L3 Neurotransmitters and Psychopharmacology

What is psychopharmacology?

The study of the effects of drugs on the nervous system and behaviour

How do drugs affect the nervous system

affect synaptic transmission

What is an agonist?

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

What is an antagonist?

A drug that opposes/inhibits the effects of a neurotransmitter on the postsynaptic cell

What are sites of action

the locations at which molecules of drugs interact with molecules located on/in cells of the body

4 main sits of action in the nervous system

1) Production of neurotransmitters, 2) Storage and release of neurotransmitters, 3) Effects on receptors, 4) Effects on reuptake

Which is the most important and complex site of action of drugs in the nervous system

effects on receptors (both presynaptic and postsynaptic)

How do drugs effect receptors

by biding on receptors like neurotransmitters

What happens after a drug has bound with a receptor

it can serve as either an agonist or an antagonist

What is a direct agonist/antagonist

a drug that binds with and activates a receptor and mimics the effects of a neurotransmitter

What is an indirect agonist/antagonist

a drug that attaches to a binding site on a receptor and facilitates the action of the receptor

What is the difference between a direct and indirect agonist/antagonist?

A direct agonist/antagonist binds to a receptor while an indirect agonist/antagonist does not interfere with the principal binding site

What is reuptake

the process of termination of the postsynaptic potential

Two process that accomplish reuptake

the process of reuptake or destruction by an enzyme

Two ways in which drugs can block reuptake

by inactivating transporter or enzyme

How do drugs block reuptake through inactivation

by attaching to transporter molecules that reabsorb neurotransmitters and inactivating them

How do some drugs inhibit neurotransmitter breakdown?

By binding to enzymes that normally break down neurotransmitters and preventing them from working

In terms of the effects on reuptake, how do drugs serve as agonists

prolong the presence of the neurotransmitter in the synaptic cleft

What is placebo

an inert substance given instead of a physiologically active drug

Purpose of placebo

used experimentally to control for the effects of mere administration of a drug

What is the placebo effect?

When a person experiences changes in symptoms due to believing they received an active treatment, even when given an inert substance

What is the nocebo effect?

When a person experiences negative effects after receiving an inert substance due to negative expectations

Two general effects of neurotransmitters on postsynaptic membranes

depolarisation or hyperpolarisation

Abbreviation for depolarisation

EPSP

Abbreviation for hyperpolarisation

IPSP

Two types of synaptic communication accomplished by neurotransmitters

excitatory effects or inhibitory effects

What type of effect does glutamate have

excitatory effects

What type of effect does GABA or glycine have

inhibitory effects

Role of neurotransmitters (if not information-transmitting)

modulating effects

What are modulating effects

activate or inhibit circuits of neurons

6 key neurotransmitters

acetylcholine, dopamine, serotonin, norepinephrine, glutamate and GABA

Acetylcholine (ACh)

What is acetylcholine’s (ACh) primary function?

release of ACh is responsible for all muscular movement

General effects of ACh

facilitatory

What 3 things is ACh involved in the brain?

Regulates REM sleep (dreaming), perceptual learning, and memory.

Where is ACh found in the nervous system

parasympathetic branch of the ANS, outside of the CNS

What are the two types of acetylcholine receptors?

Nicotinic and muscarinic

What are synapses that have acetylcholine transmitters called?

cholinergic synapses

What type of receptor is nicotinic

ionotropic

What is nicotinic receptor stimulated by and blocked by

nicotine (agonist) / curare (antagonist)

Effects of curare by blocking nicotinic receptors

causes paralysis (ACh responsible for muscular movements)

What type of receptor is muscarinic

metabotropic

What is muscarinic receptors simulated by and blocked by

muscarine / atropine

How does atropine increase heart rate

by preventing ACh from depolarising the postsynaptic membrane

Real-life example of a ACh antagonist

botulinum toxin (Botox)

Real-life example of ACh agonist

black widow spider venom

What are the four main monoamine neurotransmitters?

Dopamine, norepinephrine, epinephrine, and serotonin.

What is dopamine known as

the reward neurotransmitter

Define addiction

a state in which an organism engages in compulsive behaviour as it is reinforcing, causes loss of control for limiting intake

4 examples of natural rewards

food, water, sex, nurturing

What is dopamine’s role in addiction?

It plays a key role in the brain's reward system, reinforcing behaviours

What is the state of tolerance

a state in which organism no longer responds to a drug – i.e. a higher dose is required to achieve the same effect

What is the state of dependence

a state in which organism functions normally only in the presence of a drug

How is state of dependence manifested

physical disturbance when drug is withdraw

What brain system is associated with dopamine and movement?

The nigrostriatal system.

How does Parkinson’s disease relate to dopamine?

It is caused by degeneration of dopamine neurons in the nigrostriatal system.

How does cocaine affect dopamine levels?

It blocks dopamine reuptake, increasing its activity in the synapse.

What are 6 primary functions of serotonin?

Regulates mood, appetite, sleep, dreaming and memory, regulating pain.

Example of a drug that serves as a serotonergic agonist

MDMA

How does MDMA (Ecstasy) affect serotonin?

It prevents serotonin reuptake and reverses transporter function, increasing serotonin in the synapse.

What is the role of serotonin in depression?

Low serotonin levels are linked to depression,

Role of SSRIs in depression

increase serotonin by blocking reuptake into the presynaptic cell

Role of norepinephrine in fight-or-flight response

to give body sudden energy in times of stress

What are the three main amino acid neurotransmitters in the CNS?

Glutamate, GABA, and glycine.

What is glutamate’s modulating function in the brain?

It is the primary excitatory neurotransmitter.

What is GABA’s modulating function?

It is the main inhibitory neurotransmitter in the brain.

What is glycine’s modulating function (different location to GABA)

primary inhibitory neurotransmitter in the spinal cord

How does GABA help regulate brain activity such as thinking and acting?

It acts like a "brake" to prevent excessive neuronal firing, helping control anxiety and motor function.

What happens when GABA function is impaired?

It can lead to disorders such as anxiety, bipolar, and schizophrenia.

What class of drugs enhances GABA’s effects (agonist)?

Benzodiazepines (e.g., Valium, Xanax), which are used as tranquilizers.

What neurotransmitter is essential for muscle movement?

Acetylcholine (ACh).

What neurotransmitter is primarily involved in the brain’s reward system?

Dopamine.

What neurotransmitter regulates mood and sleep?

Serotonin.

What neurotransmitter is the main excitatory one in the brain?

Glutamate.

What neurotransmitter is the primary inhibitory one in the brain?

GABA.