The influence of serotonin transporter polymorphisms on cortical activity: A resting EEG study

• Main Authors: Hong Chen-Jee, Yu Younger WY, Lee Tien-Wen, Tsai Shih-Jen, Wu Hung-Chi, Chen Tai-Jui
• Format: Article
• Language: English
• Published: BMC 2011-04-01
• Series: BMC Neuroscience
• Subjects: electroencephalography (EEG); power spectrum; <it>5-HTTLPR</it>; <it>5-HTTVNTR</it>; polymorphism
• Online Access: http://www.biomedcentral.com/1471-2202/12/33

<p>Abstract</p> <p>Background</p> <p>The serotonin transporter gene (<it>5-HTT</it>) is a key regulator of serotonergic neurotransmission and has been linked to various psychiatric disorders. Among the genetic variants, polymorphisms in the <it>5-HTT </it>gene-linked polymorphic region (<it>5-HTTLPR</it>) and variable-number-of-tandem-repeat in the second intron (<it>5-HTTVNTR</it>) have functional consequences. However, their genetic impact on cortical oscillation remains unclear. This study examined the modulatory effects of <it>5-HTTLPR </it>(L-allele carriers vs. non-carriers) and <it>5-HTTVNTR </it>(10-repeat allele carriers vs. non-carriers) polymorphism on regional neural activity in a young female population.</p> <p>Methods</p> <p>Blood samples and resting state eyes-closed electroencephalography (EEG) signals were collected from 195 healthy women and stratified into 2 sets of comparisons of 2 groups each: L-allele carriers (<it>N </it>= 91) vs. non-carriers for <it>5-HTTLPR </it>and 10-repeat allele carriers (<it>N </it>= 25) vs. non-carriers for <it>5-HTTVNTR</it>. The mean power of 18 electrodes across theta, alpha, beta, gamma, gamma1, and gamma2 frequencies was analyzed. Between-group statistics were performed by an independent t-test, and global trends of regional power were quantified by non-parametric analyses.</p> <p>Results</p> <p>Among <it>5-HTTVNTR </it>genotypes, 10-repeat allele carriers showed significantly low regional power at gamma frequencies across the brain. We noticed a consistent global trend that carriers with low transcription efficiency of 5-HTT possessed low regional powers, regardless of frequency bands. The non-parametric analyses confirmed this observation, with <it>P </it>values of 3.071 × 10^-8and 1.459 × 10^-12for <it>5-HTTLPR </it>and <it>5-HTTVNTR</it>, respectively.</p> <p>Conclusions and Limitations</p> <p>Our analyses showed that genotypes with low 5-HTT activity are associated with less local neural synchronization during relaxation. The implication with respect to genetic vulnerability of 5-HTT across a broad range of psychiatric disorders is discussed. Given the low frequency of 10-repeat allele of <it>5-HTTVNTR </it>in our research sample, the possibility of false positive findings should also be considered.</p>