Neuropharmacology - Neurotransmission

Question 1

Cell types in the brain

Answer 1

neurons, astorycytes, microglia, endothelial cells and pericytes

Question 2

Neuron structure

Answer 2

Axon, dendrites, cell body and nucleus.

Question 3

Physiological role of astrocytes in brain function

Answer 3

Releases and takes up NTC (glutamate)
Expresses receptors (NMDA)
Regulates synaptic transmission
Conducts electrical events via gap junctions
Memory formation
Produces and releases neurotrophins

Question 4

Roles of astrocytes in brain pathology

Answer 4

Scar formation which impairs the reformation of axons

Immune activation through antigen presentation

Question 5

Types of astrocytes

Answer 5

Protoplasmic
Interlaminar
Fibrous
Polarised

Question 6

Protoplasmic astrocytes

Answer 6

• Most common type
• Resides in layers 2-6 of cortex
• Has non overlapping GFAP positive processes (domain organisation)

-Astrocyte domains may cover 10 nerve cell bodies, and 5 blood vessels therefore having an important position for coordination (e.g regulate blood flow in response to increased synaptic transmission)

Question 7

Fibrous astrocytes

Answer 7

• Found in grey and white matter
• Processes intermingle ( does not form domain structure)
• Supportive role rather than information processing. Responds to mechanical injury e.g stroke (produces scar tissue)

Question 8

Gliotransmission

Answer 8

Process where transmitters are released from astrocytes and act on neurons

Question 9

Glioneural function units

Answer 9

Thought that memories are encoded in astorcyte networks

Astrocytic adenosine release induces sleep via caffeine sensitive receptors

Question 10

Microglia

Answer 10

Resident macrophages of the brain
Surveys the brain microenvironment
Sensitive to brain perturbations
Mediates brain immune response
Phagocytose plaques, debris in Alzheimers disease?
May modulate neurotransmission
Involved in the sculpting of the brain during development and modulates synaptic transmission.

Question 11

Pericytes and brain endothelial cells

Answer 11

Pericytes enclose cells within the brain capillaries and maintain the BBB
In Neurological disorders such as alzheimers and stroke, the BBB and NV unit are compromised .
- Invasion of Hb, and T cells across the BBB. These compounds are toxic to neurons?

Question 12

Molecular targets for brain targeting drugs

Answer 12

Enzymes involved with NTC formation or degradation
Structural proteins
Ion channels
 NTC reuptake proteins
NTC receptors
 Transducer proteins, GPCR

Question 13

Synaptic transmission

Answer 13

Neurons can form synapses with thousands of other neurons. Few of these synapses convey info through NTC (1st messenger and Ca2+ dependant).
Diffuse across synaptic cleft, binds onto NTC receptor on PS membrane.
Binding leads to the formation of 2ndary messengers resulting in the excitation of the neuron or inhibition

Question 14

Termination of NTC activity

Answer 14

Reuptake and/or metabolism

Question 15

Properties of NTC and examples + classes

Answer 15

Fast effects
Monoamines: Serotonin, NA, dopamine
Aminoacids: GABA, glutamate, glycine
Neuropeptides Neuromodulators
Other: Acetylcholine

Question 16

Pathology affecting GABA transmission

Answer 16

Dampening of excitation leads to seizures

Question 17

Strychnine

Answer 17

Glycine receptor antagonist.

• Blocks Cl- ligand gated channels, preventing the inhibitory effects of glycine on the postsynaptic neuron
• Therefore, action potentials are triggered with lower levels of excitatory neurotransmitters.

Question 18

Neuromodulators vS NTC

Answer 18

NMs have slower pre and post synaptic responses and are released by nerve cells and astrocytes.

Question 19

Neurotrophic factors

Answer 19

Released by non neuronal cells (astro + microglia) and neurons.

• Works over long time scales
• Acts on tyrosine kinase receptors to mediate growth, morphology, functional properties, survival promoting effects across the Nervous system.

Question 20

NTC properties

Answer 20

Fast acting (Ion channel action) - GABA,glutamate, glycine
Slow- GPCR (Dopamine , neuropeptides, GABA, acetylcholine.

Can have both fast and slow actions depending on the receptor they act on.