8.7—Drugs and nerve impulse transmission

A drug can increase or decrease synaptic transmission by changing neurotransmitter production, release, receptor binding, breakdown or reuptake. Its effect depends on the specific step and target.

Blocking serotonin reuptake leaves more transmitter in the cleft, whereas a receptor antagonist prevents the normal transmitter from activating the postsynaptic cell.

The same principle can produce therapeutic or harmful effects: L-dopa is converted to dopamine for Parkinson’s symptoms, while recreational drugs can disrupt mood and neural control.

A drug’s effect is not simply “more neurotransmitter = better”. Identify the receptor, transmitter and direction of change before predicting behaviour.