Medische Psychologie - Semester 2
Psychofarmacologie
Lisanne Houtstra
, Lecture 1: Introduction Lecturer: Dr. Paula Mommersteeg
Most psychopharmaca act upon few major neurotransmitter systems in which several similar structures and functions can
be identified.
- In this basic lecture you learn how neurotransmitters act upon nerve cells, get to know different mechanisms of
action of receptor types, and gain insight in consequences of agonistic and antagonistic psychopharmaca.
Reading material
→ 4 th Edition Stahl
- Chapter 1: Chemical neurotransmission p1-27.
- Chapter 2: Transporters, receptors, and enzymes as targets of psychopharmacological drug action p28-51.
- Chapter 3: Ion channels as targets of psychopharmacological drug action p52-78
ttp://youtu.be/GIGqp6_PG6k
Supportive online material ‘Firing neurons’: h
Learning objectives
⇒ Note: Learning objectives are not ‘questions’ that need to be answered, but statements that describe what we expect
you to know after studying this Lecture (which includes the study material as well as lectures)
→ After studying students should be able to
Chapter 1:
- Know the six classic neurotransmitters
- Understand classic, retrograde and volume neurotransmission
- Understand how ‘volume transmission’ can activate or inhibit other regions than the postsynaptic membrane
- Describe excitation-secretion coupling
- Describe the four key signal transduction cascades
- Understand how signal transduction cascades work to activate gene expression or turn on phosphoproteins
- Describe the main actions of kinases and phosphatases
- Understand the delayed processing of a postsynaptic signal to gene transcription, and events further downstream
- Understand and describe the timing of gene expression
- Describe the role of gene activation and gene silencing on protein production
Chapter 2:
- Describe where in the cell the transmembrane and vesicular transporters are located
- Reproduce the names of the vesicular transporters, and their ligands
- Reproduce the names of the synaptic reuptake transporters, their ligands, main antidepressants, and stimulants
that act on them
- Explain the immediate consequences of blocking uptake receptors
- Acknowledge the dose-dependent selectivity of the reuptake receptors
- Acknowledge that about 1/3 of the prescribed psychotropic drugs act on one or more of the three monoamine
receptors
- Describe the role of G-protein linked receptors on signal transduction and chemical neurotransmission
- Understand the concept of constitutive activity
- Describe the actions, know examples and explain working of full agonists, partial agonists, antagonists and
inverse agonists.
- Describe examples of indirect and direct acting agonists
- Understand how an enzyme works, and how reversible and irreversible blocking of an enzyme affects the amount
of product.
- Describe the role of enzymes as targets of psychotropic drugs
- Understand the role of Cytochrome P450 drug metabolizing enzymes
Chapter 3:
- Describe the role of ligand-gated ion channels and voltage-sensitive ion channels
- Describe the role of agonists, antagonists, inverse agonists and positive and negative allosteric modulators on
ligand-gated ion channels.
- Describe the role of positive allosteric modulators and negative allosteric modulators on ion channel activity
- Understand excitation-secretion coupling, through opening or closing of voltage-sensitive sodium channels
(VSSCs), and voltage-sensitive calcium channels (VSCCs)
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, - Know that GABA and acetylcholine act upon ligand-gated ion channels
- Remember what an action potential is, and how ion channels play a part in distributing an action potential across
the neuron.
- Describe that voltage-gated calcium channels are involved in smooth muscle contraction, and as such play a role
in blood pressure
- Describe that voltage-gated calcium channels are involved in releasing neurotransmitters from synaptic vesicles
into the synaptic cleft.
- Acknowledge the role of psychopharmaca in blocking voltage gated calcium-channels in lowering blood pressure,
and reduce excessive neurotransmission, such as pain, seizures, mania or anxiety.
College
Alle somatische aandoeningen hebben een psychologische component
→ In dit college worden we een zenuwcel en ontvangen en verzenden we signalen
→ Relevantie = psychofarmaca die inwerken zenuwcellen beïnvloeden de neurotransmissie op dit niveau
Psychophathology and pharmacodynamics
→ Assumption of disturbance in brain signals
- Info over actiepotentialen, neurotransmitters, volume neurotransmissie, excitatie-secretiekoppeling: lees het
boek voor aanvullende info!
- Hoe komen signalen door de hersenen?
- Ligand
- Receptor
- Messenger pathway
- G-protein coupled receptor
- Ion channel
- Enzyme
- Signal transduction
- Hoe beïnvloeden psychofarmaca dit proces?
- Omvat zenuwcellen, neurotransmitters, receptoren en signaaltransductiewegen
- Vergelijkbare basistypen
Background
→ Stel je voor: een actiepotentiaal in een neuron heeft de het vrijkomen van een neurotransmitter veroorzaakt.
- Hoe werkt dit signaal (neurotransmitter) op de volgende cel?
- Wat gebeurt er in de volgende cel?
- Signalen moeten binden …
⇒ Proces van actiepotentiaal, threshold, actiepotentiaal → doorgegeven door zenuwbaan, wat dan? afgifte
neurotransmitters → volgende cel
Different signal transduction cascades
Four of the most important signal transduction cascades in the brain are shown here. These include G -protein-linked
systems, ion-channel-linked systems, hormone-linked systems, and neurotrophin-linked systems.
● Each begins with a different first messenger binding to a unique receptor, leading to activation of very different
downstream second, third, and subsequent chemical messengers.
● Having many different signal transduction cascades allows neurons to respond in amazingly diverse biological
ways to a whole array of chemical messaging systems.
● Neurotransmitters (NT) activate both the G-protein-linked system and the ion-channel-linked system on the left,
and both of these systems activate genes in the cell nucleus by phosphorylating a protein there called cAMP
response element-binding protein (CREB).
1. The G-protein-linked system works through a cascade involving cAMP (cyclic adenosine monophosphate) and
protein kinase A,
2. The ion-channel-linked system works through calcium and its ability to activate a different kinase called
calcium/calmodulin-dependent protein kinase (CaMK).
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, 3. Certain hormones, such as estrogen and other steroids, can enter the neuron, find their receptors in the
cytoplasm, and bind them to form a hormone–nuclear receptor complex. This complex can then enter the cell
nucleus to interact with hormone response elements (HRE) there to trigger activation of specific genes.
4. The neurotrophin system on the far right activates a series of kinase enzymes, with a confusing alphabet soup of
names, to trigger gene expression, which may control such functions as synaptogenesis and neuronal survival. Ras
is a G protein, Raf is a kinase, and the other elements in this cascade are proteins as well
(MEK stands for mitogen-activated protein kinase/extracellular-signal-regulated kinase; ERK stands for
extracellular-signalregulated kinase itself; RSK is ribosomal S6 kinase; MAPK is MAP kinase itself, and GSK-3 is glycogen
synthase kinase 3).
Messenger pathways
1. G-protein linked/coupled receptor - GPCR.
○ Fungeert als first messenger en leidt na binden van ligand tot cascade. (zie
hieronder).
■ Ligand: een molecuul dat aan een ander bindt.
● Vaak is een oplosbaar molecuul zoals een hormoon of
neurotransmitter die bindt naar een receptor.
● DUS een stofje dat receptor kan binden (neurotransmitter of
iets anders) en heeft dan een effect
■ Binding van de ligand (eerste boodschapper) aan de
receptor verandert de vorm van de receptor, die een
bijbehorend G-eiwit activeert, dat dan effector-eiwitten,
enzym functies of ionenkanalen activeert.
→ zie plaatje
○ Is een soort eiwit streng door het membraan heen die samen een
complex vormen.
○ Receptor in membraan, binden = activatie (first messenger) =
eiwitactiviteit
■ Gebonden aan g protein → ligand bindt aan receptor →
activatie g protein
○ Iedere stof heeft eigen type receptor waar die aan kan binden (5-ht,
glutamaat)
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