Mechanism of Hormone Action

1
Mechanism of Hormone Action
2
Mechanism of Hormone Action
3
Receptor Structure
4
Mechanism of Hormone Action
Protein Hormones (cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
S-ER Steroid Synthesis
Mitochondria
Nucleus
DNA
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
5
Mechanism of Hormone Action
Protein Hormones (cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
S-ER Steroid Synthesis
Mitochondria
Nucleus
DNA
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
6
Mechanism of Hormone Action
Protein Hormones (cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
S-ER Steroid Synthesis
Mitochondria
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
7
Mechanism of Hormone Action
Protein Hormones (cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
S-ER Steroid Synthesis
Mitochondria
Cholesterol
Pregnenolone
Cholesterol
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
8
Mechanism of Hormone Action
Protein Hormones (cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
S-ER Steroid Synthesis
Mitochondria
Cholesterol
Pregnenolone
Cholesterol
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
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cAMP Second Messenger Hormones

• Anterior Pituitary Hormones
• LH, FSH, Prolactin
• STH, ACTH, TSH
• Placental Hormones
• HCG, eCG

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Protein Hormones (Ca2 Second Messenger)
Plasma Membrane
Receptor
Ca2
Endoplasmic Reticulum
Plasma Membrane
11
Protein Hormones (Ca2 Second Messenger)
Plasma Membrane
Receptor
Ca2
Endoplasmic Reticulum
Plasma Membrane
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Protein Hormones (Ca2 Second Messenger)
Plasma Membrane
Receptor
Ca2
Endoplasmic Reticulum
Plasma Membrane
13
Protein Hormones (Ca2 Second Messenger)
Plasma Membrane
Receptor
Ca2
Endoplasmic Reticulum
Plasma Membrane
14
Protein Hormones (Ca2 Second Messenger)
Plasma Membrane
Receptor
Ca2
Endoplasmic Reticulum
Plasma Membrane
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Calcium Second Messenger Hormones

• GnRH
• triggers release of LH in anterior pituitary
• Oxytocin
• triggers contractions of smooth muscle
• PGF2?
• triggers apoptosis of cell
• inhibition of progesterone synthesis

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Steroid Hormone Action (Slow)
Cell Membrane
Cytoplasm
Nucleus
DNA
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Steroid Hormone Mechanism

• Estradiol
• Progesterone
• Testosterone, Dihydrotestosterone
• Cortisol

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Steroid Hormone (Fast)
(cAMP second messenger)
G
Plasma Membrane
Receptor
Protein Kinase A (PKA)
Ca2
Smooth Muscle Contraction (Uterine Myometrial
Cell)
Protein
R-ER Protein Synthesis
Synthesis
(Enzymes)
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Steroid Hormone (Fast)

• Not the classical mechanism of action of a
  steroid hormone
• Requires plasma membrane receptor
• Operates via protein kinase activation
• Estradiol smooth muscle of uterus

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Feedback Loops
Neuro-secretory Cells
Hypothalamus
Releasing Hormones
Polypeptides
Portal Vein
-
Anterior Pituitary
-
Gonadotropins FSH, LH
Proteins
Blood Stream
Gonads
Why only effects on


Receptor on Cell Surface
target organs
Cyclic AMP inside cell
Testosterone

Steroid Hormone Production
Estradiol
Progesterone
Blood Stream
Bound to Protein
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Endocrine Feedback Loops

• Negative
• gonadal steriods
• Testosterone, Progesterone, Estradiol
• Protein hormones
• inhibin
• Positive
• Gonadal steroids
• estradiol

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Chapter 5 of Textbook

• Contains more than covered here
• Responsible for all material in book