Techniques in neuropharmacology

Question 1

Neuropharmacological techniques

Answer 1

• radiogland binding assays
• autoradiography
• microiontophoresis
• molecular biology
• electrophysiology
• imaging
• behavioural and cognitive testing
• clinical trials
• and more……

Question 2

Neuropharmacology testing

Answer 2

1. Choice of test system/prep (in vitro/in situ/in vivo)
2. Route of ligand administration/delivery
3. Equilibration (penetration/didtribution)
4. Testing of pharmacological effects, establishing concentration (dose)/response relationships (electrophysiology and/or imaging)
5. Washout/reversal of pharmacological effects, or control experiments (specificity of the pharmacological effect)

Question 3

In vivo

Answer 3

Living organism

Question 4

In vitro

Answer 4

In laboratory dish/test tube

Question 5

In situ

Answer 5

experiments that occur in a lab context that focus on a specific protein or gene, looking at it inside an entire organism.

Question 6

Types of electrodes (electrophysiology recording)

Answer 6

Intracellular (or sharp) electrode —> 5um
Extracellular electrodes (e.g. microiontopheresis, but also recording) —> 20/30 u

Question 7

Electrophysiology recording

Answer 7

1. One internal electrode measures membrane potential (Vm) and is connected to the voltage clamp amplifier
2. Voltage clamp amplifier compares membrane potential to the desired (command) potential
3. When Vm is different from the command potential, the clamp amplifier injects current into the axon via a second electrode. The feedback arrangemet causes the membrane potential to become the dame as the command potential
4. The current flowing back into the axon and thus across its membrane can be measured here

(Allows specific localised findings —> a concentration response curve can be produced)

Question 8

How many electrodes do you need to record a signal ?

Answer 8

At least 2

Question 9

Ohm’s law

Answer 9

V = I * R

V = voltage
I = current
R = resistance

Question 10

ESPS

Answer 10

Excitatory postsynaptic potential
- positive change in membrane (depolarises)
- action potential hasn’t happened yet —> forced when threshold is reached

Question 11

IPSP

Answer 11

Inhibitory post synaptic potential
- opening of chloride channels
- negative change in membrane

Question 12

Extracellular

Answer 12

Excitatory
Negative = excitatory (in most cases)

Question 13

LFP

Answer 13

Local field potential
- electricity always a happening in a circuit

Question 14

Patch-clamp techniques and the study of ion channels

Answer 14

Electrode touching the cell (left) and after formation of ‘gigaseal’ and suction (right)

Recordings of electrical activity before and after ‘Gigaseal’ formation

Examples of channels opening, difference in noise levels

Question 15

Patch-clamp varieties

Answer 15

• cell attached
• inside-out patch
• whole - cell mode
• outside - out patch
  (Also perforated patch, loose patch etc..)

Question 16

Choice in systems - in vitro

Answer 16

• neurotransmitter receptors can be expressed in a system that usually lacks that particular cell receptor type: e.g xenopus oocytes or HEK293 cells (human embryonic kidney cells)
  —> immortilised cell lines, perminanlty expressing receptors
• receptor function can ne a probed application of agonists ad antagonists and responses can either be recorded electrophysiologically or using imagine techniques —> however receptor properties and function might be different from in situ and in vivo, controls are needed

Question 17

Choice in systems - in Situ

Question 18

Choice in systems - in Vivo