Topic 8B.4 The Chemical Balance of the Brain

blood-brain barrier

blood-brain barrier

a barrier formed by the endothelial cells that line the capillaries of the brain which are very tightly joined together, making it difficult for bacteria to cross into the brain but also making it difficult for therapeutic drugs to enter the brain

substantia nigra

the area of midbrain involved in the control and coordination of movement; it is affected by Parkinson’s disease

dopamine

the neurotransmitter produced by nerve cells in the substantia nigra, which is closely involved in the control and coordination of movement

levodopa (L-dopa)

a precursor of dopamine which can cross the blood-brain barrier and has been in use since the 1960s to treat Parkinson’s disease

dopamine agonists

chemicals that bind to dopamine receptors in brain synapses and mimic the effect of dopamine

monoamine oxidase B (MAOB) inhibitors

drugs which inhibit the enzyme monoamine oxidase B (MAOB), which breaks down dopamine in brain synapses; thus MAOB inhibitors reduce the destruction of the dopamine made by the cells

serotonin

the neurotransmitter in a group of cells in the brain stem which have axons that spread throughout the brain into the cortex, the cerebellum and the spinal cord, and have an extensive influence over much of the brain

SSRIs (selective serotonin reuptake inhibitors)

antidepressant drugs that inhibit the reuptake proteins in the presynaptic membrane so more serotonin remains in the synaptic cleft and more impulses travel along the post-synaptic axon, reducing the symptoms of depression by producing a more positive mood and improving the ability to sleep

tricyclic antidepressants (TCAs)

antidepressant drugs that work by increasing the levels of serotonin and noradrenalin in the brain

ecstasy (MDMA: 3,4-methylenedioxy-N-methylamphetamine)

an illegal drug that acts as a stimulant and has a psychotropic effect by blocking the serotonin reuptake transport system