This document discusses β-adrenoceptor modulation in therapeutics. It begins with an introduction to the autonomic nervous system and its regulation of involuntary functions. It then covers the history of discoveries about sympathetic neurotransmitters like norepinephrine and parasympathetic neurotransmitters. The document discusses the classification of α and β adrenergic receptors, their properties, and the ranking of agonists. It also covers receptor regulation mechanisms like desensitization, up/down regulation, and denervation supersensitivity. Finally, it states that drugs affecting the β-adrenergic system are used therapeutically and concludes with references.

1. β-ADRENOCEPTOR
MODULATION IN
THERAPEUTICS
By-Dr Amit Gupta
PG-1
Deptt of Pharmacology

2. Contents
• Introduction
• History
• Adrenergic receptors
• Receptor regulation
• Drugs for β-receptor modulation
• Conclusion

3. Introduction
• ANS is of vital importance for the well being of the
organisms
• ANS regulate the activities that are not under
voluntary control and that function below the level of
consciousness
• The efferent limb of ANS is anatomically divided into
sympathetic and parasympathetic system

4. • Many organs receive both sympathetic and
parasympathetic innervation and the two divisions are
functionally antagonistic in majority of cases
• Main function of sympathetic nervous system is
tackling stress and emergency whereas
parasympathetic part is associated with assimilation
of food and conservation of energy

5. History
• Elliot in 1905 suggested that sympathetic nerves
function by the release of adrenaline-like substance
• Dixon(1907) proposed vagus release a muscarine-like
substance
• Von Euler(1946) eventually showed sympathetic
transmitter was Noradrenaline

6. • Now, it is establishd NE is the principal transmitter of
most Sympathetic postganglionic fibres and of certain
tracts in CNS
• Epinephrine- adrenal medulla
• Dopamine-extrapyramidal system, mesocortical and
mesolimbic pathways
• Collectively these three amines are called as
Catecholamines

7. Adrenergic Receptors
• To understand diverse effects of the catecholamines and
related sympathomimetic agents, classification and
properties of different adrenergic receptors should be
known
• Ahlquist (1948) proposed designation α and β for
receptors on smooth muscle where catecholamines
produce excitatory and inhibitory responses respectively
• Exception is gut which is relaxed by activation of these
two receptors

8. • Rank order of potency of agonist
• α- receptor ---- Epi ≥ NE ˃ Isoprenaline
• β-receptor----- Isoprenaline ˃ Epi ˃ NE

10. Receptor Regulation
• Responses that follow activation of all types of
adrenergic receptors result from G-protein mediated
effects
• β-receptor function by increasing production of
second messenger cAMP

13. • Exposure of catecholamine-sensitive cells and tissues
to adrenergic agonists causes a progressive decrease
in their capacity to respond to such agents
• Three process have considerable clinical significance
1. Desensitisation
2. Up and down regulation of receptors

14. 3. Denervation supersensitivity
These phenomenon can limit the therapeutic efficacy
and duration of action of catecholamines and other
agents

15. Responses of effector organs to autonomic
nerve impulses

20. Drugs affecting β-adrenoceptor system in
therapeutics

28. Conclusion

29. REFERENCES
• Hager,A.(1981).Br.Med.Bull,37(3)287
• For various trial details (https://clinicaltrials.gov)
• HL sharma, KK sharma. Principles of Pharmacology. 2nd
ed.2011;p 901
• Katzung BG, Trevor AJ. Basics and clinical
pharmacology. 13th ed.McGraw Hill
education:2015;p664-5