PSYC20006 Lecture Notes - Lecture 19: Neuromodulation, Tryptophan, Brainstem
12 Jun 2018
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Lecture 19 - Thursday 11 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
LECTURE 19
SEROTONIN & MOOD DISORDERS
TODAY
•Serotonin Overview
•Depression Overview
•Serotonin in Depression & Personality
•Antidepressants (SSRI’s & MAOI’s)
SEROTONIN
•Serotonin = 5-Hydroxytryptamine (5-HT)
•Acts as a neuromodulator influencing the activity of a variety of neurons
throughout the brain.
•Important in many different types of functions like sleep, arousal, appetite,
temperature, working memory, hallucinations and mood. Many homeostatic
functions and also high level things like working memory and mood.
•Technically, most of the time it would be working as a neuromodulators but
it is regularly called a neurotransmitter.
SEROTONIN PATHWAYS
•All serotonin in the brain is synthesized and released from
neurons originating in the Raphe Nucleus (Raphe = midline).
•The 5-HT is synthesized in the cell body and then
transported to the synapses where it is stored. When the
neuron fires, the stored 5-HT is rapidly released from the
synapse.
•Synthesised deep within the brain stem area. Specialise
neurons; only ones in the brain that code serotonin.
SEROTONIN SYNTHESIS
•Try to remember this.
•Tryptophan in contact with tryptophan hydroxyls, it gains a
HO group on the left side.
•Goes through another little step and
becomes serotonin. Drugs affect the
steps in this synthesis pathway.
DEPRESSION OVERVIEW (1)
•DSM–V diagnosis for Major
Depression.
•A. At least 5 of the following symptoms have
been present during the same 2-week period; at
least one of the symptoms is either (1) depressed
mood or (2) loss of interest or pleasure.
•NOTE Do not include symptoms due to a
general medical condition, or mood-
incongruent delusions or hallucinations.
•(1) depressed mood most of the day,
nearly every day, as indicated by either
subjective report (e.g., feels sad or empty)
or observation !
Lecture 19 - Thursday 11 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
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made by others (e.g., appears tearful). Note: In children and adolescents, can be irritable
mood.
•(2) markedly diminished interest or pleasure in all, or almost all, activities most of the day,
nearly every day (as indicated by either subjective account or observation made by others).
•(3) significant weight loss when not dieting or weight gain (e.g., a change of more than
5% of body weight in a month), or decrease or increase in appetite nearly every day. Note:
In children, consider failure to make expected weight gains.
•(4) insomnia or hypersomnia nearly every day.
•(5) psychomotor agitation or retardation nearly every day (observable by others, not
merely subjective feelings of restlessness or being slowed down).
•(6) fatigue or loss of energy nearly every day.
•(7) feelings of worthlessness or excessive or inappropriate guilt (which may be delusional)
nearly every day (not merely self-reproach or guilt about being sick).
•(8) diminished ability to think or concentrate, or indecisiveness, nearly every day (either
by subjective account or as observed by others).
•(9) recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without
a specific plan, or a suicide attempt or a specific plan for committing suicide.
•B. The symptoms cause clinically significant distress or impairment in social, occupational, or
other important areas of functioning.
•C. The symptoms are not due to the direct physiological effects of a substance (e.g. a drug of
abuse, a medication) or a general medical condition (e.g. hypothyroidism).
•E. The symptoms are not better accounted for by Bereavement (loss of a loved one).
DEPRESSION vs GRIEF
•The argument for change....
•Grief-stricken patients frequently report symptoms that are also typical of major depression, such
as sadness, tearfulness, insomnia, and decreased appetite.
•but...
•Grief rarely produces the cognitive symptoms of depression, such as low self-esteem, feelings of
worthlessness, self-loathing or suicidal thoughts.
•It was argued that it is important not to miss people with clinical depression because the
symptoms were associated with grief.
DEPRESSION IN FAMILY & SOCIETY
•On Average 10-25% of women and 5-12% of men will experience depression in their lifetime.
•1st onset often occurs in early adolescence (~15-18yrs)
•Estimated cost to Australia in terms of health care and lost productivity is approximately $15
billion a year.
•Familial clustering:
•If you have depression, what is the risk to:
•Your neighbor (unrelated)? 16%
•Your sibling? 30%
•Your identical twin? >80%
•Both genes and environment are likely to play a role.
DEPRESSION & SEROTONIN
•Brain imaging studies show a reduction in some types of serotonin receptors in
the brain of unmedicated depressed patients.
•From a PET study, the colourful areas show serotonin receptors are relatively
reduced in depressed patients.
•Instead of detecting changes in oxygenation of blood, it uses radioactive
chemicals in a structure that mimics another receptor radioactive compound!
Document Summary
Today: serotonin overview, depression overview, serotonin in depression & personality, antidepressants (ssri"s & maoi"s) Serotonin: serotonin = 5-hydroxytryptamine (5-ht, acts as a neuromodulator influencing the activity of a variety of neurons throughout the brain, important in many different types of functions like sleep, arousal, appetite, temperature, working memory, hallucinations and mood. Many homeostatic functions and also high level things like working memory and mood: technically, most of the time it would be working as a neuromodulators but it is regularly called a neurotransmitter. Serotonin pathways: all serotonin in the brain is synthesized and released from neurons originating in the raphe nucleus (raphe = midline), the 5-ht is synthesized in the cell body and then transported to the synapses where it is stored. When the neuron fires, the stored 5-ht is rapidly released from the synapse: synthesised deep within the brain stem area. Specialise neurons; only ones in the brain that code serotonin.
