

psychiatric symptoms like aggression, violence, mania, and less frequently psychosis and suicide

53
Q

what is androgen insensitivity syndrome

A

mutations in the hormone binding region cause absence of hormone binding or changes leading to testicular feminization

54
Q

what results in estrogen receptor alpha point mutations

A

breast cancer, endometrial cancer and some psychiatric diseases

55
Q

what is generalized glucocorticoid resistance

A

mutation in ligand binding domain of GR. symptoms include fatigue, anxiety, hyperandrogenism, and hypertension

56
Q

what are some diseases involved with mutations in the vitamin D receptor

A

rickets, alopecia, intervertebral disc disease, leprosy

57
Q

what do agonists do and give example

A

bind to a steroid hormone receptor and trigger signaling pathways characteristic of the original hormone
ex: dianabol

58
Q

what do antagonists do and give example

A

bind to the nuclear hormone receptors but do not trigger signaling pathways ex: tamoxifen and raloxifene (antagonists of estrogen receptor)

59
Q

what are some environmental chemicals that target steroid hormone receptors

A

-bisphenol A in plastic bottles and plastic water pipes
- phytoestrogens in soy prodcuts

Biochem (34 decks)

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