Adrenoceptors are membrane bound receptors located throughout the body on neuronal and non-neuronal tissues where they mediate a diverse range of responses to the endogenous catecholamines- noradrenaline and adrenaline. They are G protein coupled receptors. Binding of catecholamine to the receptor is responsible for fight or flight response.

1. 1

2. 2

3. INTRODUCTI
ON
 Adrenoceptors are membrane bound receptors
located throughout the body on neuronal and non-
neuronal tissues where they mediate a diverse range
of responses to the endogenous catecholamines-
noradrenaline and adrenaline.
 They are G protein coupled receptors.
 Binding of catecholamine to the receptor is
responsible for fight or flight response.
3

4. CLASSIFICATI
ON
4

5. 5
RECEPTORNAME TYPICALLOCATIONS
α1 Vascular smooth muscle, visceral
smooth muscle, radial smooth muscle of
iris, CNS neurons
α2 Some presynaptic terminals, pancreatic
islets, platelets, ciliary epithelium,
smooth muscles, CNS neurons
β1 Myocardium, JG cells, some presynaptic
terminals, CNS neurons
β2 Visceral smooth muscle, vascular
smooth muscle, liver, myocardium,
skeletal muscle, some presynaptic
terminals, CNS neurons

6. 1. α ADRENERGIC RECEPTOR
A) α1 ADRENERGIC RECEPTOR (Gq)
ACTIVATION
Gq activates
phospholipas
e C
Increase
in Inositol
phosphate
3 (IP3) and
Calcium
Activation
of enzyme
protein
kinase C
Phospho
rylation
of other
enzymes
Increase or
decrease
of
electrolyte
transfer in
or out of
the cell
6

7. AGONISTS
Phenylephrine
Xylometazoline
Pseudoephedrin
e
Naphazoline
ANTAGONISTS
Prazosin
Terazosin
Alfuzosin
Doxazosin
7

8. 8

9. B) α2 ADRENERGIC RECEPTOR (Gi)
ACTIVATION
Gi associates with
adenylyl cyclase
Decrease in cAMP
Protein Kinase A
(PKA) is not activated
by cAMP
Proteins such as
phosphorylase kinase
cannot be
phosphorylated by
PKA
No activation of
glycogen
phosphorylase
Decreased
breakdown of
glycogen
9

10. AGONIST
Clonidine
Methyl dopa
Guanabenz
Guanfacine
ANTAGONIST
Yohimbine
Mirtazapine
Idazoxan
Atipamezole
10

11. 11

12. 12

13. 2. β ADRENERGIC RECEPTORS
A) β1 ADRENERGIC RECEPTOR (Gs)
13

14. AGONIST
• Denopamine
• Dobutamine
• Xamoterol
ANTAGONIST
• Atenolol
• Metoprolol
• Esmolol
• Nebivolol
• Bisoprolol
14

15. B) β2 ADRENERGIC RECEPTORS-
15

16. • Salbutamol
• Levosalbutamol
• Terbutaline
AGONIST
• Butoxamine
ANTAGONIST
16

17. C) β3 ADRENERGIC RECEPTORS-
They are involved in the epinephrine and
norepinephrine induced activation of adenylyl
cyclase through the action of the G proteins
of the type Gs.
• Ambigeron
• Mirabegron
• Solabegron
AGONIST
• L-748,328
• L- 748,337
ANTAGONIST
17

18. 18

19. 19

20. REFERENCES
20
 Adrenoceptor Pharmacology, Emma Robinson and
Alan Hudson, Psychopharmacology Unit, Department
of Pharmacology, School of Medical Sciences,
University of Bristol.
 www.cvpharmacology.com/vasodilator/alpha
 www.ncbi.nih.gov/pubmed/6098436
 www.wikipedia.com

21. 21