Premenstrual Syndromes : PMS and PMDD - Rutuja :: The site ...
Premenstrual Syndromes : PMS and PMDD - Rutuja :: The site ...
Premenstrual Syndromes : PMS and PMDD - Rutuja :: The site ...
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74 THE PREMENSTRUAL SYNDROMES<br />
Serotonin<br />
transporter<br />
5HT3<br />
5HT4<br />
5HT2A<br />
5HT1A<br />
5HTX<br />
5HTY<br />
5HT2C<br />
5HTZ<br />
myoclonus, nocturnal awakenings, <strong>and</strong> sexual dysfunction.<br />
73 5-HT 3 <strong>and</strong> 5-HT 4 receptors may be responsible<br />
for the gastrointestinal side effects of nausea, cramps,<br />
<strong>and</strong> diarrhea. 83<br />
Cell bodies containing serotonin are found primarily<br />
in the raphe nucleus of the brainstem <strong>and</strong> in nerve<br />
endings diffusely distributed throughout the brain. 66<br />
5-HT has been implicated in modulation of circadian<br />
rhythms, eating, mood, sleep, <strong>and</strong> arousal. 85 Projections<br />
from the raphe nucleus to the frontal cortex are<br />
important in mood regulation. 86 Projections to the basal<br />
ganglia help control movements <strong>and</strong> obsessions <strong>and</strong> compulsions.<br />
87 Those to the limbic area are implicated in<br />
anxiety <strong>and</strong> panic reactions, whereas those to the hypothalamus<br />
regulate appetite <strong>and</strong> eating disorders. 88,89<br />
Serotonergic neurons in the brainstem regulate sleep. 90<br />
Projections down the spinal cord are involved in spinal<br />
Serotonin<br />
receptors<br />
5HT1D<br />
autoreceptor<br />
α 2 heteroreceptor<br />
Figure 9.4 Illustration of presynaptic <strong>and</strong> postsynaptic receptor subtypes for seronergic neurons. (Reprinted from<br />
Stahl SM, 73 Chapter 5, page 172. © 2000. Reprinted with the permission of Cambridge University Press.)<br />
reflexes for sexual responses of orgasm <strong>and</strong> ejaculation. 91<br />
5-HT also has hormone-like effects when released into<br />
the bloodstream, regulating smooth muscle contraction<br />
<strong>and</strong> affecting platelet aggregation <strong>and</strong> immune systems.<br />
A deficiency of the serotonergic system could cause<br />
depression, anxiety, panic, obsessions, compulsions,<br />
<strong>and</strong> cravings for food. 86–89<br />
Serotonergic activity in the brain is also affected by<br />
estrogen <strong>and</strong> progesterone. Sex steroids can modify serotonin<br />
availability at the neuronal synapse. 92 Estrogen<br />
augments serotonin by increasing degradation of MAO<br />
<strong>and</strong> catechol O-methyltransferase (COMT), regulating<br />
the availability of free tryptophan in the brain, enhancing<br />
serotonin transport, <strong>and</strong> increasing the density of<br />
5-HT-binding <strong>site</strong>s in brain regions affecting mood <strong>and</strong><br />
cognition. 93 This is important, since MAO <strong>and</strong> COMT<br />
degrade 5-HT <strong>and</strong> determine its synaptic availability.
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