5: Neurochemical Basis of Affective Disorders

Monamine hypothesis

Depression is a result in a deficit in monoamines, particularly 5HT and NE

Three things that support the monoamine hypothesis

1. Resperine which decreases high BP induces depression as a side effect, and it also decreases monoamines

2. Antidepressants acutely increase NE and 5HT

3. Manic-like activity by cocaine and amphetamine is characterized by increase in monoamines

Serotonin in affective disorders

Has significant pain management properties, emotionality, and response to (-) consequences and reward

What is important about 5-HIAA

Decrease in 5-HIAA decreases serotonergic neurons which is found common in depressed individuals

Tryptophan and depression

Tryptophan is a precursor to 5-HT and can. Be decreased in depressed patients

This decrease does not cause depression it increases the chance of vulnerable individuals getting it

Antidepressants that target serotonin

Work by blocking reuptake or decreasing monoamine oxidase (enzyme that breaks down monoamines)

• long-term effects are different as at first autoreceptors are activate which further decreases serotonin levels

• But then down regulation of the synapse increases serotonin leve