How do drugs affect the synapse?

Psychoactive Drugs A psychoactive drugs is any chemical substance that changes brain function and results in alterations in perception, mood, or consciousness. Some examples of this drug are illegal but many are legal too.

Uses Anaesthetics Hormone therapy Painkillers Depressants Stimulants Mood stabilisers Antiparkinson drugs

Examples Legal Illegal Alcohol Cannabis Caffeine Cocaine MDMA ( if prescribed) Morphine (not prescribed) L-dopa  

Agonists An agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response. -Hormones e.g. Dopamine -Neurotransmitters e.g. acetylcholine

Antagonists An antagonist blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist. This is done by binding to a receptor itself so the agonist is unable to do so. They are quite large protein molecules that are there because a poison has entered the body.

L-Dopa L-Dopa is a drug that’s used to treat the symptoms of Parkinson’s disease. It has a similar structure to dopamine. It is absorbed into the brain and converted into dopamine by the enzyme dopa-decarboxylase. This increases dopamine levels in the brain.

L-Dopa A higher level of dopamine results in more nerve impulses being transmitted across synapses in the parts of the brain that control movement. This gives Parkinson’s sufferers more control of their movement.

MDMA MDMA increases the level of serotonin in the brain. Serotonin is normally taken back into the presynaptic neurone after triggering an action potential, to be used again. It increases the level of serotonin by inhibiting the reuptake of serotonin into presynaptic neurones, and triggering the release of serotonin from pre-synaptic neurones.

MDMA This means that nerve impulses are constantly triggered in post-synaptic neurones in the parts of the brain that control mood. The effect of MDMA is therefore mood elevation.