OCB03-2009 SEROTONIN Flashcards
What are the main functions of serotonergic transmission?
Inhibit sensory input
Descending pain inhibition
How can serotonin affect morphine?
Decreased serotonin antagonises the effects of morphine
What are the two principal serotonergic nuclei?
Rostral raphe nuclei
Caudal raphe nuclei
What two monoamine neurotransmitters have a similar distribution in the CNS?
NA
Serotonin
Where do the serotonergic neurons project to from the rostral raphe nuclei?
Ascend to cerebral cortex, limbic regions and specifically the basal ganglia
Where do the serotonergic neurons project to from the caudal raphe nuclei?
Descend to medulla or to spinal cord
What is another name for serotonin?
5-hydroxytryptamine
How is 5-hydroxytryptamine formed?
Tryptophan –> 5-hydroxytryptophan by tryptophan hydroxylase
5-hydroxytryptophan –> 5-hydroxytryptamine by aromatic amino acid decarboxylase
What can 5-HT be converted to?
Melatonin
5-hydroxyindoleacetic acid by MAOa
What can be measured to determine 5-HT transmission in the brain?
5-hydroxyindoleacetic acid (5-HIAA) in ECF
How can serotonin be removed from the synapse?
SERT into neurons
ENT into glial cells
What type of receptor are serotonin receptors?
All GPCRs except 5-HT3 which is an cation channel
What G protein are 5-HT1 receptors coupled to?
Gi
What are 5-HT1A receptors involved in?
Sleep
Neuronal inhibition
Anxiety
Feeding
Thermoregulation
What are 5-HT1B receptors involved in?
Presynaptic inhibition
Behaviour
Food intake
What are 5-HT1D receptors involved in?
Peripheral vasoconstriction
Behaviour
Locomotion
What G protein are 5-HT2 receptors coupled to?
Gq/11
Where are 5-HT2A receptors found and what are they involved in?
Found in CNS, PNS, smooth muscle and platelets
Neuronal excitation
Behaviour
Platelet aggregation
Vasoconstriction/dilatation
Where are 5-HT2B receptors found and what do they do?
Found in the gastric fundus
Muscle contraction
What are 5-HT2C receptors involved in?
CSF secretion
Food intake
What type of receptor is 5-HT3?
Ligand-gated cation channel
What is the 5-HT3 receptor involved in?
Neuronal excitation
Behaviour
Anxiety
Emesis (vomiting)
Which 5-HT receptors are Gs-linked?
4, 6, 7
What G protein is 5-HT5 coupled to?
Gi
What is the 5-HT4 receptor involved in?
GI motility
Neuronal excitation
What is the 5-HT6 receptor involved in?
Learning and memory
What is the 5-HT7 receptor involved in?
Thermoregulation
Circadian rhythm
What does LSD stand for?
Lysergic acid diethylamide
What receptor does buspirone act on and what is it used to treat?
Agonist of 5-HT1A
Anxiety
What receptor does sumatriptan act on and what is it used to treat?
Agonist of 5-HT1D
Migraines
What receptor does methylsergide act on and what is it used to treat?
Antagonist of 5-HT2A
Migraines
What receptor does clozapine act on and what is it used to treat? (5-HT)
Antagonist of 5-HT2A
Antipsychotic
What receptor does lorcaserin act on and what is it used to treat?
Agonist of 5-HT2C
Obesity (decreases food intake)
How does cocaine affect 5-HT transmission?
Blocks SERT
How do MAOa inhibitors affect 5-HT transmission and what are they used to treat?
Decrease 5-HT metabolism
Depression
How does fenfluramine affect 5-HT transmission and what is it used to treat?
Increases 5-HT release and blocks SERT
Previously treated obesity
What type of drugs are prozac (fluoxetine) and fluvoxamine?
SSRI (block SERT) = antidepressant
What type of drugs are venlafaxine and duloxetine and what are they used to treat?
SNRI (block SERT more than NET)
Depression, anxiety, pain
What type of neurons are inhibited by serotonergic neurons in descending pain inhibition?
Spinothalamic neurons
