Dopamine (DA), as a catecholamine neurotransmitter widely distributed in the central nervous system and the peripheral tissues, has attracted a lot of attention. Especially in recent years, DA has been found to regulate the function of the immune system, and the involvement of DA in the intestinal mucosal inflammation-related diseases has become a hot research topic. The digestive tract is an important source of peripheral DA, and DA is not only produced in the enteric nervous system and gastrointestinal epithelium, but also produced by intestinal microorganisms. In addition to the synthetases of DA, the DA contents in body tissues are also affected by the two kinds of metabolic enzymes, monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). This article reviewed the sources, metabolism, and functions of DA in digestive tract, especially focusing on the distribution and function of MAO and COMT, the enzymes degrading DA.
Catechol O-Methyltransferase ; Catechol O-Methyltransferase Inhibitors ; Dopamine ; Gastrointestinal Tract ; Monoamine Oxidase ; Monoamine Oxidase Inhibitors

OBJECTIVETo investigate the associations between the drug responses to obsessive -pulsive disorder (OCD) and six functional genes related with serotonin and dopamine.

METHODSOne hundred and thirteen OCD nuclear families were collected. The OCD patients were treated with serotonin reuptake inhibitors (SRIs) for 8 weeks and the drug responses were assessed using the Yale-Brown obsessive-compulsive scale (Y-BOCS). The patients were divided into drug responders group and non-responders group according to the reducing rate of Y-BOCS score. The genotypes of six genes were determined with the Amp-FLP and Amp-RFLP techniques and analyzed by transmission disequilibrium test (TDT). The six genes are serotonin 2A receptor (5-HT2A), serotonin transporter (5-HTT), dopamine D2 receptor ( DRD2), dopamine D4 receptor (DRD4), catechol-O- methyltransferase (COMT) and monoamine oxidase A (MAOA).

RESULTSNo association was found between the six genes and different drug responses groups. However, there was significant difference between the drug responders and non-responders in homozygosity at the 5-HT2A -1438G/A locus (chi(2)=4.69, P=0.03).

CONCLUSIONThe results suggested that the 5-HT2A may play some roles in the effects of drug treatment on OCD.

Adolescent ; Adult ; Catechol O-Methyltransferase ; genetics ; Female ; Humans ; Male ; Monoamine Oxidase ; genetics ; Obsessive-Compulsive Disorder ; drug therapy ; genetics ; Pharmacogenetics ; methods ; Receptor, Serotonin, 5-HT2A ; genetics ; Receptors, Dopamine D2 ; genetics ; Receptors, Dopamine D4 ; genetics ; Serotonin Plasma Membrane Transport Proteins ; genetics ; Serotonin Uptake Inhibitors ; therapeutic use ; Treatment Outcome ; Young Adult