lecture 3- neurotransmitters & basic psych

what is psychopharmacology

study of the effects of drugs on the NS & behaviour

how do drugs affect the NS

affects synaptic transmission

what is an agonist

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

what is an antagonist

a drug that inhibits the effects of a neurotransmitter on a postsynaptic cell

what is the site of action

parts in the synapse where molecules of drugs interact with molecules in/on cell body

what is reuptake

terminating postsynaptic potential

2 ways postsynaptic potential can be terminated

• reputake

• neurotransmitters destroyed by enzymes

how is reuptake stopped

drug attaches to transporter molecules that allow reuptake

what are direct agonists/antagonists

directly binds with the receptor & mimics a neurotransmitter

what are indirect agonists/antagonists

drugs that have different binding sites to neurotransmitters (non-competitive binding)

what do agonists do

• block reuptake of neurotransmitters

• allows for more neurotransmitters in the synaptic cleft so more effect on postsynaptic neuron

what is the nocebo effect

people feel bad when they expect side effects from a drug but they aren’t actually experiencing any

2 excitatory neurotransmitters

glutamate & norepinephrine

1 inhibitory neurotransmitter

GABA

2 neurotransmitters involved with synaptic communication in the brain

glutamate & GABA

acetylcholine

• controls muscle movement, regulates REM/perception/learning

• primary NT secreted by efferent axons in CNS

• found at the target of the parasympathetic branch of ANS

• cholingergic synapse

2 types of acetylcholine receptors

nicotinic & muscarinic

what are nicotinic receptors

ionotropic acetylcholine receptors stimulated by nicotine

3 places nicotinic receptors are found

• autonomic ganglia

• neuromuscular junctions

• some CNS pathways

nicotinic receptor antagonist

• curare

• causes paralysis

• acts at neuromuscular junction

what are muscarinic receptors

metabotropic acetylcholine receptors

• when ACh binds to a receptor metabolic processes involving enzymes happen before channel opens

muscarinic receptor agonist

muscarine

muscarinic receptor antagonist

• atropine

• stops ACh from depolarising postsynaptic membrane & increases heart rate

what are monoamines + examples

• family of compounds that have similar molecular structure so some drugs affect them all

• dopamine, norepinephrine, epinephrine, serotonin

dopamine

• reward neurotransmitter

• released from ventral tegmental area & acts in nucleus accumbens

• also released from ‘black substance’ in midbrain

• can’t pass through the blood-brain barrier

tolerance

organism no longer responding to drug so you need a higher dosage to get the same effects

dependence

organism only functions normally in presence of the drug

dopamine agonist

• cocaine

• blocks normal dopamine reputake

• dopamine left in synaptic cleft for longer (addiction)

serotonin

• mood & pain regulation, controls: eating, sleep, arousal

• released by raphe nuclei

serotonin agonist

• MDMA

• excitatory & hallucinogenic effects

8 acute effects of MDMA

1. heightened perception

2. reduced appetite

3. hallucinations

4. elevated mood

5. clouded thinking

6. hypothermia

7. jaw clenching

8. disturbed behaviour

norepinephrine

• acts on the limbic system

• hormone (secreted by adrenal gland) & neurotransmitter

• released from the ‘blue spot’

how can norepinephrine cure depression

medication that inhibits uptake

what does elevated norepinephrine levels lead to

mania

GABA

• how we think/act (fine tunes mood/actions)

• spinal cord equivalent = glycine

what does GABA inbalances lead to

bipolar, schizophrenia, anxiety

how can bipolar, schizophrenia, anxiety be treated

• tranquilsers

• GABA agonists