The 5-HT2A gene encodes for the serotonin receptor to be activated by contact with serotonin causing an excitatory effect and stimulating smooth muscle contraction in the GI tract (increasing gut motility). Genetic variants are associated with increased excitatory effects causing anxiety, restlessness, insomnia, and gastrointestinal upsets. On a more positive note, it is reported to have anti-inflammatory effects.
This receptor was first noted for its importance as a target of serotonergic psychedelic drugs such as LSD, DMT, ayahuasca, and psilocybin mushrooms. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones. Effects are increased in those with reduced MAO activity and with those taking MAO inhibitors like harmaline.[PMID 6587171]
If you carry the AA allele in this gene, you are among the 50% of the population more likely to be sensitive to serotonin and to experience irritation to the digestive system resulting in diarrhoea and IBS. This can also impact the central nervous system, via the 'gut-brain axis', causing anxiety, agitation, restlessness, and insomnia. Imbalanced gut bacteria (intestinal dysbiosis) can make symptoms worse.
The T-allele in rs6313 of the HTR2A gene is associated with successful mastering of human-computer interfaces, namely, an increase in the number of correctly submitted commands of the electromyographic and eye-tracking interfaces. This same T allele increases attention to detail and but reduces spontaneity and impulsiveness [PMID: 31767813]
Berberine and cannabidiol have been identified as agonist agents to the 5-HTRA enzyme. This means that they may bind to the receptor and activate it to produce the biological response. In nutrigenomics, we call this "upregulation of gene expression".
