Background: Suicide is a major public health concern that has been associated with several neurobiological abnormalities, including dysfunction of the serotonin (5-HT) neurotransmission system. The serotonin 2A receptor (5-HT 2A ) and the monoamine oxidase A enzyme (MAO-A), which is responsible for degrading 5-HT, are encoded by the HTR2A and MAOA genes, respectively. These genes have been associated with several psychiatric disorders and an increased risk for suicide.
Methods: Our study examined the expression levels of HTR2A and MAOA genes in the postmortem prefrontal cortex (Brodmann area 8/9) and hypothalamus (ventromedial nucleus) tissues from 15 suicide victims and 15 control subjects from a Mexican population. Gene-expression profile quantification was carried out by qPCR and determined by the method.
Results: In suicide victims, the expression levels of the HTR2A gene were significantly higher in the prefrontal cortex. In contrast, the expression of the MAOA gene in the hypothalamus of the suicide victims was significantly higher than in the control subjects. When comparing adult controls against adult suicidal victims (25-59 year-old age group), a significant decrease in HTR2A expression in the hypothalamus was observed. These results were consistent regardless of age, sex, postmortem interval, or pH of brain tissue.
Conclusions: The evidence suggests that the pattern of differential expression of the HTR2A and MAOA genes in the brain may be involved in suicide, providing a possible molecular basis for the brain abnormalities in suicide victims.