Serotonin

Serotonin or 5-Hydroxytryptamine or 5HT is a monoamine neurotransmitter derived from tryptophan. It is found in the gastrointestinal tract, platelets, and the central nervous system.

5-Hydroxytryptophan
5-Hydroxytryptophan (5HTP) is the precursor to serotonin (5HT).

Function
Serotonin is a neurotransmitter and is activated by threats to homeostasis. According to Pereira et al. 2021), serotonin is linked to the regulation of:
 * dysautonomia
 * dyspnea
 * fatigue
 * glucose control
 * hypothyroidism
 * immune system functioning
 * proprioception, and
 * sensory sensitivity

Serotonin acting drugs
Selective serotonin reuptake inhibitors (SSRIs), the most popular class of antidepressants, and selective serotonin and norepinephrine reuptake inhibitors (SNRIs) have proved ineffective in ME/CFS. SSRIs indiscriminately modulate serotonin.

ME/CFS
The CRFR2 upregulation hypothesis of ME/CFS, which is the theory behind the clinicial trials of CT38, proposes that serotonin is dysregulated in ME/CFS, and that excessive serotonin desensitizes 5HT1A, which then leaves serotonin elevated and a loss of homeostasis.

Notable studies

 * 2015, A Model of Post-Infection Fatigue Is Associated with Increased TNF and 5-HT2A Receptor Expression in Mice
 * 2008, Genetic evaluation of the serotonergic system in chronic fatigue syndrome
 * 2004 Reduction of serotonin transporters of patients with chronic fatigue syndrome
 * 1997, Blunted serotonin-mediated activation of the hypothalamic-pituitary-adrenal axis in chronic fatigue syndrome.

Learn more

 * 2016, 5HT2A Receptors: A Root Cause of Anxiety, Fatigue, Sleep Problems and CIRS