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Chapter 12
Basic Principles of
Neuropharmacology
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Basic Principles of
Neuropharmacology


Neuropharmacology can be defined as “the
study of drugs that alter processes controlled
by the nervous system.”
These drugs are used to treat conditions
ranging from depression to epilepsy to
hypertension to asthma.
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Principles of
Neuropharmacology


How neurons regulate physiologic processes
Basic mechanisms by which
neuropharmacologic agents act:



Sites of action: axons vs. synapses
Steps in synaptic transmission
Effects of drugs on the steps of synaptic
transmission
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Fig. 12-1. How neurons regulate other cells.
There are two basic steps in the process by which neurons elicit responses from other cells:
(1) axonal conduction and (2) synaptic transmission. (T = neurotransmitter.)
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Mechanisms of
Neuropharmacologic Agents

Sites of action: axons vs. synapses



Axonal conduction
Synaptic transmission
Receptors
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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How Neurons Regulate Physiologic
Processes in Two Basic Steps

Axonal conduction
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Action potential down the axon
Synaptic transmission
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Information carried across the neuron gap and the
postsynaptic cell
Postsynaptic cell
• Another neuron, muscle cell, or cell within a secretory
gland
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Mechanisms: Steps in
Synaptic Transmission
1.
Transmitter
synthesis
5.
Termination
of
transmission
2.
Transmitter
storage
Steps in
synaptic
transmission:
4.
Receptor
binding
3.
Transmitter
release
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Fig. 12-2. Steps in synaptic transmission.
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Mechanisms of
Neuropharmacologic Agents


Effects of drugs on the steps of synaptic
transmission
Transmitter synthesis




Transmitter storage


Increase transmitter synthesis
Decrease transmitter synthesis
Cause synthesis of transmitter molecules
Cause receptor activation to decrease
Transmitter release

Promote or inhibit release
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Mechanisms of
Neuropharmacologic Agents


Effects of drugs on the steps of synaptic
transmission
Receptor binding




Cause activation
Block activation
Enhance activation
Termination of transmission


Block transmitter reuptake
Inhibit transmitter degradation
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Multiple Receptor Types and
Selectivity of Drug Action

Selectivity
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
Most desirable quality a drug can have
Able to alter a disease process while leaving other
physiologic processes largely unaffected
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Meet Mort and Merv
Fig. 12-3. Multiple drug receptors and selective drug action.
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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An Approach to Learning About
Peripheral Nervous System Drugs

Three types of information needed
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Type (or types) of receptor through which the drug
acts (alpha1, alpha2, beta1, etc)
Normal response to activation of those receptors
(agonist versus antagonist)
What the drug in question does to receptor
function
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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Basic Principles of
Neuropharmacology

An approach to learning about peripheral
nervous system drugs



Knowing the receptors that the drug affects
Knowing the normal responses to activation of
those receptors
Knowing whether the drug in question increases
or decreases receptor activation
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
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