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
What are some functions of the 5-HT pathways in the CNS?
Associated with:
- sleep and wakefulness
- hallucinations
- mood and emotion
- feeding behaviour
- sensory pathways and nociception
What other drugs can be used as mood stabilisers?
- Anti-epileptics and A-typical antipsychotics.
- Electroconvulsive shock therapy ECT, electromagnetic therapy, deep brain stimulation and vagus stimulation.
