RECEPTORS

Shaik vaheeda rehman,Dept of pharmacology,129A1SO605,Nimra college of pharmacy.

WHAT IS A RECEPTOR

RECEPTORS

RECEPTOR:

RECEPTORSIt is a specific binding site on the cell which exhibits some functional groups which trigger the pharmacological action

RECEPTORS

AFFINITY: Ability of agent to combine with receptor

INTRINSIC ACTIVITY: Ability of agent to activate the receptor (efficacy)

AGONIST: maximum affinity and efficacy

ANTAGONIST: having affinity but no efficacy

INVERSE AGONIST: having affinity and negative efficacy

RECEPTORS

Types of receptors: Iono tropic receptors G-protein coupled receptors Enzymatic receptors Nuclear receptors

RECEPTORS

Ionotropic receptors:

RECEPTORS

G PROTEIN COUPLED RECEPTORS:

General Structure of receptors:

RECEPTORS

RECEPTORSStructure of G-protein:

RECEPTORSG protein coupled with receptors:

RECEPTORS

Adenyl cyclase pathway:

RECEPTORS

RECEPTORSStep by step mechanism of G protein coupling and enzyme activation

Phospholipase C pathway:

RECEPTORS

Second messengers:

RECEPTORS

cAMP system

Phosphoinositol system

Arachidonic acid system

cGMP system

Tyrosine kinase system

receptor α2,β1,β2M2

α1M1,M3

Histamine - -

Transducer Gs(β1,β2)Gi(α2, M2)

Gq Unknown G-protein

- -

Primary effector

AC Phospholipase C

Phospholipase A

Guanylate cyclase

Tyrosine kinase

Secondary messenger

cAMP IP3,DAG Arachidonic acid

cGMP Protein phosphatase

Secondary effector

Protein kinase A

Ca++ release 5-lipoxygenase Protein kinase G

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RECEPTORSExamples of G-protein receptors:

Muscarnic receptors (cholinergic) Adrenergic receptors (α,β) Histamine receptors Dopamine receptors Opiate receptors Serotonin receptors (all except 5-HT3) GABAB receptors

Enzymatic receptors:

RECEPTORS

Nuclear receptors:RECEPTORS

RECEPTORSExamples of nuclear receptors:

Glucocorticoid receptors Minero corticoid receptors Oestrogen receptors Progestero receptors Androgen receptors Vit A and vit B receptors Thyroid hormone receptors

RECEPTORSOther receptors:

Spare receptors: Maximum response is observed even though when all the receptors of tissues are not occupied by drug moiety

Orphan receptors: Receptors with no endogenous ligand Eg: PPAR-α receptors (peroxysomal proliferated activated receptors)

Silent receptors: Biologically silent even though stimulations of receptors taking place no biological response

Normal receptors: Response observed when all the receptors of the tissue occupied by drug moiety

RECEPTORSREFERENCE:

Pharmacology by RANG and DALE Integrated pharmacology by WALKER pharmacology by LIPPINCOTT pharmacology by BERTRUM www.wikkipedia.org www.winona.edu www.pharmacologycorner.com www.psychopharmacologyinstitute.com

RECEPTORS