- could it play a role in emetophobia?
Serotonin is an amine neurotransmitter also known as 5-hydroxytriptamine (5HT) which is excitatory and has an important role in regulating mood, sleep, pain and appetite.
A low level of serotonin is associated with depressive disorders while a high level is linked with anxiety disorders - including phobias. While stress and personality factors can play a role in the development of anxiety disorders, many patients show a remarkable improvement when treated with serotonin-active drugs such as tricyclic antidepressants or selective serotonin re-uptake inhibitors. This suggests that such problems may possibly have a physical cause rather than being purely psychological, as often mistakenly assumed. However, varying levels of serotonin might also be a symptom of anxiety or depression - rather than being the actual cause. At present, it is not possible to determine serotonin's precise role.
Serotonin also has links with symptoms of nausea and vomiting. Cancer patients who have been treated with aggressive chemo-therapy and radio-therapy often experience quite severe, intractable nausea and vomiting. However, following the launch of the serotonin-3 receptor antagonists, vomiting frequency reduced - although these drugs have most effect in the acute phase - on the first day following chemotherapy and have less effect upon nausea. The delayed nausea and vomiting on subsequent days lingers and appears to have a different root cause - which does not involve serotonin-3 receptors. These serotonin-blocking drugs do not help with nausea caused by motion sickness.
Research is in its early stages and there is limited information widely available at present. However, if any reader should discover any further information relating to the links between nausea, vomiting and serotonin - I would like to hear from them. Please e-mail : Serotonin@gut-reaction.freeserve.co.uk
SEROTONIN has also been implicated in other disorders including PMS and Clinical Depression.
PMS: women with severe PMS symptoms have been found to have a profound drop in serotonin levels before their period starts. Serotonin aids the transmission of nerve impulses to and within the brain. Low levels cause depression and irritability.
Serotonin is derived from the amino acid, tryptophan, which is produced by the body as carbohydrates are broken down. People with low levels of serotonin experience sudden cravings for carbohydrate - a physiological response to boost serotonin levels within the brain.
However, gorging on carbohydrate can help to contribute to a vitamin B6 deficiency - which is also allegedly linked to PMS, although opinions vary on this, and snacks can lead to obesity, while excess salt can increase fluid retention.
There are also links between Serotonin levels and the weather - see bio-meteorology
SEROTONIN-RE-UPTAKE INHIBITOR (SSRI) DRUGS are prescribed for depression, anxiety states, panic attacks and obsessive compulsive disorder. These work by reducing levels of serotonin in the brain by paradoxically increasing the level of serotonin so that serotonin receptor cells lose their sensitivity to it, become more active and increase arousal levels. SSRI's prevent the serotonin being re-absorbed to maintain a steady level. TriCyclic Antipressants (TCA) work in a similar way to prevent serotonin being reabsorbed while Mono Amine Oxidase Inhibitor antidepressants (MAOI) prevent serotonin from being broken down. However, these drugs are relatively rarely prescribed due to potentially dangerous interactions with certain food groups.
When the residual level of serotonin is low then it is boosted by SSRI drugs to relieve the depression. If the level is already very high - in the case of an anxious person, then it will be paradoxically reduced by the SSRI's to lower the level of serotonin and, consequently, anxiety.