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)
9
cAMP Second Messenger Hormones

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

10
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
12
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
15
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

16
Steroid Hormone Action
Cell Membrane
Cytoplasm
Nucleus
DNA
17
Steroid Hormone Mechanism

• Estradiol
• Testosterone, Dihydrotestosterone
• Cortisol

18
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
19
Endocrine Feedback Loops

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