Neurotransmitter

Question 1

Name the main 2 neurotransmitters.

Answer 1

1. with excitatory effects (glutamate)

2. with inhibitory effects (GABA or glycine - spinal cord)

Question 2

What do all the other neurotransmitters do?

Answer 2

• They have modulating effects rather than information-transmitting effects.
• The release of neurotransmitters other than glutamate and GABA tends to activate or inhibit entire circuits of neurons that are involved in particular brain functions.

Question 3

What is the role of Acetylcholine (ACh)?

Answer 3

• The primary neurotransmitter secreted by the efferent axons of the CNS
• All muscular movement is accomplished by the release of acetylcholine
• ACh is involved in regulating REM sleep - dreaming (doroslateral pons), perceptual learning (basal forebrain), and memory (hippocampus).
• The effects of ACh are generally facilitatory

Question 4

Where is ACh found?

Answer 4

• ACh found at the target of parasympathetic branch of the ANS – outside of the CNS, first discovered neurotransmitter

Question 5

What are the ACh receptors?

Answer 5

nicotinic and muscarinic

Question 6

Describe the nicotinic receptor.

Answer 6

And inotropic ACh receptor stimulated by nicotine.
Found in the postsynaptic membrane of;
     all autonomic ganglia
     All neuromuscular junctions
     Some CNS pathways
Depolarisation = excitation

Question 7

Describe the muscarinic receptor.

Answer 7

A metabotropic acetylcholine receptor.
- Produces parasympathetic nerve effects in the heart, Smoove muscles, and glands
- G protein coupled receptors (receptors influence ion channels by means of G proteins)
Hyperpolarisation causes K+ channels to open = inhibition
Depolarisation causes K+ channels to close = excitation

Question 8

What blocks nicotinic ACh receptors?

Answer 8

Blocked by curare (=paralysis).

Curare acts at the junction between nerve cells and muscles causing paralysis.

Question 9

What blocks muscarinic ACh receptors?

Answer 9

Blocked by atropine.
Atropine acts by preventing acetylcholine from depolarising the post-synaptic membrane in the parasympathetic branch – treatment of low heart rate

Question 10

Describe an experiment to test the water system for self-administration of dopamine.

Answer 10

• Injected rats with pleasurable addictive substances in 2 different areas. Rats would press lever when they wanted another dose
• If substance injection site was here in the brain (part of the reward pathway) they pressed the lever more often.

Question 11

Where is the location of the reward pathway?

Answer 11

• Reward pathway is located in the midbrain.

- Ventral tormentor area (VTA), nucleus accumbens, prefrontal cortex.

Question 12

Describe tolerance.

Answer 12

• A state in which organism no longer responds to a drug

- A higher dose is required to achieve the same effect.

Question 13

Describe dependence.

Answer 13

• A state in which organism functions normally only in the presence of a drug
• Manifested as physical disturbance when the drug is withdrawn
• Usually found in the thalamus and the medulla

Question 14

Describe the Nigrostriatal system.

Answer 14

Starts in the substantia nigra and terminates in the basal ganglia: plays a role in the control of movement.

Question 15

The degeneration of which brain area causes Parkinson’s disease?

Answer 15

Parkinson’s disease is a neurological condition characterized by tremors, rigidity of the limbs, poor balance, and difficulty initiating movements; caused by degeneration of the nigrostriatal system; Parkinson’s disease has been treated with L-DOPA

Question 16

What is the role of serotonin?

Answer 16

• Play a role in the regulation of mood, the control of eating, sleep, dreaming, and arousal, memory and learning, temperature regulation, mood, behaviour, cardiovascular function, muscle contraction, endocrine regulation and depression.
• Involved in the regulation of pain.

Question 17

Describe the serotonin of pathways in the brain

Answer 17

• Start in brain stem area called Raphe Nuclei
• Then go down to the spinal chord or they go through the midbrain then to the prefrontal cortex and other cortical regions to the cerebellum and the back to the raphe nuclei.

Question 18

What are the effects of LSD?

Answer 18

• LSD stimulates centres of the sympathetic nervous system in the midbrain, which leads to pupillary dilation, increase in body temperature, and rise in the blood-sugar level.

Question 19

What are the effects of MDMA?

Answer 19

• A drug that serves as a serotonergic agonist, also known as “ecstasy”; has excitatory and hallucinogenic effects
• Increases effects of serotonin

Question 20

What are the effects of ecstasy and serotonin transporter?

Answer 20

1. Prevent reuptake

2. Work in reverse mode: bring more 5-HT to the synapse

Question 21

What are the acute effects of ecstasy?

Answer 21

• Heightened perceptions
• Stimulation
• Elevated mood
• Reduced appetite

Question 22

Short-term effects after ecstasy is gone

Answer 22

• Depression-like feelings
• Irritability
• Clouded thinking
• Hyperthermia
• Jaw clenching
• Disturbed behavior

Question 23

Long-term effects of ecstasy

Answer 23

• Ecstasy prevents the reuptake of serotonin from the synapse
• It also bring more serotonin to the synaptic cleft.
• Impairments of verbal and visual memory
• Ecstasy causes degeneration of serotonin nerve terminals
• Ecstasy may damage brain areas controlling memory

Question 24

How does serotonin cause depression?

Answer 24

• Low serotonin levels are believed to be the cause of many cases of mild to severe depression which can lead to symptoms such as anxiety, apathy, fear, feelings of worthlessness, insomnia and fatigue.
• If depression arises as a result of a serotonin deficiency then pharmaceutical agents that increase the amount of serotonin in the brain should be helpful in treating depressed patients. Anti-depressant medications increase serotonin levels at the synapse by blocking the reuptake of serotonin into the presynaptic cell.

Question 25

What is the role of serotonin selective re-uptake inhibitors (SSRIs)?

Answer 25

• Serotonin selective reuptake inhibitors (SSRIs) block the reuptake of serotonin into the presynaptic neurone. E.g. Prozac
  = increasing the activation of serotonin receptors

Question 26

What is Norepinephrine?

Answer 26

Norepinephrine (NE) or noradrenaline is both a hormone and a neurotransmitter. As a hormone, secreted by the adrenal gland, it works alongside epinephrine / adrenaline to give the body sudden energy in times of stress, known as the “fight or flight” response.

• Medications that inhibit the reuptake of NE can be effective to treat depression. In addition, elevated NE are found in patients experiencing mania

Question 27

What are the most common neurotransmitters in the CNS?

Answer 27

Glutamate, gamma-aminobutyric acid (GABA), and glycine.

- all amino acids

Question 28

Describe the NMDA receptor?

Answer 28

○ NMDA receptor - A specialized ionotropic glutamate receptor
§ When glutamate bind it opens this receptor from the outside. Sodium ion then. Rush in and cause excitation.
§ This channel has a Mg2+ blocker that need to be release so the receptor can open. Synthetic drugs are indirect antagonists that bind to receptor from the inside.

Question 29

What are the effects of GABA neurotransmitter imbalances?

Answer 29

Imbalances in GABA also are relevant to bipolar disorder, schizophrenia and anxiety disorder.

Question 30

What is Benzodiazepine?

Answer 30

• A category of anxiolytic drugs; an indirect agonist for the GABAA receptor; these drugs are used for their tranquillizing effects: Valium (diazepam)
• Tranquilizers

Question 31

What is an antagonist?

Answer 31

A drug that opposes or inhibits the effects of a particular neurotransmitter on the postsynaptic cell.

Question 32

What is an Agonist?

Answer 32

A drug that facilitates the effects of a particular neurotransmitter on the postsynaptic cell.

Question 33

Describe the Nigrostriatal system

Answer 33

• starts in the sunstantia nigra and terminates in the basal ganglia : plays a role in the control of movement.