Vasoactive monoamines {serotonin}| {5-hydroxytryptamine} (5-HT) can inhibit or excite metabolic activity, depending on receptor. Serotonin comes from tryptophan.
location
Serotonin is in area postrema, medulla oblongata, pineal gland, gut parasympathetic system, and pons raphé nucleus. Brain has 300,000 serotonergic neurons.
functions
Serotonergic-neuron activity is proportional to arousal, wakefulness, and muscular activity. Serotonin excites cortex pyramidal neurons. It inhibits neurons that receive excitations. It regulates neurite nerve process outgrowth and aids neuronal population survival. It causes or inhibits intestinal contraction. It constricts or relaxes blood vessels. Serotonin enhances substance P release from axons to excite spinal cord. Substance P releases serotonin from terminals inhibited by serotonin.
receptors
Neurons make serotonin and release it into synaptic clefts. Mammals have more than 13 different serotonin receptors. Animals have over 30 different serotonin receptors, which connect to G proteins.
uptake
Serotonin reuptake transport molecules remove serotonin from synaptic clefts. Selective serotonin reuptake inhibitors inhibit serotonin uptake back into cells.
damage
If serotonin level decreases, activity increases. Inhibiting serotonin receptor does not modulate behavior.
derivatives
5-HIAA comes from serotonin and causes higher male social status, more female grooming, and quieter activity.
evolution
Serotonergic neurons and serotonin receptors evolved 500,000,000 years ago. Gene duplication allowed different kinds. Anthropoid apes evolved 40,000,000 years ago and have different promoter sequence for serotonin-reuptake-transport gene than humans do.
Biological Sciences>Zoology>Organ>Nerve>Neural Chemical>Transmitter
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Date Modified: 2022.0224