L15 - Drug Action in the CNS - Antidepressants Flashcards
What is depression?
A mental disorder characterised by low mood.
What are the 2 types of depression?
Unipolar - mood swings always in the same direction.
- Reactive 75% of the time (arise from life events)
- Endogenous 25% of the time (no distinguished cause)
Bipolar - depression alternates with mania
Typical Symptoms of depression
- Low mood (anhedonia) - unable to take pleasure from pleasurable things or situations.
- Apathy - loss of interest in daily activities.
- severe loss or gain of weight
- loss of libido
- Insomnia or excessive sleep
Brain areas implicated in depression?
The Cingulate Nucleus
The Nucleus Acccumbens
The Amygdala
The Hippocampus
How is appetite affected by depression?
there is a disruption of signalling by ghrelin and leptin which causes problems with appetite.
What is postnatal depression?
depressive period usually 2-8 weeks after delivery of a baby and may stay a year in some places.
How are children with postnatally depressed parents affected?
they are more susceptible to depression due to epigenetic changes.
What is the monoamine hypothesis?
A function deficit in sodium and serotonin causes long term trophic effects.
What is some evidence to support the monoamine hypothesis?
Iproniazid - the first specific antidepressant, a MAO inhibitor.
Reserpine - Produces depression and Parkinson’s, which depletes the stores of monoamine transmitters.
Tricyclic ADS - originally synthesised in attempt to develop new antipsychotics.
What is the principle action of MAOIs?
- Inhibits MAO (monoamine oxidase) type As produces an antidepressant effect.
- Produces a rapid and sustained increase of serotonin and noradrenaline.
What are some side effects of MAOIs?
Noradrenaline depletion in sympathetic terminals causing postural hypotension.
What is the principle action of TCAs?
- Inhibit the neuronal uptake of 5-HT and Noradrenaline.
What are some side effects of TCAs?
Associated with:
- Anticholinergic effects (dry mouth, blurred vision, constipation)
- Adrenergic effects (postural hypotension)
- Histaminergic effects (H1 blocks, sedation)
What are some functions of NA pathways in the CNS?
arousal/attention, mood, blood pressure regulation, pain.
It also has a role in regulatory sensory processing relating it to withdrawal, increased sleep and anorexia.
What does inhibition of NA reuptake do in the frontal cortex?
Improves mood
