Lecture 25 - Antidepressants Flashcards
a recurring and debilitating mental disorder that impairs social and/or occupational functioning
depression
subjective feelings regulated by the limbic system
emotions
behaviour that is purposeful and goal directed and is regulated by the mesocorticolimbic dopamine system
motivation
an evolutionarily ‘old’ neocortex that includes the amygdala, hippocampus, basal ganglia, and cingulate gyrus with connections to the frontal cortex and hypothalamus
the limbic brain
major depressive disorder is associated with increased engagement of ____ and decreased engagement of ____ compared to healthy controls
limbic regions (amygdala), regions involving motivation (striatum)
changes in brain activity reflect changes in:
neurotransmitter release and/or postsynaptic response
dopamine, norepinephrine, and serotonin are collectively known as the:
monoaminergic neurotransmitters
have a ‘modulatory’ role in the brain, and are involved in mood, arousal, and attention
monoamineergic neurotransmitters
what is the amine hypothesis of depression
alterations in the monoaminergic neurotransmitters are associated with mood disorders
depression is associated with inadequate monoamine neurotransmission in the brain. this may be due to:
- less neurotransmitter release
- fewer receptors
- impaired signal transduction
where did the amine hypothesis of depression originate?
from observations that manipulation of the monoaminergic system influences depression symptoms
15% of patients who receive long term treatment with the antihypertensive drug ______ developed a syndrome indistinguishable from naturally occuring depression
reserpine
what does reserpine do?
depletes neurons of dopamine and norepinephrine transmitters
in the 1950s, it was noted that the anti-tubercular drug, ______, alleviated depression
ipronazid
what does ipronazid do?
inhibits monoamine oxidase (MAO)
what are the three major issue with the amine hypothesis of depression?
- drugs that restore monoamineric levels are only moderately effective in 30-50% of patients
- inconclusive evidence that serotonin and noradrenergic systems are disrupted in depression
- antidepressants take several weeks before a clinical effect is seen
what is the glutamatergic hypothesis of depression?
depression is associated with a reduction of glutamatergic signalling in the cortex
a loss of glutamatergic signalling impacts both excitatory and inhibitory functions leading to:
reduced signal to noise
